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Technological developments in processing Australian mineral sand deposits


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Almost all Australian mineral sand deposits are placer deposits, with the major commercial deposits located in four provinces along the east, west, and south coasts and in ancient basins in the southeast of the country. The development of new technology for mineral separation and its adaption to changes in the mineralogy of the deposits are discussed. Also, a summary is given of novel processing conditions developed to lower the levels of impurity elements (in particular manganese and radionuclides) in the heavy minerals, and to remove gangue minerals to obtain the maximum value from the deposits. The extensive, but still undeveloped, fine-grained Murray Basin deposits will require unique flotation conditions and roasting processes to produce marketable heavy mineral concentrates. The numerous potential novel processes that have been proposed for these deposits are discussed.
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The Journal of the Southern African Institute of Mining and Metallurgy VOLUME 120 FEBRUARY 2020 105
Technological developments in
processing Australian mineral sand
M.I. Pownceby1, W.J. Bruckard1, and G.J. Sparrow1
Almost all Australian mineral sand deposits are placer deposits, with the major commercial deposits
located in four provinces along the east, west, and south coasts and in ancient basins in the southeast
of the country. The development of new technology for mineral separation and its adaption to changes
in the mineralogy of the deposits are discussed. Also, a summary is given of novel processing conditions
developed to lower the levels of impurity elements (in particular manganese and radionuclides) in
the heavy minerals, and to remove gangue minerals to obtain the maximum value from the deposits.
The extensive, but still undeveloped, fine-grained Murray Basin deposits will require unique flotation
conditions and roasting processes to produce marketable heavy mineral concentrates. The numerous
potential novel processes that have been proposed for these deposits are discussed.
mineral sands, mineral processing, technological developments, Australia.
Australia is a major world producer of titanium and zirconium minerals from mineral sand deposits.
The principal heavy minerals of commercial value recovered from these deposits are ilmenite (FeTiO3),
rutile (TiO2), and zircon (ZrSiO4). According to Geoscience Australia, Australia has the world’s largest
economic resources of rutile and zircon, and the second largest share of the world’s ilmenite resources
after China (Britt et al., 2019). Commercial concentrations of titanium and zirconium minerals are found
around the world in hard rock deposits, or in placer (alluvial) deposits resulting from the weathering of
a hard rock deposit and the concentration of the heavy minerals by wave action on modern or ancient
beaches, or by deposition in fluvial (river) systems. Almost all Australian mineral sand deposits are
placer deposits, but although alluvial mineral sands occur in many places, commercial concentrations
are found in only a small number of locations. The major commercial deposits in Australia are found
along the east and west coasts and in ancient basins in the south (Eucla Basin) and southeast (Murray
Basin) of the country.
In addition to ilmenite, and its alteration products (including pseudorutile, hydroxylian pseudorutile,
and leucoxene, as discussed below), rutile, and zircon, there are usually small amounts of anatase
(TiO2), monazite ([Ce,La,Th]PO4), xenotime (YPO4), cassiterite (SnO2), and other lower-value heavy
minerals also present in the deposits (Popp, 2005). Major gangue minerals in Australian deposits that
can affect processing conditions are aluminium silicates, in particular clay minerals, and oxides such as
spinels (e.g., chromite, FeCr2O4). Gangue minerals can form significant proportions (>20%) of the heavy
mineral assemblage and the specific mineral suite can vary significantly.
While ilmenite has a nominal chemical formula of FeTiO3 (FeO.TiO2), assaying 52.7 wt% TiO2 and
47.3 wt% FeO (52.6 wt% Fe2O3), this ideal composition seldom occurs in nature due to substitution of
impurity elements (e.g., Mg, Mn, V, Nb, Fe3+) for Fe2+ in the crystal lattice, the presence of Fe3+ in Fe2O3
in solid solution in ilmenite, and incorporation of elements such as Al, Si, U, Th, P and Cr in the pores
of grains during weathering of the ilmenite. Weathering is also associated with removal of iron and
an increase in TiO2 levels. As a result, in a commercial mineral concentrate, the individual titanium-
containing grains may have a range of compositions.
Primary or unaltered ilmenite contains 48–55 wt% TiO2 with a composition close to the
theoretical formula and a Ti/[Ti+Fe] ratio of 0.5. It may contain some Fe3+ as a haematite-ilmenite
solid solution (Fe2O3-FeTiO3) or as exsolution lamellae of ilmenite-haematite, and appreciable
amounts of impurities give rise to the formula Fe3+2-2x(Fe2+,Mg,Mn)xTixO3.
CSIRO Mineral Resources,
Clayton South, Australia.
Correspondence to:
M.I. Pownceby
Received: 15 Aug. 2019
Revised: 21 Nov. 2019
Accepted: 29 Nov. 2019
Published: February 2020
How to cite:
Pownceby, M.I., Bruckard, W.J.,
and Sparrow, G.J.
Technological developments in
processing Australian mineral
sand deposits.
The Southern African Insitute of
Mining and Metallurgy
This paper was rst presented at
The Eleventh International Heavy
Minerals Conference, 5–6 August
2019, The Vineyard, Cape Town,
South Africa.
Technological developments in processing Australian mineral sand deposits
106 FEBRUARY 2020 VOLUME 120 The Journal of the Southern African Institute of Mining and Metallurgy
Secondary or weathered ilmenite has 55–65 wt% TiO2
and a Ti/[Ti+Fe] ratio between 0.5 and 0.6. It has a variable
composition consisting of a mixture of ilmenite and
Pseudorutile is formed on further weathering and has
a composition of 60–71 wt% TiO2 and a Ti/[Ti+Fe] ratio
of 0.6–0.7. This is an iron titanium oxyhydroxide solid
solution with one end-member close to Fe3+2Ti3O9 and an
extended range of homogeneity towards Fe3+1.5Ti3O7.5(OH)1.5
(Grey and Reid, 1975).
Hydroxylian pseudorutile, with a composition of around
70 wt% TiO2 and a Ti/[Ti+Fe] ratio of 0.85–0.9, is a porous
hydrated iron titanate that can contain more than 10 wt%
water. This mineral is present in the Murray Basin deposits.
It has recently been accepted as a new mineral by the
International Mineralogical Association and has been given
the name kleberite (Grey and Li, 2003; Grey, Steinike, and
MacRae 2013).
