Maelgwyn Imhoflot (Chile)

7/29/2019 Maelgwyn Imhoflot (Chile)

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PNEUMATIC FLOTATION TECHNOLOGY - EXPERIENCE IN THE CHILEAN MININGINDUSTRY

Eng. M.Sc.Eng Samuel Snchez-Pino,Ingeniera de Minerales S.A. General Manager1423 Ave. Padre Alberto Hurtado

Antofagasta, [email protected].

Dr. Eng. Rainer M. Imhof,Julian Brown C. Eng,Maelgwyn Mineral Services LimitedLeharweg 23, Dorsten 46282, Germany and4a Mostyn Street, Llandudno, Wales, U.K., LL30 [email protected]

Eng. Samuel Snchez-Baquedano, Flavio Rojos-Tapia,Ingeniera de Minerales S.A. Process Metallurgist1423 Ave. Padre Alberto Hurtado

Antofagasta, Chile

Key Words: Flotation, Pneumatic Flotation, Copper Flotation, Quartz-Silicate Flotation.

ABSTRACT

Pneumatic flotation was introduced to the Chilean copper mining industry in 1993 byIngeniera de Minerales S.A., being first implemented in 1994/95. The technology is based on thedesigns of Dr. Rainer Imhof and from Chilean copper processing experience.

Pneumatic flotation has been successfully applied for sulphide and oxide copper

minerals, copper slag, iron ores (reverse flotation) and gold, and also appears promising formolybdenum concentrates. Difficult separating conditions have been encountered in variousprocess stages, including roughing, cleaning and scavenging. Pneumatic flotation can essentiallybe applied in any separation where differences exist between mineral and gangue interactionswith water. Even high relative density slurries can be processed because the range of amenableparticle sizes is quite broad, and the number of cleaning stages required has not exceeded one inour experience.

The performance efficiency of this technique can be explained by the high gas hold-upand the effective micro-turbulences which boost attachment to the bubbles, resulting in muchreduced flotation time. Economic benefits include lower energy consumption, lower maintenancecosts, simplicity and reliability and minimal plant area requirements.

In view of the Chilean mining industry experience, it can be concluded that pneumaticflotation can be regarded as a highly effective alternative to conventional methods in mineral

processing.


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INTRODUCTION

The technology originates from pneumatic flotation developments in the 1970s inGermany by Prof. Simonis (Technical University of Berlin) and Prof. Bahr (Technical Universityof Clausthal). Since then Dr. Rainer Imhof has been known widely for his contributions to designat Ekof, KHD, Allmineral and most recently Maelgwyn Mineral Services where he is TechnicalDirector (Imhof, 1998). Ingeniera de Minerales S.A. has been involved with the technologydevelopment by Dr. Imhof for more than ten years and is broadly experienced with flotation, fromWits University and Mintek in South Africa (Snchez, 1990).

There are many academic treatise available concerning the separating phenomena andmethods for better control in traditional flotation. Pneumatic flotation, however, is a viable meansto separate feed conditions, particle and bubble interactions, and phase separations (froth andtailings). In combination this provides a completely different flotation concept with the flexibilityand simplicity for a realistic alternative in the Chilean mining market.

The first plant using this kind of flotation technology was in 1993/94 as a means toprovide a fast separation of sulphide and to re-use existing mechanical cell circuits to float oxidecopper. In this way only two rougher cells were required, and together with one cleaner stage,

were sufficient to float sulphide to sale quality (Snchez, 1997). Flotation of slag containingaround 1% copper was another important application, with two rougher cells working in seriesand a single stage cleaner incorporating two cells in series, for 3300 tons/day (Barrera, 1996).Both of these industrial applications used sea water.

Modifying an old-style flotation plant consisting of two circuits to float chalcopyrite andgold provided us with an interesting experience to see how effective the change could be whennew technologies are used. The two circuits processed 18,000 tons per month (600-700 t/d),using 30 cells in total including rougher-scavengers, eight cleaners two re cleaners. With theaddition of two rougher cells and one cleaner stage with two cells in series this increased capacityto 2,300 t/d, (Tapia, 1995).

