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PORT DURNFORD: CLAY MINERALOGY EFFECTS IN A THICKENER 83
IntroductionThe Port Durnford mineral deposit is situated south
of thecurrent Hillendale mine and extends for about 13 km
southtowards the town of Mtunzini on the east coast of SouthAfrica.
The Port Durnford deposit is characterized by highslimes content,
typically more than 20% of the expectedrun-of-mine (ROM). Slimes
are defined in this case asmaterial passing a 63 m laboratory
screen. This usuallyconsists of fine particles and clay minerals,
and it is the clayminerals that cause recovery losses at the
primary gravityconcentrator if not effectively removed (Marcos
andGilman, 2007). Once removed, the slimes need to bedisposed of
and water recovered for reuse in the process. Atypical slimes
processing route in a heavy mineralsoperation is to separate the
slimes from the rest of the ROMby using hydrocyclones. The slimes
would then report tothe hydrocyclone overflow and further processed
in athickener. Very fine particles of a few microns in
diametersettle slowly by gravity alone (Wills, 2007, Hayes,
2003).Chemicals, such as flocculants, are added to aid
withagglomeration and settling of these particles in largediameter
thickening vessels (Wills, 2007).
When one considers the feasibility of a mining project,the
technical viability of the proposed process needs to beconfirmed
and relevant design information needs to begenerated. For the
evaluation of the proposed Port Durnforddeposit the slimes handling
process was one of the majorcost drivers of the project. For this
reason a pilot thickenerstudy was under taken to assist in the
technical evaluation.The aims of the pilot campaign were:
To confirm the ability to settle the Port Durnford slimesusing
available thickener technology
To determine design information to enable the designof the
thickener circuit and thus allow a detailed capitalcost estimation
of the required plant
To determine operational parameters to allowconsumption rates
and thus operating cost to bedetermined.
In this paper a brief introduction of the importanttheoretical
aspects that influence slimes behaviour duringthickening are
discussedespecially clay mineralogy sinceit influences thickening
behaviour. The approach followedfor the Port Durnford pilot
thickening tests as well as resultsare discussed with the focus on
how the clay mineralogy ofthe deposit influences the thickening
performance. Toconclude the implications on the slimes handling
system arealso discussed.
Theoretical considerations
Flocculants Flocculants are high molecular polymers,
mostlypolyacrylamide monomers (PAM), which consist ofsignificantly
long chain lengths. The charge of theflocculant molecule can either
be positive, negative orneutral. Due to the negative surface charge
of clay mineralsone would assume that cationic flocculants would
showbetter results. However, the pH of the environment affectsthe
surface charge of a particle. In an aqueous solution thehydroxyl
group (OH-) attaches itself to the edges of the clayparticle
(Svarovsky, 1981). In a solution with a low pH theacid will
protonate the OH-, leading to an overall positivecharge. As the pH
of the solution increases the OH-depronates until a neutral edge
charge is reached. A furtherincrease in pH will result in an
overall negative charge atthe edges of the clay particle. The pH of
the solutiontherefore strongly influences the flocculant charge
that willbe most effective. Apart from the pH influence,
differentclay mineral may also respond differently to
specificflocculants.
RAMSAYWOK, P., BEUKES, J.A., and FOWLER, M. Port Durnford: clay
mineralogy effects in a thickener. The 7th International Heavy
MineralsConference What next, The Southern African Institute of
Mining and Metallurgy, 2009.
Port Durnford: clay mineralogy effects in a thickenerP.
RAMSAYWOK, J.A. BEUKES, and M. FOWLER
Exxaro Resources
The Port Durnford mineral deposit is situated south of the
current Hillendale mine and extends forabout 13 km southwards
towards the town of Mtunzini on the east coast of South Africa.
PortDurnfords run-of-mine (ROM) material typically contains more
than 20% slimes on a weightbasis. As part of the feasibility study
for this proposed project, thickening of the slimes wasevaluated
using a pilot-scale high rate thickener. Samples representing
different material typesfound in the Port Durnford deposit were
tested. Results showed that the thickener solids flux ratesfor Port
Durnford material are lower than that of Hillendale, which is the
current Exxaro mine onthe South African east coast. Underflow
densities achieved varied depending on the material typetested. The
flocculant demand was also determined during the pilot campaign and
the resultscompared well to actual consumption rates achieved at
the Hillendale operation. For the overallslimes handling process to
be successful the most important criteria for the thickening
operationare the underflow properties achieved. The paper will
therefore focus on the underflow propertiesachieved and show how
clay mineralogy influenced the results obtained from pilot
thickenertrials.