Leucoxene is an inhomogeneous, cryptocrystalline, high-
TiO2 (>70 wt% TiO2) product of ilmenite weathering with a
Ti/[Ti+Fe] ratio of 0.7–0.9. Further weathering can proceed
to form microcrystalline phases similar in composition to
Rutile (and its low-temperature polymorph, anatase) is a
titanate mineral that usually contains over 95 wt% TiO2.
In natural systems V, Fe, Cr, Sn, Mo, Mn, Bi, Nb, Ta, and
Sb may substitute into the rutile lattice (Bramdeo and
Dunlevey, 1999).
As a result of the wide range of heavy minerals with similar
physical properties, and the variable compositions and particle
sizes of some, the concentration and separation of the minerals of
value in alluvial mineral sand deposits is often not totally efficient
and the final mineral products usually contain small amounts of
gangue minerals (e.g., quartz and aluminium silicate minerals).
A commercial ilmenite concentrate may contain 45–65 wt% TiO2,
the value depending on the composition of the individual mineral
ilmenite grains.
Most of the heavy minerals in Australian mineral sand
deposits are coarse-grained, such as in the deposits in Western
Australia, where the ilmenite has a particle size of nominally
90–300 μm. In the Murray Basin deposits, the mineralization is
generally finer with deposits in the north of the basin containing
ilmenite with a particle size in the range 75–180 μm, while the
further south in the basin that the deposits are located, the finer
the particle size of the mineralization. There are major heavy
mineral resources in the southeast of the Murray Basin that
contain very fine-grained WIM-type mineralization with a particle
size of 40–80 μm (Pownceby, 2010).
In this paper the properties of the Australian heavy mineral
deposits are discussed, along with the development and advances
made in equipment used to produce individual heavy mineral
concentrates. Processing conditions developed and modified to
treat the changing impurities in these deposits are reviewed.
Australian mineral sand deposits
Areas in Australia containing the major commercial deposits of
mineral sands are shown in Figure 1. Mining of these alluvial
mineral sand deposits is done either dry, with earthmoving
equipment to excavate and transport the sand, or wet, using
dredging techniques when the ground conditions are suitable
and access to water is not a problem. The heavy minerals in the
mined sand are processed by gravity separation processes or
flotation to yield a heavy mineral concentrate (HMC), and then
the valuable minerals are separated in a mineral separation plant
(MSP) into individual mineral concentrates using a combination
of gravity, magnetic, and electrostatic separations or flotation.
The commercial development of the Australian mineral sand
provinces is discussed in chronological order here.
East coast deposits
Sediments weathered and eroded from the Lachlan fold belt of
eastern Australia were captured by high-energy fluvial systems
and transported to the east, where they were deposited to form
the eastern Australian heavy mineral deposits along the coast of
New South Wales and Queensland. Morley (1981) has presented
a detailed review of the people and companies involved in the
development and processing of these east coast deposits and the
following summary is taken from his publication.
Concentrations of heavy minerals were identified along
the east coast of Australia in the 1870s but these ‘sniggers’
were initially mined for their gold, tin, and platinum content.
The first commercial production of zircon, rutile, and ilmenite
commenced in 1934 at Byron Bay and expanded to various sites
along the New South Wales and Queensland coastlines such
that in the 1950s there were up to 33 operations in production.
Production from eastern Australia reached its peak in the 1970s
but has since decreased and only the mining operations on
North Stradbroke Island by Sibelco Australia remain. These are
the longest continuously operating sand mining operations in
Queensland, but are expected to cease production before 2025
(fact sheet by Wort in Rankin, 2013). Final separation of the
minerals is done at the MSP at Pinkenba on the mainland near
The first three companies to commercially produce heavy
minerals from the beach sands were Zircon-Rutile Ltd, Metal
Recoveries Ltd, and the Titanium Alloy Manufacturing Company.
Dry mining with shovels and scoops was used to collect the black
beach sand and the heavy minerals were initially recovered as a
mixed zircon-rutile-ilmenite concentrate by passing the sand over
sluice boxes lined with carpet material and using tables. Zircon-
Rutile Ltd discovered (accidentally) that when the beach sand
was added to hot water in the presence of kerosene and soap, on
stirring the heavy minerals floated to the surface. Today this ‘hot
Figure 1—Location of the major mineral sand provinces in Australia (modi-
ed from Pownceby, Sparrow, and Fisher-White, 2008)
Technological developments in processing Australian mineral sand deposits
The Journal of the Southern African Institute of Mining and Metallurgy VOLUME 120 FEBRUARY 2020
soap’ flotation process is used to recover many oxide minerals.
Moreover, it also was found that the addition of sulphuric acid to
the heavy mineral concentrate depressed the rutile and ilmenite,
leaving a froth of white zircon. Using this technology, Zircon-
Rutile Ltd focused on producing a zircon concentrate (96–98%
zircon) and a rutile-ilmenite mixture from the beaches around
Byron Bay.
After 1945, mining of the sand was carried out with
bulldozers and front-end loaders. A dragline was used to strip
overburden and a bucket wheel excavator was used to mine
hard indurated deposits. Later, when areas were re-worked, the
lower grades resulted in the introduction of the floating dredge-
concentrator arrangement. Gravity concentration was with
pinched sluices and trays, spirals, and cones. The introduction of
magnetic and electrostatic separators allowed the production of
individual zircon, rutile, and ilmenite concentrates rather than a
combined concentrate.
Mineral Deposits Pty Ltd (now Mineral Technologies, based
at Carrara south of Brisbane) was formed at this time, and
became a major developer and supplier of gravity, magnetic, and
electrostatic separation equipment, and a construction company
for the mineral sand industry. Early equipment developed by the
company included the Reichert spiral and cone concentrators
and electrostatic separators. Also during the same period,
H.T. Readings at Lismore commenced the development and
manufacturing of electromagnetic separators. Readings is now
part of Mineral Technologies.
In the 1930s, the Commonwealth Council for Scientific and
Industrial Research (CSIR) established an Ore Dressing Section
at Melbourne University. This group worked with the fledgling
mineral sands industry to assist in improving processing
conditions and the development of downstream products. This
government-industry collaboration has continued to the present
day through the Commonwealth Scientific and Industrial Research
Organisation (CSIRO), with research scientists located at several
laboratories around the country.
