Australia hosts some 330m tonnes of economic demonstrated
magnesite resources, including 95m tonnes of reserves. The
industry is starting to recover from recent slumps in demand
and a number of explorers are looking to develop new resources,
particularly for Asia-Pacific export markets.
According to the Queensland state government, the Kunwarara
deposit in central Queensland is the world’s
largest known source of ultrafine-grain cryptocrystalline to
microcrystalline nodular magnesite and is the only magnesium
carbonate mine belonging to Belgian speciality mineral company,
Myrtle Springs magnesite mine.
Magnesite was discovered at Kunwarara in 1985 by Queensland
Metals Corp. (QMC), which quickly recognised the
deposit’s refractory grade potential. Kunwarara
produced its first magnesite in 1991 under QMC, later renamed
Queensland Magnesia Ltd (QMAG). In 2012, QMAG was purchased by
Sibelco, in an acquisition underlining the
company’s long term optimistic view of the
QMAG commenced mining at the Yaamba magnesite deposit in
September 2010. Together, the Kunwarara and Yaamba mines
produced magnesite worth just over Australian dollar (A$) $45m
($33.2m**) in the 2014-15 financial year. Approximately 3m tpa
run of mine (ROM) ore is produced from Kunwarara and 1m tpa
from Yaamba. In the 2013-14 financial year, QMAG’s
Queensland operations produced 586,495 tonnes magnesite, rising
to 658,562 tonnes in 2014-15.
ROM ore is crushed, scrubbed and screened at the mine site,
which has a processing capacity of about 600,000 tonnes. The
processed ore is then sent to the Parkhurst processing plant
for further beneficiation. Parkurst is one of the
world’s largest magnesite processing plants, with
340,000 tpa calcination capacity for final products,
electrofusion capacity of 32,000 tpa and deadburning capacity
of 110,000 tpa.
Fused and deadburned magnesia (FM and DBM) products are
supplied to the refractories industry and caustic calcined
magnesia (CCM) is supplied for agricultural, metallurgical,
paper and environmental applications.
Calix Ltd operates the Myrtle Springs mine in the Leigh
Creek area of South Australia. The deposit has a total
exploration target of around 3m tonnes and in 2013, Calix
produced 3,632 tonnes magnesite. Magnesite ore mined at Myrtle
Springs is sent to the company’s Bacchus Marsh
plant, where it is crushed, milled and calcined. Calix also
heats magnesite using method called "flash calcination", where
the mineral is heated indirectly and in the presence of steam,
affecting the surface area and pore size and hence the
reactivity of the magnesium oxide formed. Bacchus Marsh has
capacity of 4 tph of fully calcined high value products and 9
tph of partially calcined lower value products.
Calix is now supplying its newly commissioned magnesium
hydroxide liquid (MHL) production plant in Queensland in order
to better serve customers in that state. The plant has a
capacity of 6,000 tonnes per operating shift and the capability
to produce a batch of 60% solids MHL in less than 90 minutes.
Magnesium oxide (MgO) feed powder is sourced from the Bacchus
New South Wales
New South Wales magnesite is sourced solely from Causmag
International’s Thuddungra project, which has a
measured resource of 3.8m tonnes grading at 55.1% magnesium
carbonate (MgCO3). The ore is cryptocrystalline and
nodular, high quality (>99.8% MgCO3) and suitable
for refractories and pharmaceuticals. Thuddungra produced up to
30,000 tonnes magnesite in 2015, according the GSNSW. CCM is
produced in rotary and shaft kilns and, according to Causmag,
its products go into fertilisers, animal feed, pharmaceuticals,
water treatment and soil remediation applications.
World magnesite reserves totalling 2.4bn
tonnes, with Australia containing
95m tonnes, or 4% (excludes the
Source: USGS 2016
Australian magnesite and magnesia export trade
Trade data is notoriously misleading, due to local data
restrictions and limitations as well as re-exports. However, a
combination of export and import data, along with some
commercial knowledge, can usually identify significant
Australia is a small importer of magnesite, at about 5,000
tpa, but is a significant exporter of both magnesite and
magnesia (FM, DBM and CCM). Prior to 2009, the year in the
aftermath of the global economic crash, exports had reached
150-200,000 tpa and recovered to this level shortly after 2009.
Australian exports then declined rapidly to about 100,000
tonnes in 2013, before rebounding slightly in 2014. Exports of
hydrometallurgical caustic magnesia are considered to be
understated in the data prior to 2012 and the decline in
exports may be larger than indicated.
This period coincided with the change of ownership of the
largest producer and exporter, Sibelco’s QMAG, the
reaching of "peak refractories demand" and increased
competition in export markets for hydrometallurgical grade CCM.
