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CHARACTERIZATION OF OIL SANDS MINERALCOMPONENTS AND CLAY-ORGANIC COMPLEXESDavid E. Axelson

a , Randy J. Mikula

a & Zenon M. Potoczny

a

a CRL, Fuel Processing Laboratory,CANMET Energy, Mines and Resources Canada , P.O. Bag

1280, Devon, Alberta, TOC 1E0, Canada

Published online: 31 May 2007.

To cite this article: David E. Axelson , Randy J. Mikula & Zenon M. Potoczny (1989) CHARACTERIZATION OF OIL SANDS

MINERAL COMPONENTS AND CLAY-ORGANIC COMPLEXES, Fuel Science and Technology International, 7:5-6, 659-673, DOI:

10.1080/08843758908962263

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7/25/2019 Axel Son 1989


FUEL SCIENCE TECHNOLOGY INTERNATIONAL, 7 5-6), 659-673 1989)

CEARACTERIZATION OF OIL SANDS MINERAL COMPONENTS

AND CLAY-ORGANIC COMPLEXES

David E. Axelson, Randy J Mikula and Zenon H. Potoczny

CRL, Fuel Processing Laboratory, CANHET

Energy, Mines and Resources Canada

P.O. Bag 1280, Devon, Alberta, TOC 1E0, Canada

ABSTRACT

Differences in oil sands processability and extraction yields

can be dependent upon many factors including the composition of

the mineral components and the organic complexes that are

associated vith certain minerals. These mineral-organic

associations help provide the bridge which leads to carry over of

bitumen with the tailings as well as carry over of water and

mineral matter with the product. The nature of the organic

component of clay-organic complexes extracted from various streams

in an oil sands recovery.process is discussed in relation to the

stability of both vater-in-oil and oil-in-water emulsions formed;

These samples have been studied with nuclear magnetic resonance

NMR), scanning electron microscopy SEM) as vell as vith other

techniques such as interfaciql tension measurements.

INTRODUCTION

fundamental understanding of the origin s) of stable

emulsions would be of invaluable assistance in optimizing the

operation of heavy oil/bitumen recovery plants. Bovever, this

goal requires the establishment of an extensive data base vith

particular emphasis on the effects of both physical froth

Copyriahi 1989 by Marcel Dekker Inc

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660

AXELSON, MIKULA AND POTOCZNY

flotation, centrifugation) and chemical (demulsification)

processes. Although ve recognize the importance of considering

all interactions, the present discussion will confine itself to

the possible role of clay-organic complexes in determining

emulsion stability at various stages of the oil sands extraction

process.

The results presented here represent the some of the

data from an ongoing study, the purpose of which is to provide a

baseline .identification of the nature of the organic materials

complexed to clays in heavy oil upgrading processes. Correlations

with extraction plant performance is one of the goals to

facilitate the prediction of processing behaviour. Although many

samples have been studied representing ideal and bad

extraction performance, the present discussion will focus on

results from samples of feed to the final centrifugation step in

the bitumen extraction process. The general observations which

will be discussed in this study are representative of samples

studied from various points in the extraction process, including

the feed samples.

EXPERIMENTAL

In the present case, both good and bad samples have

been

collected over a period of

18

months. These terms refer to those

emulsions vhich are associated vith low water content 5

Itgood ) and high water content

> 5

badn

)

oil products from

the extraction plant. The solids are all Dean-Stark extracted

from the sample in question so the organic matter which is

characterized by the various techniques is relatively strongly

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OWONENTS AND OMPLEXES

associated vith the solids; the so-called insoluble oroganic

matter. For samples taken early in the process, the solids

content is greater and measurements are much easier but

there is a

disadvantage in that sometimes the effect one is looking for is

masked by the large proportion of extraneousw solids contributing

to the signal. In the present discussion, the samples are from

further downstreamw and although there are far fewer solids

contributing to the signal, the proportion vhich are probably

important in determining the carry over of vater and minerals with

the final bitumen product is much greater.