While the zircon and rutile separated from the east coast
deposits were easily marketed, the ilmenite was not suited to
the production of white titania pigment by either the sulphate or
chloride process due to its high chromium content. It was usually
stockpiled or buried. However, with an increased demand for
rutile as a feedstock for the new chloride process, Murphyores
Inc. Pty Ltd, working with CSIRO from 1963 to 1977, developed
the Murso process to upgrade ilmenite (and lower its chromium
content) to a synthetic rutile that was a suitable feedstock for
the chloride process. The ilmenite was oxidized in air at 1000°C
to convert Fe2+ to Fe3+ and form micro-cracks in the ilmenite
grains. The oxidized product was then reduced at 850–900°C in
a reducing gas mixture of H2–CO–CO2–H2O under conditions that
minimized the formation of metallic iron. The highly reactive
reduced product was dissolved in 20% HCl at 105–110°C under
reflux and from the acid a high-grade synthetic rutile product
containing 96 wt% TiO2 precipitated. Although a pilot plant was
run successfully in Japan, the process was never implemented in
practice (Sinha, 1973).
In 1985, in response to a shortfall in world ilmenite
production, Consolidated Rutile commenced upgrading stockpiled
high-chrome ilmenite at its Pinkenba (Brisbane) MSP using
dry magnetic separation to produce a product with a minimum
of 50 wt% TiO2 and a maximum of 0.40 wt% Cr2O3 for pigment
production (Woodcock and Hamilton, 1993).
The Goondicum mine in central Queensland, owned by
Melior Resources Inc. (Melior), is a weathered residual hard-
rock deposit. Material in the Goondicum crater is mined,
crushed, screened and sized, and gravity (spirals) and magnetic
separations are used to produce primary ilmenite and apatite
West coast deposits
Mineral sand deposits, many of a commercial size, have been
formed by wave action along the coast of Western Australia
in the Swan Coastal Plain, which stretches over 600 km from
Jangardup south of Perth to Eneabba in the north. Many of these
mineral-bearing strandlines are now located as much as 50 km
inland from the current coastline. The degree of weathering of
ilmenite in Western Australian deposits generally increases from
south to north. Manganese is a major impurity element in west
coast ilmenites. Also, the levels of uranium, thorium, and their
radionuclide daughters tend to increase the further north the
deposit is located, in association with the increased degree of
weathering of the ilmenite.
Numerous companies have been established over the years to
recover heavy minerals from these west coast deposits. However,
few have been able to ride out the cyclical nature of market
conditions (demand and price) and overcome difficult mining and
processing conditions.
Commercial production of heavy minerals commenced in
1956 in the Capel region, south of Perth, with the operations
of Cable Sands Pty Ltd (Cable Sands) and Western Titanium NL
(which became Associated Minerals Consolidated Ltd, and then
Renison Goldfields Consolidated Mineral Sands Ltd, RGC). In
1959 Westralian Sands Ltd (Westralian Sands) began mining
near Capel. Initial operations in the Capel area generally used
dry mining with scrapers and dozers to mine the sand and wet
gravity concentration with spirals and cones to produce a heavy
mineral concentrate (HMC). Mineral separation was carried out in
plants at Capel (RGC), Bunbury (Cable Sands), and in the North
Capel and Capel plants of Westralian Sands using spirals, cones,
and magnetic and electrostatic separators.
Currently the major operators in Western Australia are Iluka
Resources Ltd (Iluka, a merger of Westralian Sands and RGC in
1998) and Tronox Management Pty Ltd (Tronox, formerly TiWest
Joint Venture). In April 2019, Tronox acquired Cristal Mining
Australia Ltd (Cristal) and with it the Cable Sands operations that
Cristal had acquired previously. Tronox has the only integrated
operation, with ilmenite from its Cooljarloo mine being fed to
its pigment plant at Kwinana. Through the acquisition of Cristal
it also has pigment plants near Bunbury. Individual mineral
concentrates and upgraded products are exported to overseas
Initially, Western Titanium NL produced a primary ilmenite
concentrate (approx. 54 wt% TiO2) as a feedstock for production
of titania pigment by the sulphate process. With the supply of
rutile (>95 wt% TiO2), the preferred feedstock for the chloride
process, diminishing, the Becher process was developed by the
Western Australian Government Research Laboratory (Becher
et al., 1965) to upgrade the primary ilmenite from 54 wt% TiO2
to a synthetic rutile containing over 90 wt% TiO2. Large-scale
commercial production of synthetic rutile commenced from ‘B
plant’ at Capel in 1974.
In the Becher process, iron in the ilmenite is reduced at
1100–1180°C in a rotary kiln (5.1 m diameter and 62 m in
length) for 10 hours to form metallic iron dispersed in a titania
Technological developments in processing Australian mineral sand deposits
108 FEBRUARY 2020 VOLUME 120 The Journal of the Southern African Institute of Mining and Metallurgy
matrix (reduced ilmenite, RI). The locally available reactive
Collie coal (and char) is used as the reductant. After magnetic
separation to remove residual char, aeration of the reduced
ilmenite in an ammonium chloride solution results in oxidation
of the metallic iron and precipitation of finely divided iron oxides
in the suspension that can be separated easily from the coarser
titania grains, typically with a hydrocyclone. The iron oxide is
discharged to a storage area from which an iron-rich concentrate
is recovered for sale. A leach with dilute sulphuric acid is used
to remove residual iron and other impurities from the aeration
product to produce a premium-grade synthetic rutile (SR) product
containing around 92.5 wt% TiO2. To increase the reactivity of
the primary Capel ilmenite for the Becher process, initially it was
necessary to pre-oxidize the mineral at around 1000°C in air.
When, subsequently, the ilmenite mined at Capel, and from the
Eneabba deposits discovered north of Perth in the early 1970s,
became progressively more oxidized (58–62 wt% TiO2), the pre-
oxidation step was no longer necessary.
Work commenced in the late 1960s at CSIRO, in collaboration
with Western Titanium NL, to identify the phase changes
occurring in the reduction step of the Becher process in order
to optimize the process. Subsequent work targeted the removal
of specific impurities by modifications to the Becher processing
conditions. To lower the manganese levels, elemental sulphur
is added to the reduction kiln to form a manganese sulphide
phase (Rolfe, 1973; Li and Merritt, 1990) that dissolves in the
acid leach after the aeration step. In another modification, the
Synthetic Rutile Enhancement Process (SREP), a borate flux is
added during the reduction step to collect uranium and thorium
and their radionuclide daughters into an acid-soluble glassy
phase that can be leached out after the aeration step to lower
uranium and thorium levels in the synthetic rutile to <100 ppm
U+Th (Ellis, Harris, and Hudson, 1994; Aral et al., 1997).