Keywords: heavy mineral slimes, clay minerals, smectite,
rheology.
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HEAVY MINERALS 200984
Figure 1 schematically illustrates this mechanism
offlocculation. The length of the chain enables it to bepartially
absorbed onto the particle surface leaving themajority of the chain
length to swerve around until itattaches to an adjacent particle.
This leads to the formationof multi-particle aggregates also known
as flocs whichsettle out more quickly and easily. The longer the
molecularchains, the faster the bridging between two
adjacentparticles can take place, leading to rapid floc formation
andquicker settling (Moss and Dymond, 1978).
Once the flocculant and slimes are mixed and allowed tosettle,
the process of thickening begins.
Thickening and slimes disposalThickening or gravity
sedimentation is the most widelyapplied dewatering technique in
mineral processing.Relative to other dewatering processes,
thickening is cost-effective and a high capacity process (Wills,
2007). Anotheradvantage is that it involves very low shear forces,
thusproviding good conditions for flocculation of fine
particles.Two primary functions of a thickener are:
Clarification of the overflow to enable reuse of water
Thickening of the underflow to a required concen-
tration (Wills, 2007). The thickener overflow water is returned
to the process
water system for reuse in the process. The thickenedunderflow is
disposed of typically in a residue disposalfacility which allows
for further dewatering. For the PortDurnford project, apart from
the normal residue damdisposal, the reconstitution of soil using
the thickenerunderflow and coarse sand was also a key
considerationduring the evaluation.
During rehabilitation efforts at the current Hillendalemine it
has become apparent that slimes and sand need tobe reconstituted to
assure water retention of the soil andestablishment of sugar cane
production (Hattingh et al.,2007). For Port Durnford it is expected
that the samerehabilitation method will be required as practised
currentlyat the Hillendale mine. For both the disposal of
thickenedslimes in a residue disposal facility or for use to
reconstitutesoil, the underflow rheology is the main
performancecriteria. In the thickener pilot study for Port
Durnford, thefocus was on achieving the required underflow density
asrequired for the rehabilitation process based on
Hillendalerheology.
Clay mineralogyPort Durnford material was analysed to
characterize its claymineralogy, since clay mineralogy can have a
determiningeffect on the performance during the thickening process
andsubsequent disposal. From X-ray diffraction (XRD)analysis it was
determined that the Port Durnford orebodyis rich in clay minerals.
In this document the term clay isused as a mineralogical term, i.e.
any of a diverse group offine-grained platy minerals, not a size
fraction. Thenegative surface charge, cation exchange
capabilities,swelling characteristics and small particle size of
clayminerals negatively affect the settling behaviour of theslimes
fraction within a thickener (Van Olphen, 1977).These factors also
affects the rheology of the slurry as itinfluences the solids
concentration and the manner in whichthe particles stack during
settling. The latter affects therheology and consolidation
behaviour of the slimes afterdeposition (Addai-Mensah, 2007).
Clay minerals belong to the phyllosilicate groupthecrystal
structures of minerals in this group consist of anarrangement of
octahedral and tetrahedral sheets.Tetrahedral sheets consist of two
planes of oxygen atomsarranged in tetrahedral coordination around
Si4+ cations andshare basal oxygen atoms between adjacent
tetrahedralsheets. Octahedral sheets comprise six oxygen or
hydroxylions which share octahedral edges. This type of
linkingresults in a net charge of -2 which is balanced by
divalentcations or trivalent cations that bond to the sheet (Horn
andStrydom, 1998).
Clay minerals are defined as 1:1 or 2:1 clays. 1:1 clayminerals
consist of a single octahedral sheet linked with onetetrahedral
sheet. The linkage occurs through sharing of theapical oxygen
between the octahedral and tetrahedralsheets. Two of the layers
formed through the abovementioned bonding, link together through
weakintermolecular forces (Horn and Strydom, 1998). Theenclosed ion
of each tetrahedron is normally Si4+, but thiscan be replaced by
Al3+ or Fe3+. Water cannot enterbetween these layers and these
clays are termed non-swelling clays, which include clays such as
kaolinite andserpentine.