Carbon-13 solid state nuclear magnetic resonance data were

obtained at 50.306 MHz on a Bruker CXPZOO equipped vith a 4 7T

superconducting solenoid. Spectral conditions vere as follows:

spectral width 20000 Hz, 4 K data points,

75 Hz line broadening,

us (90 ) pulse width, lms contact time, quadrature detection,

spin temperature alternation, 3 kHz magic angle spinning, 50 ms

high pover decoupling, and boron nitride rotors. All chemical

shifts are referenced to tetramethylsilane via adamantane as a

secondary reference. The lov total carbon content (10 20%) of

the small samples studied (<I00 mg) necessitated data acquisition

times ranging from about 12 to 150 hours. It is notevorthy that

as little as 300 pg of carbon will yield an acceptable C-13

PMS

spectrum vith present probe sensitivity.

Interfacial tension measurements were performed using the

Freezing Front Technique (Smith, Ornenyi and Neumann, 1983).

In particular, particle interactions vith the freezing or

solidification front vere studied in a copper chamber 4 t h

external dimensions of 80 m m 1 ) x 30 mm(v) x 5 mm(h), with a

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AXELSON

NIKULA

A N D

POTOCZNY

PHYSICAL PROPERTIES OF MATRlX YATERULS

TABLE :

Physical properties of the matrix materials used in the

freezing front experiment.

Substance

lhymol

enmphonone

Water

ice

machined groove 0 6 mm deep, 5 mm wide and about 30mm long. In

order to establish a suitable temperature gradient along the

groove, the chamber was heated electrically at one end and cooled

by circulating water through a copper tube at the other end. Clay

particles vere placed in the groove and covered vith povdered

matrix material zone-refined thymol or benzophenone). The

physical properties of the matrix materials are shown in Table

I.

The chamber was covered with a microscope cover slide and then

Density

@ L

(kg/&)

925

1148

999.8

Vl8coalty

P

(N-s

/mi

0.00397

0.005l6

0.0017~7

u t w a

trtda\ YLV

at ~ l t h g

point

(mJ/&)

29.9 at 51.5

39.9 at 480

75.8 at

0

Specific

Mo8I

P

(k ~/kg.K)

2.370

1.856

4.21177

T k n n d

Conduethdty

(J/~.I.K)

0.1288

0.

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COMPONENTS AND COMPLEXES

66

mounted on a microscope stage and heated electrically to melt the

matrix material. The velocity of the solidification front was

varied over a vide range, observed and video-taped through the

microscope.

The

driving forces which determine particle rejection by the

freezing front are provided by the interfacial free energies,

vhereas the main retarding force is hydrodynamic drag. As the

rate of solidification increases the viscous drag opposing the

particle motion vill increase and at

a

certain rate, called the

critical velocity, Vc, the two forces become equal and engulfment

occurs. Vc was determined for the samples as a function of

particle aggregate size. With Vc determined experimentally, the

free energy of adhesion can be calculated from a set of equations

Smith, Omenyi and Neumann, 1983). The advantage of this

technique is that the surface tension or contact angle of small

particles can be measured.

Scanning electron microscopy was performed on

a

Hitachi X 650

equipped vith both wavelength and energy-dispersive spectrometers.

The x-ray spectra vas aquired for

1000

seconds.

The electron beam

current vas 0.2nA at 25keV.

RESULTS AND DISCUSSION

The final centrifuge feed samples in Figure 1 exhibit

dramatic differences in the NMR spectra of their clay-organic

complexes. In fact, the low vater content sample contains no

detectable carbonyl carbon component, vhereas the high vater

content sample contains a significant resonance in this region of

the NMR spectra. The remaining carbon functional group

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AXELSON MIKULA AND POTOCZNY

CHEMICAL SHI T

FIG 1: C-13 solid state N M spectra of insoluble organic

matter in clay organic complexes from bitumen product streams

A

high water content and 8 low vater content.

distribution

is

similar in all respects in these samples however.

These minimal non-carboxylic acid carbon differences allov us to

make much stronger comments regarding the relative importance of

the acid groups themselves. These data indicate that the high

vater content product might originate to a great extent from the

presence of

a

very hydrophilic organic matrix attached to the

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C O M P O N E N T S N D C O M P L E X E S 66

surfaces of the clay and heavy metal minerals, leaving a

relatively hydrophobic end to interact with the bitumen.