RGC (later Iluka) processed the large Eneabba strandline
deposits north of Perth until 2015. Dry and wet mining
operations were used, with MSPs at Eneabba and at Narngulu
near Geraldton. Two reduction kilns (the C and D plants) were
commissioned at Narngulu to upgrade ilmenite to synthetic rutile
(92–95 wt% TiO2). Over the years Iluka (and its predecessors)
processed numerous deposits south of Perth, but in 2018
their operations at the Tutunup South deposit were completed.
Production from the Cataby deposit north of Perth commenced
in 2019, with an estimated mine life of around 8.5 years. The
HMC is separated on site into a nonmagnetic fraction that is
transported to the Narngulu MSP for separation of zircon and
rutile and a magnetic fraction that is feed for SR production at
The Tiwest Joint Venture commenced operations at Cooljarloo
north of Perth in 1989 using a dredge and floating concentrator
to mine and concentrate the heavy minerals. The HMC was
transported to a MSP at Chandala. A Becher plant was also built
at Chandala to produce SR as a feedstock for the company’s
chloride pigment plant at Kwinana. Now known as Tronox, the
company continues to source its ilmenite from deposits in the
Lancelin to Gingin area north of Perth. Image Resources NL
recently commenced production of HMC from its Boonanarring
deposit near Gingin. The HMC is exported to China for separation.
Several other operations are currently producing ilmenite in
the southwest of Western Australia. Tronox (previously Cristal) is
producing HMC from its Wonnerup mine, with separation of the
minerals at the Cable Sands MSP at Bunbury. The company has
five other mines scheduled to come into production and expects
to continue mining in the southwest for the next two decades.
Doral Mineral Sands Pty Ltd (Doral) is mining deposits in the
Jangardup area, also in the southwest of Western Australia, with
treatment of the HMC at its MSP at Picton. The current operation
is in the western extension to the original project (Burekup),
which has a mine life of 3.5–5 years.
Details of the processing conditions for the major operations
in Western Australia have been presented in the Maurice Mawby
memorial volumes produced by the Australasian Institute
of Mining and Metallurgy (Woodcock, 1980; Woodcock and
Hamilton, 1993; Rankin, 2013).
Over the years there have been significant developments in
concentration and separation equipment used in the Western
Australian operations. More efficient gravity concentration has
been achieved with banks of spirals of improved design and
materials of construction and improved flow sheets (Palmer
and Vadeikis, 2010). Kelsey centrifugal jigs have been used to
separate zircon from gangue minerals such as kyanite (Jones
and Foster, 2010). The development of higher strength rare
earth permanent magnets has resulted in advances in magnetic
separators. Several types of rare earth magnetic separators,
including rare earth roll (RERMS) and rare earth drum magnetic
separators (REDMS) for both wet and dry separations, and
matrix-type separators such as wet high-intensity magnetic
separators (WHIMS) are used to concentrate and separate heavy
minerals in different parts of the processing circuit. Traditional
electrostatic separation equipment for nonmagnetic minerals have
used combinations of high-tension roll (HTR) and electrostatic
plate (ESP) separators. Germain et al. (2003) summarized novel
technology that gave better separation efficiency by reducing the
effects of particle size. The Julius Kruttschnitt Mineral Research
Centre (JKMRC), through the industry-funded Australian
Minerals Industry Research Association (AMIRA) P255 project,
has developed a range of instruments and process models for
improved optimization and control in separation plants (Kojovic,
Pax, and Holtham, 1999). Pax (2011) has used finite element
modelling of the equipment to improve mineral separation.
Significant developments have also occurred in the
characterization of heavy mineral ores, concentrates, and
processed products through the commercial availability of
instruments such as scanning electron microscopes (SEMs)
and electron probe microanalysers (EPMAs) in the 1950s and
1960s. The value of these systems in process mineralogy was
quickly established (Jones, 1987; Sutherland and Gottlieb,
1991), although it was not until the late 1990s, when computing
hardware and speed were sufficiently advanced, that automated
SEMs (Reid et al., 1984; Gu, 2003; Fandrich et al., 2007), and
more recently EPMAs (Pownceby and MacRae, 2011, 2016)
became commercially available and were routinely applied to
mineral sands characterization.
Automated SEM-based systems such as the original
QEMSCAN and MLA systems (now owned by Thermo Fisher
Scientific) and the more recent TIMA (Tescan), Mineralogic
(Carl Zeiss NV), INCAMineral (Oxford Instruments), and AMICS
(Hitachi/Bruker) systems have found the greatest use in heavy
mineral characterization by providing information such as
quantitative modal analysis, mineral grain size, liberation,
and textural analysis. The advantage of automated SEM-
based mineralogy systems is their ability to rapidly collect
quantitative data for many thousands of particle sections, with
Technological developments in processing Australian mineral sand deposits
The Journal of the Southern African Institute of Mining and Metallurgy VOLUME 120 FEBRUARY 2020
minimal operator intervention (Baum, 2014), and automated
mineralogical methods are now widely used in heavy mineral
mines and MSPs for ore characterization, grade control, and
process design optimization. EPMAs, being of higher cost
and usually requiring specialist operators, have largely been
limited to generating quantitative chemical information on
individual valuable minerals to assess potential marketability
and to guide and improve process parameters (e.g. in MSP
plants or after upgrading to a high-TiO2 product). More recent
EPMA advances have seen the development of integrated
X-ray and cathodoluminescence mapping systems (MacRae
et al., 2005; Wilson and MacRae, 2005) to illustrate mineral
phase distributions (particularly useful for determining particle
coatings), impurity mineral/element distributions (Pownceby,
2005; Pownceby, MacRae, and Wilson, 2007), and textural
information (Pownceby, 2010), thereby providing a powerful
technique for characterizing heavy mineral deposits and process
Murray Basin deposits
Detritus from the weathering and erosion of sediments from the
Lachlan fold belt of eastern Australia that was shed to the west
was reworked in the palaeo-Darling, Lachlan, Murrumbidgee,
and Murray River systems and subsequently deposited in the
Murray Basin, the remains of a shallow inland sea (Roy et al.,
2000). The basin extends over an area of 320,000 km2 across
Victoria, New South Wales and South Australia. In Pliocene times
(approx. 5.3–1.8 Ma), economic heavy mineral concentrations
formed within the Loxton-Parilla sands unit. These were first
reported in the late 1960s and extensive exploration commenced
in 1970, leading to the discovery of over a hundred areas
of mineralization. However, few of the occurrences contain
economic quantities of heavy minerals. Locations of the more
important deposits are shown in Figure 2.