Clay minerals defined as 2:1 consist of a singleoctahedral sheet
which is bordered on both sides by atetrahedral sheet in which the
apical oxygen point towardsthe central octahedral sheet. This forms
one layer which canbe linked to a similar layer through interlayer
cations. Thefact that the interlayer cations can be replaced by
othercations is important as it relates directly to the ease
withwhich these clay minerals can be chemically altered.
Thehydration of the interlayer cations results in the
physicalswelling of the clay minerals which could lead to
thedisintegration of the crystallite (also known as
weathering)(Horn and Strydom, 1998).
Particle-packing relationshipThe packing of particles on top of
each other during settlinginfluences rheology and density of the
thickened underflow.The most familiar packing types are referred to
asedgeface also referred to as house of cards, and faceface also
known as a band structure packing relationship(Van Olpen,
1977).
Figure 1. Schematic illustration of flocculation mechanism
(Mossand Dymond, 1978)
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PORT DURNFORD: CLAY MINERALOGY EFFECTS IN A THICKENER 85
Kaolinite typically stacks into a deck of cards
structure,whereas smectite forms a honeycomb structure. Figure
2illustrates this packing behaviour. The honeycomb packingretains
large amounts of water which fills the voids formedby this type of
arrangement (McFarlane et al., 2005a).Great effort and highly
effective dewatering systems arerequired to remove the interstitial
water (McFarlane et al.,2005a)
RheologyRheology is concerned with the flow and deformation
ofmaterials experiencing an applied force (Boger, 2006).There are
several factors that influence the rheologybehaviour of thickener
underflow of which density, particlesize, stacking relationship and
the clay mineralogy seems tobe the most important. The rheology of
the underflow ismeasured in yield stress which refers to the stress
at whichthe slurry starts to flow. Rheology is an
importantcharacteristic of the underflow as it determines how
theslurry behaves during transfer to the deposition site as wellas
behaviour after it has been deposited. One of thedeposition
requirements for tailings disposal is that theyield stress is
sufficiently high to support the largestparticles which will ensure
homogenous suspension wheresegregation does not occur (Boger,
2006). The non-segregating nature of the reconstituted soil for use
inrehabilitation proposed for Port Durnford is the mainperformance
criteria for the Port Durnford thickener design.The thickener pilot
campaign thus focused on achieving therequired underflow properties
as required for the twodisposal methods.
ExperimentalConsidering the theoretical background discussed,
the pilotcampaign was planned to generate the required
informationto assess the viability of slimes handling at Port
Durnford.
Quantitative X-ray diffraction analysisFor this study all
quantitative X-ray diffraction analysis wasperformed at the
University of Pretoria. A PANalyticalXPert pro powder
diffractometer with XCelerator detectorand variable divergence and
receiving slits with Fe filteredCo-K radiation was used.
Quantification was performedusing the Rietveld method (Autoquan
Program).
Yield stress measurementsYield stress (Pa) was measured using a
Haake rheometerwith a built in shear program. The vane design
included 4
blades. Yield stress was measured and the peak yield stresswas
recorded for each measurement.
Particle size distributionsA Malvern Instruments Mastersizer was
used to determineparticle size distribution. The stirrer and
ultrasonic modewere utilized. The particle refractive index setting
was 1.53and a 300RF lens was utilized. Water was used as
adispersant and the ultrasonic stirrer and other settings werekept
constant for all tests.
Sample selectionThe Port Durnford orebody is about 10 km long
and around4 km wideat its deepest point it is in excess of 60 m
deep. Due to the size of the deposit care had to betaken to ensure
that all geological variations are consideredwhen evaluating
aspects such as thickening of the slimesfraction. As part of the
geological evaluation of theorebody, extensive drilling was carried
out and drillsamples analysed to determine the valuable
mineralquantities in the deposit.
Based on the lithological information generated by
fieldgeologists during exploration drilling, the orebody wasdivided
into several sections. These sections, based onlithology, were
further organized based on analyses done aspart of the exploration
process to define different materialtypes found in the Port
Durnford deposit. These materialtypes were distinguished from each
other by features suchas typical slimes content, colour, sand
sizing and responseto magnetic separation on a Carpco magnetic
separator.Based on experience at the Hillendale operation, it is
knownthat differences in processing behaviour can be
experiencedwhen processing materials with variations in some of
thesefeatures. The thickening pilot trial thus had to ensure
thatall material types present in Port Durnford could
besuccessfully treated.