One of the largets pneumatic flotation plants in the world is now working in Chile, toremove silica and silicate from magnetite concentrates. The plant has a capacity of 13,390 t/d ofintermediate concentrate, a slurry density of 1.47 (40 % solids), and a specific gravity of solid of

5.05 working with sweet water. The plant is a stand-alone flotation circuit and is fully automated(Melendez, 2002).

PNEUMATIC FLOTATION DESIGNFlotation technology could be categorised into mechanical agitation cells, column cells

and pneumatic cells, the latter which were developed mainly in Germany in the 1970s. ProfessorsWolfgang Simonis and Albert Bahr developed Jet Flotation (Simonis, 1981) and the Bahr cell(Bahr, 1982) mainly for coal. Imhofs designs, however, have been implemented for a wide rangeof industrial applications in the world including metallic and industrial minerals. Most industrialminerals applications are in Europe, and most metallic mineral applications are in Chile.

Fig. 1 2 illustrate the main designs from Imhof, and which are used in the mineral

industries worldwide. The principle feature of the technology is a separate device for the aerationunit from which the outlet mixture flows into the separating vessel, where the slurry particles arepredominantly in close bubble contact. The separator uses a high gas hold-up and effectivemicro-turbulences in the medium which boost particle-bubble contact, while ensuring no deadzones and very short residence times.

The self aspirating aeration unit at the top of the cell is an important component of thistechnology. The slurry is pumped with enough fluid energy to induce a large quantity of air in theform of fine bubbles with extensive micro-turbulences. Due to the high velocity in the device


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silicon carbide (SiSiC) components are required to avoid wear. Normally the slurry pressure forfeed to the aeration unit is 2 2.5bar.

Consequently, the conditioning time of the slurry is more important, due to the shortresident time with high gas hold up. The particles have to be prepared for collision andattachment before entering the vessel. The froth separation process involves lower turbulence toavoid entrainment of gangue particles in the concentrate.

A further useful feature of the technology is the froth and interface level control, forexample the froth height can be varied easily with a precision of 2-3 cm through a range to 140cm, which is a parameter for the enrichment factor. The cross sectional surface area for frothremoval is also variable according to the mass to be removed with the froth and the kind of frothin question in other words: for scavenging low froth thickness and small areas are required forthe froth to flow, and for cleaning high froth thickness and large areas are required.

Recycling a portion of the cell tailings discharge, such as in a mill circuit, provides the means toincrease recovery in the same cell. In this way it is possible to reduce the number of cells inseries, i.e. 2 instead of 3 for the same recovery. Furthermore the high gas hold up in the down-comer promotes recovery. The fast kinetics of pneumatic flotation make it possible to operate withshorter and fewer circuits to produce optimal products. In our experience two cells for roughing

are sufficient. In most applications the primary concentrate is of sufficient grade that only a singlecleaner step with 2 cells in series is required.

Fig. 2 shows a completely different cell. Because low residence time is already achieved for theaeration and collection process the greatest time dependence is the residence time to separatebubbles from slurry in the vessel. Sedimentation and buoyancy are the main parameter toseparate bubbles, so the forces are multiplied in the centrifugal field and accelerate theseparation dramatically. The retention time of the slurry in this system is only about 25 30 s,which results in small apparatus with high capacities.

Fig. 1 Second Design In Chile (1996-2002)


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Fig. 2 Third Design In Chile (2003)

INDUSTRIAL APPLICATIONS IN CHILE

MINERA MICHILLA S.A.

The company Minera Michilla is located about 1400 km north of Santiago in the coastal

zone of the Atacama desert. The process plant was normally supplied with a wide range ofgrades and different type of minerals from a variety of underground and open pit mines in thecompany. Compositions ranged 2.6 3.4 % Cu total, 1.9 2.6% Cu sulphide and 0.9 0.6% Cuoxide, and sea water was used. Common mineralogy included chalcocite, bornite, covellite,chalcopyrite, atacamite, and chrysocolla, (Fuentes, 1995)

In order to increase oxide recovery and simultaneously to improve the performance of sulphidematerial in the process with a low investment, Michilla chose to introduce pneumatic flotation: twocells operated as roughers and a single third one cleaned the rougher concentrate in one step.The old mechanical circuit continued to process oxides after treatment with sodium sulphide. Forhigher feed grades there still remained the option to use the old mechanical cleaners, which wereearlier needed for cleaning, before pneumatic flotation was implemented. After a while, pneumaticflotation was introduced in the oxide flotation circuit.