The first major discovery in the Murray Basin, in 1982, was
the fine-grained WIM 150 deposit near Horsham in the southeast
of the basin. Subsequently, four similar deposits (WIM 050,
WIM 100, WIM 200, and WIM 250) were discovered nearby. The
discovery of the WIM 150 deposit led to increased exploration
across the basin and between 1989 and 1999 coarser strandline
deposits were discovered and subsequently brought into
production. These included Mindarie in the west, Wemen, Kulwin,
Woornack, and Rownack in the centre, Douglas in the south, and
Ginkgo and Snapper in the north of the basin (Figure 2).
Murray Basin Titanium Joint Venture (MBTJV) commenced
the first operation in the basin at their Wemen deposit in 2001.
It was a relatively small resource and mining was completed
in 2004. Bemax Resources NL (Bemax) acquired MBTJV, and
Cable Sands in Western Australia, in 2004. Iluka commenced
their operations in the basin with the Douglas and nearby Echo
deposits in 2004, with mining of these two deposits completed
in 2012. The Kulwin deposit was mined between 2009 and 2012
and production from the Woornack, Rownack and Pirro (KWP)
deposits commenced in 2012 and finished in 2015. Iluka is
currently undertaking the development of a large deposit in the
Balranald area of New South Wales.
Iluka used wet gravity concentration equipment to produce
a HMC. WHIMS was used to separate part of the ilmenite (the
most magnetic fraction) which was retained on-site due to its
high chromium levels (1–2 wt% Cr2O3). The rest of the HMC was
sent to the MSP at Hamilton where zircon, rutile, and weathered
ilmenite products were produced. Since completing the treatment
of stockpiled HMC, the MSP at Hamilton has closed. Processing
conditions used by Iluka are summarized by Hugo and Jones in
Rankin (2013).
Bemax commenced production from its Pooncarie deposits
in the north of the Murray Basin in New South Wales in 2005.
Initial production was from the Ginkgo deposit with the HMC sent
to the MSP at Broken Hill that was commissioned in 2006. In
2010 production commenced from the Snapper deposit, and from
the nearby Crayfish deposit in 2017. In 2008 Cristal acquired
Bemax, and in 2019 Tronox procured Cristal. The HMC produced
at the Ginkgo, Snapper, and Crayfish mines is trucked to the
recently expanded MSP at Broken Hill, where magnetic leucoxene
and secondary ilmenite products are produced and railed to Port
Adelaide in South Australia for export. The nonmagnetic fraction
is shipped to the Bunbury dry plant for separation of rutile and
zircon products that are exported through the port of Bunbury.
Little of the ilmenite concentrate was sold initially because of its
high chromium content of over 1 wt% Cr2O3.
The Mindarie deposit in the west of the basin consists of
numerous strandlines between Mindarie and Karoonda in South
Australia. Mineralogical data for the deposit reports a grain size
of between 45 μm and 63 μm, suggesting that the mineralization
Figure 2—Location map of Murray Basin mineral sand deposits (modied from Pownceby, 2010)
Technological developments in processing Australian mineral sand deposits
110 FEBRUARY 2020 VOLUME 120 The Journal of the Southern African Institute of Mining and Metallurgy
is finer than that in other strandline deposits in the Murray Basin.
The deposit was developed by Australian Zircon NL (Australian
Zircon) with production commencing in 2007. The HMC was
exported to China. After several changes in ownership, the project
was put on care and maintenance in 2015.
Ilmenite concentrates produced from the Murray Basin
deposits contain high levels of chromium due to the presence of
chrome spinel minerals. The wide range in the composition of
these spinels makes it hard to remove them during processing.
Extensive experimental work has been done to characterize the
compositional variations (Pownceby, 2010), and Bruckard et al.
(2015) summarized the various treatment conditions evaluated
to remove the chrome spinels to obtain products with chromium
levels low enough for pigment production. A magnetizing roast to
increase the magnetic susceptibility of the titanate grains relative
to that of the chrome spinels has been shown to yield a titanate
product with a lower chromia content after magnetic separation.
For a primary ilmenite fraction, a low-temperature magnetizing
roast around 600°C, which limits the amount of rutile produced
in the roast, is successful. (Rutile does not dissolve well in
concentrated sulphuric acid.) A higher roasting temperature may
be used with weathered ilmenite since the formation of rutile
during the roast is not a problem in the subsequent chlorination
process. Bemax has proposed constructing a multi-hearth fluid
bed roaster at its Broken Hill MSP to roast high-chromium
ilmenite at around 620°C under reducing conditions to yield a
magnetic product suitable as a chlorinatable feedstock in which
the chromium content has been lowered from >1.5 wt% to
<0.3 wt% Cr2O3 (Everett et al., 2003).
Under reducing conditions, such as in a Becher reduction kiln,
chromium is chalcophilic and has a strong affinity for sulphur.
The possibility of modifying the chemical and physical properties
of the chrome spinels in a Murray Basin ilmenite concentrate was
investigated by adding elemental sulphur to the Becher reduction
step. Examination of the reduced ilmenite product revealed the
presence of small amounts of bronze-coloured grains indicating
chrome spinels coated with rims of sulphur-rich phases (i.e.,
selective chromite sulphidization). After de-metallization of the
reduced ilmenite, removal of the sulphur-coated chrome spinel
grains may be possible by flotation using reagents typically used
to float base metal sulphides. Initial results were promising,
and further work is in progress to optimize the treatment
conditions (Ahmad et al., 2014, 2016; Rhamdhani et al., 2018).
In Western Australian Becher plants, chromite is removed in
the nonmagnetic fraction from the magnetic separation after
reduction of the ilmenite.
