Some good news in the mineral
sector at last. It would appear that prospects are promising
for the sillimanite group minerals and alusite, kyanite,
sillimanite, and mullite whose key market is refractories,
followed by casting, abrasives, and ceramics (see panel for
At the expense of bauxite, and with
the refractories market showing some signs of initial recovery,
those active in the supply of sillimanite minerals might be
forgiven for some cautious optimism not long after the dark
days of 2009.
Indeed, if truth be told,
sillimanite mineral suppliers were already on the
case as it were in 2008 with Imerys unveiling its
30m. investment in new and expanded aluminosilicate
refractory raw materials supply, and the much awaited Peruvian
andalusite source beginning (at last) to show serious signs of
coming to fruition.
However, the rapidly unfolding
financial debacle of late 2008-2009 squandered any hope of
anticipated market demand for 2009, and unsurprisingly, some
plans were placed on hold.
But it was hoped to be only a
temporary setback. Come the latter months of 2009, as the steel
market, and China especially, started to recover, optimism
returned with the same signs of anticipated buoyancy in the
market. This trend has reassured and strengthened continued
plans for increasing production capacity for sillimanite
Andalusite dawn: South African andalusite
output is set to rise significantly by 2014.
Courtesy Andalusite Resources (Pty) Ltd
The global sillimanite minerals
supply market is a relatively limited one, owing to avery few
deposits being commercially developed (see map
The natural sillimanite mineral
supply sector is restricted in the main to just two primary
geographic sources of andalusite (France and South Africa) and
one primary source of kyanite (the USA).
On a smaller scale, kyanite is
produced in India (five mines), Ukraine (one miner, one
processor), captively in Brazil by a refractories producer, and
produced intermittently as a by-product of mineral sands mining
Sillimanite is rarely produced in
any large volumes and production appears restricted to India
(four mines) and China.
Data on Chinese sillimanite group
production is sparse. Aside from the established Yilong,
Xinjiang andalusite mine, kyanite and sillimanite supply is
certainly small scale: in 2003 China operated three mines
producing 28,000 tonnes kyanite and 19 mines producing 36,000
From a corporate viewpoint, of
significance is the ownership by Imerys, France, through
subsidiaries, of the dominant andalusite producing mines in
France, South Africa, and China.
However, in recent years,
Andalusite Resources (Pty) Ltd, South Africa, has emerged as
the one independent andalusite supplier to Imerys. Towards the
end of 2009, a second independent emerged in the form of
Andalucita SA, of Peru.
In Ukraine, Ukraine Minerals Ltd
intends to increase kyanite processing and develop a new
kyanite deposit and plant.
With regard to synthetic mullite
production, this is concentrated in the USA, Brazil, Europe,
China, India, and Japan. With the exception of C-E Minerals,
USA, and a few Chinese producers, most sintered production
units are <20,000 tpa, while fused mullite units are
Again, it is worth noting that
significant mullite production capacity comes under Imerys in
the USA, Germany, and Brazil (see producer tables for
summary of main sillimanite mineral producers
Andalusite Resources Maroeloesfontein mine and
plant, Thabazimbi, Limpopo
province, South Africa; very close to Samrec's Rhino mine.
at 50,000 tpa has been a limiting factor, and has prompted
for 2012. Courtesy Andalusite Resources (Pty) Ltd.
For many years, the andalusite
within unconsolidated sands and gravels of the Tablazo Mancora
flood plain of northern Peru, and the as yet unproven resource
of in situ andalusite in nearby shales and schists, has been
In 2006, Andalucita SA, owned by
Refractarios Peruanos SA, was formed to develop the 10m. tonne
58-60% Al2O3 alluvial andalusite deposit
20km south of the port of Paita, north-west Peru.
After a series of studies,
September 2009 saw production start for an initial operating
phase of 30,000 tpa, with, at that time, eventual production
for export planned for 60,000 tpa.