The conventional circuit changed with the time and its evolution can be observed as follows:


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Fig. 3 Original mechanical cells circuit (only sulphide flotation)

Fig. 4 Initial pneumatic cells circuit( oxide and sulphide concentrate production and higher throughput)

Fig. 5 Second pneumatic flotation circuit (sulphide and oxide)


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Table 1Rougher Tests (single pneumatic cell)

TEST FEED TAILING SULPHIDE CONCCu wt% Cu wt% Cu wt%

Total Sol Insol Total Sol Insol Total Sol Insol

1 2.82 1.61 1.21 1.51 1.21 0.3 19.88 3.73 16.15

2 3.33 1.11 2.22 1.61 0.96 0.65 17.25 2.27 14.98

3 3.33 1.26 2.07 1.41 0.86 0.55 32.68 3.03 29.66

4 3.73 1.21 2.52 1.82 1.05 0.76 22.6 2.42 20.18

TESTCOPPER

RECOVERYGENERAL

CONDITIONSTotal Sol Insol

1 50,27 36,77 76,63 SOLIDS % w/w 27 - 42

2 56,97 23,42 73,93 % -200# Ty 46 - 33

3 60,26 44,33 74,82 % +65# Ty 12 - 18

4 56,69 22,06 72,57 pH 9.5 - 10.5

Table 2Comparison between both plant configurations illustrated: mechanical cells only (Fig. 4) andmixed circuit (Fig. 5)

TEST FEED TAILING SULPHIDE CONC OXIDE CONCCu wt% Cu wt% Cu wt% Cu wt%

Total Sol Insol Total Sol Insol Total Sol Insol Total Sol Insol

1 4.48 1.49 2.99 1.34 1.02 0.32 42.05 7.01 35.04

2 4.47 1.08 3.39 1.25 0.84 0.41 43.09 4.06 39.03

3 3.53 1.18 2.35 0.78 0.75 0.03 42.48 3.58 38.90 6.52 3.74 2.78

4 3.33 1.00 2.33 0.70 0.67 0.03 50.35 4.65 45.70 5.38 2.28 3.10

5 4.24 0.95 3.29 0.59 0.56 0.03 49.14 3.44 45.70 6.44 4.05 2.39

6 4.43 1.05 3.38 0.87 0.72 0.15 46.41 2.73 43.68 7.23 4.20 3.03

TEST COPPER RECOVERYGENERAL


1 72.28 36.33 90.14 SOLIDS % w/w 36 - 38

2 74.20 28.81 88.73 % -200# Ty 48 - 45

3 81.13 43.54 98.02 % +65# Ty 20 - 25

4 81.27 39.95 98.95 pH 8.3

5 87.77 48.22 99.21

6 82.87 40.32 96.11


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Fig 6. Pneumatic cells at Michilla

Fig. 7 Overall comparison of technology effects (Snchez, 1997)


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Fig. 8 Third pneumatic flotation circuit sulphide and oxide

Table 3Results from Third Pneumatic CircuitThe table indicates results from the alternative circuit which was tested at production scale, inorder to improve the oxide concentrate grade.