For the Port Durnford thickening pilot campaign,dedicated
samples representing each of these material typeswere obtained
using Wallis Air Core drilling at nominatedpositions in the
deposit. Several drill samples of eachmaterial type were combined
to obtain bulk samples. Waterfrom the Hillendale plant was used as
the proposed PortDurnford mine would use the same water source.
Sample preparationAs with Hillendale, the Port Durnford ore is
shear sensitive.Figure 3 illustrates the shear sensitive nature of
PortDurnford slime.
Figure 2. (A) Honeycomb packing relationship (B) Deck of card
packing relationship
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HEAVY MINERALS 200986
As energy is transferred to the slurry, more fine particlesare
generated which in turn influences the settlingbehaviour of the
slimes. It was important to ensure thatrepresentative feed was
prepared for the thickenercampaigns. The mining process proposed
for Port Durnfordwould include slurrying of the ore and pumping
itsignificant distances before sand and slimes are separated
incyclones. Before feeding slimes to the pilot thickener, theslimes
had to be exposed to a similar amount of shear tothat expected
during the actual mining process. To preparethe slimes for the
thickener trials, a sump and cyclone set-up in closed circuit was
used to ensure adequate andconsistent shear to the ROM. The
required time in the set-up to simulate the mining process was
determined based onprevious thickener campaigns conducted at
ExxarosHillendale mine. The assumption made for the PortDurnford
pilot trial was that the mining process at PortDurnford would be
similar to that of the current Hillendalemine.
Thickener test set-upFigure 4 is a photograph of the pilot test
thickener duringinstallation. The thickener consisted of a 190 mm
diameterPerspex vessel standing about 2 metres high with a feedwell
and rake mechanism.
The sheared and diluted feed slurry was introduced to
thethickener unit at a controlled rate using a peristaltic pump.The
feed density was kept constant for all tests at 1.012 kg/l.
Flocculant was made up to a concentration of0.1% by mass and then
further diluted to 0.01% by massprior to dosing to the thickener.
Dosing was controlled bytwo peristaltic pumps which allowed
two-stage dosing. Thethickener feed lines had some inserted bends
to aid mixingof the flocculant and feed. The thickener underflow
wasextracted using a peristaltic pump and discharged into aholding
bucket for further testing and analysis.
Thickener test programDuring the sample selection process six
distinct materialtypes were identified. For the purpose of this
article onlythe two main types representing around 80% of the
PortDurnford orebody are discussed. The two material types
arereferred to as type 2 and type 6. A sample from each of
thematerial types of Port Durnford were subjected to theprocedure
as shown in Figure 5.
Flocculant screeningPrior to the thickener pilot study
flocculant screening trialswere conducted on a laboratory scale by
flocculant supplycompanies. Static jar settling tests were
conducted andsettling rates achieved were recorded. The best
performingflocculants based on the settling rates were shortlisted
forfurther evaluation during the thickener pilot trial. The
pilotthickener was run at fixed settings to evaluate the
differentcandidate flocculants based on static jar tests. The flux
rate,
Figure 3. Shearing of slime in the cyclone test rig showing
howthe number of particles of less than 1m increase in time as
analysed using a Malvern particle size analyser
Figure 4. Pilot thickener rig
Figure 5. Thickener experimental plan
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PORT DURNFORD: CLAY MINERALOGY EFFECTS IN A THICKENER 87
flocculant dosage and bed heights were kept constant foreach
flocculant trial and the underflow density wasmeasured. The
flocculant providing the best underflowdensity was selected.
Flocculant demandTests on the pilot thickener were run for each
material typeto determine the flocculant demand (optimum dosage
rate).The bed height was built to 40 cm and the flocculant
dosagerate (g/t) systematically increased. As the flocculant
dosageincreased the underflow was sampled and underflowdensity
determined. The flocculant demand was taken as therate at which any
further increase in flocculant dosage ratehad no further beneficial
effect on the underflow. Theflocculant demand tests were all run at
a constant flux rate.