In January 2010, plans were revised
slightly. Carlos De Ferrari, managing director at Andalucita
told IM: This new state-of-the art
andalusite operation in Peru is presently scheduled to reach
its initial first phase full capacity production level of
40,000 tpa by mid-year 2010.
The primary andalusite grade being
produced and intended for shipment contains a minimum of 58 %
Al2O3 and a maximum of 0.8 %
Works trial production
samples are now being distributed to key world refractory
markets. Markets presently placing initial orders for Paita
andalusite involve refractory consumers in Europe, Asia, and
North America. said de Ferrari.
Keen to boost production capacity at its kyanite
operations at Dillwyn, Virgina,
Kyanite Mining Corp. used the 2009 slowdown to completely
upgrade the iron
reduction stage of its kyanite beneficiation process; shown
here are spirals
and the new magnetic separation house under construction at the
Ridge facility. Courtesy KMC.
In September 2009, Andalusite
Resources (Pty) Ltd, announced plans to increase its andalusite
production from 50,000 tpa up to 100,000 tpa by 2012.
Maroeloesfontein mine, Thabazimbi, Limpopo province, is about
220km north-west of Johannesburg. We are mining the same
strike line as Rhino Minerals [Samrecs Thabazimbi mine].
We are mining the southern tail end of this ore body.
said Andreas Pabst, sales and marketing director Andalusite
Andalusite Resources main
markets are in Europe, South Africa, China, and India.Ê
We also sell into Russia, Japan, Korea, Taiwan and other
countries in Asia and the Middle East, but our production
capacity so far has been the main limiting factor when selling
into these territories. Pabst told
The company is producing at almost
its full capacity of 50,000 tpa, and at this rate the mine life
is about 20 years.
Andalusite Resources has
licenses to mine all the farms north of its site up to the
Rhino mine (except for one farm). The immediate extension which
borders onto Maroeloesfontein has already been found to add at
least another 25 years of life to the mine (at 50,000 tpa).
At the end of 2009, the company
completed its latest drilling programme, which encompassed the
remaining six farms between Maroeloesfonteins northern
extension and Samrecs concessions to the north. We
have found bigger reserves there than expected; which will add
an additional 25 years of life. So in total, Maroeloesfontein
has reserves to last at least 70 years at 50,000 tpa.
Given the proven large reserves,
Andalusite Resources has decided to aim for a production
expansion in the region of 80,000-100,000 tpa by the end of
Imerys, the Paris based world
leader in industrial minerals, over the years has steadily
built up its portfolio of impressive aluminosilicate producing
subsidiaries, and has made no secret of its expansion
In October 2008, in response to
customer demand and as a strategic move for the future, Imerys
launched a 30m. investment programme to secure near and
medium term supply of aluminosilicate minerals primarily for
the refractories market.
The programme included: adding a
new 70,000 tpa sintered mullite rotary kiln to C-E
Minerals plant at Andersonville, Georgia in February
2009; debottlenecking at Samrecs Krugerspost and
Thabazimbi andalusite mines in South Africa, adding 30,000 tpa;
ongoing work to start a new andalusite mine at Segorong; adding
25,000 tpa capacity to the existing 15,000 tpa capacity at
Imerys Yilong Andalusite Mineral Co., Xinjiang province (Imerys
acquired a 65% stake in 2007); and a new 20,000 tpa white fused
alumina furnace at Treibacher Schleifmittel Zschornewitz
At that time, the management of
Minerals for Refractories, Imerys, told IM:
We are very bullish about mid-term prospects [for
Some 15 months on, despite the
recession slowing things somewhat, Imerys is still on course to
bring these developments to fruition.
Talking to IM in January 2010,
Damien Chauveinc, general manager Imerys Andalusite Business
Unit, said: Our debottlenecking investments at Thabazimbi
and Krugerpost are now nearly completed and will be fully
commissioned during Q1 2010. Our Capex in China at Yilong in
Xinjiang was commissioned late 2009 and is ready to start up
after the winter break. As for the so called Segorong project,
involving village relocation and opening up of a new mine, we
are still in line with the plan announced at that time, and
start building up the new village beginning of 2010.