Weathered ilmenites are usually upgraded to over 90 wt%
TiO2 to serve as feedstock for a chloride pigment plant. Processes
that may be used for Murray Basin weathered ilmenites
include kiln-based or fluidized bed processes. Magnesium and
manganese are major impurities in Murray Basin ilmenites, and
while manganese levels can be lowered by addition of elemental
sulphur in the reduction step of the Becher process, magnesium
is not removed in a standard Becher treatment. Consequently,
modifications to the Becher processing conditions have been
proposed to produce satisfactory sulphate and chloride pigment
feedstocks from weathered Murray Basin ilmenites. Kiln-based
processes that have been evaluated for Murray Basin weathered
ilmenite concentrates include the Hybrid, Acid Soluble Synthetic
Rutile (ASSR) and the Recovery of Upgraded Titania by Impurity
Liquefaction and Extraction (RUTILE) processes. While these
processes have been tested at pilot plant scale, the use of a
modified Becher process is likely to require demonstration of
the technology at a larger scale. The Murso, Austpac ERMS and
NewGenSR processes use fluidized bed reactors to oxidize and
reduce iron in the ilmenite at temperatures between 750 and
1000°C. All these processes have been demonstrated at pilot plant
scale, but no commercial operation has been established as yet.
A summary of the application of these processes to weathered
Murray Basin ilmenites has been given by Bruckard et al. (2015).
Eucla Basin deposits
Another major heavy mineral province in Australia is the Eucla
Basin, an approximately 2000 km wide marginal marine basin
spanning the border between South Australia and Western
Australia (Hou, Keeling, and Hocking, 2011). Exploration
since 2004 has led to the discovery of numerous major heavy-
mineral deposits in Tertiary shorelines along the east of the
basin (Jacinth, Ambrosia, Atacama, Typhoon, and Cyclone).
Other prospects (Cyclone Extended, Balladonia, and Plumridge)
are around the western edge of the basin (Hou, Keeling, and
Hocking, 2011; Pownceby, Sparrow, and Fisher-White, 2008).
Iluka commenced production from the Jacinth deposit in October
2009, primarily for production of zircon. After a short suspension
in production in April 2016, production recommenced in
December 2017 with the HMC being transported to the Narngulu
MSP in Western Australia. Mining of the Ambrosia deposit is
expected to commence in 2019. At Narngulu, a hot acid leach is
used to clean the surfaces of the final zircon product to lower iron
contamination levels.
Future developments
New deposits
In addition to the commercial operations noted above, several
companies are actively evaluating other resources in Western
Australia. Sheffield Resources Limited is evaluating several
prospects in the Eneabba area. North of Geraldton, Strandline
Resources Limited has the Coburn heavy mineral sands project
just south of Shark Bay, and even further north is the flagship
Thunderbird mineral sands deposit of Sheffield Resources
Limited. This project is in the Canning Basin, on the Dampier
Peninsula west of Derby, and is the first major mineral sand
deposit discovered in the Canning Basin. A prefeasibility study
indicated that an ilmenite product with 56.1% TiO2 and low levels
of alkalis and chromium could be produced from the deposit
following a low-temperature roast.
In Victoria, future developments are expected to occur in the
north of the Murray Basin. Iluka is developing a large deposit
in the Balranald area. This deposit is under 60 m of overburden
and underground mining and backfilling techniques are being
evaluated to recover the heavy minerals. Cristal Mining is
developing the Atlas/Campaspe Project north of Balranald with a
planned mine life of 11–20 years.
Also in Victoria, there are many occurrences of mineral sands
around the eastern edge of the Murray Basin. Over the years
numerous companies have evaluated them but no development
has occurred. The Gippsland Basin in the southern part of
Victoria also is host to extensive late Miocene-Pliocene strandline
deposits and exploration and drilling have shown that these have
similar properties to the Murray Basin strandline deposits. The
Glenaladale deposit was discovered by Rio Tinto Exploration in
2004, and in 2013, Kalbar Resources Ltd (Kalbar) acquired the
Technological developments in processing Australian mineral sand deposits
The Journal of the Southern African Institute of Mining and Metallurgy VOLUME 120 FEBRUARY 2020
resource and has started developing the higher grade areas as its
Fingerboards Mineral Sands Project.
Developments for ne-grained mineralization
The five WIM-type deposits located in the south of the Murray
Basin around Horsham are fine-grained, sheet-like heavy mineral
deposits. The WIM 150 deposit was discovered by CRA Limited,
now Rio Tinto Pty Ltd, with initial development carried out
through its subsidiary company, Wimmera Industrial Minerals Pty
Ltd (WIM). An intensive effort was made to develop processing
options for the WIM 150 deposit, including pilot plant test work,
but no commercial operation resulted and WIM relinquished its
leases on the deposits. They were subsequently taken up by other
companies (e.g., Australian Zircon and Murray Zircon – now
a joint venture between OZC and Million Up Ltd) but despite a
significant amount of further development work the deposits still
have not come into production.
Astron Ltd (Astron) is evaluating two WIM-type deposits;
WIM 200 (the Jackson deposit) and WIM 250 (the Donald
deposit). Astron is concentrating on production from the Donald
deposit first, and proposes to produce a HMC for export to China
for further processing.
While the extensive WIM-type deposits located in the south
of the Murray Basin contain more heavy minerals than there are
in the strandline deposits in the basin, they remain undeveloped.
Although they are low grade, the fine particle size has been the
major issue preventing them from being developed to date. A
significant amount of research has been undertaken to design
equipment and identify processing options to concentrate and
separate these fine minerals.
Continuing developments are being made with the design
of spirals to increase the recovery of the finer mineralization
from the WIM-type deposits (Richards et al., 2000). Higher
mineral recoveries of fines down to around 6 μm, with better
concentrate grades, and separation of minerals with small specific
gravity differences are claimed with a Kelsey jig compared with
other gravity separation techniques (Jones and Foster, 2010).
Kelsey jigs, along with spirals and flotation, are proposed to be
used in processing the WIM 150 deposit. Capps and Waldram
(1986) have reported the recovery of fine-grained (32–75 μm)
heavy minerals from a mineral sand deposit using Kelsey jigs.
Wet magnetic separators are usually considered to be efficient
for minerals with particle sizes above 75 μm. Consequently, it
is likely that magnetic separation efficiencies for fine-grained
deposits may not be satisfactory.
