Dein king Recycled Paper Using Column Flotationcollectionscanada.gc.ca/obj/s4/f2/dsk2/ftp01/MQ29636.pdf · 2005. 2. 8. · Dein king Recycled Paper Using Column Flotation Jeffrey

Dein king Recycled Paper Using Column Flotation

Jeffrey .A. Watson

Depanment of klining and Metallurgical Engineering McGill University Montreal. Canada

A thesis submitted to the Faculty of Graduate Studies and Research

in parrial fulfillment of the requirements of the drgree of Master of Engineering

O Jeffrey Watson. 1996

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Abstract I

Abstract

The degree of waste paper recyciing has been increasing steadily in North

Amerka over the last decade. Flotation is a popular method for removing ink from fibres

(deinking) and is traditionally performed in mechanical cells. Column flotation has been

proposed as an alternative to mechanical cells. In this work. open and packed laboratory

and pilot-scale colurnns were operated to determine their relative ments and how they

compare to a circuit of mechanical cells

It was found that the type of sparger kvas cntical for obtaining high flotation

efficiencies. Fine porous stainless steel spargers t 0.5 prn) produced flotation efficiencies

which were qua1 to those of the mechanical cells. Packing was effective in increasing

tlotation efficiency when the coarse porous stainless steel sparger ( 100 pm) was used in

the laboratory column and when the variable gap sparger was used in the pilot column.

The organic loss from al1 colurnn configurations (laboratory and pilot-scale) was

less than 3%.

The scale up procedure \vas evaiuated using data from the laboratory column and

pilot coiurnn dimensions. Finally. using data from the hboratory colurnn. industrial

columns were designed.

Résumé LI

Résumé

Le recyclage du papier est une pratique qui n'a cessé d'augmenter dans les dix

dernières années en Amérique du Nord. La tlottation est un procédé courant qui permet

d'enlever l'encre des fibres ( désencrage). ce qui Ctait originalement accompli par des

cellules méchaniques. Les colonnes de flottation sont une alternative aux cellules

méchaniques. Pour ce projecr. des çolomes ouvertes et de Yang (une colonne remplie

avec un réseau de chicanes metalliques) de laboratoire et pilote ont été utilisées afin de

determiner leurs differents avantages: elles ont Cté également comparées aux circuits de

celIu1es méchaniques.

Nous avons dkcouven que Ic type de générateur de bulles irait important pour

obtenir une meilleure flottation. Des ginérateurs de bulles en acier inoxydable qui

produisent des petites bulles permettent une meilleure tlottation. kgale j. celle des cellules

méchaniques. Le réseau de chicanes metalliques est efficace pour augmenter le

rendement de flottation lorsque les gknérateurs de bulles en acier inoxydable qui

produisent des grosses bulles sont utilisés dans la colonne de laboratoire. Le réseau de

chicanes metalliques est également efficace lorsque le générateur de bulles à ouverture

variable fut utilisé dans la colonne pilote.

Les pertes organiques de toutes les différentes colonnes (de laboratoire et pilote)

ont été de moins de 39'0.

La procédure pour constuire des colonnes industrielles fût evaluée selon les

données de In colonne de laboratoire et des dimensions de la colonne pilote. Finalement.

les colonnes industrielle furent concues à partir des données de la colorne de laboratoire.

Acknowledgrnents

I would Iike to thank the following people and oganizations for their

contributions ro my work:

rny supervisor. Prof. Jirn Finch. for his assistance and for recruiting me to do the

project.

Dr. Ccsar Gomez. whose ideas and contributions proved to be invaluable.

the Mechanical and Chernimechanical Wood-Pulps Network for their financial

support.

Avenor for providing the facility and their services.

Abitibi-Price. GL&V. Minnovex. and CESL for supplying equipment and

technical expertise.

Dr. Gilles Doms and his staff at Papncan for their assistance.

Jamie Femandez. Dr. Gang Shen. Gunther Leichtle. Steven Keller. and al1 the

other members of the column lab at McGill University.

Table of Contents i v

Table of Contents

Abstract

Résumé

Acknowledgments

Table of Contents

List of Figures

List of Tables

Nomenclature

Chapter 1 : Introduction

1.1 Deinking 1.1.1 High-Consistency Pulping 1.1.3 Coarse Cleaning 1.1.3 Flotation 1.1.4 Fine Cleaning 1 - 1 3 Thickening 1 -1.6 Disperging 1.1.7 Bleaching

1.2 Flotation C h e m i s t ~ 1.3.1 Sodium Wydroxide 1 2 . 2 Hydrogen Peroxide 1 2.3 Sodium SiIicate 12.4 Fany Acid Soap

1.3 Flotation ~Mechanisms

1.4 Project Objectives

Chapter 2: Theoretical Principies

2.1 Nomenclature 2.1.1 Open Column 2.1.2 Packed Column

Table of Contents v

3.2 Collection Zone 2.2.1 Gas Holdup 3.22 Flow Regime 2.2.3 Bubbly Flow iModel

2.2.3.1 Bubble Size Estimation 3.2.3.2 Bubble Surface Area Rate

2.2.4 Particle Collection 2.2.5 blixing

2-3 Froth Zone

1.4 Colurnn Scale Up

2.5 Analytical Techniques 2.5.1 Effective Residual Ink Concentration

3.5.1.1 Flotation Efficiency 2.5.1.2 ïnk Recovei-y

2.5.2 hlass Balance 2.5.2.1 Organic Loss 2.5.2.2 Yietd

Chapter 3 : Experimental

3.1 Approac h

3 2 Apparatus 3-21 Laboratory-Scale Column 3 - 2 2 Pilot-Scale Colurnn

3 -3 Procedure 3 3 . 1 Column Operation 3 -3 -2 Sample Preparation

Chapter 4: Results and Discussion

4.1 Selection of Operating Conditions 4.1.1 Open Column

4.1.1.1 Gas Rate 41.1 2 Retention Time 41.1.3 Froth Depth 4.1.1.4 Bias Rate

Table of Contents v i

4.1.2 Packed Column 4.1-2.1 Gas Rate 4.1.2.2 Retention Time

4.2 Comparison of Columns and Mechanical Cells 42.1 Laboratory-Scale Comparison 4.2.3 Pilot-Scale Comparison

4.3 Alternative Flotation Evaluation Techniques 4.3.1 Bubble Surface Area Rate 4.32 Yield-Flotarion Efficiency Relationship

4.1 Evaluation o f Colurnn Scale Up Procedure

Chapter 5 : Conclusions and Recornmendations

5.1 Conclusions

5.2 Recommendations

References

Appendix A

Appendix B

Appendix C

-4ppendi.u D

hppendix E

-4ppendis F

List of Figures vii

List of Figures

1. I Diagrarn of a high-consistency pulper.

1 2 Picture of Voith flotation cells at Avenor's Gatineau Mill.

1.3 Effect of pH on pulper brightness: 7030 ONP/OMG fürnish.

1.4 Chemical composition of fatty acid soaps.

1.5 Basic operating pnnciple of flotation deinking.

2.1 Schematic diagrarn of an open column.

2.2 Schematic of packed column.

2.3 Pressure difference method for measunng gas holdup.

2.4 Gas holdup as a function of gas rate.

2.5 Classical U,, versus d, results in an air-water system.

2.6 Diagram of froth structure.

2.7 Conceptual configuration of collection and fioth zones.

3 . l Schematic diagrarn of Iaboratory-scale column and instrumentation.

3 -2 Schematic diagrarn of pilot-scale column and instrumentation.

1.1 Flotation eficiency versus superficial gas velocity (open column).

4.2 Organic Ioss venus superficial gas velocity (open column).

4.3 Flotation efficiency versus retention time (open column).

4 4 Organic loss versus retention time (open column).

4.5 Flotation efficiency versus fioth depth (open column).

4.6 Organic loss versus fioth depth (open column).

4.7 Flotation eficiency versus bias velocity (open column).

4.8 Organic loss versus bias rate (open column).

4.9 Flotation efficiency versus superficial gas velocity (packed column).

4.10 Organic loss versus superficial gas velocity ( packed coiumn).

4.1 1 Flotation efficiency versus retention time (packed column).

4.12 Organic Ioss versus retention time (packed column).

4.13 Flotation efficiency results (laboratory column).

.-- List of Figures ~ I I I

4.14 Organic loss results ( laboratory column). 48

4.1 5 Flotation efficiency versus time ( laboratory column). 48

4.16 Organic loss venus time (laboratory column). 49

4.17 Flotation eficiency versus time (pilot column). 5 1

4.1 8 Organic loss versus time (pilot column). 5 1

4-19 Flotation eficiency versus bubble surface area rate in the open laboratory 53 column.

4.20 Flotation effciency versus bubble surface area rate in the packed laboratory 54 column.

4.2 1 Yield-flotation efficiency relationship for open and packed laboratos-scale 55 columns.

1.22 Gas holdup versus gas velocity relationship for the variable gap sparger 56 (operated at 50 psi) in the pilot column and the porous sparger (sparger B) in the laboratory column.

List of Tables I s

List of Tables

5 - 1 Sparger characteristics.

4.1 Sumrnq of seiected operating conditions in open and packed laboraton- columns.

4.2 Average flotarion eficiency and organic loss for columns and rnechanical cells.

4.3 Average flotation efficirncy and organic ioss for colurnns usine sparger B and mechanicd ce1Is ( repeat 1.

4.4 Sumrnary of openting conditions in pilot column.

4.5 Average ilotation efficiency and organic loss for columns and rnechanical cells.

4.6 S u r n m q of pilot column scaie up.

4.7 Surnrnary of indusuial columns.

B. 1 Test conditions for open laboratop-scale coiumn.

B.? Test conditions for packed laboratop-scale column.

B.3 Test conditions for comparative work in laborarory-scale column.

B.1 Test conditions for comparative work in pilot-scale column.

C. 1 Flotation efficiency and brightness gain results for open laboratory-scale column.

C.2 Flotation efficiency and brightness gain results for packed laborarory-scaie column.

C.3 Flotation efficiency and brightness gain results for the comparative n-ork in the laboratory-scale coiumn.

CA Flotation efficiency and brightness gain results for the comparative work in the pilot-scale column.

D. 1 Consistent). and ash data for tests peiiormed in open laboraroryscale colwnn.

D.2 Pulp tlowate and standard deviation data for tests performed in open laboraton-scale column.

D.3 Corrected pulp flowate data and organic loss resulrs for tests performed in open laboratory-scale column.

D.4 Consistency and ash data for tests performed in packed laboratory-scale

List of Tables .Y

column.

D.5 Pulp tlowrate and standard deviation data for tests performed in packed laboratory-scale column.

D.6 Corrected pulp tlowrate data and organic loss resuits for tests pertorrned in packed laboratory-scale column.

D.7 Consistency and ash data for the comparative work in the laboratory-scale column.

D.8 Pulp tlowrate and standard deviation data for the comparative work in the laboratory-scale column.

D.9 Corrected pulp flotvrate data and organic loss results for the comparative work in the laboratory-scaie column.

D. 1 0 Consistency and ash data for the comparative work in the pilot-scale co lum.

D. 1 1 Pulp tlowrate and standard deviation data for the comparative work in the pilot-scale column.

D. 13 Corrected pulp f lo i a t e data and organic loss results for the comparative work in the pilot-scale column.

D. 13 Consistency and ash data for the mechanical cells.

D. 14 Pulp flowate data and organic loss results for the mechanical cells.

E. 1 Bubble size and surface area rate data for tests performed in open laboratory-scale colurnn.

E.2 Bubble size and surface area rate data for tests pertormed in packed laboratory-scale column.

E.3 Bubble size and surface area rate data for rests performed in pilot-scale cofumn.

F. 1 Summary of pilot colurnn scale up.

F.2 Surnrnary of industrial columns.

F.3 Determination of rate constant in open laboratory column using sparger A.

F.4 Determination of rate constant in open laboratory column using sparger B.

F.5 Determination of rate constant in packed laborato. column using sparger B.

F.6 Deterrnination of rate constant in packed laboratory colurnn using no sparger. 88

Nomenclature xi

Nomenclature

coiumn cross-sectional area

drag coefficient

ink concentration

particle concentration

bubble diarneter

column diameter

particle diarneter

flotation efficiency

attachent efficiency

collection ef'flciency

gravitational acceleration

collection zone height

froth zone height

superficial velocity (flowate/column cross-sectional area)

absorption coefficient

rate constant

organic loss

length

vesse1 dispersion number

pressure

volumetric flowate

collection zone recovery

Reynolds number

equili brium recovery

froth zone recovery

overall flotation column recovery

opaque pad reflectance

Nomenclature xii

scattering coefficient

bubble surface area generation rate

induction time

contact time

single bubble terminai velocity

relative slip velocity

particle slip velocity

basis weight

organic mass fraction

yield

ash mass fraction

Greek Letters

6 gas hoidup

9 volume fraction

p fluid viscosity

PP particle density

p,, pulp density

5 I liquid retention time

s, particle retention time

Chapter 1 : Introduction I

Chapter 1: Introduction

The degree of waste paper recycling in North America has been increasing

steadiiy over the past few years. The 1990 US and Canadian recovery rates. defined as

the amount of waste paper recovered for reuse compared with paper consumed. reached

33% and 25% respectively. Countnes without forest reserves. such as Japan. have

recovery rates as high as 50%. Another rneasure of the level of recycling is the arnount of

secondary fibre used in paperhoard production compared with the total fibre used. also

known as the utilization rate. Second. fibre utilization is approximately 25% in the

United States and about 10% in Canada. The utilization rate in Japan is considerably

higher at 50% [ I l . The main problem facing recycling mills is high waste paper transportation costs.

As a result. most recycling faciiities are located near urban centers. Other problems

facing the recycling industry include finding a suitable deinking process. dealing with

contarninants. and fighting a consumer opinion that recycled products are lower in quality

[ 2 ] . Utilization rates of 50% are considered to be a practical maximum and as a result are

the major limitations for mills. Significant losses of both fibre substance and strength

occw during each recycle.

This chapter will focus on the flotation deinking of old newspapers (ONP) and old

magazines (OMG) at Avenor's Gatineau paper recycling facility. The stages found in the

deinking mil1 will be described. Finally, the flotation chemistry and possible tlotation

mechanisms will be discussed.

Chapter 1 : Introduction - 3

1.1 Deinking

Deinking is defined as any process which removes ink and other objectionable

non-fibrous materials from a sluny of wastepaper (31. Contarninants include al1 foreign

elements such as rocks. sand. glass. and tramp metal. Glues. hot melts. and latexes are

also contaminants and are genencally called "stickies" [ I I . "Stickies" are the result of

book bindings. label backings. and adhesive coatings.

Avenor's Gatineau mil1 is an example of a recycling plant where newspnnt.

containing about 40% recycled fibres. is produced. The makeup of the newsprint consists

of 59% thermomechanical pulp (TMP) and 1% kraft pulp. The deinking plant processes

approximately 70% ONP and 30% OMG and has a capacity of approximately 500 tld.

The main stages in the deinking plant include: high-consistency pulping. coarse cleaning.

flotation. fine cleaninç. thickening. disperging. and bleaching [4]. A flowsheet of the

deinking plant is s h o w in Appendix A.

1.1.1 High-Consistency Pulping

Pulping at Avenor. as with most deinking plants. is done on a batch bais . The

main purpose of the pulping stage is to: l ) disperse the secondary fibre into a wet pulp

s l w ; 2) chemically and rnechanically detach the ink particles from the fibres: ruid 3)

maintain the integrity of contaminants. such as plastic and insoluble glues for later

removal. Pulping is equivalent to liberation in mineral flotation. In minera1 flotation the

ore is crushed and ground into small particles in order to facilitate flotation or other

separation techniques.