TEST FEED TAILING SULPHIDE CONC OXIDE CONCCu wt% Cu wt% Cu wt% Cu wt%

Total Sol Insol Total Sol Insol Total Sol Insol Total Sol Insol

1 2.86 0.83 2.03 0.57 0.48 0.09 45.40 2.51 42.89 23.00 15.88 7.12

2 2.46 0.74 1.72 0.57 0.42 0.15 39.19 1.88 37.31 28.34 20.13 8.21

3 2.40 0.47 1.93 0.55 0.37 0.18 47.80 1.49 46.31 13.80 2.92 10.88

TEST COPPER RECOVERY

GENERAL


1 81.26 45.62 95.8 SOLIDS % w/w 36 - 43

2 78.11 46.41 91.8 % -200# Ty 48 - 55

3 77.78 23.23 90.96 % +65# Ty 20 - 25


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The application of this technology at Minera Michilla S.A. improved flexibility in the circuits at highcapacity allowing the plant to adapt to changes of grades and mineral compositions. For bothkinds of product, sulphide and oxide concentrate, the production was increased from 2.4 t/h to arange of 4.0 5.2 t/h. Throughput of the plant increased from 40 t/h to 80 t/h and sometimes evenup to 100 t/h.

2.- COMPAA MINERA TAMAYA S.A.

Minera Tamaya is located about 450 km north of Santiago de Chile. An expansion project wasinitiated to increase capacity from 18,000 t/m to 23,000 t/m treatment rate for a chalcopyrite gold mineral ore (Tapia, 1995).

Pilot tests were conducted under production conditions in order to evaluate pneumatic flotationtechnology. Two parallel circuits with mechanical cells normally operated in production, due to theplant feed originating from different mines, with different grades and mineralogy. Fig. 9 shows theoriginal conventional circuits with mechanical cells.

Fig.9 Mechanical cells circuit

The overall tests results are shown in Table 4 where one of the conventional industrial circuits iscompared with one pneumatic cell.


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Table 4Single pneumatic cell performance

Comparison of single pneumatic cell with mechanical circuit type 2

MINERALOGY Au RECOVERY % Cu RECOVERY %Pneumatic Mechanical Pneumatic Mechanical

A 77.2 78.79 84.63 82.62

B 59.38 56.24 53.43 50.94

C 63.06 78.93 36.37 56.64

D 86.62 83.38 92.66 83.99

Additional pilot tests were conducted treating the tailings from the same industrial circuit (seeTable 5).

Table 5

Tailings treatment with pilot pneumatic cell from type 2 circuit

GRADES RECOVERY % CONC RATIOAu (g/t) Cu (tot %) Au Cu (tot) Au Cu

Feed 0.6 0.14 54.29 22.57 11.67 69.00

Concentrate 3.8 2.18

Tailings 0.3 0.11

Feed 0.5 0.05 43.00 22.86 20.00 28.00


Tailings 0.3 0.04

Feed 0.5 0.06 42.03 17.58 29.50 91.00


Tailings 0.3 0.05

As a consequence of the pilot scale tests, Minera Tamaya decided to change the mechanical

flotation circuits to pneumatic flotation, also drawing on the experience at Minera Michilla, whichbelongs to the same company.Both mechanical circuits (see Fig. 9) were changed to pneumatic flotation (see Fig. 10) whichcomprised two pneumatic cells of 2.5 m diameter in series as roughers, and two cells of 2.0 mdiameter in series as cleaners.


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Fig. 10 New pneumatic flotation plant at Tamaya (800 t/d)

Table 6Feed circuit No. 2 rougher flotation comparison

GRADES RECOVERY % CONC RATIOAu (g/t) Cu (tot %) Au Cu (tot) Au Cu

Pneumatic Cell

Feed 3.4 1.11 72.63 82.72 24.70 24.51

Concentrate 61 22.5

Tailings 0.97 0.2

Feed 7 1.05 72.24 81.85 35.00 21.14

Concentrate 177 18.17

Tailings 2 0.2

Feed 9.1 0.52 71.63 77.51 38.63 39.20


Tailings 2.65 0.12

Average 72.17 80.69 32.78 28.28

Mechanical circuit

Feed 5 1.22 92.19 93.61 5.92 7.46


Tailings 0.47 0.09

Feed 9.45 1.03 89.66 93.24 7.84 7.69


Tailings 1.12 0.08


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(Table 6 cont.)