Flotation has been used to concentrate and separate
heavy minerals, and since it operates efficiently with fine
(<100 μm) particle sizes, it can be expected to be applicable to
the concentration and separation of heavy minerals in the fine-
grained deposits (Bruckard et al., 1999). A strategy of producing
a bulk float of the valuable minerals, depression of the titanium
minerals, and a float to separate the rutile and ilmenite using
modern collectors (e.g., sulphosuccinamates, phosphonic acids,
amines) is expected to be able to yield individual concentrates
of the fine-grained minerals. Pownceby et al. (2015) have
summarized some of the reported flotation work with WIM
150 samples.
Removal of chrome spinels from the ilmenite concentrate
will also be an issue with the fine-grained deposits. Flotation
and roasting conditions discussed above for the coarser-grain
deposits should also be applicable to the finer mineralization.
However, there are expected to be problems in treating the fine-
grained mineralization with a fluidized bed or kiln-based process
as the particles may be blown out of the fluidized bed, or from a
rotary kiln in the high exhaust gas flows from the kiln. Research
is required to design a circulating fluidized bed reactor capable
of treating fine-grained mineralization, or to determine whether
agglomeration of fine-grained ilmenite can successfully be used
in existing reactor designs.
The final zircon concentrate, as well as requiring attritioning
in water and acid or alkaline solutions to remove surface
contaminants, is also likely to require further treatment to lower
radionuclide (uranium, thorium, and their daughter products)
levels in the grains. Heat and leach treatments that involve
decomposition of zircon either through the addition of a flux, or
through the application of temperatures above the temperature at
which zircon breaks down to zirconia and quartz, and other flux-
based treatments that retain the integrity of the zircon crystalline
lattice have been used to significantly lower the U+Th levels in
the fine-grained zircon. Pownceby et al. (2015) have summarized
this work.
Australia has four major mineral sands provinces. Since 1934,
when the commercial mining of mineral sands commenced
in eastern Australia, there has been continuous mining and
processing of heavy minerals from these deposits. This has
been associated with significant advances in equipment design
to recover the heavy minerals and in processing conditions to
remove impurity elements from the heavy minerals to produce
marketable products for further local processing or for export.
New deposits currently being characterized and developed will
ensure continuing production of heavy minerals in Australia.
Some information and details of current operations were taken
from company web sites. Alex de Andrade is acknowledged for
information on recent developments in separation equipment by
Minerals Technologies. The external reviewers are thanked for
their valuable comments.
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... The problems of determining the parameters of effective technological schemes of hydromechanized method of mineral mining from the open pits and technogenic formations are analyzed in papers [29], [30]; but there is still no solution for a problem of determining the influence of secondary raw material use on the indices of land capacity of mining. Papers [31], [32] deal with the increasing efficiency of the placer deposit development. Despite the fact that the issue of resource saving in these papers is of high priority, the research results do not take into account handling the enclosing rocks of titanium-zirconium ores. ...
Purpose. The present paper aims to develop methodological principles for the selection of effective parameters of resource-saving technologies while developing water-bearing titanium-zirconium deposits basing on the complex of analytical studies. Methods. The paper applies a complex of research methods: analytical – to analyze and generalize the main differences of the development technology for water-bearing placer deposits and problem statement; technical-economic analysis for identifying the effect of a resource-saving technology on the indices of land use of the open-pit mining and involvement of associate raw materials in the economic activity; forecasting – to determine the influence on complex development of a titanium-zirconium deposit on the operating parameters of the regional nonmetallic raw material open pits. Findings. Effective trends in using the associate raw materials located in the enclosing and overburden rocks of a titanium-zirconium deposit are identified. Key differences between the technologies of associate raw material mining from the overburden rocks and their recovery from the enclosing rocks while mineral mining are defined. Predictive influence of a resource-saving technology of the development of titanium-zirconium deposits on the extraction of building materials from the regional nonmetallic open pits is specified. Volumes of possible associate raw material mining while developing the Motronivskyi GZK open pit during its operation are determined. Originality. New dependences of a land capacity coefficient while mining nonmetallic raw material in the region, prime cost of ore development as well as number of open pits for sand and clay production in the region on the volumes of involved associate raw material of the titanium-zirconium open pits are identified. Practical implications. A structural-logical scheme is elaborated for the selection of a resource-saving technology while operating open pits for the development of titanium-zirconium deposits.
A novel approach for the removal of chrome-bearing spinel impurities (chromite) from weathered ilmenite concentrates has been proposed. This involves a two-stage process where in Stage 1 the spinel impurities are subjected to selective surface sulphidation followed by physicochemical separation in Stage 2. In this Part 1 paper, the applicability of the selective sulphidation of spinel impurities at 1100 °C was investigated for different ilmenite concentrates sourced from the Murray Basin region in south-eastern Australia and from Bangka Island Indonesia. The results demonstrated that the selective sulphidation of the impurities can be applied to the Murray Basin ilmenites. This was indicated by the formation of sulphide-rich rims on the spinel impurities. The chrome spinels from the Indonesian ilmenite, however, were not sulphidised. This was most likely due to the refractory nature of the spinels as they contain higher concentrations of Mg and Al. The current study also simulated an industrial Becher kiln process in a laboratory roller-bed-furnace. The results show that the selective sulphidation conditions can be achieved using char and sulphur sources. It was also observed from these experiments that Mn impurities are also sulphidised. The current study also identified and presented the range of high temperature and gaseous conditions (pO2 and pS2) that promote the selective sulphidation of Mg, Mn, Sn and Y impurities.
Records indicate that spiral separators have been utilised in mineral separation for over 100 years. The Spiral's predecessor, the sluice, has been in use for centuries in different forms and a spiral can be thought of as a sluice wound around a column. The spiral separator is distinguished from the straight sluice, and other fl owing fi lm separators, in uniquely introducing centrifugal motion. The elegance of the spiral concept was embraced due to signifi cantly improved separation effi ciencies, ease of operation and tolerance of variation in feed conditions. Advances in spiral technology have improved the metallurgical performance, modernised the materials of construction, increased unit capacities and simplifi ed operation. These advances have ensured that spirals continue to play a major industry role amidst other advancing and competing technologies. Recent developments in spiral and spiral plant technology include: • the launch of the VHG spiral model, specifi cally aimed at feeds with very high levels of highdensity mineral particles; • the introduction of a high capacity wash water spiral model; and • innovations in feed stabilisation and control. Details of these developments are presented together with the resultant operational benefi ts including feed stabilisation, product control and improved metallurgical performances.