At this stage. the ONP and OMG are fed automatically to two high-consistency

pulpers until a batch of 8 tomes is reached. The pulpers mix the material at 15%

consistency for 30 minutes. The chernicals (sodium hydroxide. fatty acid soap. hydrogen

peroxide. and sodium silicate) required for downstream operations are also added to the

pulpers. Figure 1.1 is a diagram of a high-consistency pulper.

Chapter 1 : Introduction 3

The development of high-consistency pulpers has improved the performance of

batch pulpinç systems. The advantages of high-consistency pulpers include [j]: 1 ) better

ink sepantion and increased puip briçhtness: 2 ) pulping time reduced to less than one

hour per batch: and 3 ) lower power requirernents by increasing the batch size for a given

pulper.

1.1.2 Coarse Cleaning

In the coarse cleaning stage the accepts frorn the pulpers are passed through

primarv? secondary. and tertiary screens. The primary screen is a trash screen Iocated at

the outlet of the pulper which prevents large objects such as plastic bags. cans. and wïre

from continuing through the process. The second. screens consist of high-density

cleaners which remove staples. sand. and pieces of glass. Finally the tertiary 0.055"

screens remove large ink particles. plastic. and pieces of glue. The rejects from this

screening circuit report back to the p n m q coarse screen Eeed box.

Fig. 1.1 Diagram of r high-consistency pulper Ill.


1.1.3 Flotation

In the flotation process. the chernicals which were introduced in the pulpers cause

the ink particles to flocculate and produce a foam. In a tlotation cell the pulp slurry is

aerated at low consistencies (percent solids). The ink and din particies becorne artached

to the air bubbles. causing them to rise to the top of the ce11 and are removed as rejects.

Flotation deinking can be divided into threc stages [6 ] : 1) collision between the ink

particle and the air bubble: 2) at tachent between the ink particle and air bubble: and 3)

flotation of the ink particle-bubbie aggregate to the surface. Flotation chemistry and

tlotation mechanisms will be discussed in sections 1.2 and 1.3.

The flotation process at Avenor consists of two banks of six p n m q cells and two

secondary cells (Figure 1.1). The rejects from the six pnmary celis are fed to the two

secondary cells for further ink removal. The final rejects are sent for disposal and the

accepts from the secondary cells are retumed to the first primary cell.

Fig. 1.2 Picture of Voitb flotation cells at Avenor's Gatineau rnill.


1.1.4 Fine Cleaning

Fine cleaning is a three step operation designed to ma..imize the cleaning

efficiency at Iow pulp consistencies. The first stage consists of centrifuga1 lightweight

cleaners. These cleaners separate the lighter contaminants such as glue. plastic. and light

ink compounds according to density. The accepts are then treated with five stages of

fonvard cleaners in order to remove sand. Finally. the accepts are passed through three

stages of 0.008" fine screens.

1.1.5 Thickening

The pulp from the fine screens is thickened from 0.6% consistency to

approximately 10% consistency using two disc filters. The pulp is then washed with

water from the paper machine and fed through two twin wire presses. In the twin wire

presses the pulp is washed with hot water and thickened to approximately 30%

consistency. As a result of these operations. the dissolved solids in the pulp are removed.

The water fiom the presses is sent for clarification and reused in the plant.

1.1.6 Disperging

The dispergers are used to refine and enhance the cleaned fibers at high

temperature and high consistency. The dispergers break up any remaining ink particles

so that they are essentially invisible. The dispergers are also used as mixers when

hydrogen peroxide bleaching takes place.

1.1.7 Bleaching

Hydrogen peroxide bleaching takes place in the bleach tower. The retention time

for the stock in the tower is approximately 45 minutes. The bieaching stage is used only

if additional bnghtness is required. The stock is then diluted to about 10% consistency

with recycled water From the paper machine and pumped to the high-density storage tank.

Chapter 1 : introduction 6

1.2 Flotation Chernist~

Chemistry is the key component in any flotation process. Most of the chemicals

are added in the pulper in order to assist in the removal of the contarninants and to make

them accessible for flotation. The chemicals added to the pulper at Avenor are: sodium

hydroxide. hydrogen peroxide. sodium silicate. and a fatty acid soap. Calcium chlonde is

added to the flotation cells in order to improve ink particle collection (the Function of

calcium chloride will be discussed in the same section as the fatty acid soap). Clay is

also important for flotation deinking. Due to its optical properties clay was found to

improve tlotation results [7.8]. Approximately 840% clay is required for tlotation [9].

This amount of clay is supplied to the system by the OMG (30% of the feed) which

contain 2540% clay.

1.2.1 Sodium Hydroxide

Sodium hydroxide (NaOH). aiso known as caustic soda is used to increase the pH

to the alkaiine region and to saponie or hydrolyze the ink resins. By raising the pH to 8-

12 in the pulper. fibre swelling occurs which aids in ink removal and disintegration of

paper into individual fibres [IO]. During the swelling process. the fibres retain some

water and becorne more flexible. When sodium hydroxide is added. "alkali darkening"

occurs. Alkali darkening is a phenornena where the pulp fibres yellow and darken due to

the high pH. Figure 1.3 shows the results of alkaii darkening on a 7030 ONP/OMG

funiish when only caustic soda was added. X decrease in brightness can be observed

after a pH of approximately 10.25.

1.2.2 Hydrogen Peroxide

Hydrogen peroxide (HZO,) is used to prevent alkali darkening in the pulper. The

peroxide reacts with caustic soda as follows:

H,O, + NaOH tt HOO- + Na- + H 2 0 (1.1)

Chapter 1 : Introduction

where pH = 10.0 to 1 1.5 and temperature = 40 to 80°C. The active bleaching agent in

reaction 1 is the perhydroxyl anion (HOO').

In order to mavimize the amount of perhydroxyl anion the side reactions which

decompose peroxide must be reduced [ I l ] . The side reactions are s h o w by reaction 1.2:

where M represents heaw metal ions such as rnanganese. copper. and iron. The metals

are found in the waste paper or in the mil1 water. Enzymes like catalase and high pH and

temperature promote the decomposition reaction.

Fig. 1.3 Effect of pH on pulper brightness; 70:30 ONP/OMG furnish (111.

1.2.3 Sodium Silicate

Sodium silicate (Na2Si0,) is a multi-purpose reagent. Silicate performs three

operations. nameiy: 1 ) peroxide stabilizer: 2 ) acts as a dispersant to prevent ink from

redepositing on the fiber surface: and 3) source of alkalinity and pH buffer. Silicate acts

as a peroxide stabilizer since it is believed to form a colloidal stnicture with the heaw


rnetal ions. Silicate is a source of alkalinity according to the reaction with water as

shown below:

Na2Si0, - H,O o ZNa- i OH- + HSiO, ( 1.3)

1.2.4 Fatty Acid Soap

Fatty acid soaps. as shown in Figure 1.4. are a type of surfactant. The sodium

soap is usually a blend of acids with 16 to I8 carbon atoms. such as stearic and oleic

acids [12]. At Avenor. the soap is supplied in liquid form and must be convened to the

calcium soap before it can b c r i o n as a collecter. -4 source of caicium ions must be

introduced into the system in order to form the calcium salt of the fatty acid. Calcium

ions are present in the magazine coatings as calcium carbonate and are added to the

tlotation cells as calcium chloride. In the flotation ce11 the water hardness must be at least

200 ppm calcium.

1.3 Flotation Mechanisms

In the process of flotation deinking. the ink particles must attach themselves to the

air bubbies rising through the îùmish. For flotation to be effective. the size of the ink

particles must be maintained within an optimum range ( 10- 100 p m ). If the i d particles

are too srnall they will not be collected efficiently due to the low probability of

rncountenng an air bubble. When the ink particles are too large. low collection

rfficiencies are also obsenied due to reduced a t t achen t efficiencies il3.l JI. Figure 1.5

illustrates the general operating pnnciple in flotation deinking.

In flotation deinking, surfactants (fkity acid soaps) are used as collectors. The oil

based printing inks used in magazines and newspapers are naturally hydrophobie. When

the anionic surfactant is absorbed onto the ink particles. the hydrophilic part of the

surfactant is oriented into the water. The same situation is believed to occur at the air

bubbles. that is. the surfactant's hydrophilic part orients into the water and the


hydrophobic part aligns itself with the hydrophobic air bubble. The ink panicles become

hydrophilic and are dispersed in water. Larssen et al [ l 5.161 and Putz et al [17] have

proposed two different models for bubble-particle attachent in the presence of calcium

ions.

Larssen et al proposed that calcium soap precipitates ont0 the ink particles. This

produces a coating of small soap tlakes on the ink particles ailowing agglomeration to

occur. Once agglornerated. the ink particles are large enough for rapid attachment to air

bubbles. Putz et al proposed that the calcium ions bridge the hydrophilic groups of the

ink pmicles and air bubbles together making particle collection possible. Regardless of

the particle-bubble attachment mechanism. calcium ions play a vital role.

I (Hydfophobk end) I (Hydrophllk end)

I I I I

Fig. 1.4 Chemical composition of fatty acid soaps [121.

Chapter 1 : Introduction I O

Smrll dliporred Ink prnlclra

Fig. 1.5 Basic operaîing principle of flotation deinking [13].

1.4 Proiect Obiectives

The general objective of this project is to run laboratory and pilot-scale tests to

cstabiish the relative merits of open and packed column tlotation in the deinking of

wastepaper. and to compare these foms of column tlotation against mechanical ce11

tlotation. Avenor's Gatineau mil1 \vas the site of al1 experiments. This general objective

will be met through the cornpletion of the follorving tasks:

1 ) Selection of operatine conditions for open and packed columns.

2 ) Assessrnent of colurnn performance over long term operation.

3) Evaluation of scale up procedures.

Chapter 2: Theoretical Principles I I

Chapter 2: Theoretical Principles

2.1 Nomenclature

Flotation is traditionally pertormed using banks of mechanical cells. Column

flotation consists of ta11 vertical reactors where gas bubbles are generated with spargers at

the bottom and wash \vater is added ot the top. The main advantages of columns include

improved separation performance. low capital and operationai costs. low tloor space

requirements. and adaptability to automated control [18]. Many different types of column

ce11 configurations exisr. however only the open and packed cells will be discussed. Al1

terms and definitions are referenced fiom Finch and Dobby [IJ] (unless othenvise

specified).

2.1.1 Open Column

The conventional. or open tlotation column. is illustrated in Figure 2.1. In

column flotation rising gas bubbles interact with the descending pulp in the collection

zone (H,). Gas bubbles are normally generated with intemal spargers. such as porous

stainless steel pipes or variable gap spargers.

Wash water is added in order to stabilize the froth. Wash water replaces the water

which is naturally drained fiom the froth. The remainder of the wash water flows through

the froth and cleans the Froth of particles entrained in the water crossing with the bubbles

from the coIlection zone. Therefore. the froth zone is also called the cleaning zone (HJ.

The flow of water moving through the froth is called the bias water. a positive value

Chapter 2: Theoretical Pinciples 1 2

corresponding to a net tlow downwards. For efficient cleaning of entrained particles bias

rate must be positive.

The overtlow is nch in the floatable (hydrophobic) material. which ofien forms

the concentrate in mineral systems. The d o a t a b l e (hydrophilic) material is collected as

undedow tiom the bonom of the colurnn. Deinking is a reverse flotation process where

the valuable matenal (the accepts) is the underflow and the overtlow is the \vaste material

( the rejects).

The flowrates of the different streams in the column are normally expressed as

superficial velocities (or rates). Superficial velocity is the volumetric flowrate of a

particular steam divided by the colurnn cross sectional area:

QI J , =- 4,

where i can be gas (G). feed (F), wash water (W. bias (B). rejrcts (R), or accepts (A).

Superficial velocities are useful for cornparing columns of different diameters and are

usually expressed in crn/s.

2.1.2 Packed Column

-4 packed column incorporates stacks of corrugated stainless steel plates inside an

open colurnn (Figure 2.2). The packing plates are manged in blocks positioned at nght

angles to each other. A packed column is operated in the same manner as an open

colurnn and the terms are identical.

The reported technical advantages of packed columns are [19]: 1) provision of

small tomious flow passages for intimate particle-bubble contact: 2) allowance for

efficient water washing through an almost unlimited fioth depth: 3) elimination of the

need for spargers since the packing elements break up the air into bubbles: and 4)

darnping of axial mixing.

Chapter 2: Theoretical Pnnciples 13

Wash water

f Fted

Cleaning zone

I '4 Concentrate

Coikctionzone Hc

Fig. 2.1 Schematic diagram of an open column. From Finch and Dobby [ 1 JI.

Chapter 2: Theoretical Principies 14

froth Concentra

Flowrneter

Conditioned Feed 1 Pulp Leuel Discharge Control

4-t- wuter Flowmeter

Fitter Flowmeter

1 ails

Fig. 2.2 Schematic of packed column. From Yang et al 1191.

Chapter 2: Theoretical Principles 15

2.2 Collection Zone

2.2.1 Gas Holdup

When air is injected into a colurnn. pulp is displaced. The volume fraction of gas

(air bubbles) is defined as the gas holdup (E,). Gas holdup is usefûl in determining the

tlow regime in the collection zone (discussed in section 2-22) and is essential for

rstimating bubble size (section 2.2.3. l ). bubble surface area rate (section 7-2-32), and

pulp retention time. Local &as holdup measurements can be used to determine mial

variations in gas holdup dong the column.

The pressure difference rnethod c m be used to measure local gas holdup in a

column. In this rnerhod. the local section is defined by the distance between the

pressure tapping points. In order to calculate the gas holdup usine the pressure difference

method. it is assumed that the dynamic component of the pressure and the bubbie-particle

aggregate density are negligible. The pressure at A and B (Figure 2.3) is given by:

P.% = RI g LA ( 1 -E,J (3.1 a)

PB = pi g LB ( '-'gB) (2.1 b)

where psi is the pulp density. and E,, and E,, are the gas holdup above A and B

respectively. The pressure difference between A and B (AP) is:

where E_ is the gas holdup between A and B and is given by:

Fig. 2.3 Pressure difference method for measuring gas holdup [1JI.

Chapter 2: Theoretical Principies 16

2.2.2 Flow Regirne

The tlow regime in the collection zone can be determined from the relationship

between E , and J, (Figure 7.4). Gas holdup increases approximately linearly and then

deviates at some J,. The linear section is charactenzed by a homogeneous distribution of

bubbles of uniform size rising at a uniform rate and is called the bubbly tlow regime.

Above the transition J, the tlow regirne becomes churn-turbulent. Chun-turbulent tlow

is characterized by large bubbles nsing rapidly. displacing water and srnail bubbles

downward.

Normally. columns are operated in the bubbly flow regime. Therefore. there is an

upper constraint on the gas rate. Level control and gas holdup measurement become

difficult in the churn-turbulent regime.

/ bubbly flow churn - turbulent ragima flow rsgims

Superficial gas velocity, J, (crn/s)

Fig. 2.4 Gas holdup as a function of gas rate [14\.


2.2.3 Bubbly Flow Mode1

The bubbly flow model. also referred to as the drift flux mode1 [10]. can be usrd

to infer otherwise dificuit to obtain information. e.g. bubble size and bubble surface area

rate. from readily measured data such as E,, J,, and J,. The slip velocity is the velocity of

one phase relative to another. In column notation the relative slip velocity (U,,) between

the gas phase and the liquid phase is detined as:

The slip velocity is also given by:

Usg = ubT ( 1 - E ~ ) ~ - ' (2 .5)

where U,, is the single bubble terminal velocity [Il] . For most cases m is 3. Therefore

equation 2.5 becomes:

Us, = U,, ( 1 - E,): 12.6)

Results for single bubbles in air-water systems are presented in Figure 2.5. An

approximation of the relationship between UbT and bubble diarneter (d,) for contaminated

systems is given by Karamanev et al [22] :

u,, = - \i" where CD is the drag coefficient of the gas bubbles and is given by [ X I :

For light ngid spheres rising in a Newtonian liquid with Re greater than 130 (bubbles in

water) CD is approximately 0.95. Therefore. equation 2.7 becomes:

U, = ,/1.4~d,

Equation 2.9 is included on Figure 2.5.