The Segorong project has clearly
taken more time than Imerys initially expected, with
inhabitants of Segorong village proposed to be relocated at a
new village at Praktiseer, a few kilometres distant. Imerys
secured final approval from the South African government for
this development in July 2009.
The new Segorong mine, expected to
produce 85,000 tpa by 2014, is to be located between
Samrecs existing Havercroft and Annesley mines, and will
apparently extend reserves currently exploited by these mines
by 15 years.
Andalucita SAs new operation near Paita,
is scheduled to reach its initial first phase full
capacity production level of 40,000 tpa by mid-year
2010. Courtesy Andalucita SA.
Kyanite Mining Corp.
The worlds unsurpassed leader
in kyanite production and development is Kyanite Mining Corp.
(KMC) which has been exploiting the kyanite deposits in central
Virginia, USA, since 1945. The company produces both kyanite
KMCs operations are
concentrated around Dillwyn, Virginia and produce one kyanite
grade, Virginia Kyanite ranging between 55-60%
Al2O3, and a second product, Virginia
Mullite, which KMC describes as a true mullite, and not a
Variations of the two products are
limited to their particle sizes offered, which are mesh sizes
35, 48, 100, 200, 325, and micronised kyanite and mullite with
a d50 value of around 4.7 microns.
Hank Jamerson, vice president,
director of sales and marketing, KMC, told IM:
The key markets for KMC are refractories for steel
production, investment casting flours and grains, kiln
furniture, ceramic parts, and metal foundries. We also
participate in the brake shoe/abrasive market, electrical
insulating porcelains and the sanitaryware/whiteware
Although KMC is confident of its
kyanite reserve base, the company continues to actively invest
in the exploration of suitable deposits around the world.
Given the current consumption
levels for kyanite, we conservatively feel that the reserves
from Willis Mt. and East Ridge will last for 50-75 years, which
does not include our reserves in Canada. Jamerson
That said, KMC is still keen to
boost production capacity at Dillwyn. KMC used the slowdown in
the market during 2009 to completely re-engineer and replace
the critical iron reduction stage of its beneficiation
This significant plant
renovation will allow us to produce a higher quality kyanite
through significant removal of the current existing iron in our
product while also increasing our recovery of kyanite.
KMC is hopeful that these upgrades
and re-designs will permit an increase in production capacities
at this stage of the process.
KMC has also completed its
automated processing and bagging facility, which included
construction of additional warehouses that allows KMC to have
>5,000 s.tons of certified and pre-qualified
material bagged in inventory which is available to be shipped
at a moments notice.
Brazilian refractories producer
Togni S/A Materiais Refratarios, which celebrates its centenary
in 2010, mines kyanite for captive use and produces sintered
mullite based on Brazilian gibbsitic clays containing 72%
Al2O3 at its plant in Sacramento, Minas
Togni also produces 15,000 tpa
chamotte (45-60% Al2O3) at its Plant 1 at
Pocos de Caldas, Minas Gerais, where a wide range of
refractories are produced. By mid-2011 Togni expects to expand
this plant to 120,000 tpa. The expansion will include a new
milling facility, a mixing facility for unshaped
ofÊeightÊautomaticÊhydraulic presses and a
tunnel kiln for high temperature operation.Ê
The company is augmenting its
aluminosilicate portfolio by expanding its Plant 2 in Pocos de
Caldas, Minas Gerais. The plant currently comprises two kilns
for dead burned magnesia production, and Togni has bought a new
rotary kiln for the production of 45-60%
Al2O3 chamotte to be in operation by
The total production capacity
of raw materials [at Plant 2] will be in the range of 40,000
tpa. This facility is also equipped with a milling plant and a
concentration plant for kyanite. said Livio Togni,
operation vice president, at Togni.
Regarding markets, Togni told
IM: As with other refractories
producers, iron and steel is the most important market to our
company (45%), but we also supply to
non-ferrousÊmetalsÊ(15%), cement, lime and
non-metallic mineralsÊ(15%), glass (10%), petrochemical,
ceramics, and others (15%).
