Economic deposits of the natural magnesium minerals brucite,
huntite and hydromagnesite are found in only a few places in
the world and are extracted mainly for use as flame retardants.
There are two main areas of brucite deposits globally
– in Liaoning, China and in Russia, both with
Russian brucite miner Russian Mining Chemical Co. (RMCC) has
grown significantly over the last 10 years, largely on the back
of international sales to the flame retardant
Brucite (magnesium hydroxide, or Mg(OH)2), along with
huntite (magnesium calcium carbonate) and hyrdromagnesite
(hydrated magnesium carbonate), are among the lesser known
magnesium minerals. Their chemical compositions are shown in
Brucite is distributed in a wide range of rock types, but
there are only a few large scale deposits globally.
The mechanism for brucite formation is generally when
dolomitic marble, or magnesium-bearing limestone, is subject
to contact metamorphism and the mineral pericalse (MgO) is
formed and hydrates to brucite in the presence of water.
The main characteristics of brucite are shown in Table 1 and
the principal global resources of brucite are shown in Table 2,
with China at 26m tonnes and Russia with 32m tonnes.
RMCC specialises in the mining, processing and trading of
brucite from the Kuldur deposit in the Jewish Autonomous
Region of Far East Russia. Kuldur was discovered in 1966 and
has reserves of 10m tonnes brucite. The brucite is a
crystalline massive rock, white to light grey in colour. The
chemistry of the three grades of ore extracted from the mine
is shown in Table 3.
RMCC was established in 2002 and started its first
production plant in Vyazma, Smolensk Oblast, 220km west of
Moscow, in 2006.
RMCC established Kuldur Mining Company in 2011 and a second
processing plant in Vyazma in 2011. RMCC purchased a
controlling block of shares in Kuldur Mining in 2012. A view of
the Kuldur deposit is shown in Figure 2.
RMCC established a European subsidiary, Europiren BV, in
Rotterdam in 2013 and in 2015 opened a polymeric
Kuldur’s main business is mining brucite with
crushing and sorting. In 2011 it introduced XRF
separators after crushing to separate brucite according to
percentage content of MgO, silicon dioxide (SiO2) and iron
oxide (Fe2O3). There is also a fully equipped laboratory on
site that monitors quality. A view of the facility is shown in
Figure 3 with a flowsheet shown in Figure 4.
The Kuldur quarry is located 20km from the railway junction
of Izveskovaya, which connects to the Baikal-Amur Mainline
(BAM) and Trans-Siberian Railway, which allow Kuldur ore to
be railed to several major ports including Saint-Petersburg,
Nahodka, Novorossiysk and Vanino.
Once sorted, the best quality material is railed from Kuldur
to Vyazma, where it is milled, classified and surface coated by
a plant operated by Vyazma Brucite LLC.
The Vyazma plant was upgraded in 2009-2013 to meet increasing
demand for brucite. In January 2013, the company received ISO
9001-2008 standard certification for quality management. A
flowsheet of the processing plant is shown in Figure 5.
Europiren handles sales of RMCC’s brucite
products (see Table 4) to Europe, the Middle East and North
Africa, North America and South East Asia. It also provides
technical support to RMCC’s customers and manages
the company’s polymer research laboratory.
Prior to 2006, there were only sales from Kuldur and overall
production that year was 38,714 tonnes. Output has since
increased steadily, but the introduction of XRF sorting in
2011 led to a significant increase in production.
The capacity of each of the two processing plants in Vyazma
is 100,000 tpa and sales in 2016 totalled 189,500 tonnes. A
third mill is under construction to increase capacity by a
further 30,000 tpa.
RMCC acquired the mining rights for the Savinsky deposit,
80km from the Kuldur mine, in January 2017. Savinsky has
combined reserves and resources of 22m tonnes brucite and could
ship as much as 500,000 tpa.
|Figure 2: Kuldur brucite mine
Mining at Kuldur is open cast and
benched; the mine’s crushing plant can
be seen in
|Figure 3: Kuldur crushing
and sorting complex
Chinese brucite is found mainly in Liaoning province, in
Fengcheng, Kuandian and Xiuyan, with some fibrous brucite
operations in Henan, Shaanxi and Hebei provinces.
Brucite resources in China are around 26m tonnes, 24.3m
tonnes of which is whitish-greyish brucite in Liaoning, the
remainder being fibrous brucite found elsewhere. There are 13
brucite mines in Liaoning, 10 of which are in the Fencheng
area, with two in Kuandian and one in Xiuyan.
Details of Liaoning’s brucite producers are
shown in Table 5.
Four companies in the fibrous brucite areas, which have
combined resources of 1.7m tonnes and production capacity of
31,000 tpa, hand mine ore at surface and underground. The
brucite is processed as a float material and the resulting
product is mainly used as a substitute for asbestos in
thermal insulation and sealing and as a friction resistant
material in brakes.
Between 2011 and 2016, Chinese export quotas on brucite
varied between 400,000 and 500,000 tpa, not all of which was
used up each year and these quotas have now been scrapped.