7.2.3- 1 Bubble Size Estimation

Bubble size cm be measured accurately by photography. However. rhis method is

time consuming and cm only be applied to transparent colurnns. Lrsing the bubbly flow

mode1 bubble size c m be estimated. By equating equations 7.4 and 1.6. a relationship for

U,, c m be obtained:

Therefore. if E,. J,. and J, are h o w n U,, c m be calculated. Finally. using eq. 1.9. d, c m

be estimated.

2.2.3.2 Bubble Surface Area Generation Rate

The surface area genrration rate of bubbles Sb ((cm' bubble areais)l(crn: column

area) or s") is the variable which controls solids removal rate (or c q i n g rate ). Bubble

surface area generation rate is given by:

Mo=2.% 1 O"' .

O Oistilled water A Tap water

Fig. 2.5 Classical U, versus d, results in an air-water system [ Z l l : Upper curve is water only; lower curve is for "contaminated" water, e.g. water with surfactant.

Chapter 3: Theoretical PrincipIes 19

2.2.4 Particle Collection

In notation deinking. pmicles c m be collected by one of h e e mechanisms: 1 )

particle-bubble collision followed by anachment due to the hydrophobic nature of the

particle surface: 2 ) entrainment of the particle within the boundary layer and wake of the

bubble: and 3) entraprnent of bubbles. The Eirst mechanism is seiective and is important

for ink collection. Depending on water hardness. this mechanism is also responsible for

removing fibres [24]. The entrainment mechanism is not selective. Large bubbles tend to

carry less water per unit gas volume across the froth/pulp interface than small bubbles.

Therefore fibre loss by entrainment will be lower when larger bubbles are generated (251.

The thirci mechanism is another method for fibre loss [XI. Fibres c m form networks or

tlocs while in suspension and small bubbles c m become tnpped. As a result the bulk

density of the fibre network is reduced and the fibres are carried to the t'roth.

Only the first mechanism for particle collection will be discussed in detail. The

collection efficiency (EL) is defined as the fraction of particles swept out by a bubble that

collide with. attach to. and remain attached to the bubble. The rare of particle removal is

given by:

dc, lU,E,c, -- -

where c, is the concentration of particles. This is equivalent to the tirst-order rate process

with rate constant k, given by:

The collection zone in laboratory-scale columns (large HJd, ratios) tend to exhibit plug

flow transport conditions. For a first-order rate process with plug flow transport the

recovery of particles in the coIlection zone (RJ is given by:

k = ELq[ 1 - e w - k , ~ , ) l (2.14)


where r, is the particle retention tirne and R, is the equilibrium recovery at long tiotation

times. For non plug tlow conditions (industrial-scale colurnns) cquation 1.14 must be

modified to account for short circuiting of particles (section 2.2.5).

Collection efficiency can be expressed in terms of collision efficiency (E,) and

attac hment efficient y (EA) according to:

EK = Ec E, (2.15)

Collision efficiency is the fraction of al1 particles swept out by the projected area of the

bubble that collide with the bubble. Hydrodynarnic drag tends to sweep the panicle

around the bubble. following the fluid streamlines and the particle will slide dong the

bubble surface for a period of time called the contact time (tJ. Attachrnent etticiency is

the fraction of al1 colliding particles that undergo successtùl attachment dunng the time

of contact. At tachent occurs when the intenrening liquid (disjoining) tïlrn between the

particle and the bubble thins. ruptures. and a three phase (solid-liquid-air) contact line

fonns. The tirne for this to occur is the induction time (t,). At tachent will occur when

the contact time is greater than the induction time. Particle detachment is not considered

since detachment is minimal for the small particles encountered in flotation deinking

(cl00 p).

2.2.5 lMixing

Laboratory-scale colurnns with large HJdC ratios exhibit plug tlow conditions.

The recovery in the collection zone for a first-order rate process with plug tlow transport

is given by equation 2.14. The recovery for particles in a system exhibiting perfect

mixing is given by [27]:

k = %Li - (1 + kq-'] (2.16)

where k,. r,. and 4, are the same as in Eq. 3.14. Mixing has a detrimental sffect on

recovery since particles are short circuited and have reduced probability of encomtering

to air bubbles. The liquids and solids in industrial-scale colurnns are transported under

conditions between those of plug flow and perfectly mixed flow. The plug flow

Chapter 2: Theoretical Principles 2 1

dispersion mode1 c m be used to describe the a i a i mixing process in the collection zone.

The effect of mixing on recovery is given by the following equation:

where

and Y, is the vesse1 dispersion nurnber given by:

O.O63d ( J .' 1.6)') ?

Y4 = (2.18) RJ', , ( 1 -q + ~ s p l H ,

where LTTp is the pmicie slip velocity and c m be obtained fiom the followïng equation:

where

The particle mean retention time (s,) c m be estimated accordinp to:

- q(Jsl / ' ( l - & : ) ) T~ - J, .! ( 1 - E , ) + CIEP

\vhere r! is the liquid retention time and is defined as:

2.3 Froth Zone

One of the advantages of column flotation is the abilin; to add tvash water to the

froth. Wash mter provides the bias water and the water necessary to overflow the

coilected solids into the launder. The bias water replaces the water naturally drained fiom

the froth. As a result. bias water tends to promote fioth stability. Wash water decreases

the gas holdup in the froth b'; increasing the rvater content. The froth zone consists of

Chapter 2: Theoreticai PrincipIes

three zones i Figure 2.6 1: 1 1 an enpanded bubble bed: 2 a packed bubble bed: and 3 a

con\.entional draining froth above die w s h water inlet.

Bubbles hom the collection zone enter the expanded bubble bed afier coiliding

wi-ith the fint Iayer of bubbies \h ich define a distinct interface. Cpon en- to the froth.

the bubbles remain sphencal. smail. and are relatively homo~eneous. Bubble coalescence

in d i i s region ma) be caused bu the shock pressure waïes generated as bubbles from the

collection zone collide nith the interface. The liquid content ( 1 -EJ in the expanded

bubble bed is generaiiy greater than 2j0h.

The next zone in the froth is the packed bubble bed region and extends to the

wash warer inlet level. In this zone the bubbles are relativeiy sphericai but range in size.

In this region the liquid content is Iess than 25%. The tlou- of bubbles upwards. at least

in a laboratoq column. is close to plug ilowv provided the wash \vater is \el1 distributed.

The rate of coalescence is lower in the packed bed region than in the expanded bed

region. Coalescence in this region is due to collisions caused bu the larger bubbles which

are rising faster.

Depending on the ~ a s h water dimibutor position. the con\-entiond draining fioth

zone may not exin. In some applications. the wash warer dimibutors are placed above

the frodi and a drained froth region does not form. The main purpose of this region is to

convert vertical into horizontal motion to recover the solids. A disadmntage associated

with submerging the distributor inro the froth is that solid accumulation ma? occur.

However. more wash water niIl be splir to the bias the deeper the distriburor is

submerged.

Cleaning in the fioth zone iaiso referred to as cleaning zonei is dsfined as the

remo\-al of particles which are recovered by entrainment in the warer. A11 panides

i hydrophobie and hydrophilic 1 are subject to entrainment. Entrained particle recoven-

has been found to be proportional to feed water recoveq-. The variables xhich atfect the

recovery of entrained panicles are the gas rate. bias rate. and froth deprh. .As .J2 increases

the concentration of feed water in the frorh increases. -4 high J, tends to have detrimentai

Chapter 2: Theoretical Principles -3 Y -

effects on water recovery. It is dificult to compensate entrainment with wash \vater if the

J, becomes too h i a . Ofien deep froths ( - 100 cm 1 are more advantageous rhan shallow

ones. Deep frodir accommodate surges in Ievel and darnpen d o w the entrainment

caused by hi& gas rates.

wash water concentrate I

drainhg , mgative froth f , bias -

t > a a 1 positive

interface Jievd

Fig. 2.6 Diagram of froth structure [la].

At the interface between ~ i e coilection zone and rhe froth zone panicle transport

occurs in both directions. Panicles are transponed fiom the collection zone to the tioth

zone by a t tachent to nsing bubbles. A portion of the panicles wirhin the froth are

dislodged from the bubbles as a result of coalescence and are trawported from the froth

zone back to the collection zone by the bias water. This phenornena is referred to as fioth

drop back. The complement to froth drop back is fioth zone recoveF (R). The

interaction benveen the two zones is shown schemarically in Fi-me 2.7.

Chapter 2: Theorerical Pnncipies 21

Froth

Fig. 2.7 Conceptual configuration of collection and c--,L r i uru zones.

The overail flotation column recovery (R,) is defined as:

There is limited data for K. It is believed that R, in laboratorypilot coiumns is between

40 and 80%. In larger diarneter columns Rcan be considerably lower.

2.1 Column Scale Uo

Column scde up involves speci-ing a target recoven and a required throughput.

Column geometry is then determined using the goveming equations. Laboratop or pilot-

scale coiumns are used to collect scaling up data and also to perform amenabilin resting.

hnenability tesring determines whether column cells are suired to the task.

Csing the laboratory-scale colurnn overail recovery and retention time data can be

coilected. Csing equation 2.14 (collection zone recovery for a tirsr-order rate process

with plug flow transport) the overall coiiection rate constant c m be determined. Overall

rate constants can be equated to collection zone rate constants assurnine perfect tioth

C hapter 2: Theoretical Principies 25

zone recovery. This assumption is valid in small diameter columns due to the stability of

the froth provided by the walls.

Once the collection rate constant has been determined the rnixing regirne and

retention time in the target column can be estimated using the equations for the plug flow

dispersion mode1 as discussed in section 2-25. ï h e target recovery is an overall recovery

but the recovery used in equation 2.17 is the collection zone recovery. Therefore. the

target recovery rnust be converted to R, using equation 2.23 afier assurning a value for R,

(typically 0.5) [28]. Perfect fioth zone recovery cannot be assumed for large diameter

columns since significant fioth dropback occurs.

Al1 ~ariables (Le. tluid viscosity and particle diameter) and operatine conditions

(Le. J, and s,) are specified or assumed and the equations for the plug flow dispersion

mode1 are solved by iteration.

2.5 Analvtical Techniaues

2.5.1 Effective Residual Ink Concentration

Effective residual ink concentration (ERIC) is a usehl method for determining the

amount of ink on a pad [29]. The relationship relating the reflectance of an opaque pad of

paper (RJ rneasured at a wavelength of 950 nm to the amount of ink in the paper is given

by:

Equation 2.31 can also be expressed as:

k f(RJ = - (2.25)

S

where k is an absorption coefficient and s is a scattering coefficient. Absorption and

scattering coefficients of recycled newsprint are averages of its components (paper and

ink). weighted by their concentrations (c ) . Therefore the coeficients become:

k, = ( 1 - c d kprp + cinrkn* (2.26)


S m = ( 1 - ctnd Spap Cm~Smii (2.27)

where rec and pap stand for recycled newspaper and paper. respectively. Ink

concentrations are very small. therefore ( I - C , , ~ tends to uni-. The term k,,, is much

greater than 4,. As a result the product c,,,k,,, contributes significantly to k. The

product of c,,,~,,, does not contribute to s, since the term s,,, is nor significant.

Therefore. equations 2.26 and 3.27 become:

L = &ap C I ~ ~ ~ I I L (2.36b) d

S m - Spap (2 27b)

The scattenng coefficient of a sheet with known ba is weight (w) can be found by

rneasuring its retlectance over a black backing (RJ and the

of the same paper (L) according to:

i-

reflectance of an opaque pad

(2.28)

The absorption coefficient for any sample can be detemined by reiating equations

2.24 and 2.25 and multiplying both sides by the scattenng coefficient:

where s can be determined using equation 2.77 or 2.28 when s,, is known. For recycled

newspaper. the k in equation 2.29 is equal to k,, in equation 2.26b. Therefore. the

effective residual ink concentration (c,,J c m be determined from equation E 6 b provided

2.5.1.1 Flotation Efficiency

Flotation efficiency (E) is used to measure deinking performance. Flotation

efficiency in this thesis is defined as:


where c is the concentration of ink and the subscnpts are for initial ( i ) and final (f).

2.5.1.2 Ink Recovery

Ink recovery (R) is defined as:

where S. Q. and p represent consistency. volumetnc flownte. and stream density.

2.5.2 Mass Balance

The overall mass balance of the column is a balance between the tlowrates of the

different strearns: feed (F). wash water (W). accepts (A). and rejects (R). The mass

balance c m be expressed as follows:

F + W = A + R (2.32)

The main components of each stream are: water. organics. and ash. Organics consist of

tibres. oils. and other materials which are combustible at 575°C. Ink is a cornponent of

each stream. however it can be assurned that its mass is negligible [;O]. The water

balance c m be expressed as:

F p F ( I - X F - Y F ) + W = A p , ( l - X , \ - Y , ) + R p , ( l - X R - Y , ) (2.33)

where X, and Y, are the mass fractions of organics and ah in their respective streams.

where i = F. W. A. and R. In addition. p, is the density of each stream and is given by:

1 (2.34) = ( l - X - Y , ) +-+- Xi Y,

Pfibrcs Prish

where p, is expressed in &cm3. n e organic and ash balances can be expressed as:

PF XF= A PA X A PR XR (2.3 5)

F pF Y F = A pA Y A + R YR (2.36)

Chapter 2: Theoretical Principles 2 8

3.5.2.1 Organic Loss

Organic loss (L) is another method for assessing column performance. Organic

loss represents the hydrophilic materiai (primarily fibres) which is recovered to the rejects

by entrainment. Organic loss is calculated according to the following equation:

2-5-22 Yield

Yield (Y) is used to determine throughput. Yield is the complement of organic

loss and is given by:

Y = 1-L (2.3 8)

Data for the mass balance was reconciled using NORBAL3 [XI. Data

reconciliation is necessary due to the uncertainty (quantified by the standard deviation)

associated with experirnental data. The pulp feed consists of low percent solids (- 1%)

and the slurry densities of a11 strearns is approximately 1 g/crn5. Therefore. data

reconciliation kvas only performed on the pulp flowrates. The pulp tlowrates have the

çreatest effect on the m a s balance since they have significant magnitudes and standard

deviations.

Chapter 3: Expenmental 39

Chapter 3: Experimental

3.1 Approach

Deinking expenments were performed at Avenor using open and packed

laboratos and pilot-scaie flotation colurnns. The colurnns were fed continuously with

pulp frorn the feed end of the plant flotation cells. Various operating conditions were

altered in the columns. narnely: gas rate. retention time. froth depth. and bias rate. In the

laboratory column. these parameters were studied for two porous stainless steel spargers

(nominal pore diameters of 0.5 and 100 pn) and no sparger (in the case of packing). The

operating conditions in the pilot column were investigated using an industrial variable

gap sparger [XI. Deinking expenments were compared according to flotation eficiency

and organic loss.

The laboratory-scale columns (open and packed) were used to select the operating

conditions required depending on sparger type. Once the conditions were determined. the

performance (flotation efficiency and organic loss) of both columns were compared to

each other and to the mechanical cells. The pilot-scale columns (open and packed) were

used to veriQ the scale up of the laboratory columns. The pilot columns were also used

to assess long term operation and to make a further cornparison to the mechanical cells.