Ukraine Minerals Ltd (Umin) was
formed in 2008, and owns several mineral processing plants in
Ukraine, and exports worldwide. Umins key minerals
processed include kyanite, and also kaolin, ilmenite, rutile,
zircon, staurolite, foundry and glass sands, and
Based in Dnepropetrovsk, Umin
operates a processing plant in Volnogorsk (Ukraine trans. =
Vilnohirsk), which it acquired from mineral sands producer
Vilnohirsk Mining & Metallurgical Plant (VMMP), itself once
state owned, but owned by Ukrainian titanium dioxide producer
(80,000 tpa) CJSC Crimea Titan since November 2004.
Umin was effectively born out of
DVS Co. Ltd, a trading company founded in May 1994,
specialising in Ukrainian minerals and chemicals, and
distributing VMMP products.
VMMP operates a huge open pit mine
complex producing ilmenite, rutile, zircon, staurolite, and
kyanite (in the past, latter was <20,000 tpa). Umin has a
license to process certain VMMP tailings resources as well as
some new deposits yet to be developed by Umin as mining
operations. The Volnogorsk deposit is claimed to host 2m.
tonnes of aluminosilicates.
Umin processes 25,000 tpa
aluminosilicate minerals, including kyanite, and 25,000 tpa
titanium-zircon minerals. The natural grain size of the
products is about 140-200 microns, and it is milled up to 45-60
Umins kyanite-sillimanite has
found application in the production of high-alumina
refractories and in non-stick coatings in the foundry industry.
Key markets are in Ukraine, Russia, Belorussia, Turkey, Italy,
Germany, India, and Iran.
Umin is also looking to expand its
kyanite production. In the near future, in Prosyana [site
of Umins kaolin mine and plant], we plan to quarry
another deposit that contains kyanite. Denis Prohorov,
export manager, Umin Ltd told IM.
Umin also plans to increase mineral
production by 300% through expanding its processing plant in
In China, there were unconfirmed
reports that Hainan Chansheng Mineral Industry Co. Ltd was
investing $146m. into developing a possible 200,000 tpa
andalusite and sericite resource near Danzhou city, Hainan
island, south China.
The company plans to construct an
initial 20,000 tpa processing facility near the 6.38m. tonne
deposit, before implementing further expansion to the reach
200,000 tpa at a later date.
In Russia, Moscow-based miner,
Kianit LLC, a subsidiary of JSC Granit, has announced plans to
mine 100,000 tpa kyanite ore from the Khysovaarskoe deposit in
the Republic of Karelia, north-west Russia.
The company intends to construct a
mill, in addition to an open pit kyanite mine, with processing
capacity to produce 20,000 tpa kyanite concentrate. Mining is
expected to start in 2011, with metallurgical tests of bulk
samples currently in process.
Refractory markets, especially
steel refractories, consume the vast majority of sillimanite
minerals, although they are also used in casting, abrasive, and
Consumption of sillimanite minerals
generally reflects the geographic distribution of mineral
sources. For example, consumption of andalusite is relatively
low in the USA, around 15,000 tpa, compared to Europes
approximate 150,000 tpa. This is mainly owing to the distance
the North American markets are from established andalusite
sources, creating high freight costs, and thus encouraging US
refractory formulations to use alternative aluminosilicates
such as bauxites, mullite, and kyanite.
Towards the end of 2009, refractory
mineral markets were showing some signs of recovery, with
traders and consumers reporting healthy signs of some returning
The World Steel Association
reported that global steel production grew to 107.5m. tonnes in
November 2009, representing the third consecutive year-on-year
growth since September 2009, and a 24.2% rise on November 2008
Perhaps not surprisingly, China led
the way with a steel output of 47.3m. tonnes in November a
37.4% growth on November 2008 figures, and almost half of total
Across the board production rises
were seen throughout Asia, Europe and North America, with the
most promising increases coming from Russia (up 42.6% year on
year), Ukraine (up 67.1%), and the USA (up 26.9%).