Selected Freezing Front-derived interfacial tension

measurements of the same sample, for comparison with

NWR

analysis,

are shovn in Figure 2. It is evident from the results that y

PV

vary with the aggregate diameter and there are significant

differences in the hydrophobicity of these solids samples. The

low water content sample appears to be very-hydrophobic compared

4 t h the high water content sample. The tests on the good , low

water content sample vere carried out with both benzophenone and

thymol. In both cases the particles were engulfed by the

solidification front, therefore suggesting that (particle)

PV

ylv(matrix material), or (particle)

29.9

mJ ml (thymol)

P

39.9 mJ/m2 (benzophenone) This compares to for the high

PV

water content sample of about 5 mJ/m2. The smaller degree of

hydrophobicity in the bad sample probably contributes to the

greater amount of water carried vith the final bitumen product.

This coincides with the observation of relatively hydrophylic

carbonyl/carboxylic resonances in the

NHR

spectra.

The size dependence of the interfacial tension (Figure 2)

seems to follow the

NHR

behaviour of peats as a function of both

size fraction and depth of burial. The smaller the size fraction

and/or the greater the depth of burial, the larger the relative

proportion of aliphatic and/or paraffinic hydrocarbons (Figure

3).

The larger this relative proportion, the more hydrophobic one

would expect the particles to be. Although the origins of oil

sands and peats are thought to be different, general similarities

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AXELSON

MIKUL

ND

POTOCZNY

I I

4

5

200 15 2

AGGREGATE DIAMETER D

Irm)

FIG. 2: Interfacial tension yPV versus aggregate diameter D

for

A

high water content and B low vater content bitumen product

samples.

might

be expected especially when considering only

the

insoluble

organic matter components.

Figure

4 shows x-ray spectra of the same solids discussed in

Figures

1

to 3.

The differences in iron content are quite

clear

from a comparison of the iron x-ray intensities: the high vater

content product contains significantly. more iron. Furthermore

micro-probe analysis of the iron containing components on

a

particle by particle basis has shown that a significant portion of

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C O M P O N E NT S N D C O M P L E X E S

1 L

2 1 2 1

2 mesh 2

mesh

I

F IG

3:

C 13

solid state NHR spectrum of peats as a function of

size fraction.

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AXELSON,

MIKUL

AND POTOCZNY

FIG 4: X-ray spectra of the solids from bitumen product streams

vhich had A high and B lov vater content.

this

iron is in the form of carbonates and hydroxides rather than

pyrite. Iron hydroxides are known for their colloidal nature and

gel-like properties and they, along vith iron carbonates, are

thought to provide a bridge for interactions betveen organic

components in the bitumen and the mineral and water phases.

This data can certainly be interpreted in terms of the

existing literature concerning clay-organic complexation, soil

organic matter decomposition and previous studies related to heavy

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COMPONENTS ND COMPLEXES

oil recovery (although mostly related to studies of tailings).

The presence of insoluble organic matter bound to mineral surfaces

has been implicated as one major problem with respect to the

processability of oil sands. The common perception is that

preferential oil wettability is caused by strongly held insoluble

organic material (IOH) which is not removed by normal extraction

process operating conditions (McCaffery and Bennion, 1974;

Berkovitz and Speight, 1975; Carrigy and Kramers, 1973).

In practical terms, it has been noted that losses of bitumen

to tailings increase dramatically as the amount of fines

(i.e. -44vm) increases.

An

increase in the fraction of fines also

appears to correlate with a large increase in the amount of

residual organic matter bound to the clay minerals and heavy

metals. Several factors have been considered as contributors to

the

binding o f organic matter in tailings:

1)

adhesion of polar

and humic.substances to the, quartz grains, (2) agglomeration of

clays and associated organic matter with larger quartz grains,

where bitumen acts as

a

bridging agent and (3) adsorption of

organic matter on quartz or clay particles already coated with

metal oxide or possibly PeCO films. Solids derived from Syncrude

oil sand tailings have been reported to have 50-75 vtX of the

grains stained with a film of iron oxides (Kotlyar, Kodama,

Sparks, and Grattan-Bellew, 1987).