Chapter 3 : Experimental 30

3.2.1 Laboratory-Scale Column

The laboratory-scale columns (0.102 m in diarneter and 4.65 rn high) were fblly

automated (Figure 3.1 ). Figure 3.1 is a diagrarn of the open colurnn: the packed column

had the sarne instrumentation and is identical except for the packing material placed

inside. Four pressure transmitters ( Bailey. mode1 PTSDDD 123B2 100) were installed

alone the lenfi of the columns in order to measure the gas holdup profile and froth

depth. Three peristaltic pumps (Masterflex. model 7579-20). equipped with 110 cards.

were used to control the flow of feed. accepts. and wash water. The rate of feed and

accepts was measured with magnetic flowmeters (Fisher & Porter. mode1

1 ODI475PN07PL29). The gas rate was controlled with the aid of a mass tlowrneter and

controller (MKS. model 1 162B-30000SV). Compressed air for the air flowmeter was

supplied at 80 psi from the plant and was reduced to 50 psi using a regulator. The

pressure transmitters. pumps. and flowmeten were controlled or monitored using a senal

I/O (Transduction. model OPTOI) and a computer (IBM compatible. model 486). F E

DMACS was the software package for data collection and colurnn operation. Two

porous stainless steel spargers were tested (details are given in Table 1).

3.2.2 Pilot-Scale Column

The pilot-scaie colurnn (0.5 m in diameter and 4.00 m high) kvas also hlly

automated and used the same pressure transmitters. serial interface. and control software

as the laboratory coiurnn (Figure 3.2). In addition. magnetic flowmeters (Fisher & Porter.

model 10D 1475PN 1 1 P L D ) and an air flowmeter (MKS. model 1 162B400000SV) were

used. Centrifuga1 pumps (Pnce. model 4MS50-SS-150 and Lobee. model 700-D-2) were

used to supply wash water and pulp to the columns. The flow of feed and accepts were

controlled using two control valves (DeZuric. mode1 EPSN-DE190P-TA). Compressed

air for the air flowmeter and control valves was supplied at 80 psi fiom the plant.

Chapter 3: Experimental 3 1

Table 3.1 Sparger characteristics.

1 Sparger 1 Length (cm) ( Area ( c d ) 1 Nominal Pore 1 Permeability [33] 1

3.3 Procedure

A

3.3.1 Column Operation

The Ievel. pump speed. and gas rate w r e controlled using FI?( DiLIACS with the

required pararneters for each test being entered into the computer. The retention time in

the column was fixed by setting the accepts at a pre-determined tlow. The feed flow was

varied in order to maintain the froth height at a desired set point. Samples of the feed.

accepts. and rejects for each test were collected for analysis. Sarnples were collected

once steady state was achieved. and after (i penod of 3 times the retention time. as

recommended [ 1 41.

FIX DMACS \vas also used for data acquisition. The following pararneters were

collected continuously: feed and accepts rates. gas rate. =as holdup. and level. Other

parameters. such as- wash water and rejects rates were rneasured manually.

3.3.2 Sample Preparation

In order to measure the ERIC values for the feed and accrpts streams. 4 gram pads

were prepared according to the CPPA C.IU method [XI. An average of 10 ERIC values

( 5 per side) was obtained using a Tecnodyne ERIC 950.

Ashing was performed to detennine the composition (ash and organic content) of

cach strearn. Approitimateiy 1 gram from rach pad was placed into an ovcn at 575°C

using cerarnic crucibles. .At 575°C a11 organic constituents ( primarily fibres) are

combusted. leaving inorganic rnaterial (Ca0 and CaCO,). This ashing technique is

necessary to mass balance the column.

10.0 75.5 Diameter (pm )

0.5 ( rn Darcy )

0.072

Chapter 3 : Experimental j 2

Intefice and Signal

4 w Conditionhg

1 iûptomu.. 2 1

rbl t ' Y .) + Accepts

Air

Fig. 3.1 Schematic diagram of laboratory-scale column and instrumentation: column is 1b.l cm in diameter, 4.65 rn high, and divided inio sections for transport.

C hapter 3 : Expenmental 2 .-. 3

-.

Water '

- Rejects

/- Feed - ,,

Cornputer Running FIX DMA

-

cV- Accepts

Interthce and Signal Conditioning

Fig. 3.2 Schematic diagrarn of pilot-scale column and instmmentation: column is 50 cm in diameter and 4.0 m high and divided into 1 m sections for transport.

Chapter 4: Results and Discussion 3 J


This chapter is divided in 4 parts. Part 1 is concemed with the selection of the

operating conditions in the open and packed laboratory-scale columns which were

subsequently used for the comparative test work reponed in part 5. Part 1 is also resented

for pilot-scale comparative test work. .Alternative tlotation rvaluation techniques.

including gas surtace area rate and the yield-notation efficiency relationship. are

investigated in part 3. FinaIl?. part 4 is concerned with colurnn scale up. .-\II flows are

rxpressed as superficial rates (volumetnc tlow per unit column cross-sectional area

Q/A,,) with units of cmis. m e pulp consistency (?/O solids) for al1 experirnents was

maintained at approximately 1.2% by the plant. Test conditions are surnmarized in

Appendix B. Flotation efficiency and organic loss results are presented in .4ppendices C

and D. Results for part 3 are eiven in -4ppendix E. -4ppendix F is resen-ed for the scale

up results.

4.1 Selection of Operating Conditions

4.1.1 Open Column

In order to determine the selected operating conditions in the open colurnn the

following parameters were altered in the laboratory-scale columns: -as rate. pulp

retention time. froth depth. and bias rate. The effect of gas rate and retention time were

Chapter 4: Rssults and Discussion -. - - d

investigatrd using the two porous stainless steel spargers idescribed in Table 3.1 1.

Column performance is usually linle riffected by froth height and hias rare ( provided it is

positive] [l-!]. therefore unly sparger .-\ \vas used in testing these parameters. The

selected operating conditions represent a compromise benveen flotation eficiency.

organic loss. and operational stabiliry.

4.1.1.1 Gas Rate

The effet[ of superticid gas rate tJ,) on tlotation rfficiency and organic loss for

both spargers is chown in Figures 4.1 and 1.2 respectively. In order to isolate the effect

of J.. the retention time. froth depth. and u-ah water rate t e r e maintainsd 3t constant

values

For sparger -4. tlotation eificisnc). \as relatively unaffected bv . - cas rate ( Fig. 4.1 1.

.At gas rates higher than 2 crrvs the tlow regime of the collection zone visibly changed

from bubbly to chum-turbulent. The selected superficial gas velocity for sparger .A u?is

about 1 -5 cm!s. .At this .IL. organic loss was approsimateiy 1 O/a. tt is advamageou to

opente at a low value of J, since organic loss \vas found to increase linrad! with gas rate

(Fig. 4-21.

Sparger B produced Iarger bubbles than sparger -4 and as a result lower tlotation

rfficiencies were obsenved for similar \.ahes of J.. Flotation sfficiency for sparger B is

more dependent on gas rate than for sparger .A (Fig. 4.1 ). The transition to chum-

turbulent flow was not obsened wirh sparger B. This suggests that sven higher sas rates

could have been used to produce higher flotation efficiencies. However. nt high gas rates

(Ji > 3 ) it \vas dificult to control the froth depth. indicating that the transition to chuni-

turbulent does occur. h o t h e r disadvantage associated with higher gas rates is that higner

organic losses occur t F i . 4.2). Therefore. the selected I, for sparger B \vas determined to

be -3 cms.

From Figure 4.7 it can be seen that sparger B produced lower organic Iosses than

sparger A for al1 gas rates. Large bubbles (produced from sparger B) tend to carry less

Chapter 4: Results and Discussion 36

\vater across the froth interface than small bubbles. Therefore organic loss by

entrainment will be lower when Iarger bubbles are genented. This effect \vas discussed

bu .?jersch and Pelton [3 J.

4.1.1.2 Retention Time

To calculate retention time. the height of the collection zone \vas divided by the

superficial accepts velocity. J,. Therefore. the retenrion rime was changed by controlling

the accepts rate. The effect of retention tirne on tlotation efficiency (Fie. 4.3) and organic

loss (Fig. 1.1) \vas determined bu sening the gas rate. froth depth. and wash water rate at

pre-detennined \-dues.

Retention time had little effect on flotation efficiency when sparger A \vas used.

Flotarion rfficiency \vas found to increase with retention time when sparger B t a s used.

Organic loss was found to increase with retention tirne for both spargers. Therefore. long

retention times should be avoided. The selected retention times were taken to be 6

minutes for sparger A and 8 minutes for sparger B.

4.1 -1 -3 Froth Depth

Flotarion efficiency (Fie. 4.5) and organic loss (Fig. 4.6) were undfectsd by froth

depth. However. extremes in froth depth are not favorable to colurnn operarion: a

shal10~- froth ofien means it is lost when surges occur: and deep fioths reduce retention

time. A froth depth of approximately 60 cm wvas determined as adequate.

1. I - 1 -4 Bias Rate

Bias rate \vas investigated using sparger A with a J, of 1.5 cms. It was found that

bias rate had no effect on flotation efficiency (Fig. -1.7) and organic loss (Fig. 1.8). Bias

rate \vas found to have a slighr effect on fibre loss. It \vas difficult to produce a froth with

no w s h water (negative bias). Therefore. a bias rate of about 0.16 cmk !vas selected.

High bias rates are to be avoided since they reduce retention time and dilute the accepts.


Figure 4.8 indicates that bias rate has no cffect on organic loss. Howcver. visual

inspection of the reject pads indicate that the pads become more fibrous as the wash water

is reduced. Fibrous pads contain large arnounts of long fibres [36]. Long tibres report to

the rejects primarily due to entrainment. Wash water is effective in removing the long

tibres (reject pads at high J, are not 'hairf). At high bias rates other organic matenal is

entering the froth and maintaining the organic Ioss value constant.

+ Sparger A Sparger B

O O 1 2 3 4 5 6

Superficial Gas Velocity (cmls)

Fig. 1.1 Flotation eniciency versus superficial gas velocity (open column). Conditions: retention time = 8 minutes; froth depth = 50 cm; bias rate = 0.16 c d s .



Fig. 4.2 Organic loss versus superficial gas velocity (open column). Conditions: see Fig. 4.1.

+ Sparger A Sparger 0

40 -

30 -

20 -

10 -

O 2 4 6 8 10 12 14 16

Retention Time (min)

Fig. 4 3 Flotation efficiency versus retention time (open column). Conditions: gas rate = 1.5 cm/s (sparger A) and 2.0 cm/s (sparger B); froth height = 50 cm; bias rate = 0.16 cm/s.


0 ------- ---

O 2 4 6 8 10 12 14 16


Fig. 4.4 Organic loss venus retention tirne (open column). Conditions: see Fig. 4.3.

40 - 10 20 30 40 50 60 70 80 90

Froth Depth (cm)

Fig. 4.5 Flotation efficiency versus froth depth (open column). Conditions: sparger A; gas rate = 1.5 cm/s; retention time = 6 minutes; bias rate = 0.16 cm/s.


O - --

10 20 30 40 50 60 70 80 90

Froth Depth (cm)

Fig. 4.6 Organic ioss venus froth depth (open column). Conditions: see Fig. 4.5.

40

-0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30

Superficial Bias Velocity (cmls)

Fig. 4.7 Flotation effîciency versus bias rate (open column). Conditions: sparger A; gas rate = 1.5 c d s ; retention time = 6 minutes; froth depth = 50 cm.

Chapter 4: Results and Discussion I I

O - -0.05 0.00 0.05 0.10 O. 15 0.20 0.25 0.30

Superficial Bias Velocity (cmls)

Fig. 4.8 Organic loss versus bias rate (open column). Conditions: see Fig. 4.7.

4.1.2 Packed Column

The operating variables tested in the packed laboratory-scale column were the gas

rate and retention time. Froth depth and bias rate had little effect on Rotation efficiency

and organic loss from the open column tests. therefore the same values were chosen for

the packed colurnn.

4.1.2-1 Gas Rate

The effect of J, on performance for the different spargers is shown in Fig. 4.9

(flotation efficiency) and 4.10 (organic Ioss). To determine the effect of J,, the retention

time, froth depth. and bias rate were maintained constant.

For sparger A. the selected Jg was determined to be about 2 cmk (Fig. 4.9). At J,

less than 2 c d s pulp accumulated in the packing. At Jg greater than 2 c d s it became


difficuit to control the froth depth due to a change in flow regime from bubbly to chum-

turbulent. At this J,. the organic loss was approximately 4.5% (Fig. 4.10).

Superficial gas velocity had a similar effect on notation efficiency when sparger B

and no sparger were used (Fig. 4.9). (The performance of sparger B and no sparger

cannot be compared at this point since the expenments were performed with different

feed consistencies due to plant variations.) The selected I, for sparger B was determined

to be 3 cmis since above this the fioth depth could no longer be controlled easily. When

no sparger was used the transition in the collection zone to churn-turbulent was not

observed until higher values of J,. Therefore. a J, of about 4 cm/s was selected when no

sparger was used. At their selected values of J.. sparger B and no sparger produced

organic losses less than 2% (Fig. 4.10).

4.1.2.3 Retention Time

The effect of retention time was only investigated using sparger B and no sparger.

The effect on flotation efficiency (Fig. 4.1 1) and organic loss (Fig. 4.12) was determined

by setting the gas rate, froth depth, and bias rate at the selected values. Retention time

had no effect on flotation efficiency when sparger A was used in the open column. and

thus was assumed to be the case in the packed COILUM. As a result. the selected retention

time for sparger A was taken to be about 6 minutes. Retention time had a similar effect

on flotation efficiency and organic loss when sparger B and no sparger were used. The

selected retention tirne for sparger B and no sparger was determined to be approximately

8 minutes.

A summary of the selected operating conditions for the packed column is given in

Table 4.1 along with those previously selected for the open column.

Chapter 4: Results and Discussion -I 3

Table 4.1 Summary of selected operating conditions laboratory columns.

A

s V

% O E aa .I

$ W e O

m- u m - O 1L

Fig.

Column

open open

pac ked packed packed

4 Sparger A

a Sparger B

A No Sparger

Sparger

A B A B

none


4.9 Flotation eficiency versus superfkial gas velocity (packed column).

J, (cmk)

1.5 3.0 2.0 3 .O 4.0

Conditions: retention time = 8 minutes; froth depth = 60 cm; bias rate = 0.16 c d s .

Retention Time (min.)

6 8 6 8

8 1

Froth Depth (cm) 60 60 60 60 60

Bias Rate ( c ~ s )

1

O. 16 0.16 0.16 O. 16 O. 16

Chapter 4: ResuIts and Discussion -44

+ Sparger A

Sparger B

A No Sparger


Fig. 4.10 Organic loss versus superficiai gas velocity (packed coiurnn). Conditions: see Fig. 4.9.

Sparger 6

A No Sparger


Fig. 4.1 1 Flotation efficiency versus retention time (packed coiumn). Conditions: gas rate = 3.0 cmls (sparger B) and 4.0 cmfs (no sparger); froth depth = 60 cm; bias rate = 0.16 cmls.


Sparger 6

A No Sparger --


Fig. 4.12 Organic loss versus retention time (packed column). Conditions: see Fig. 4.11.

4.2 Cornparison of Columns and Mechanical Cells

4.2.1 La boratory-Scale Comparison

The laboratory-scale columns were compared at their selected operating

conditions (Table 4.1) and compared to the mechanical cells. The columns were nin for 3

hours with 4 samples from each column being collected and analyzed. Al1 the

experiments were completed during a 30 hour period so that the feed from the plant

would remain relatively constant to permit the cornparison. Samples fiom the mechanical

cell circuit were also taken during this tirne penod. Certain experiments were repeated

two weeks Iater to test reproducibility.

The open and packed colurnns using sparger A equaied the performance of the

mechanical cells in terms of flotation efficiency (Fig. 4.13 and Table 4.2). The packed


colurnn using sparger B also produced a sirnilar flotation efficiency to the mechanical

cells. The open column using sparger B and the packed column using no sparger had

similar flotation efficiencies and were both inferior to the mechanical cells. The

expenments with sparger B were repeated and cornpared to the mechanical cells. In this

case. al1 three were statisticaily indistinguishable in terms of flotation eficiency (Table

4.3). When sparger A was used a drop in gas holdup with tirne was observed indicating

that the sparger was becoming blocked. This phenornenon did not occur with sparger B.

Sparger A in the open and packed columns produced the highest organic loss (Fig.