With relatively coarse grained and easy-to-process ore sources rapidly dwindling, smarter techniques are becoming more necessary for the continued success of mineral processing operations, while increasing environmental pressures also require more environmentally friendly solutions. Gravity concentration has long been employed to pre-concentrate minerals using water, reducing or eliminating the need for less environmentally friendly processing techniques such as fl otation. Conventional gravity recovery devices however, operate in a 1 g environment with limited effi ciency in the separation of fi ne particles of heavy and gangue minerals. More recently developed centrifugal concentrators operate in a multi-g environment and enable fi ner heavy minerals to be recovered, but also exhibit limited separation effi ciency due to the separations being based on solid particle mass differentials. Further enhancement of gravity separation has been achieved using the Kelsey Centrifugal Jig (KCJ), which also operates in a multi-g environment, but separates minerals on the basis of specifi c gravity differentials, using 'ragging' media and a pulsation mechanism, which maximises the effect of differential particle accelerations. This enables the effi cient separation/recovery of minerals down to a particle size of ~6 μm and/or separation of minerals with a low specifi c gravity differential. This paper presents details on the principals of operation of the KCJ, recent improvements in the technology and recent developments in modular KCJ plants, as well as some KCJ application areas, which offer smarter, environmentally friendly processing opportunities for the mineral processing industry.
The Murray Basin in southeastern Australia is proving to be a major mineral sand province that eventually will replace Australia’s east and west coasts in production of rutile, zircon, and ilmenite. Concentrations of relatively coarse-grained heavy mineral occur as beach placers in the Pliocene Loxton-Parilla sands in the upper part of the Murray Basin sequence. These formed as 400-km-long barrier complexes in the "Murravian Gulf" under the action of long-period ocean swell waves. We think the main source of barrier sand, at least initially, was from erosion of Miocene sands on the bed of the Murravian Gulf; progradation was a response to sea level fluctuations linked to Milankovitch climatic cycles in the Pliocene. In most areas, the resulting 400-km-wide barrier strand plain is now overlain by fluvial, aeolian, and lacustrine deposits. Typically, the heavy mineral deposits are ilmenite rich, with 30 to 40 percent rutile and zircon. They occur as single, or as multiple, stacked strandline deposits, are often more than 10 m thick, have mineral grades that exceed 20 percent in places, are several hundred meters wide and 10 to 25 km long; some contain up to several million tonnes of heavy mineral. The rutile and zircon are comparable in grain size and quality to minerals traditionally mined in Australia. Many of the deposits are associated with topographic ridges—the Neckarboo and Iona Ridges are the best known—that appear to be fault-bounded blocks. Deposits of major commercial significance found so far contain a total of over 12 million tonnes (Mt) of rutile, zircon, and ilmenite. The total, coarse-grained mineral sand resources in the Murray Basin are conservatively estimated to be over 50 Mt. The distribution of mineral sands in the Murray Basin seems to be associated with two aspects of the region’s geology and geomorphology: (1) a zone bordering the central part of the basin where the Pliocene barriers were derived from underlying Miocene sands that probably already contained some mineral concentrations and (2) growth faulting with deposits preferentially occurring on upfaulted blocks especially in the zone defined by (1) above. We speculate that localized uplift during the formation of the Loxton-Parilla barriers was sufficient to modify coastal processes on uplifted blocks so as to increase the rate of alongshore sediment bypass compared to nearby areas. This phenomenon has been simulated in computer modeling. Where the barrier sands were already enriched in heavy minerals, winnowing by storm waves formed beach placers on the uplifted fault-blocks. Based on criteria (1) and (2), the prospective areas of the Murray Basin account for 80 percent of the beach placers found to date.
After forty years of exploration and development, the heavy mineral sand deposits of the Murray Basin are on the eve of substantial exploitation by Iluka Resources Limited, Southern Titanium NL and RZM/Cable/Bemax, whom plan to initiate mining and processing operations in 2005. A trial mining and processing operation was undertaken on the Wemen North strandline deposit in 2001-2003 by Murray Basin Titanium, a joint venture of Sons of Gwalia and RZM/Cable, which brought to light a number of mining and processing problems which have since been the subject of extensive studies and process development work. The mineralogy of these weathered strandline deposits is complex by industry standards due to the variety of the heavy minerals present, coatings on the mineral grains and the extensive weathering and alteration which has taken place during the past 50 million years. This paper provides an overview of the complex mineralogy that, in turn, dictates the processes that can be used to recover the valuable heavy minerals. The Murray Basin encompasses some 300,000 km 2 and has been a depositional basin, often land locked, since the start of the Cenezoic Era. The economic heavy minerals include ilmenite, altered ilmenite, leucoxene of highly variable composition, rutile, and zircon. There are also other heavy minerals present such as cassiterite, chromite, and monazite in quantities that pose both problems and opportunities. The clay content and overburden thickness also play a major role in the selection of the deposits to be mined. Project Services Consultants (PSC) has undertaken the preparation of this paper as part of its ongoing participation in the mineral sands industry and in particular the project development activities in the Murray Basin region currently being undertaken by Iluka Resources. PSC has been involved with the mineral sands business for several years with senior staff having in excess of 30 years global industry experience. The company is well placed to provide a range of services to clients like Iluka Resources in the areas of project development, execution and strategic development and industry advice.
Electrostatic separation is a core requirement for the benefi ciation of mineral sands suites to provide valuable product. Although the basis of electrostatic separation has been understood for some time, the details required to be able to calculate the metallurgical performance of a separator has not previously been achieved from a mechanistic perspective. Empirical models have had some success but require extensive test work. Traditionally, performance of an electrostatic separator is determined by careful experimental work using the target mineral suite. Although electrostatic separation was invented at the end of the 19th century, very little modification of the basic equipment occurred until relatively recently, with the addition of a plate electrode to aid separation. Previously, the author has presented results, calculated using finite element modelling (FEM), of the electric fields present in an electrostatic separator in various configurations. This paper will present some new mathematical modelling work, which uses the FEM determined electric field configurations but also incorporates some fundamental physical processes that provide insight as to the limitations and opportunities for this important separation technique.