Meanwhile, total crude steel
production for the first 11 months of 2009 was 1,090m. tonnes;
almost 11% lower than steel production during the same period
In India, CUMI , which is mostly a
captive producer of fused mullite, reported that its Q2 2009
(to 30 September 2009) fused minerals business continued with
strong performance, with a 11% growth in sales over Q2 of 2008
(to Rs.400m.($8.7m.)). CUMI has expanded markets for its
mullite in glass and carbon black refractory applications.
Most sillimanite producers would
have experienced a tough 2009, and many will hope that 2010
will provide some welcome relief.
Denis Prohorov, export manager,
Umin Ltd, told IM: The market situation
of the refractory industry in 2009 was not good. The downturn
started in the first quarter of 2009, and only in
September-October 2009 did we see some positive trends in that
industry. Production capacities of refractory plants in Ukraine
and Russia were functioning only at 40% of their
Andreas Pabst, director, Andalusite
Resources, echoed the trials of 2009: Last year was
obviously a tough trial for Andalusite Resources. Many of our
traditional markets contracted sharply, whilst India and China
performed much better overall and thus really proved their
value to us. Very recently, we have seen a solid resurgence of
demand across the board, from our long-standing customers as
well as new ones whom we have not supplied recently (or only
with limited volumes).
Certainly, owing the range of
activity in production expansions and upgrades reported earlier
in the article, it seems that recovery is anticipated, although
caution is still the watchword.
Damien Chauveinc, general manager
Imerys Andalusite Business Unit, commented: As far as
2010 market trends are concerned, we have been experiencing a
pick-up in demand for a few months, since November, but
its far too early to be able to give any
Phlippe Bourg, sales &
marketing manager - Minerals for Refractories Division at
Imerys, added: The situation both on the end users demand
side, mainly steel producers, and Chinese supplies, mainly
bauxite, needs to be clarified first.
Regarding kyanite, there are some
new market directions, as Hank Jamerson, vice president,
director of sales and marketing, KMC, explained: We are
currently experiencing success in new markets such as ceramic
foam filters for metal production, and refractories for
aluminium production. In general, the performance of our key
markets is weaker than it was 18 months ago, but much more
lively than it was 8-12 months ago. We look to the near term
future with cautious optimism.
Perhaps the greatest talking point
surrounding the outlook for sillimanite minerals is whether
they can make any inroads into markets supplied by bauxite.
This topic, while a traditional talking point, has been
increasingly in discussion over the last two years, and is now
generating even more interest.
The key driver for this has been
the steady decline of cheap and readily available refractory
bauxite from China. Indeed, many refractory manufacturers had
actually used sillimanite minerals before being wooed
to cheap Chinese bauxite exports from the 1980s. They were
further lured to China by intermittent supply of RASC bauxite
from Guyana and limited, specific grade bauxite production from
Par, Brazil, which eventually halted in December
Since then the tables have turned,
with Chinese government policies reducing bauxite (and other
mineral) exports, increased demand for bauxite within China,
and Bosai Minerals Group, of Chongqing, China acquiring the
RASC Guyana operations.
Matters have been compounded with
government restrictions and closures in bauxite mining in
Shanxi, and closures of shaft and round kilns, owing to
environmental and safety controls.
Pre-recession, this created tight
availability of refractory bauxite worldwide with a consequent
rise in its price. Then the recession provided somewhat of a
breathing spot, as global consumers cleared their inventories
and battened down the hatches to ride out the crisis.
With market recovery underway, and,
critically, no change in Chinas position on bauxite
exports nor domestic bauxite mining (the former likely to
remain unchanged, the latter might possibly change in H2 2010),
a return to tight supply and high prices is anticipated.
Jack Gao, general manager of
mineral processor and exporter Refmin China Co. Ltd told
IM: The alternative material for bauxite
we are now selling is low grade bauxite with 75-84%
Al2O3, plus mullite, Alpha Star bauxite
[a calcined high alumina aggregate produced in Xiuwen, Guizhou,
by Guizhou Star Minerals, a C-E Minerals j-v], and brick grog.