4.14 and Table 4.7). The packed column using no sparger yielded the lowest organic

loss. The organic loss for the mechanical ceIl circuit at this stage could nor be determined

since an accurare flow rate of the rejects could not be obtained. XII of the organic losses

frorn the coIumns were less than 2%.

Experiments were also performed in both columns using sparger B and in the

packed column with no sparger without wash water. Without wash water. a froth could

nor be produced. The bias water replaces the water naturally drained from the tioth [11].

Therefore wash warer is essential when sparger B and no sparger are to be used.

Flotation efficiency and organic loss results were also plotted versus time (Fig.

4.15 and 4-16) to show the effect of the standard deviation.

Table 4.2 Average flotation effkiency and organic loss for columns and mechanical cells. Variation is given as a 95% confidence interval.

( Flotation Ce11 1 Sparger 1 Flotation 1 Organic 1

open column B 72.3 * 1.6 1.3 0.2

1 packed colurnn 1 A 1 79.9 * 0.7 1 1.7 * 0.1 ] packed column

packed column

8

L

mechanical

none

79.6 * 1.6

-

0.9 0.2

73.3 1.4 0.6 * O. 1

79.2 ;c 1 .O 4

N/A


Table 4.3 Average flotation efficiency and organic loss for columns using sparger B and mechanieal cells (repeat). Variation is given as a 95% confidence interval.

1 Flotation Ce11 1 Sparger 1 Flotation I Organic

open colurnn

packed colunin

. sparger A . sparger 8

B

mec hanical

open packed mechanical cells

B

Fig 4.13 Flotation efiiciency results (laboratory colurnn). Conditions: see table 4.1.

Efliciency (%)

76.0 * 1.4

-

Loss (96)

1.9 i 0.6

76.0 i 0.9 1.7 I 0.2

77.3 i 0.4 N/A


open pac ked

I sparger A

sparger B U no sparger

Fig. 4-14 Organic loss results (laboratory column). Conditions: see table 4.1.

1 2 Time (hr)

i Open-A A Open-B o Packed-A A Packed-B O Packed-none Q Mechanical Cells

Fig. 4.15 Flotation efiiciency versus time (laboratory column). Conditions: see Table 4.1.


Time (hr)

Fig. 4.16 Organic loss versus time (laboratory column). Conditions: see Table 4.1.

4.2.2 Pilot-Scale Cornparison

The open and packed pilot columns were operated with a variable gap sparger and

with no sparger (in the case of packing) for extended periods of time. The operating

conditions for the columns and the length of test are presenred in Table 4.4. Higher

residence times could not be obtained due to the absence of an accepts pump. Samples

fiom the columns and mechanical cells were collected every two hours.

Table 4.1 Summary of operating conditions in pilot columns.

1 Column ( Sparger 1 Test Duration 1 I, (cmh) 1 Residence 1 Froth Depth ( Bias Rate 1

packed variable gap 22 2.8 13.4 59 0.17

packed none 6 3 -4 11.8 6 1 0.16

Chapter 4: Results and Discussion 5 O

The open and packed colurnns had average flotation efficiencies which were

inferior to that of the mechanical cells (Fig. 4.17 and Table 4.5). The packed column

using the variable gap sparger had higher flotation eficiencies than the open column.

The open column and the packed column with no sparger had similar tlotation

efficiencies.

The average organic loss from al1 of the colurnns was less than 3% (Fig. 4.18 and

Table 4.5). In al1 cases the c o l m s had lower organic losses than the mechanical cells.

The average organic loss fiom the mechanical cells was 8.5% (Fig. 4.1 8 and Table 4.5).

Organic loss data for the packed colurnn with the sparger are not available at 8 and 10

hours due to operational dificulties.

The flotation efficiency results for the packed column with a sparger (Fie. 4.17)

remained relatively constant (standard deviation of 2.5%) during the 22 hour test period.

As a result. pulp accumulation in the packing and in the sparger did not occur or did not

affect the performance of the packed column with time.

Table 4.5 Average flotation efficiency and organic Loss for colurnns and mechanical ceils. Variation is given as a 95% confidence interval.

1 open column 1 variable gap 1 65.3 i 2.9 1 1 . 2 = 0.3 1

Flotation Ce11

1 packed column 1 variable gap 1 72.9 * 1.4 1 1.8k0.3 I

Organic Loss (94)

S parger

packed column

Flotation Efficiencv (%)

mec hanical

none

- 67.0 * 3.1 1.8 * 2.3

80.5 2 1.2 8.5 I 0.6

Chapter 4: Results and Discussion 5 1

A

s O h O pechanical cells (80.5%)

n O - 80' 0 5 O 3

- - E a .- m m O pac&d colurnn (72.9%) O U I E 70;

I I w w A p a c d no sparger (67.0%) 0

d

E n

O I .-

Ci O

n p open c o l u v (65.3%)

60 --

Time (hr)

Fig. 4.17 Flotation efficiency versus time (pilot column). Conditions: see Table 4.5.

packed column (i -8%)

A packed column - no sparger (1.8%)

O .- a open column (2.2%) s 4 - eu 0 mechanical cells (8.5%) p 3 - 0 O 2 4

u rn m - 4

I I I Y - rn l m A a

Time (hr)

Fig. 4.18 Organic loss versus time (pilot column). Conditions: see Table 4.5.


4.3 Alternative Flotation Evaluation Techniques

4.3.1 Bubble Surface Rrea Generation Rate

The surface area generation rate of bubbles is the parameter which govems the

solids removal rate. By increasing the bubble surface area available for particle

attachrnent more solids will be removed. Bubble surface area generation rate is usefûl for

relating flotation eficiency since surface area rates incorporate bubble size and gas

velocity (eq. 2.1 1).

Figure 4.19 shows the effect of surface area generation rate on tlotation efficiency

in the open laboratory-scale column. The curve in Fig. 4.19 was constructed using data

from sparger B (coarse sparger. producing large bubbles) and fiom sparger A (fine

sparger. producing small bubbles). The right side of the cuve (produced by sparger A)

forms a plateau since the maximum flotation efficiency was reached when sparger A was

used. The left side of the c u v e (produced by sparger B) increases linearly until the

maximum flotation efficiency for sparger B is reached. It can be seen that a relationship

exists between flotation effkiency and bubble surface area generation rate. I f the gas rate

were increased with sparger B. the lefi portion of Fig. 4.19 would approach the plateau

obtained with sparger A. Similady. the right portion of Fig. 4.1 9 should decrease iinearly

as the gas rate is decreased. The same relationship between flotation efficiency and

bubble surface area generation rate is observed in the packed laboratory-scale column

(Fig. 4.20).

From the extrapolated portions of Figures 4.19 and 4.20 the transition to

maximum tlotation efficiency occurs at a bubble surface area generation rate of

approximately 35 s-'. Therefore, the combination of bubble size (govemed by sparger

type and surfactant dosage) and gas rate which yields a bubble surface area generation

rate of 35 s'l will produce the maximum flotation efficiency. Additional work is required

to completed the interpoiated portions of Figures 4.19 and 4.20. This can be

accomplished by testing spargers with intermediate porosities at different gas velocities.


The dashed interpolations of Figures 4.19 and 4.20 will only be obtained if there is no

regime change. Le. if the flow remains bubbly over the entire range of generation rates.

The average surface area generation rates for the open and packed pilot columns

were 22.6 and 23.4 s" (Appendix E). Both of these values are below the theoretical

maximum of 35 s" obtained fiom the laboratory-scale columns. Therefore. the low

notation eficiencies obtained in the pilot column are reflected in the low surface area

generation rates.

o Sparger B

O Sparger A

Surface Area Rate ( I l s )

Fig. 4.19 Flotation efticiency versus bubble surface area rate in the open laboratory column.


ci Sparger B

o Sparger A -

O - -

O 10 20 30 40 50

Surface Area Rate ( I ls)

Fig. 4.20 Floiation efficiency venus bubble surface area rate in the packed laboratory column.

4.3.2 Yield - Flotation Eflïciency Relationsbip

Recovery-grade relationships are used to assess mineral flotation. In flotation

deinking, recovery translates to organic yield and grade refers to the accepts pulp quality

(flotation eficiency). Figure 4.21 is a yield-flotation efficiency curve for the open and

packed laboratory colurnns. It can be seen that as flotation eEciency increases yield

decreases and vice versa. To a first approximation al1 forms of column operation follow

the same relationship. Feed variations make an absolute relationship impossible. it may

be necessary to construct several yield-efficiency curves to take al1 plant variations into

account.


0 Open - Sparger A

Open - Sparger 8

+ Packed - Sparger A

85 Packed - Sparger 8

A Packed - No Sparger

Flotation Efikiency (%)

Fig. 4.21 Yield-notation eaciency relationship for open and packed laboratory-scale columns.

4.4 Evaluation of Column Scale UD Procedure

In addition to the comparative test work descnbed in section 4.2.7. the pilot scale

column was used as an intermediate step to evaluate the scale up procedure. The open

and packed pilot columns were operated at selected operating conditions (Table 4.4)

using a variable gap sparger. In order to scale up. ink recovery was used as a means to

assess column performance. Ink recovery is descnbed in section 2.5.1.2 (equation 2.3 1).

Using data fiom the laboratory colurnn coupled with pilot c o l m dimensions. predicted

pilot column recovenes were caiculated. Laboratory column data was collected using a

porous stainless steel sparger (sparger B). Sparger B was chosen for the laboratory

colurnn since it gave a similar gas holdup venus gas rate relationship as the variable gap

Chapter 4: Results and Discussion 5 6

sparger in the pilot column (Fig. 4.22). Al1 data for the pilot column scale up is presented

in Table 4.6 and Appendix F.

+ sparger B

0.5 1 1.5 2 2.5

Superficial Gas Velocity (crnls)

Fig. 4-22 Cas holdup versus gas velocity relationship for the variable gap sparger (operated at 50 psi) in the pilot column and the porous sparger (sparger B) in the laboratory column.

In order to calculate ink recoveries. an equilibrium ink recovery was estimated.

The highest recovery obtained with sparger A was 87%. Therefore R, was estimated at

87%.

The predicted ink recovery in the open pilot column was calculated using the piug

flow dispersion (P.F.D.) model [14]. The P.F.D. model predicts the degree of rnixing in

the pilot column. The predicted and experimental ink recoveries in the open pilot column

were 58.1 % and 63.5%. respectively.


One of the reported technical advantages of packed column flotation is that

packing reduces mixing [19]. If mixing were completely eliminated then the plug flow

(P.F.) mode1 could be used for calculating the predicted ink recovenes in the packed pilot

column. With the variable gap ssparger the predicted P.F. and P.F.D. recovenes were

calculated to be 80.7 and 65.1%. The experimental recovery in both cases was 70.9%.

The percent difference between the predicted and experimental recovenes for the P.F.

model was 12.1%. The percent difference in the case of the P.F.D. model was 8.9%.

When no sparger \vas used in the packed coiurnn the percent difference between the

predicted and experimental recoveries for the P.F. and P.F.D. modets were 22.1 and

2.4%. Therefore the P.F.D. model. in the present case. appears to be more accurate than

the P.F. model for scaling up packed colurnns. When scaling up columns it is appropriate

to underestimate the recovery (lower predicted than experimental recovery). if recovery

is over predicted then srnaller columns will be designed which may prove incapable of

reaching the target recovery.

Table 4.6 S u m m a ~ of pilot column scale up.

open

packed

variable gap

The colurnns required to replace one line of mechanical cells were scaled up using

the P.F.D. mode1 and data from the laboratory column. Industrial column scale up is

summarized in Table 4.7. A constraint of a maximum coIumn diarneter of 3.5 m was

variablegap f

none

none

P.F.D.

65.1 variable gap

P.F.

P.F.D.

P.F.

P.F.D.

58.1

70.9

80.7

-8.9

79.5

63 -4

63 .5 (%) 1

-9.3

70.9

6 1.9

61.9

+12.1

+22.1

-2.4


imposed based on current practice. Due to higher kinetics (due to producing smaller

bubbles). the columns incorporating sparger A were smaller in size than the columns

using sparger B (or the variable gap sparger). When sparger B is used the feed

throughput must be reduced and extra columns added (if the maximum diameter of 3.5 m

is respected). Determination of the rate constant is presented in Appendix F.

From Table 4.7 it is evident that packing is not required when sparger A is used

(colurnn dimensions are equivalent with or without packing). Packing is necessary when

sparger B (or variable gap) or no sparger are used. In this case packing darnpened the

axial mixing and fewer columns were required.

Table 4.7 Summary of industrial columns.

open

packed

sparger

A

diameter (m)

2.65

3 of columns

1

height (m)

12

Chapter 5: Conclusions and Recommendations 59

Chapter 5: Conclusions and Recommendations

5.1 Conclusions

Selected operating conditions in the open and packed laboratory-scale columns

were identified and are summarized in Table 4.1. During the determination of the

operatine - conditions it was found that wash water is essentid for producine a fioth with

sparger B but not with sparger A. The conclusions from the laboratory-scale cornparison

tests are as follows:

sparger A in rhe open and packed columns produced the highest flotation efficiencies

and equded the flotation efficiency of the mechanical cells.

the packed column with sparger B gave sirnilar flotation efficiency to the mechanical

cells.

the open column with sparger B approached the efficiency of the mechanical cells.

the packed column with no sparger gave the poorest flotation efliciency.

the organic loss from al1 laboratory column configurations was Iess than 1°/o (Le. 98%

yield).

The conclusions from the pilot-scale comparative work are as follows:

the variable gap sparger in the pilot column \vas incapable of matchinp the flotation

efficiency of the mechanical cells.

the packed column produced higher flotation efficiencies than the open column.

Chapter 5: Conclusions and Recommendations 60

the open column with the variable gap sparger and the packed column with no sparger

had equivalent flotation efficiencies.

the organic loss fiom al1 pilot colurnn configurations was less than 3% (i.e. 97% yield).

The following conclusions were made from the alternative flotation evaluation

techniques:

a relationship between flotation efficiency and bubble surface area generation rate

exists.

sparger B produced lower surface area generation rates (hence lower flotation

efficiencies) than sparger -4.

the maximum flotation efficiency was found (by interpolation) to occur at a surface area

generation rate of approximately 35 s-' .

the average surface area generation rates in the open and packed pilot columns were

f o n d to be 22.6 and 23.9 s". which helps explain why the pilot columns couid not match

the flotation eficiencies of the laboratory columns.

The scale up procedure was evaiuated using data fiom the laboratory columns and

pilot column dimensions. It appears that the plue flow dispersion mode1 is more

appropriate than the plug flow mode1 for scale up. Csing data from the laboratory

columns. industriai-scale columns were designed. The dimensions of the industrial

colurnns are sumrnarized in Table 4.7. The conclusions fiom the industriai coiumn scale

up are as follows:

columns incorporating sparger A are smaller than those with sparger B due to faster

flotation.

packing is not required when sparger A is used.

packing is effective in reducing mixing when sparger B or no sparger are used.

Chapter 5 : Conclusions and Recomrnendations 6 1

5.2 Recommendations

Spargers were found to have the greatest effect on tlotation deinking. Therefore.

it is recommended to find spargers that wil1 maximize Hotation efficiency while

minimizing the bubble surface area rate. The advantage of this approach is that it may

lead to sparger porosities larger than the current industrial standard of 0.5 um with less

likelihood of blockage.

Pilot-scale expenments should be perfomed using commercial porous spargers to

ensure that flotation efficiencies of 80% or higher can be obtained.

The maximum flotation efficiency obtained by the mechanical cells and the

coiumns in this work was approximately 80%. To determine whedier higher flotation

efficiencies are possible. a tlotation column using sparger -4 could be placed in series

with the mechanical cells to process the plant accepts.

Consistency was one variable which could not be controlled during the

experiments at Avenor. In column flotation wash water is added and the accepts are

diluted. The feed and accepts consistencies for al1 expenments were approxirnately 1.3

and 0.9% respectively. It may be possible to process higher consistencies (1 -8-2.0%)

using flotation colurnns given that wash water acts to dilute the column contents.