China’s current brucite production levels are
unknown, as many mines in Liaoning have been closed due to a
wave of environmental inspections to combat air pollution and
strict controls on the use of dynamite for blasting
Liaoning companies produce ultra-fine magnesium hydroxide
powder. Brucite is selectively mined, crushed into coarse and
fine fractions and then ball milled to produce powder with an
94% minimum Mg(OH)2 content.
After fine milling, surface treatment – mainly
stearic acid and a silane-coupling agent – is applied
and the material is then sold as a flame retardant.
The chemistry of Grade 1 brucite lump from China is compared
with equivalent material from Russia’s Kuldur mine
in Table 6. The main difference is the very low level of Fe2O3
in the Russian brucite.
The US produces most of its magnesium hydroxide from lake
brines, well brines and seawater, but the country also has
resources of naturally occurring brucite and brucitic marble.
Premier Magnesia LLC produces caustic calcined magnesia
(CCM) from a magnesite deposit at Gabbs, in Nye County, Nevada.
The Gabbs deposit contains a reported 3m tonnes brucite
resource, but at present this is not mined.
Applied Chemical Magnesias Corp. (ACM) used to mine brucitic
marble – a mix of brucite and calcite – at
Marble Canyon in Van Horn, Texas. Following legal
issues with the mine, ACM-Texas filed for bankruptcy in 2008
and the Marble Canyon operation is now owned by International
Brucite Corporation (IBC), which is held by Texas
Architectural Aggregate Inc (TAA).
Garrison Minerals specialises in hydroxide, oxide and
carbonate magnesium materials, including Mg(OH)2 which it sells
as dry powders and slurry (see box). It imports brucite from
Liaoning, China and has 11 slurry distribution terminals
located across the US.
Cimbar Performance Minerals partners with Garrison to
produce slurry and dry powder. The company’s
UltraMag product is used in water treatment, slurries,
plastics, rubber and flame retardants and smoke suppressants.
Huntite and hydromagnesite
Hydromagnesite and huntite, along with aragonite, are formed
in closed lacustrine basins of Tertiary to recent age.
The two minerals are found in the same deposits and their
main characteristics are shown in Table 7.
The two known operating mines that produce hydromagnesite and
huntite are Sibelco Hellas SA Mining Co.’s
deposit in Greece and LKAB’s Likya Mining Co.
operation in Turkey.
White Minerals SA in Greece was established in 1994 with
Dutch company Ankerpoort NV extracting huntite-hydromagnesite
from mines and selling it mainly as crude material.
Belgium’s Sibelco acquired Ankerpoort in 2000
and since 2001 Sibelco has been responsible for mining and
marketing both crude and finished products.
Sibelco Hellas has two quarries, concessions 72 and 74, in
the area between the villages of Lefkara and Neraida,
southeast of Kozani, in western Macedonia in Greece, with
estimated reserves of 250,000 tonnes. Hard porous white plugs
located inside the mine are aragonite sinters that feed the
basin with magnesium and calcium-rich solutions.
The deposit has an average thickness of 3 metres and
selective mining obtains material with 65% huntite and 35%
hydromagnesite content. The overburden and ore is soft, meaning
that the company does not need to use explosives for mining,
which takes place between May and September.
Sibelco’s plant at Kerida consists of drying,
grinding, classification and bagging.
Beneath the marlstone is the white huntite-hydromagnesite
layer, with huntite:hydromagnesite ratios of between 70:30 and
50:50. After processing, the mixture has a composition of
50:50. The contact between the marlstone and the
underlying layer is irregular, due to the underlying
Sibelco Hellas has gradually built up its sales of finished
products from zero in 2001 to a peak of 24,200 tonnes in 2012,
including 7,450 tonnes of processed material and 5,420 tonnes
of raw material. Output and sales both declined in 2013 and
2014, and no figures are available for 2015 or 2016 (See Table
Likya Minerals (LKAB)
In Turkey, reserves of mixed huntite and hydromagnesite are
found in South Denizili, Cameli Basin in the southwest of the
One large deposit there was originally mined and processed
by Likya Minelco, a joint venture between Likya Mining and
Mincelco Specialities. The mine’s current owner,
Likya Minerals, is now a joint venture partly owned by
The size of the reserves is reported vaguely by LKAB as
being in the "tens of millions of tonnes".
The company operates a processing plant near Izmir, using a
special classification system to achieve a "sharp top cut"
grade for coated and uncoated products. Hydromagnesite and
huntite are flame retardants on their own, but combined they
result in a product which specific properties that can be
adjusted by selective mining and processing to fit a variety
Likya Mining’s products marketed under the
trademark Ultracarb and are used as fire retardant fillers in a
range of polymers such as polyethylene, polypropylene, PVC and
Whereas the classical endothermic flame retardant fillers act
by releasing water in a single action process, Ultracarb has
a unique three-stage fire retardant mechanism.
First, water is released at temperatures of around 220°C
as part of the thermal decomposition phase. Then, carbon
dioxide is released at temperatures of around 330°C and
then, at temperatures of around 560°C, UltraCarb particles
accumulate on the surface of the burning polymer to form a
stable char which inhibits the combustion process and thus the
propagation of the fire through burning droplets.
This, like many of the other minerals discussed above,
demonstrates the unique performance characteristics of
magnesium minerals which makes them suitable substitute flame
retardant materials in applications where halogenated or
other mineral-based products cannot be used.