Significantly, the recovery of exports in 2014 was
predominantly in markets closer to Australia (New Zealand,
India, Indonesia and New Caledonia) and mainly for
Trade data indicates a pickup in exports to the US in 2015,
which is back to historical levels of about 35,000 tpa, as well
as indicating retention of exports to New Zealand of about
27,000 tpa. The growth of Australian CCM exports into the large
and mostly agricultural New Zealand market against Chinese
production is a significant trend.
Australia also increased exports of DBM to India in 2014 and
again in 2015, with competition mainly from Turkey
(Kümaş Kütahya Manyezit Sanayi AŞ).
For the two-year period 2014-2015, Australia supplied 52% of
total DBM imports to India, with Turkey and China supplying 38%
and 9%, respectively.
Cross-section of palaeochannel fill in the
Thuddungra district (diagrammatic only)
Source: GSNSW, David Forster
Exploration in Australia is being spurred on by a perceived
increase in international demand for raw magnesite, DBM, CCM,
FM, magnesium metals, and more recently, speculation about the
potential of magnesium-ion batteries. Market analysis carried
out by Rockstone Research in 2015 determined that demand for FM
is growing at twice the rate of other magnesia products.
Australian magnesite and magnesia exports
Source: Trade data, various sources
Australia’s largest magnesite ore body is the
Leigh Creek deposit, having JORC measured, indicated and
inferred resources of 453m tonnes, grading at 41.4% MgO. Leigh
Creek is also the world’s largest
cryptocrystalline magnesite deposit. The owner of the project,
Archer Exploration Ltd, plans to produce either CCM or DBM
suitable for a range of monolithic applications. In February
2016, Archer appointed Paul Rix, ex-general manager marketing
for Sibelco’s QMAG, as a director.
Archer, through its subsidiary Leigh Creek Magnesite Pty
Ltd, holds four exploration licences in South Australia, while
Agricola Mining Pty Ltd holds one.
New Zealand magnesite and magnesia imports
Source: Richard Flook, Mosman Resources
In the Northern Territory, exploration is focused on the
Huandot, Area 44 and Winchester deposits, all located within
about 80km south of Darwin.
At the Winchester deposit, exploration is progressing under
Ausmag Pty Ltd, a wholly-owned subsidiary of Korab Resources
Ltd. Winchester is held over a granted mining lease and is
being developed to produce high grade, direct shipping ore
grade magnesite to supply producers of MgO, refractories and
other uses. The company says that the "market for magnesium
carbonate has been growing at a strong historical trend rate
(…) over several decades, with the trend pointing to yet
higher consumption over coming years."
In December 2015, Korab and AusMag entered into a memorandum
of understanding with "interests associated with the Chinese
steel industry, with a view to funding the development,
operation and commencement of producing magnesium carbonate
from the Winchester mine, offtake agreements with Chinese steel
industry and listing AusMag on Shanghai, Hong Kong, or another
suitable stock exchange". In January 2016, Korab revealed that
discussions were with Shandong Iron and Steel Group Co. Ltd,
which has requested samples of magnesite rock from Winchester
The Huandot and Area 44 deposits are owned by Thessally
Resources, which holds two exploration licences and two
exploration licence applications in the Northern Territory.
The Huandot deposit hosts a JORC indicated and inferred
mineral resource of around 9m tonnes, grading at 44% MgO, with
much of the deposit having a purity greater than 44% MgO,
according to Thessally. Thessally previously undertook a
scoping study on the basis of direct shipping magnesia for
export. The study contemplated a 20-year mine life, producing
300,000 tpa and will extend this research into a currently
prefeasibility study for the production of CCM for export into
Southeast and east Asia.
Area 44, less advanced than Huandot, has an exploration
target of 6-18m tonnes, grading at 41-43% MgO.
Indian magnesite and magnesia imports (tonnes)
Source: Richard Flook, Mosman Resources
New South Wales
New South Wales hosts large, ultrapure, cryptocrystalline
and nodular magnesite deposits, as well as widespread regolith
hosted replacement deposits. According to the GSNSW, the state
has previously produced around 1m tonnes magnesite from the BHP
mine near Thuddungra, as well as about 895,000 tonnes hard
magnesite (99.19% MgO calcined) from the Fifield magnesite
mine. In addition, New South Wales hosts the Cargelligo
(Whitton Road) deposits, with 93.4-97.3% MgCO3 and
ferric oxide from 0.5–1.8%; the Noakes deposit, with a
measured resource of 12.6m tonnes grading at 43%
MgCO3; and numerous other opportunities
across the state.
The serpentinite-hosted cryptocrystalline Attunga
deposit in the northeast of the state was the source of
about 100,000 tonnes of characteristically high-purity
magnesite from 1916 to 1960.
In Western Australia, BMAG holds the granted mining lease
M74/110 over the Bandalup Magnesite deposit, 20km east of
Ravensthorpe and immediately adjacent to Canadian miner First
Quantum Minerals Ltd’s Ravensthorpe nickel
According to BMAG, the site was a historical production
centre for beneficiated magnesite and has metallurgical
evaluations showing that the product has the ability to produce
CCM suitable for agricultural and nickel hydrometallurgical
applications. Trial work is underway to determine if 200,000
tonnes of fines stockpiled on site are suitable for kiln feed.