References 62

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References 63

14. Finch. J.A. and Dobby. G.S.. Column Flotation. Pergamon Press. 1990.

15. Larsson. A.. Stenius. P.. and Odberg, L.. "Surface Chemise in Flotation Deinking. Part 1. The Floatability of Model Ink Particles". Svensk Pappersridning 87( 18): R 158-164 (1984).

16. Larsson. A.. Stenius, P.. and Odberg, L.. "Surface Chemisw in Flotation Deinking. Part 2. The Importance of Ink Particle Size". Svensk Papperstidning W(l8): R 165- 169 (1 984).

17. Putz. H.J.. Schaffiath. H.J.. and Gottsching, L.. "De-Inking of Oil- and Water- Borne Printing Inks: A New Flotation De-Inking Model". Pulp & Paper Canada 94(7): T193-198 (1993).

18. Wills. B.A.. Minerai Processine Technoloev, Pergamon Press. 1992.

19. Yang, D.C.. "Technical Advantages of Packed Flotation Columns". in Coliirnn 91, Proceedings of an International Conference on Column Flotation. Agar. G.E.. Huls. B.J.. and D.B. Hyma, vol. 2: 63 1-04; (1 99 1).

20. Wallis, G.B.. One Dimensional Two-Phase Flow. McGraw-Hill. N.Y.. ch. 9. 1969.

21. Clifi, R.. Grace. J.R.. and Weber. M.E.. Bubbles. Dro~s. and Particles. Academic Press. 1978.

33. Karamanev. D.G. and Nikolov. L.N.. "Freely Rising Spheres Do Not Obey Newton's Law For Free Settling". A I C E Journal. Vol 38(9) ( 1 992).

23- Karamanev, D.G.. "Rise of Bubbles in Quiescent Liquids". AIChE Journal. Vol 40(8) ( r 994).

14. Turvey, R.W.. "Why Do Fibres Float?', J. Pulp Paper Sci. 19(2): J52-57 (1993).

25. Ajersch. M. and Pelton, R.. "Mechanisms of Pulp Loss in Flotation Deiniking". Proceedings of the 3" Research Forum on Recycling, pp. 27. (1 995).

26. Pelton. R.. and Piette. R.. "Air Bubble Holdup in Quiescent Wood Pulp Suspensions". Cm. J. Chem. Eng. 70: 660-663 (1992).

27. Klimpel. R.R.. "The Industrial Sulphide Mineral Flotation System". Advances in Coal and A4ineral Processing Using Flotation, Proceedings of an Engineering Foundation Conference. Chander. S., and R.R. Klimpel, ch. 30: 273-285 (1989).

References 64

28. Wilson. S.W.. and Stratton-Crawley. R.. "Design of Production Scale Fiotation Columns Using a First Order Kinetic Model". Proceedings of Colurnn 9 1. Canadian Institute of Mining and Metallurgy and Petroleum. pp. 165- 180. ( 1 99 1 ).

19. Jordan. B.D.. and Popson. S.J.. "Measuring the Concentration of Residual Ink in Recycled Newsprint". J. Pulp Paper Sci. 20(6): 11 6 1 - 1 67 ( 1 994).

30. Dorris. G.. private communication.

3 1. Spring, R.. "NORBAL3 - Software for Matenal Balance Reconciliation". Noranda Technology Centre. (1 985).

32. Finch. J.A., "Column Flotation: A Selected Review - Part IV: Novet Flotation Devices". Minerals Engineering. vol. 8. no. 6: 587-602 ( 1995).

3 3. Escudero. R.. private communication.

34. CPPA Usehl Method C.4U. "Forming pads for reflectance tests of pulp (Büchner funnel method)". CPPA Useful Method. CPPA Standard Methoa.

35. Ajersch. M.. and Pelton. R.. "Mechanisms of Pulp Loss in Flotation Deinking". jfd

Research Forum on Recycling, Vancouver. Canada: 27-40 ( 1 995).

36. Vidotti, R.M.. Johnson, D.A.. and Thompson. E.V.. "Influence of Toner Detachment During Mixed Office Waste Paper Repulping on Flotation Efficiency". Yd Research Forum on Recycling, Vancouver. Canada: 257-268 (1 995).

Appendices 65

Fig. A.1 Flowsheet of Avenor's deinking plant.

Apendices 66

Ap~endix B

Table B.1 Test conditions for open laboratory-scale column.

test # -

feed

0.55 0.72 0.6 1 0.77 0.66 1.34 0.73 0.39 1 .O0 0.59 0.70 0.73 0.80 O .6S 0.56 0.79 0.85 0.68 0.68 0.76 0.80 0.71 1.52 0.77 0.36 1.31 0.69 0.27 0.98 0.45

superficiaI velocity W. water

0.23 0.23 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 O -22 0.22 0.22 0.36 0.08 0.00 0.24 0.24 0.24 0.24 O -24 0.24 O .24 0.24 0.24 0.24 0.24 0.24 0.24

accepts - 0.64 0.65 0.83 0.65 0.83 1.46 0.87 0.39 1.10 0.67 0.80 0.89 0.95 0.84 0.83 0.82 0.83 0.90 O .9O 0.93 0.95 0.93 I .69 0.99 0.59 1.55 0.89 0.45 1.13 0.67

bias - 0.05 -0.08 0.20 -0.03 0.17 0.1 1 0.09 0.07 0.09 0.08 0.14 O. 13 0.1 1 0.16 0.27 0.05 -0.0 1 0.23 0.23 0.20 0.15 0.20 0.23 0.23 0.23 0.22 O .22 0.22 0.22 0.22

leveI (cm)

53 .O 40.0 50.0 48.0 51.0 54.0 50.0 50.0 53 .O 48.0 77.0 43 -0 20.0 55.0 56.0 50.0 51.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0

r (min)

5.88 7.00 5.92 6.83 5-33 2.57 4.59 8.48 2 35 6.10 4.43 5.19 5.26 5.44 5.43 5.80 5.84 6.02 6.19 5 -48 5.22 5.5 1 3.15 5 -42 8.98 3.47 6.04 1 1.73 4.76 7.97

Apendices 67

Table B.2 Test conditions for packed laboratory-seale column.

SI

feed - 0.70 0.97 0.73 0.7 1 0.46 0.43 0.4 1 0.45 O S 1 0.87 O -44 1.32 0.30 0.53 0.43 0.52 0.50 0.50 0.73 0.46 1 -23 0.52 0.25

W. water

0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.32 0.23 0.23 0 -23 0.23 0.23 0.22 0.22 0 2 2 0 2 2 O .22 0.22 0.22 0.22 0.22

bias

0.05 -0.07 0.16 0.18 O. 18 O. 14 0.2 1 O. 17 0.15 O. 16 O. IJ O. 19 o. 1s O. 17 0.20 O. 16 O. 18 O. 14 O. 17 0.16 O. 18 O. 16 O. 15

accepts - 0.8 1 0.82 0.83 0.84 0.62 0.60 0.64 0.6 1 0.64 0.99 0.55 1.46 0.43 0.68 0.70 0.68 0.69 0.69 0.94 0.58 1.40 0.69 0.42

test ;: --

rejects

0.17 0.29 0.06 0.04 0.04 0.08 0.0 1 0.05 0.07 0.07 0.09 0.04 0.1 1 0.06 0.02 0.06 0.04 0.08 0.05 O .O6 0.04 0.06 0.07

level (cm)

60.0 63.0 63 .O 60.0 57.0 58.0 57.0 57.0 58.0 58.0 58.0 58.0 57.0 58.0 58.0 60.0 59.0 59.0 55.0 63 .O 63.0 62.0 63 .O

s (min)

5.98 5.4 1 6.08 6.54 8.33 8. I O 8.54 8.24 7.54 5 .O0 9.08 3.40 1 1.74 7.32 7.44 7.15 7.30 6.93 5.3 1 8.37 3.48 7.12 1 1.60

packA- l packA-2 packA-3 packA4 packB- 1 packB-2 packB-3 packB-4 packB-5 packB-6 packB-7 packB-8 packB-9 packB- 10 packNO- 1 pac kNO-2 packNo-3 packNO-4 packNo-5 packNo-6 packNo-7 packNO-8 packNO-9

Table B.3a Test conditions for comparative work in laboratory-scale column.

level (cm)

62.0 62.0 62.0 62.0 60.0 60.0 60.0 60.0 58.0 58.0 58.0 58.0 56.0

r (min)

5.65 5.96 5.96 6.00 7.53 7.54 7.5 1 7.39 7.87 8.05 8 -44 8.52 6.62

rejects

0.06 0.06 0.05 0.06 0.04 0.04 0.04 0.05 0.08 0.07 0.06 0.07 0.07

bias - O. 16 O. 16 O. 17 O. 16 O. 18 O. 18 O. 18 O, 17 O. 14 O. 15 O. 16 O. 15 0.15

test #

openA- 1 8 openA- 19 openA-20 openA-2 1 openB- 14 openB- 1 5 openB- 16 openB- 1 7 openB- 1 8 openB- 1 9 openB-20 openB-2 1 packA-5

W. water

0 2 2 O -22 0.22 0.22 O .22 O .22 0.22 0.22 0.22 0.22 0.22 0.22 0.22

accepts - 0.79 0.75 0.75 0.75 0.68 0.67 0.67 0.68 0.64 0.63 0.60 0.60 0.68

Apendices 6s

Table B.3b Continuation from Table B.3a.

W. water

0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22 0.22

test #

packA-6 packA-7 packA-8 packB- 1 l packB- 1 2 packB- 13 packB- 14 packB- 15 packB- 16 packB- 17 packB- 18

packNo- 1 O packNo-l l

packNO- 12 packNo- 13

level (cm)

56.0 56.0 56.0 63 .O 63.0 63.0 63 .O 62.0 62.0 62.0 62.0 57.0 57.0 57.0 57.0

accepts - 0.68 0.68 0.69 0.64 0.66 0.69 0.67 0.6 1 0.62 0.60 0.67 0.68 0.68 0.67 0.67

rejects

0.06 0.06 0.05 0.05 0.05 0.05 0.04 0.07 0.07 0.07 0.07 0.03 0.03 0.03 0.03

b i s

0. 16 O. 16 0.17 0.17 0-17 0.17 O. I8 0.15 0.15 0.15 0.15 O. 19 O . 19 0.19 0.19

Table B.4 Test conditions for comparative work in pilot-scale column.

Superîicial velocity (cm/s)

Ievel (cm)

72-12 71.89 66.86 65.60 65.24 63.97 63.93 63.07 65.12 56.79 63.52 58.15 57.46 60.1 1 59.9 1 59.66 54.21 53.06 59.85 59.78 59.7 1 60.24 6 1 .O2 6 1-52 60.07

W. water - 0.16 0.16 0.16 0.16 0.16 O. 16 O. 16 0.16 0.16 0.18 0.18 O. I8 0.18 0.18 O. 18 0.18 0.17 O. 17 0.17 0.17 0.17 0.17 0.17 0.17 0.17

b ias - O. 15 0.15 0.15 0.15 o. 15 O. 15 o. 15 0.15 0.15 0.17 0.17 0.17 0.17 0.17 0.17 0.17 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 O. 15

test #

open50- l open5O-2 open50-3 open504 open50-5 open50-6 openS0-7 open50-8 openSO-9 pack50- l pack50-2 pack503 pack504 pack50-5 pack50-6 pack50-7 pack50-8 pack50-9 pack50- 10 pack50-1 I pack50- 12 pack50- 1 3 pack50- 14 pack50- I 5 pack50- 1 6

feed - 0.39 0.36 0.33 0.34 0.38 0.43 0.43 0.33 0.33 0.30 0.38 0.27 0.30 0.32 0.30 0.30 0.27 0.25 0.33 0.40 0.36 0.28 0.32 0.38 0.38

rejects

0.004 0.0 1 0.0 1 0.0 1 0.00 0.00 0.0 1 0.0 1 0.0 1 0.0 I 0.0 1 0.0 I 0.02 0.0 1 0.0 1 0.0 1 0.0 1 0.0 1 0.0 1 0.0 1 0.0 1 0.0 1 0.0 1 0.0 1 0.02

Appendices 69

Ap~endix C

Table C.l Flotation efficiency and brightness gain results for open laboratow column.

test rt openA- 1 openA-2 openA-3 0penA-l openA-5 openA-6 openA-7 openA-8 openA-9

openA- 10 openA- I l openA- 12 openA- 13 openA- 14 openA- 1 5 openA- 16 openA- 1 7 openB- l openB-2 openB-3 openB-4 openB-5 openB-6 openB-7 openE3-8 openB-9

openB- I O openB- 1 l openB- 12 openB- 1 3

feed

737.5 1 668.92 655.9 1 773.87 763.84 8 15.96 765.38 835.2 1 747.27 668.8 1 708.26 707.32 752.83 758.0 1 749.72 697. f 8 753.3 i 553 5 0 90 1.7 1 847.75 849.45 779.55 NIA.

767.1 1 833 -62 853.30 835.36 849.00 864.99 836.3 1

riccepa

123 .O5 126.16 120.57 1 18-95 124.00 148.6 1 148.16 146.82 15 1.78 138.54 152.33 1 49 -96 152.55 149.32 143 3.1 145.89 141.04 430.15 642.1 3 292.49 247.5 1 269 -20 NIA.

30 1.76 236.25 408.18 3 1 1 .O6 285.86 428.86 31 1.31

reduction

6 14-46 542.76 535.34 654.92 639.84 667.35 6 17.22 688.39 595.49 530.27 555.93 557.36 600.28 608.69 606.3 8 55 1 .D 6 12.27 423.35 259.58 555.26 60 1-94 5 10.35 N A .

465.35 597.37 us. 12 524.30 563.14 436.13 525.00

tlotation e ffkiency (?G)

83 -3 2 81.14 8 1.62 84.63 83 -77 8 1.79 80.64 82.42 79.69 79.29 78.49 78.80 79.74 80.30 80.88 79.07 8 1.28 49.60 28.79 65.50 70.86 65.47 NIA. 60.66 7 1.66 52.16 62.76 66.3 3 50.42 62.78

brie feed

49.02 49.62 49-47 48.80 48.58 47.62 48.37 48.37 49.27 49. I O 47.88 47.77 48.08 48.14 48.36 48.88 38.78 47.64 46.68 47.75 47.53 48.05 47.78 48.83 38.0 1 47.58 48-82 47.90 47.05 47.88

ness (% ISO) accepts - 58.77 58.60 59.22 58.89 58.97 58.82 59.07 58.70 58.70 58.43 56.58 56.35 56.68 56.58 57.09 57.80 58.3 t 5 3 -43 50.34 55.42 56-15 55.28 54.89 55.9 1 57.15 54.77 55.88 56.45 53 -63 55.72

gain - 9.75 8.98 9.75 10.09 10.39 I 1.20 10.70 10.33 9.43 9.3; 8.70 8.58 8.60 8 .LW 8.73 8.92 9.53 5.79 3 -66 7.67 8.62 7.23 7.1 1 7.08 9.14 7.19 7 .O6 8.55 6.58 7.84

Appendices 70

Table C.2 Flotation eficiency and brightness gain results for packed laboratory coiumn.