Feed 9.5 0.62 88.83 87.77 6.33 6.34


Tailings 1.26 0.09

Average 90.23 91.54 6.70 7.16

The new Tamaya flotation concentrator, comprising only pneumatic cells, improved productioneconomics dramatically. Additionally the plant was highly flexible, with low maintenancerequirements, and contained in a compact area with a high degree of automation.

3. COMPAA MINERA MAITENES

The Los Maitenes concentrator treats copper slag arising from Empresa Nacional de Minera

Smelting, which belongs to the government. The plant is located 150 km north-west of Santiagode Chile. Basically the project requirements were to process 3000 t/d, containing 1.30% totalcopper, with a grind of 90% -200 mesh (Tyler) for the feed, at 30% solids (w/w) pulp density usingsea water.Pneumatic flotation laboratory scale tests provided results (Table 7) which demonstrated thepotential of an alternative to conventional flotation. Samples from the slag dump were used forthe testing. In conclusion the circuit of Fig. 11 was proposed to Los Maitenes, to be a fullyautomated plant (Barrera, 1996). The initial results from the plant were somewhat different toexpectations, in terms of recovery, while product grade was acceptable in the range of 25 27 %Cu total. The lower than anticipated feed grade was considered to be partially responsible, as itwas only in the range of 1.10 0.91% Cu total, and also the grind size of only 80 % -200 mesh.This meant that liberation was insufficient, and hence recovery was lower than expected.

The problem was concluded to be caused by the mineral grain size in the slag. Rapid quenchingof the slag after the smelting process produces ultra fine metallic Cu particles and effectively onlya grind to more than 90 % -200 mesh would have improved the recovery.

Table 7Preliminary results from conceptual analysis

FlotationProcess ROUGHER CLEANER SCAVENGER RECLEANER TAILINGS FEED

Rec.% Cu %

Rec.% Cu %

Rec.% Cu %

Rec.% Cu % Cu % Cu %

1 83 7.99 91.00 10.44 85.60 0.84 56.90 23.10 0.24 1.24

2 77.2 5.66 89.2 9.35 87 0.78 55.4 21.25 0.32 1.24


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Fig. 11 Proposed circuit to float copper slag

Fig. 12 Industrial slag flotation Plant ( 3,000 t/d)

CODELCO CHILE DIVISIN CHUQUICAMATA

An industrial pneumatic flotation cell of 4.5m diameter is already operating at theMolybdenum Plant at Chuquicamata. Intensive testing was carried out at a normal feed rate tothe Moly Plant, i.e. 250 m

3/h to 400 m

3/h slurry with usual feed variations. Flotation products were

recycled to the large capacity storage tank. The range of conditions shown in Table 8 present an


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overview of normal operations. Additionally the height of froth was tested between 40 - 140 cmand, using a wash water device it was possible to increase the concentrate grade to contents of36% Mo even though the wash water distribution was not optimised.

The main target for integration of the cell in the production circuit was to test the cell as apre-rougher to see whether the high consumption of NaSH can be reduced. NaSH is used todepress the chalcopyrite in the mechanical flotation cells. The results were positive, due to therapid kinetics of the pneumatic flotation process.

The performance analyses of the campaigns were carried out by engineers fromChuquicamata. The commercial interest is to extend the existing mechanical flotation by using thepneumatic cell and to reduce reagent costs while improving the overall performance of theflotation circuit. This means increasing the average recovery by around 5%. The experimentaltests will be continued by operating the cell for a longer period in order to analyse the availability.

Table 8Experimental Parameters on a real

operational base (single cell)

FRESH FLOW (m3/h)

VARIABLES 250 300 400

43,0 37,6 35,0

%SOLIDS (fresh feed) 45,8 46,6 41,5

46,0 51,6 45,5

40,0 36,4 25,8

%SOLIDS (compound feed) 35,8 30,9 37,0

35,5 37,2 35,2

1,524 1,43 1,389

DENSITY (fresh feed) 1,579 1,594 1,497

1,582 1,703 1,572

1,471 1,41 1,277

DENSITY (compound feed) 1,414 1,336 1,416

1,383 1,428 1,396

9,67 9,77 11,45

pH (fresh feed) 9,56 9,31 10,30

9,73 10,02 11,22

11,04 10,98 11,6

pH (compound feed) 11,33 11,07 11,05

11,09 11,44 11,47

5,225 0,498 0,304

Mo grade % (fresh feed) 1,185 0,860 0,552

1,479 1,240 0,478

19,227 12,880 3,768

Mo grade % (concentrate) 10,680 7,720 4,000

10,559 16,950 11,920


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(Table 8 cont.)