Heavy metal and inorganic carbon concentrations also have

been seen to increase as particle size decreases (Kotlyar,

Sparks,

and

Kodama, 1985). For example, Kotlyar et a1 examined

different grades of oil sands for particle size distribution of

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67 AXELSON

MIKUL AND POTOCZNY

fines, amount of IOH, heavy elements and clays. The x-ray

diffraction of all particle sizes indicated that there vas

an

increase in kaolinite and mica content with decrease in size for

all grades of oil sands. The advantage of the electron

microanalysis techniques used in the present study is that there

is no restriction on mineral crystallinity and indeed, it is

probably the non-crystalline components vhich are the most

impor tan

Strausz et a1 rationalized bitumen losses in terms of the

surface properties of the clay minerals. They determined that the

relative surface area of various size fractions was poorly

correlated with the weight retained bitumen. Their model

related the probability of attachment of bitumen to the presence

of a given type of surface. They assumed that mineral matter of

was covered in part by a film of humins of a given thickness,

density and weight. The probability of attachment of bitumen was

proportional to these factors and humin content Strausz,

Ignasiak, and Zhang, 1984). The present data indicate that one

might also consider the carbon functional group distribution in

order to maintain a good correlation with vater content. Of

considerable importance to the present study is consideration of

the forma ion of complexes betveen organics and clays, especially

when they appear to be strongly dependent upon the iron content,

and the type of iron.

Surface tension increases as particle size, increases,

indicative of a more hydrophilic surface coating for the larger

particles. These data also correlate well with the NHR data in

that the most hydrophilic sample was also determined to contain

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COWONE NTS AND COMPLEXES 671

significantly more carboxylic acid functional groups. The

carboxylic group on what appear to be long -c hai n aliphatic

moieties bridge with the clay/mineral/heavy metal components to

stabilize the oil and water system, leading to high water contents

in the bitumen product. This high water content correlates very

strongly vith the mineral and organic components identified in

this discussion.

CONCLUSIONS

As an elaboration of the findings of Strausz et a1 ve have

determined that the amount of organic material alone does not

necessarily correlate well vith emulsion stability/water content

in the samples investigated. Ye would expect that the amount of

organics only correlates well if the functional group distribution

is the same for all samples. However, the exact nature of the

organic components and functional group distribution is of prime

importance and may vary considerably among process streams and oil

sands feeds. In particular, a strong correlation vith

carbonyl/carboxylic groups has been observed with processability.

All factors considered, the presence of large amounts of aliphatic

hydrocarbons adsorbed on the minerals regardless of the presence

of

hydrophilic/oxygen-containing

carbons) appears to be the rule.

This vould indicate that a certain amount of water carry over vill

occur, with unacceptably high water

in

the final bitumen product

appearing when certain mineral and/or organic components become

higher.

Local variations in oil sands feeds therefore give rise to

variations in terms of processability as a consequence of the

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672

AXELSON

MIRULA

AND POTOCZNY

differences in composition possibly both mineral and organic.

The variability in the feed and subsequently in the processing

behaviour could therefore be random and severe depending on the

area being mined. The question of vhich factor may be the

determining one in terms of processability mineral composition or

organic functionality is a moot one considering

the

vide variety

of mineral and organic species in the oil sands systems. In terms

of process control and optimization of extraction yields it is

sufficient to recognize the correlations and react according to

the factor vhich might be the easiest to measure.

REFERENCES

Berkovitz N. and Speight J. G. 1975. Fuel 54 138-149.

Carrigy

H. A.

and Kramers

J. V .

1973. Guide to the Alberta

Oil Sands Area Alberta Research Council No. 213.

Kotlyar

L.

S. Sparks B. D. and Kodama H. 1985. 35th Can.

Chem. Eng. Conf. vol. 1.

Kotlyar

L.

S. Kodama

fi.

Sparks P.

E.

and Grattan-Bellev

P. E. 1987. Appl. Clay Sci. 2 253-271.

HcCaffery

F.

G. and Bennion

D. W.

1974.

J.

Can. Petrol.

Tech. 42-53.

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COUPONENTS AND COMPLEXES 67

Smith R. P. Omenyi S. N. and Neumann A.

V.

1983.

Physicochemical Aspects of Polymer Surfaces Vol.

I

i t tal K.L. ed. Plenum pp. 155-171.

Strausz 0 P. Ignasiak T.

M

and Zhang Q. 1984 Progress

Report to AOSTRA Haster Agreement 2 4 2 , Research Project

8323.

R E C E I V E D u g u s t

9

1988

ACCEPTED: September

1 1988

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Axel Son 1989