-

-

test n packA- 1 packA-2 packA-3 packA-4 packB- 1 packB-2 packB-3 packB-4 packB-5 packB-6 packB-7 packB-8 packB-9

pac kB- 10 packNo- l packNo-2 packNo-3 packNO-4 packNo-5 packNO-6 packNo-7 packNo-8 pac kNO-9

feed

13 18-17 1294.50 1319.17 1245.17 841.61 749.49 633 -26 830.35 893 -65 819.21 8 10.35 76 1.30 749.59 863.24 779.98 882.76 880.06 846.39 855.65 882.92 904.69 85 1.32 840.49

accepts reduction flotation

efficiency (96)

86.67 86.97 86.25 76.72 68.50 73.15 42.60 72.99 78-14 68.88 71.84 65.16 75.68 63.3 1 59.39 77.24 7 1 -50 75.59 64.64 73 -87 6 1-64 72.72 78-15

brightness (9'0 ISO) feed -

42.1 8 42.3 8 42.90 42.90 48.66 49.3 1 51-33 48.52 48.3 8 47.1 O 47.80 49.70 48.68 46.93 46.79 45.62 46.2 1 46.77 48.28 47.65 47.14 48.09 47.83

accepts - 56.27 55.80 56.06 54.64 57.02 58.48 55.38 5 8 . Z 58.82 56.86 57.16 57.45 58.39 55.83 53.01 54.68 54-39 55.24 55.6 1 57.12 54.86 56.86 57.4 1

gain

14.09 1 3 -42 13.16 1 1.74 8.36 9.17 4.05 9.71 10.44 9.76 9.36 7.75 9.7 1 3.90 6.22 9.06 8.18 8.47 7.33 9.47 7.72 8.77 9.58 -

Table C.3a Flotation efticiency and brightness gain results from the comparative work in the laboratory column.

--

test # feed 1 accepts reduction

160.66 678.29 164.88 757.50 165.96 762.29 145.32 656.54 249.89 644.34 249.28 6 18.53 236.60 585.46

flotation efficiency (%)

80.85 82.12 82-12 81.88 72.06

brighmess (?6 [SO) tèed

46.37 46.23 46.42 47.3 1 45.30 45.34 46.61

accepts

57.53 57.55 57.49 58.26 55.54 55.55 55.70

gain

I 1 .I6 11.32 11.07 10.95 10.24 10.21 9.09

Appendices 7 1

Table C.3b Continuation from Table C.3a.

test ~4

openB- 17 openB- 18 openB- 19 openB-20 openB-2 1 packA-5 packA-6 packA-7 packA-8 packB- l l packEl- 12 packB- 13 packB- 14 packB- I 5 packB- 16 pack& 1 7 packB- 18

3ackNO- 1 O 3ackNO- I l 3ackNO- 12 ~ackNO- 13

cells- l cells-2 ce1 1s-3 cells-4 cells-5 cells-6 cells-7 cells-8

feed

886.34 826.17 965.06 902.45 986.25 861.91 860.39 909.02 829.1 1 1000.98 903.15 824.93 876.24 583.33 939.56 966.34 942.38 834.72 85 1 .O0 844.94 87 1.57 838.95 922.3 8 928.25 80 1.86 883.33 939.56 966.34 942.38

. . accepts

324.48 197.8 1 32 1.95 334.45 227.85 18 1 .O3 174.08 179.45 t 60.22 226.96 179.80 162.54 168.74 213.69 215.88 228.35 23 7.23 230.48 239.71 2 16.92 220.66 181.18 196.83 179.18 169.36 201.3 l 2 16.57 230.9 1 208.17

reduction - 66 1.86 628.36 743.1 1 668.00 758.40 680.88 686.3 I 729.57 668.89 774.02 723.35 662.39 707.50 669.64 723.68 737.99 705.15 604.24 6 I 1.29 628.02 650.9 1 657.77 725.55 749.07 632.50 682.02 722.99 745.43 734.2 1

flotation brig feed -

46.26 45.98 44.60 45-45 45.17 45.84 47.3 1 45.62 47.28 46.58 47.05 47.89 49.00 46.98 46.20 45.92 46.72 47.54 47.6 1 47.16 37.30 46.37 46.23 46.42 47.3 1 46.98 46.20 45.92 46.72

mess (96 1SO) accepts - 56.36 55.74 55.14 56.05 57.08 57.53 58.22 58.09 57.55 57.2 l 58.02 58.39 57.83 56.79 56.34 56.04 56.15 56.26 56.82 57.49 57.6 1 57.3 1 56.88 57.33 57.72 56.99 56.43 55.90 56.82

gain

IO. 10 9.76 10.54 10.62 11.91 1 1-69 10.9 1 12.47 10.27 10.63 10.97 10.50 8.83 9.8 1 IO. IJ 10.12 9.33 8.72 9.2 1 10.33 10.3 1 10.94 10.65 10.9 1 10.4 1 10.01 10.23 9.98 10.10

Table C.4 Flotation efficiency results from the comparative work in the pilot column.

plant tlotanor K~T. (96)

80.6 1 78.28 8 1.32 78.9 1 S 1.95 ' 5 59 76.27 8 1 2 6 82. 1 I 79 .O

80.82 '8.19 82.36 '4.83 52.58 51.06 82.1 1 8 1.37 80.15 '8.51 79 04 8 1-85 8 1.42

- Gain = 8.19 9 85 7 47 8 36 10.14 7 I I 7 66 8.90 8 33 lO.07 10.65 I r ) 84 I O 5-1 10.85 I O M 9 07 1 1.82 10.55 10 93 10.10 10 51 IO 74 9 45

10 46 8.40 -

plant sain

10.46 10.87 10.60 4 77 i 1.38 10.70 10.50 11.88 12.45 12.13 12.17 11.43 1 1 21 9 98 :2 76 1 1 99 12.3 l 12.19 12.77 12.18 11.84 12.58 12.09

Table D.2 Pulp flowrate and standard deviation data for tests performed in open labo rat op-scale column.

std. dev. of puip flowrate (ml s j

1 W. water / acceprr [ rejens

Table D.3 Corrected pulp flowrate data and organic loss results for tests performed in open laboratory-scale coiumn.

- .. -

test #

openA- l open A-2 openA-3 openA-4 openA-5 openA-6 openA-7 open A-8 openA-9 openA- 1 0 openA- l l openA- 12 openA- 1 3 openA- 14 openA- 1 5 openA- 1 6 openA- 1 7 openB- 1 openB-2 openB-3 openB-4 openB-5 open%-6 openB-7 openB-8 openB-9

openB- 10 openB- I 1 openB- 13 openB- 1 3

feed - 47.1 53.9 50.5 50.2 52.1 107.5 61.3 23.8 78. 1 47.0 52.9 59.2 60.2 50.3 33.9 68.2 67.4 54.2 54.4 59.1 63.8 57.5 1 18.0 61.3 29.1 104.7 54.3 21.4 73.3 36.5

corrected pu

W. water

17.8 18.5 17.7 18.6 17.7 17.9 18.2 17.6 18.6 17.7 17.7 18.1 17.2 18.2 28.8 6.4 0 .O 19.1 18.8 19.1 19.2 19.5 19.0 19.1 19.3 19.3 18.6 19.2 18.8 19.3

1 flowrate (mus) accepts -

51.4 52.1 66.4 5 1.7 66.1 1 16.6 69.8 39.1 87.3 53.7 63 -8 70.6 67.9 66.8 66.2 65.9 66.2 73.2 72.6 74.9 76.1 73.6 135.8 79.5 47.3 122.6 71.7 38.8 90.8 54.0

rejects

13.6 20.3 1.9

17.1 3.8 8.8 9.7 12.4 9.3 11.0 6.7 6.7 3.8 4.5 7.5 2.8 1.1 1.2 0.6 3.3 6.9 2 -4 1.2 0.8 1.1 1.1 1 .Z 1.8 I .3 1.8

organic loss

(%)

4-27 9.75

Appendices 76

Table D.4 Consisiency and ash data for tests performed in packed laboratory-scale column.

rejects - 55.20 54.3 5 55.19 48.3 5 50.55 54.44 48.70 50.04 50.99 52.44 46.90 44-72 51.17 49.24 4 1.37 48.52 46.32 47.09 47.25 50.22 41 -75 46.U 48.90

consistencv (O 'O) ash content (O/;

accepts

0.76 0.80 0.66 0.68 0.70 0.82 0.60 0.85 0.9 1 0.87 0.92 1.05 0.88 0.93 0.85 0.78 O .82 0.87 1 .O4 0.93 1 .O8 0.92 0.76

feed test # - packA- 1 packA-2 packA-3 packA-4 packB- 1 packB-2 packB-3 packB-4 packi3-5 packB-6 packB-7 packB-8 packB-9 packB- 10 packNo- 1 packNo-2 packNo-3 packNO-4 packNo-5 ?ackNO-6 ?ackNO-7 ?ackNO-8 2ackNO-9

feed

1 -03 1 .O2 0.98 0.97 1.10 1.30 0.9 1 1.26 1.34 1-28 1.34 1.20 1.30 1.29 1.34 1.17 1.24 1 -24 1.36 l.33 1.38 1.33 1.3 1

rejects - 0.40 0.45 0.72 0.15 0.3 8 0.39 0.2 1 0.40 0.48 0.52 0.29 1.13 0.19 0.32 0.3 5 0.34 0.29 0.35 0.64 0.35 1 .O0 0.45 0.19

accepts

Table D.5a Pulp flowrate and standard deviation data for tests performed in packed laboratory-scate colurnn.

std. dev. of oulp flowrate (mVs) 1 test #

packA- 1 packA-2 packA-3 packA-4 packB- 1 packB-2 packB-3 packB-4 packB-5 packEl-6 packB-7 packs-8 packs-9 packB- 10

accepts

65.07 65.40 66.49 67.03 49-93 48.15 5 1 .O3 48.98 5 1 .O4 79.32 44.18 1 17.33 34.19 54.78

feed - 55.92 77.40 58.12 57.2 1 36.68 34.73 32.99 35.97 4 1.23 69.50 35.28 105.98 24.43 42.50

feed - 5.83 7.96 2.64 3.07 12.13 1 1.26 7.12 14-08 11.51 3.96 13.86 8.42 2.37 3.30

W. water - 17.63 17.63 17.63 17.63 17.63 17.63 17.63 17.63 17.63 18.43 1 8.43 1 8.43 18.43 1 8.43

rejects

13.34 23.19 4.54 2.90 3.28 6.14 0.5 1 3.88 5.83 5 S O 7.28 3.36 8.97 5.14

W. water

1-76 I .76 1.76 1-76 1.76 1-76 1.76 1.76 1.76 1.84 1.84 1.84 1.84 1 -84

Appendices 77

Table D.5b Continuation from Table DSa.

Table D.6 Corrected pulp flowrate data and organic loss results for tests performed

r

test d

packNo-l packNo-2 packNo-3 packNO-4 packNO-5 packNo-6 packNo-7 packNo-8 packNo-9

in packed la boratory-scale column.

test if

packA- 1 packA-2 packA-3 pack44 packB- i packs-2 packB-3 packB-4 packB-5 packB-6 packB-7 packB-8 packB-9

packB- I O packNo- l packNo-2 packNo-3 packNo4 packNo-5 packNO-6 packNo-7 packNo-8 packNO-9

1 Corrected pu1

pulp flowrate (mus)

W. water

17.9 17.3 16.5 17.0 17.7 17.5 17.4 17.5 17.8 18.3 18.4 18.4 I8.5 18.3 18.0 17.7 17.6 17.8 18.4 17.5 17.6 17.7 17.9

feed

34-18 $1.36 40.42 40.06 58.60 36.84 98.21 41 -45 20.38

std. dev. of pulp tlowrate ( r n V s )

p flowrate (mL1s)

feed

5.80 10.37 9.29 6.84 8.01 1 1.4 1 12.27 3-28 I.56

accepts

64.8 65.8 67.1 67.4 49.8 48.4 5 1-3 49.5 50.9 80.2 44.9 120.8 33.9 54.9 55.4 54.5 55.6 54.8 74.2 46.9 1 12.7 55.0 32.4

w.water 17.63 17.63 17.63 17.63 17.63 17.63 17-63 17.63 17.63

rejects

12.9 24.3 1.7 2.9 3.3 6.2 0.5 3 -9 5.8 5.5 7.3 3 -4 9.0 5.2 1.3 4.6 3 -4 6.2 3.7 5.1 3.1 4.6 5 -9

organic loss (96)

accepts

56.45 54.8 1 55.57 55.20 75.35 46.65 1 1 I .78 55.07 33-63

rejecn

0.20 0.70 0.51 0.93 0.57 0.76 0.46 0.69 0.90

w-water 1 accepts rejects

1.34 4.65 3.38 6.21 3.80 5.06 3.09 4.59 6.00

1.76 1-76 1.76 1.76 1.76 1.76 1.76 1.76 1-76

3.08 3.64 3 1 3.22 4.48 2.51 12.69 2.83 4.05

Appendices 7 8

Table D.7 Consistency and ash data for the comparative work in the laboratory- scale column.

test #

openA- 1 8 openA- 19 openA-20 openA-2 1 openB- 14 openB- 1 5 openB- 16 openEl- 1 7 openB- 1 8 openB- 19 openB-20 openB-2 1 packA-5 packA-6 packA-7 packA-8 packB- l 1 pack& 12 packB- 1 3 packB- 14 packB- 1 5 packB- 16 packB- 1 7 packB- 1 8

packNO- 10 packN0- 1 l packNo- 12 packNo- 1 3

consistencv ash content feed - 1-35 1.36 1.23 1.28 1.32 l .33 1.34 1.36 1-30 1.36 1.12 1.42 1-38 1-38 1.34 1.37 1.28 1.34 1.3 1 I.30 1 -44 1.31 1.40 1-44 1-34 1-26 1.32 1.34

accepts 0.97 0.97 O -92 0.90 0.89 0.90 0.92 0.9 1 0.8 1 0.92 0.99 0.93 0.94 0.89 0.96 0.96 0.86 0.90 0.88 0.9 1 0.94 0.92 0.93 0.95 0.88 0.89 0.88 0.88

rejects - 0.37 O .4O 0.43 0.36 0.3 8 0.39 0.28 0.32 0.17 0.3 1 O .45 0.42 0.37 0.39 0.3 7 0.43 0.22 0.23 0.18 O. 16 0.3 1 0.25 O -29 0.30 o. 18 0.20 0.22 0.2 1

feed accepts - 8.18 8.15 8.59 8-34 9.90 9.73 8.94 8.63 9.16 10.16 10.05 10.62 8.98 9.74 13-02 8.97 9.68 9.3 1 9.57 8.86 8.09 7.37 7.3 8 7.48 9.75 10.13 10.19 10.47

rejects

53.18 54.0 1 5 1 .j6 5 1-07 49.05 18.58 47.76 46 .X 49-50 47.78 52.55 53 2 5 52.32 55.13 54.4 1 53.18 45-49 45.62 44.32 42.89 44.39 45.69 46-82 45.0 1 44.62 44.19 45.07 45.26

Table D.8a Pulp flowrate and standard deviation data for the comparative work in the laboratory-scale column.