Flux rate The thickener solids flux rate is measured in the
units oftonnes/hour metre2. For a fixed thickener set-up as used
forthe pilot trial the flux rate will be directly proportional
tothe solids feed rate. To determine the optimum flux rate foreach
material type the thickener was operated at a bedheight of 40 cm
and the underflow density determined for aset of flux rates. At low
flux rates the underflow density isindependent of the flux rate. As
the flux rate increases apoint is reached where further increases
in the flux rateyields reduced underflow density. The optimum flux
rate isdefined as the point where the underflow density becomes
afunction of the flux rate. The flux rate is used to size
thethickeners.
Underflow densityThe final design parameter determined was the
underflowdensity achievable. As the bed height in the thickener
isincreased the underflow density increases due to
highercompression. The bed height was increased for each of
thematerial types and the thickener underflow densitymeasured at
different bed heights. The terminal density isthe density achieved
where any further increase in bedheight has no further impact in
increasing the density. Theterminal density that could be achieved
would give anindication of densities that could be expected from
anoperational thickener. Apart from underflow density, theyield
stress of the underflow was determined as it wouldinfluence the
design of the raking mechanism. This wasdone by using the Haake
rheometer. Both the rheology ofthe underflow as removed from the
thickener as well as therheology of the underflow following
shearing wasdetermined. This was done as underflow rheology
changeswith shearing. Generally the underflow yield stress
willreduce following shearing. Figure 6 shows typical
thickenerunderflow produced during the pilot campaign.
Results and discussionThe required design information for the
thickener wasgenerated based on the tests described. Flux rates
weredetermined and these would serve as input to specify
thethickener area required. The relative required thickeningarea
for Port Durnford material was found to be larger thanfor material
from the Hillendale deposit. Flocculant dosingrates were determined
and compared well to those currentlyexperienced at the Hillendale
mine. The main focus of thispaper is, however, the key design
criteria for the thickeningoperation, which are the underflow
properties from thethickener.
Figure 7 shows the relation between the underflow
solidsconcentration in percentage and the bed height from
thethickener trials for type 2 and type 6 materials respectively.On
comparing underflow solids concentration as bed heightis increased
for the two material types, it can be seen thattype 2 yielded
higher solids concentrations than type 6. Therate of increase of
solids concentration as bed heightincreases is also lower for type
6 material than type 2material. This indicates that type 6 material
does notdewater efficiently under the compressive conditions in
athickener bed.
In parallel to the pilot thickener campaign, claymineralogy was
investigated on the same samples togenerate information to assist
in the understanding of thematerials behaviour in processing. XRD
analysis was usedto define the clay minerals present in the
different materialtypes. Type 6 material was found to have high
amounts(>35%) of the clay mineral smectite
[Na0.7(Al3Mg0.7).Si8O20(OH)4.nH2O]. Smectite is a swelling clay and
absorbsvarious amounts of water thereby increasing volume andthus
decreasing bulk density. As shown in Figure 2 thesmectite tends to
form honeycomb like structures that retainwater (McFarlane et al.,
2005a). The main clay mineralpresent for type 2 material was
kaolinite (Al2Si4O5(OH)4),which typically has a low swelling
capacity and is also themain clay mineral in the current Hillendale
mine slimesfraction. The difference in clay mineralogy thus
explainsthe difference in observed behaviour as shown in Figure
7.
Figure 6. Underflow discharged into holding bucket for
furthertests
Figure 7. Pilot thickener underflow solids percentage as
afunction of mud bed height
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HEAVY MINERALS 200988
The yield stress of the thickener underflow produced wasalso
determined. Figure 8 gives the yield stress for bothmaterial types
at different underflow solid percentages.
From Figure 8 it can be seen that the yield stress as afunction
of the underflow solids percentage has a similarrelation with type
6 marginally higher at similar underflow% solids. A larger
difference was, however, expected basedon the differences as
observed in Figure 7. The underflowtested and represented in Figure
8 was, however, tested asremoved from the test vessel and the
influence of theflocculant on the yield stress is expected to still
besignificant.
In practice the thickener underflow is removed from thethickener
by pumps and pumped to the final disposal sites.The pumping
operation shears the underflow leading to aloss in yield stress
(for a shear thinning application). Figure 9 shows the yield stress
and underflow percentagesolids relation for the material tested
following a shearingsimulation. The rheometer had a built-in shear
simulationprogram; after measuring the yield stress the vane
wouldspeed up for 10 seconds to shear the slurry after which
theyield stress was remeasured.