Total estimated reserves of magnesite at Bandalup are around
Fine-grained, massive magnesite, formed by the replacement
of limestone and dolomite, occurs at Arthur River and in the
Lyons River area 50km south west of Burnie.
The Arthur River deposit in Tasmania, hosts 25m tonnes
magnesite, based on a 40% MgO cut-off and 42.4% MgO average
grade to a maximum depth of 40 metres. The resource, which is
not currently held under any exploration licence, is part of a
much larger global resource of 195m tonnes in
Tasmania’s Arthur-Lyons River area, about 53km
south of Burnie.
Selected products and end uses derived from
magnesite, excluding magnesium metal
Feedstock for DBM, FM and CCM.
Fertiliser, acid soil agent, fillers,
Feeds into DBM and EFM.
Paints, paper, water treatment, plastics,
rubber, oil, pharmaceutical products,
fertiliser, animal feed, building materials,
acid neutralisation, hydrometallurgy, slag
conditioner, magnesium chemicals
DBM (sintered magnesia or clinker)
Refractory bricks to line steel making
Premium grade refractory bricks, electrical
substrates, high temperature insulators, and
ceramics special refractory applications in the
nuclear and space industries.
Magnesium metal’s false starts
As well as being the feedstock for FM, DBM and CCM,
magnesite is also the principal source of magnesium metal.
Australia does not currently produce magnesium metal, even
though it has abundant magnesium sources. Several companies
have tried and failed to start magnesium metal processing
plants across the country.
Australian Magnesium Corp. had intended to build a magnesium
smelter using the electrolytic route in Queensland, but closed
down in 2003 before production began.
The South Australian Magnesium project (or SAMAG), owned by
Pima (later known as Magnesium International Ltd), had plans in
the early 2000s to build a magnesium plant at Port Pirie in
South Australia. The project intended to utilise the large
Leigh Creek deposit to provide raw material in a Dow process.
However, it failed in 2003-2004, when SAMAG failed to raise the
necessary capital to develop the $670m, 520,000 tpa plant, at a
time when the magnesium metal market was experiencing a
downturn as a result of Chinese over supply and escalating
construction and power costs.
LaTrobe Magnesium plans to build a 40,000 tpa smelter (using
the Pidgeon process technology) from brown coal fly ash,
produced as a by-product of nearby power generation in Latrobe
Valley, Victoria. LaTrobe is currently in the feasibility study
phase, which it expects to complete in April 2016. Typical
lignite coal fly ash has an MgO content of 3-10% and calcium
oxide (CaO) content of 15-40%.
The meaning of magnesite
The location of the Leigh Creek Magnesite project,
currently held under an exploration
licence by Archer and its proximity to Port Pirie and
Adelaide in the south.
Magnesite refers to magnesium carbonate (MgCO3,
theoretically 47.8% MgO and 52.2% CO2) but is also
sometimes used to refer to magnesia products made from natural
magnesite or synthetic magnesia. It occurs in two physical
forms: cryptocrystalline (or amorphous) magnesite and
macrocrystalline magnesite. It occurs in five different ways:
as a replacement mineral in carbonate rocks; an alteration
product in ultramafic rocks; a vein-filling material; a
sedimentary rock; or, as nodules formed in a lake environment.
However, according to the Geological Survey of New South Wales
(GSNSW), Australian magnesite deposits differ from European
types often quoted in the relevant literature on the mineral,
as they have arguably been developed via low temperature
groundwater, rather than high temperature hot springs.
According to studies by Pohl and Brownlow, in 1989 and 2007,
respectively, stratabound sedimentary sparry magnesite deposits
generally provide the best economic potential for the use of
magnesite as a refractory in steel, cement, glass and copper
industries because of their larger volume and relative ease of
mining. However, according to the study by Pohl, some
ultramafic hosted, cryptocrystalline-nodular magnesite deposits
have been exploited due to the higher purity of the
The pathway of carbon in ultramafic-hosted magnesite vein
and massive deposits has been subject of continuing debate in
scientific literature. This may have direct implementation in
industrial, in situ, or passive mineral carbonation approaches,
due to it being a potential natural analogue for carbon
sequestration and storage.
About the Authors
Cameron Perksis a
freelance writer and industrial minerals consultant. Cameron
previously worked with the Geological Survey of New South Wales
and has also worked with CSIRO, developing methods to eliminate
low frequency noise in SQUID magnetometers.
Dr Richard Flook has worked for both suppliers and
consumers of minerals with global companies including, Steetley
plc, Anglo American, Commercial Minerals (now Sibelco),
Normandy Mining Ltd, Omya AG and Shinagawa
commencing consulting in 2014, Richard’s clients
have come from five continents.
**Conversion made March 2016