- test #

openA- 1 8

std. dev. of pulp flowrate (mus) W. water

17.63

pulp fl owrate (mVs) feed

45.94 accepts 63.10

feed 3.1 1

- -- -

rejects 4.72

W. water 1.76

accep& ---- 2.97

rejects 0.7 1

Appendices 79

Table D.8b Continuation from Table D.8a.

pulp fl owrate (mus)

2

-

std. dev. of DU fl owrace (mus) W. watei -

17-63 17.63 17.63 17.63 17.63 17.63

W. watei feed test #

openB- 16 openB- 17 openB- 18 openB- 19 openB-30 openB-2 1 packA-5 packA-6 packA-7 packA-8 packB- 1 1 packB- 12 packB- 1 3 packB- 14 packB- 15 pac kB- 1 6 packB- 1 7 packB- 1 8 ackNO- 1 0 ackNO- l 1 ackNO- 1 2 ackNO- 13

feed - 40.57 39.71 43 -25 43 -77 47.6 1 37.47 41.51 40.96 41.71 42-13 58.29 42.98 30. 12 32.0 1 41.35 43-37 38.86 46.52 38.97 51.35 38.35 45.06

rejects - 3 -58 3 -80 6.55 5.61 4.80 5 -55 5-54 5. I6 5.09 3 -94 4.12 3 -89 3.77 3 2 0 5-30 5.79 5.45 5.3 1 2.55 2.3 I 2.37 2.63

accepts - 4.98 4.27 3-96 6.55 4.30 4.19 2.85 1.66 1.55 3.1 1 12-05 5.04 2.75 2.7 1 6.45 8.27 5.73 8.53 3-46 3-57 3.38 3 .O7

-

rejects - 0.54 0.57 0.98 0.84 0.72 0.83 0.83 0.77 0.76 0.59 0.62 0.58 0.57 0.48 0.80 0.87 0.82 0.8 1 0.38 0.35 0.36 0.39

Table D.9a Corrected pulp flowrate data and organic loss results for the comparative work in the laboratory-scale column.

test #

openA- 1 8 openA- 19 openA-20 openA-2 1 openfl- 14 openB- 15 openB- 16 openB- 17 openB- 18 openB- 19 openB-20 openB-2 1 packA-5 packA-6 packA-7 packA-8

mUs) rejects -

4.6 5.2 4.0 4.9 3 .O 3.6 3.6 3.8 6.6 5.7 4.8 5 -6 5.5 5.1 5.1 3 -9

~rganic loss ('w 1.39 1.69 1.65 1.63 1 -22 1.5 1 1 . IO 1.28 1.21 1.79 2.28 2.48 1.90 1.78 1.72 1.58

corrected pulp fl owGte feed N . watec accepts -

61.4 58.8 60.1 58.9 55.0 53 -7 53 -3 55.0 5 1.5 55.1 49.1 47.8 54.1 54.4 54.2 55.0

Appendices 80


1 1 corrected pulp flowrate (mus) organic loss r accepts rejects (%)

57.7 4.1 0.96

test # feed

Table D.10 Consistency and ash data for the comparative work in the pilot-scale

packB- l l packi3- 12 packB- 13 packB- 14 pack& 1 5 packB- 16 packB- 17 packB- 18

packNo- 10 packNo- 1 1 packNo- 12 packNO-13

column.

- 44.4 40.6 40.8 39.7 36.5 3 9.6 35.7 42.8 40.0 39.0 38.3 38.6

test # feed consistency (%)

accepts

1 .O5 1 .O0 0.98 0.88 0.84 0.92 0.86 0.89 0.93 0.90 0.89 0.77 0.85 0.74 0.72 0.82 0.62 0.77 0.84 0.82 0.88 0.8 1 0.94 0.92 1-16

rejects

4-13 I .99 2.33 2-76 3-5 1 3 .O4 1.95 1.64 1.47 0.65 0.84 0.75 0.57 1.65 3.74 0.75 0.57 0.86 0.66 0.70 0.65 0.70 0.63 0.83 0.78

ash content (?/a)

feed

1 1 .O7 10.60 9.16 8.75 9.76 8.48 9.16 8.77 9 20 9.89 9.73 8.80 9.4 1 10.00 9.77 10.80 10.40 9.96 10. IO 1 0.20 9.75 8.65 8.8 1 9.86 9.15

rejects

41.10 40. IO 37.30 39.50 40.02 40.00 40.90 39-50 40.00 38.45 40.99 4 1.44 42. t 5 4232 44.99 43 -90 3 1.67 38.14 37.46 38.55 40.8 1 37.10 38.70 40.70 40.50

Appendices s 1

Table D . l l Pulp flowrate and standard deviation data for the comparative work in the pilot-scale column.

test #

open50- 1 open50-2 open50-3 open504 open50-5 open50-6 open50-7 open50-8 open50-9 pack50- l pack50-2 pack50-3 pack504 pack50-5 packS0-6 pack50-7 pack50-8 pack50-9 1ack50- 1 0 ~ack50- I l jack50- 12 1ack50- 13 ~ack50- 14 1ack50- 15 JackSO- 16

pulp flownte (Vmin) feed -

46.17 JI -84 38.79 39.58 44.62 5 1.93 51.13 38.76 35.50 35.08 44.62 3 1.55 34.73 37.37 35.54 35.17 3 1.35 29.48 39.22 47.27 42.26 32.5 1 37.36 44.6 1 44.40

W. water - 1 8.50 18.50 I 8.50 18.50 18.50 f 8.50 18.50 18.50 18-50 2 1.60 2 1.60 2 1.60 2 1.60 2 1.60 2 1-60 2 1-60 20.20 20.20 20.20 20.20 20.20 20.20 20.20 20.20 20.20

accepts - 5 1-09 44.33 46.59 46.9 1 46.96 47.18 47.26 47.7 1 47.84 46.7 1 43.39 42. IJ 45.3 1 45.79 45.03 46.36 38.8 1 35.92 40.48 44.99 44.72 44.22 47.43 52.93 52.77

rejects

O .44 0.92 0.63 0.70 0.28 0.35 0.78 0.68 0.76 1.12 1-06 1.69 1.79 1.50 1-37 1.66 0.88 1.77 1.45 1.1 1 1.64 1 .52 0.95 1.58 2 . I O

std. dev. of pu1 flowrate ( I/rnin) feed W. water acce pts -

5.90 0.27 0.43 0.40 0 -42 0.45 0.54 0.42 0.28 1 .1 1 4-23 2.90 1.51 0.20 0.28 0.27 9.42 5.25 2-13 0.29 0.5 1 0.18 4.08 2.15 4.76

-

rejects

0.07 O. 14 0.09 0.1 1 0.04 0.05 0.12 o. 10 0.1 1 O. 17 0.16 0.25 0.27 0.22 0.2 1 0.25 0.13 0.19 0.22 O. 17 0.25 0.23 0.14 0.24 0.32

Table D.12a Corrected pulp flowrate data and organic loss results for the comparative work in the pilot-scale column.

test #

open50- l open5O-2 open50-3 open504 open50-5 open50-6 open50-7 open50-8 open50-9

corrected pu111 flowrate (mus) 1 organic loss feed

38.4 29.9 3 1.3 x . 4 29.9 30.5 30.8 33.7 33.2

accepts

54.5 44.3 46.7 47.1 47.0 47.3 47.4 47.9 47.9

rejects 1

0.7

0.4 0.8 0.7

Appendices 82


test #

pack50- l pack5O-2 pack50-3 pack504 pack50-5 pack50-6 pack50-7 pack50-8 pack50-9

pack50- 10 pack50- i l pack50- 12 pack50- t 3 pack50- 14 pack50- 15 pack50- 16

corrected pulp flowrate (mus) feed

29.9 25.8 28.8 30.7 30.5 31.0 30.4 26.3 29.5 33.9 31.2 37.2 28.9 25.1 38.8 41.2

- -

W. water

18.7 21.0 19.3 18.2 16.9 15.6 17.8 19.9 15.3 19.2 16.8 19.2 16.9 20.8 18.1 19.2

-

accepts

Table D.13 Consistency and ash data for the mechanical cells.

test #

cellsO-3 ceilsO-5 ce llsO-7 cellsO-9 cellsP- 1 cellsP-3 cellsP-5 cellsP-7 cet1sP-9

cellsP- l l celIsP- 1 3 celIsP- 15

feed

1.28 1.22 1.28 1-29 1.4 1 1.15 1-10 1.12 1.24 1.28 1.27 1.28

consistency (%)

accepts

1.14 1 .O6 1 .O6 1.12 1.21 1 .O0 0.97 0.99 1 .O6 1 .O4 1 .O6 1.10

rejects

2.24 1.46 2.0 1 2.39 2.67 2.55 3.36 4.93 1.69 1.89 1.47 3 -34

- --

organic loss (%)

1.16 1.69 Z,46 1.76 5.04 9.5 1 2.3 5 1.01 2.10 2.39 1 .O7 I .92 2. I O 1.16 1.76 2.02

feed

9.16 9.76 9.16 9.20 9.89 8.80 10.00 lO.80 9.96 j0.20 8.65 9.86

ah content (96) 1 accepts

7.5 1 6.60 7.04 7.35 5.44 7.28 8.32 8.90 7.62 7.6 1 7 20 7.98

Appendices 8 3

Table D.14 Pulp flowrate data and organic loss results for the mechanical cells.

test #

cellsO-3 cellsO-5 ceilsO-7 cellsO-9 cellsP- 1 cellsP-3 cellsP-5 cellsP-7 cellsP-9 cellsP- 1 l celIsP- 13 cellsP- 15

pulp flownte (Vmin)

feed

1 5000 15000 15250 15393 15250 15350 15405 1504 1 14200 15 100 15250 15000

rejects

2130 3130 2130 2130 1860 1860 1860 1860 1860 1860 1860 1860

std. dev. of flowrate (Vmin)

feed

325 3 02 3 89 3 O0 357 3 76 343 2 22 432 3 29 3 58 3 10

rejects

300 500 300 300 300 300 3 O0 3 O0 300 3 O0 300 3 O0

:orrected flowrate ( Vmin)

feed

15123 15245 15009 15587 14990 1536 t 15503 14870 1.1665 15083 14932 15287

rejects

1960 2005 1971 1983 1 745 1860 i 698 1943 1887 1702 1899 1785

organic

loss ('36)

9.18 9.00 8 -92 9.5 1 5.96 7.66 7.76 8.50 8.28 7.23 9.28 8.47

Appendices 84

Ap~endix E

Table E.l Bubble size and surface area generation rate data for tests performed in open laboratory-scale column.

test r#

openA- 1 openA-2 openA-3 openA-4 openA-5 openA-6 openA-7 openA-8 openA-9

openA- 10 opewl- 1 1 openA- 12 openA- 13 openA- 14 openA- 15 openA- 16 openA- 1 7 openB- l openB-2 openB-3 openB-4 openB-5 openB-6 openB-7 openB-8 openB-9 open& 10 openB- 1 1 openB- 12 openB- 13

Ubt (cms)

10.34 22.72 8.66 17-44 9.88 10.05 8.8 1 5.2 1 9.27 5.48 5 -49 10.06 10.60 1 0.44 1 O. I6 1 1.35 1 1.89 30.66 26.68 36.95 40.12 21.15 26.77 27.41 25.08 2 8.95 28.87 25.93 29-15 28.4 1

db (cm)

0.08 0.38 0.05 0.22 0.07 0.07 0.06 0.05 0.06 0.05 0.05 0.07 0.08 0.08 0.08 0.09 0.10 0.68 0.52 0.99 1.17 0.7 1 0.52 0.55 0.46 0.6 1 0.6 1 0.49 0.62 0.59

Sb (s")

Table E.2 Bubble size and surface area generation rate data for tests performed in packed laboratory-scale column.

test + packA- 1 packA-:! packA-3 packA-4 packs- 1 packB-2 packB-3 packB-4 packB-5 packB-6 packB-7 pac kB-8 packB-9 packB- 10 packNo- 1 packNo-2 packNO-3 9ackNO-4 ?ackNO-5 ?ackNO-6 2ackNO-7 3ackNO-8 ~ackNO-9

Ubt (crnls)

17.46 16.2 1 1 1.94 1 6.22 24.72 32.93 22.58 29.52 38-53 2?.60 25.85 29-10 25.28 28.92 27.87 54.70 3 1.79 58.17 36.3 1 35.64 35.75 56.1 1 3 5.29

db (cm)

0.22 O. 19 0.10 O. 19 0.44 0.79 0.37 0.63 1 .O8 0.55 0.6 1 0.62 0.58 0.6 1 0.57 0.88 0.74 1 .O6 0.96 0.92 0.93 0.95 0.9 1

Appendices 86

Table E 3 Bubble size and surface area generation rate data for tests performed in pilot-scale column.

Ubt tcms i 33.80 32.9 1 35-80 33.73 3 1.96 34.97 32.03 30.75 30.75 34-45 36.86 34.46 32.77 30.04 29.03 30.3; 29.90 28.66 27.93 30.05 j0.07 29.87 2 1-24 32.59 32.30

db (cm

0.83 0.79 0.83 0.83 0.74 0.89 0.75 0.69 0.69 0.86 0.99 0.86 0.78 0.66 0.6 1 0.67 0.65 0.60 0.57 0.66 0.66 0.65 0.7 1 0.77 0.76

Appendices 87

Appendix F

Table F.l Surnmary of pilot column scale up.

packed P.F.

1 ?.F.D. = plue

OP=" - P.F.D. 12.29 0.2 1 0.5 3.35 0.1 1 2.92 0.10

47.63 2.18 5.1 1 0.75

3.6493 3.58 14 1.635 1

packed (no sparger) P.F. 1 P.F.D.

- P.F.D. 13 -36 0.28 0.5 2-41 0.1 1 2.75 0.38

U.60 2.55 6.22 0.75

0.713 1 0.6508 0.709 1

r exp (min) (min- l ) dc (m) Hc (m)

&3

J, (CITUS)

I, (cm5 1

Q, (cm's) Nd a

Rf Rc

M c theo 1 MC exo J

low dispersion and P.F. = plug flow) , . i:

* model refers ro the scale up model

Table F.2 Summary of industrial columns. Feed flow to one bank of cells = 15000 Vmin; feed throughput = 282 tonnedday ( 1 3 % consistency).

I packed

sparger = colurnns

dc (rn) Hc (rn) r (min)

kc (min-1)

&3

Qf (Vrnin) Qw (Vminj Qa (L'min)

J, (cmfs) Jr ( C ~ S )

J, (cm%) J, (cms)

Rf Rfc

Rc req Nd a

Rc cal

Appendices 88

Table F.3 Detemination of rate constant in open laboratory column using sparger

tcst tr 1 tlow (mus) 1 dcnsity (g/ml) 1 consisrcncy 1 ERIC (ppm) 1 (min) rlf(?i) Rc(%l kc (min*') 1

openA-5 optnA-6 operu\-7 openA-8 openA-9

opcnA-l0

Table F.4 Determination of rate constant in open laboratory column using sparger

test # ( tlow (mus) 1 density (g/mt) 1 con

I 1 fecd 1 acce~ts 1 feed 1 acceots 1 feed

fecd 32.1 107.5 61.3 33.8 78.1 57.0

accepts - 0.57

accepts

66.1 116.6 69.8 39.1 87.3 53.7

fecd 1.003 1.003 1.003 1.003 1.003 1.003

acccpn 1 .O02 1.002 1.002 1.002 1.002 1 .O02

ERIC (pprn)

Table F.5 Determination of rate constant in packed laboratory column using sparger B.

(?/O)

test rt

- pack04 packB-7 packB-8 packB-9 pack&

1 O

feed 1.24 1.28 2 1.28 1.32 1.26

feed 763.84 815.96 765.38 835.21 747.27 668.81

t (min)

feed 767.1 1 833.62 853.30 835.36 849.00 864.99 836.31

tlow (ml/s)

accepts 0.89 4 1.03 0.84 1.13 0.97

accepts 5

124.00 148.61 143.16 146.82 151.73 138.54

5.42 8.98 3 47 6.04 i 1.73 4.76 7.97

accepts 301.76 236.25 408.18 31 1.06 285.86 428.86 31 1.31

densit

feed - 1 .O03 1 .O03 1 .O03 1 .O03 1.003

etT(?/o)

acccprs fced accepts 1.002 1.18 0.87

60.66 71.66 52.16 62.76 66.33 50.42 62.78

ERtC (ppm) r {min) etT(94) Rc(%) kc (min")

Rci?/o)

feed accepts 1 1

819.21 154.95 1 5.00 68.88 74.20 0.38

kc (min")

61.73 72.55 55.71 63.83 67.74 50.87 65.67

Table F.6 Determination of rate constant in packed laboratory column using no sparger.

0.23 0.20 0.29 0.23 O. 13 0.18 O. 18

cff (%) Rc(%) kc (min")

IMAGE EVALUATION TEST TARGET (QA-3)

APPLIED IWGE . lnc - = 1653 East Main Street -. - Rochester. NY 14609 USA -- -- - - Phone: i l 6i482-0300 -- -- - - Fa : 71 6/288-5989

O 1993. Applied Image. Inc.. Ail Rights Reserved

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