From Figure 9 it can be seen that after shearing type 6material
has higher yield stress at similar underflow solidspercentages
compared to type 2 material. Figure 10represents the pre-shear and
post-shear yield stress for eachtest for the two material
types.
Figure 10 shows that type 2 material exhibits a higherdegree of
shear thinning compared to type 6 material. Thiscan be attributed
to the high smectite content in type 6material. In the swelled
state, smectite occupies greaterpulp volume, forming a high yield
stress, water retaininggel structure (McFarlane et al., 2005a).
McFarlane et al.(2005a) also concluded that the formation of
honeycombnetwork structures that retain water also results in
higheryield stress and opposes gravitational and shear
inducedcompaction. McFarlane et al. (2005b) described howkaolinite
dispersions flocculated with polyacrylamides(PAM) based flocculants
deform when subjected tocompression. The inter-flocculant porosity
is also reduced,forming a higher pulp density following shear.
It can thus be seen that for type 2 material higherunderflow
solids concentrations can be achieved withcorresponding high yield
stress. Following shearing, theyield stress of type 2 material
will, however, be reduced.For type 6 material the thickener will
not be able to producehigh underflow solids concentrations.
Subsequent yieldstress will typically also be lower than the high
solid
concentration underflow when treating type 2 material.Type 6
material will, however, maintain its as thickenedyield stress
following pumping operations yielding a higheryield stress at the
point of disposal than for type 2 materialof similar solids
concentration.
The objective for the thickener tests was to achieve
highunderflow densities that would allow maximum flexibilityfor
downstream disposal processes. The proposed PortDurnford project
would dispose of slimes on a sub-aerialresidue dam as well as a
bulk mix with sand for dunecoating. For the bulk mixing process,
the requirements toachieve high densities and yield stress in the
thickenerunderflow are more stringent than for the residue
damdisposal. The residue dams pumping system incorporatesdilution
facilities which enable it to handle high thickenerunderflow
densities and yield stress. The successfuldisposal dam as well as
bulk mixing operation is, however,dependent on the thickened slimes
rheology more than onthe underflow density. There are significant
differencesbetween the behaviour of type 2 and type 6 materials
asdetermined from the pilot thickener campaign. The higheryield
stresses achieved for type 6 following shear comparedto that of
type 2 at similar densities can, however, possiblyoffset the lower
thickener underflow solid concentrationsachievable with type 6
material compared to type 2material. This would thus possibly lead
to both materialtypes, even though behaving differently in the
thickenerprocess, being successfully disposed of via the two
disposalroutes.
Figure 8. Yield stress as a function of underflow solids
percentagemeasured as discharged from the thickener (unsheared)
Figure 9. Yield stress as a function of underflow solids
percentagemeasured following shearing
Figure 10. Comparison of yield stress achieved before and
aftershearing for each of the material types
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PORT DURNFORD: CLAY MINERALOGY EFFECTS IN A THICKENER 89
ConclusionsFrom the pilot thickener campaign the required
designinformation was generated to confirm the suitability of
highrate thickening for treating Port Durnford material.
Theinvestigations revealed marked differences in
thickeningbehaviour between the material types tested for
PortDurnford. It was shown that these differences are primarilydue
to differences in clay mineralogy. Since the rheology ofthe
thickened slimes will determine the downstreamdisposal behaviour,
follow-on studies will have to be doneto confirm the performance of
the material types in disposalprocesses.
AcknowledgementsThe authors would like to acknowledge Schalk
Bekker andChris Meintjies from Outotec for providing equipment
andvaluable assistance in executing the test programme. Theauthors
would also like to thank Dr Thys Vermaak andHennie Burger from
Exxaro for guidance and valuablefeedback during the compilation of
the paper.
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P. RamsaywokChief Scientist, Physical Beneficiation, Exxaro
Resources
Exxaro KZN Sands (6 years of experience), Exxaro R&D (3
Years of experience) started atExxaro as a technician, later
appointed as a technologist and recently as Chief Scientist.
Premeethwas involved in the setup and commissioning of the quality
control laboratory at KZN Sands.Presently Premeeth manages heavy
mineral and occasionally coal projects. Premeeth is alsocurrently
studying towards a BSc Honours degree in Technology Management at
the University ofPretoria.
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HEAVY MINERALS 200990