3,078 0,320 0,238

Mo grade % (tailing) 0,354 0,342 0,346

0,553 0,656 0,43648,920 36,650 23,170

Recovery Mo % 72,530 48,990 21,810

66,070 63,060 40,850

Fig. 13 Effect of pneumatic flotation working as pre rougher cell in a Mo circuit(Gonzalez, 2002)

Fig. 14 Industrial cell testing at Mo Plant

PRE ROUGHER PNEUMATIC CELL EFFECT

60

65

70

75

80

85

90

95

100

1 2 3 4 5 6 7

RANGE OF ALTERNATIVE

MoRECOVERY

STANDARD FLOTATION CIRCUITWITHOUT PNEUMATIC CELL

STANDARD CIRCUIT WITH

PNEUMATIC FLOTATION

AS PRE ROUGHER


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Fig. 15 Froth from pre rougher pneumatic cell

HUASCO MINING COMPANY

Huasco Mining Co. (CMH) is located about 800 km north of Santiago de Chile. LosColorados mine and the Pellet Plant are the main industrial center in this area. They are ownedand managed by Compaa Minera del Pacfico (CAP) and Mitsubishi from Japan.

In the process development department at CMH pellet plant there has been considerablework on the process for reverse flotation of the magnetite concentrates. Ultimately this improvesthe product for direct reduction. The SiO2 grades in these concentrates may not exceed 1.5%. Itis common in Brazil to float quartz from hematite concentrates with relative ease, but the silicatesin the magnetite ores of the CMH ore bodies contain only a small proportion of quartz. The mainmineral components of the undesirable silicates tend to be rather difficult to float. Extensive tests

in mechanical cells and with columns failed.Magnetic beneficiation has a limited effect in separating silicates from the magnetite, assilicate particles with microscopic inclusions of magnetite are generally recovered, thuscontaminating the Fe-concentrate. The analytical test procedure for magnetic assessment usesthe Davis Tube, which indicates the values of a theoretical separation but which cannot beobtained in a plant. In Table 9, the results from tests with different flotation techniques arecompared (Melendez, 2002). It is obvious that only pneumatic flotation could be feasible.

The designed plant has a capacity of 13,390 t/d of dry mineral feed, with two parallel lines offlotation. Received pulp density is 40% solids (w/w) slurry SG 1.47 - and a size distribution of

80% -45m (325 mesh). Secondary amines are used as collector reagents with Methyl IsobutylCarbinol (MIBC) as frother and starch to depress magnetite.

Each flotation line has three 4.5 m diameter pneumatic cells working in series. Each cell workswith a compound flow of 756 m3/h containing 50% recycle load. Variable speed pumps are usedto feed the aeration units and recycle tailings by controlling the level of slurry in the vessel. Eachcell uses this control philosophy while another control loop manages the feed balance to theconditioning tank for each stream and regulates a discharge pump at the end of each line. Theflotation circuit represents a new concept of plant design and has a local control cabinet per linewith the capability to transfer all process data to the main control room.


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Table 9Comparisons of separation performance.

Components MagneticConcentrate

Flotation Technology

(feed to flotation) Pneumatic Column MechanicalH H dtt C C dtt C C dtt C C dtt

Fe 68.61 69.64 69.18 69.86 68.67 69.61 69.25 69.76

P 0.021 0.019 0.019 0.015 0.027 0.027

SiO2 2.31 1.56 1.67 1.3 2.08 1.47 1.84 1.6

CaO 0.3 0.22 0.27 0.19 0.3 0.39 0.22

MgO 0.69 0.56 0.66 0.51 0.75 0.63 0.51

Al2O3 0.68 0.63 0.65 0.58 0.74 0.68 0.58

V 0.17 0.15 0.17 0.15 0.16 0.16 0.16

TiO2 0.15 0.11 0.15 0.12 0.11 0.1 0.1

(dtt refers to davis tube magnetic separation)

Table 10Test results using preconcentrated RD

Material %Fe %SiO2 %Fe dtt %SiO2 dtt

Feed 64.43 3.84 70.50 1.01

Primary magnetic concentrate 69.66 1.54 70.11 1.31

PILOT TESTS

Magnetic concentrate 69.92 1.42 70.40 1.28

Peumatic flotation concentrate 70.11 1.09 70.48 1.00Final magnetic concentrate 70.48 1.06 70.56 1.00

Table 11Test results using basic preconcentrate

Material %Fe %SiO2 %Fe dtt %SiO2 dtt

Feed 57.99 8.62 70.55 0.96

Primary magnetic concentrate 68.61 2.31 69.64 1.56

Pneumatic flotation concentrate 69.18 1.67 69.86 1.30


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Fig. 16 Reverse flotation plant at CMH iron ore concentrator

Fig. 17 General view of CMH concentrator with flotation plant

Discussion and conclusions

Ten years of work in the Chilean market with pneumatic flotation demonstrates that Imhoflottechnology is a promising industrial alternative. As shown the range of applications is quitediverse, and it is to be expected that these techniques will be increasingly implemented in the


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minerals industry in the near future. The main advantage is the capability easily to adapt to theapplication concerned, and since each cell in the circuit is independent they can be individuallyoptimised. Pneumatic flotation provides a high operational flexibility and can be fully automated.Other benefits include energy, maintenance and investment savings.

The high concentration of bubbles and the intensive use of energy provide a flotation cell with fastkinetics, which, using recycling loads, requires compact plant design.

As a general conclusion it is clear that the pneumatic flotation is a real competitor to conventionaltechnologies in the market of flotation.

References

1- Bahr A., Ludke H, Mehrhoff F., 1982, The Development and Introduction of a NewCoal Flotation Cell, Clausthal University.XV International Mineral Processing Congress, 17 23 October, 1982, .

2- Barrera V., 1996. Experimental slag flotation results using lab pneumatic pilot tests.Technical Report, Antofagasta, Chile.

3- Fuentes B. G., Espoz A. H., 1995, Incorporacin de Nuevas tecnologas de Flotacin enla Planta Concentradora de Minera Michilla S.A.

Proyecto de Innovacin Tecnolgica, Corfo, 1995, Antofagasta, Chile4- Gonzalez L.R., 2002, Pneumatic Flotation Study as a Pre Rougher Cell at the

Molybdenum Plant.Technical Report, Chuquicamata, Chile.

5- Imhof R.M., 1988. Pneumatic Flotation a Modern Alternative.Aufbereitungs Technik 29: 451 458, Weisbaden, Germany.

6- Melndez Mario, 2002, Uso de Celdas Neumticas en Flotacin Inversa de FierroCMP.Taller de Procesamiento de Minerales 2002, Octubre 23-25, Antofagasta, Chile

7- Patent Germany, October 15, 1981; May 5, 1983, Number: DE 314066 A1Prof. Wolfgang Simonis, et al.

8- Snchez-Pino S. E., 1990. New Flotation Technology.Mintek Bulletin 31: Johannesburg, South Africa.

9- Snchez-Pino S. E., 1990. A Comparative Study of kinetics of conventional columnand the co-current downwards flotation column.Witwatersrand University, Johannesburg, South Africa.

10- Snchez-Pino S.E., 1997, Ekof pneumatic Flotation Technology, the alternative forrougher scavenger or cleaner flotation of metallic ores.XX International Mineral Processing Congress, Vol. 3,: 255 263, Aachen, Germany.

11- Tapia S. J., 1995, Pilot Pneumatic Flotation Cell Tests, Study as Alternative to theConventional Flotation Circuit.Technical Report, Cia. Minera Tamaya, Chile.

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Maelgwyn Imhoflot (Chile)