Shanxi material is quite short and a new source is Guizhou,
where some refractory grade is now coming out. Supply [of
refractory grade] is very short due to strong demand at the end
of 2009, and it is very difficult to get 85-89%
Al2O3 bauxite, and also the price keeps
Owing to this situation, consumers
are researching the economic and technical suitability of using
andalusite. This has very much helped to oil the wheels of the
expansion plans of Imerys and Andalusite Resources, but has
also prompted Andalucita to emerge as a new player in Peru.
Traditionally, andalusite has not
competed directly with bauxite in refractories. Indeed, it is
not always a straightforward substitution of sillimanite
minerals for bauxite. For certain applications it is possible,
but not for others.
In his paper Andalusite in
Peru, South America, presented at UNITECR09 last
October, Bill McCracken discussed that certain performance
factors of andalusite (eg. high degree of mullitisation at
1,400¼C, high thermal conductivity, small expansion
coefficient, low porosity, and increased spalling resistance)
could be favourably compared to 85-90%
Al2O3 refractories, and not directly
compared favourably nor equivalent to other 60%
Al2O3 mullitised refractory
However, McCracken noted that:
The iron content in refractory grade andalusite is a
major negative factor, with global usage specifications calling
for less than 1%.
The bottomline appears to be that
alumina content is not everything, with sillimanite minerals
offering key properties, and the outcome against bauxite coming
down to price versus performance (see panel
left) as outlined by Bernd Durstberger, former Head
of Minerals for Refractories Division, Imerys, in his
presentation Alternative solutions to non-metallurgical
metallurgical bauxite and alumina in a tight supply
scenario, at the 15th International Bauxite
& Alumina Seminar, 11-13 February 2009 .
Durstberger was of the opinion that
the price/performance ratio in many refractory applications is
favorable for mullite/chamotte versus Chinese bauxite.
Significantly, influencing risk factors for continued bauxite
reliance by consumers include currency fluctuations, freight
market developments, and most crucially, the unpredictability
of Chinese bauxite supply (exports and actual mining).
Durstberger considered that there
is taking place a revision of previous overshooting
by refractory manufacturers, ie. where they
overshot their initial replacement of
aluminosilicates with Chinese bauxite, especially in lower
The upshot is that low-temperature
applications are leaning to chamotte/flint clay usage and high
temperature applications to mullite/andalusite usage. There is
also a trend in blending in of lower alumina raw materials.
Talking to IM in
January 2010, Damien Chauveinc, general manager Imerys
Andalusite Business Unit confirmed: We still believe our
capacity expansions make sense in light of our assessment of
the demand trends for our minerals in refractories and of the
development of Chinese bauxite pricing and
Some sillimanite mineral producers
are already reaping the benefits of consumers looking to
alternative aluminosilicate sources.
KMC has enjoyed raw material
substitutions of its Virginia Kyanite in place of bauxite
fines, andalusite fines, calcined alumina, and fumed silica.
The utilisation of Virginia Kyanite as a substitute for
the [previously mentioned] raw materials has been driven by a
number of factors such stable/reasonable pricing,
consistent/repeatable quality, as well as the fact that
Virginia Kyanite has always been readily available while other
materials were in limited supply. said Jamerson.
Clearly, there is potential for
sillimanite minerals like andalusite and kyanite to benefit
from refractory bauxites predicament. But it still
requires a bit of a leap on the part of the consumers, many of
which remain to be converted.
Andreas Pabst, Andalusite
Resources, observed: With regard to bauxite, I truly
believe that andalusites potential to act as substitute
or added product, is not fully grasped yet by the
Pabst makes the point that the
larger refractory groups, such as RHI and Vesuvius, which enjoy
well funded research and development programmes, are very much
clued up about what andalusite can and cannot do in refractory
applications. However, many of the mid-sized and smaller
refractory companies are not yet fully in this position.
We often encounter real
reluctance of technological departments to change their
approach. They stick to what they know and that is it. However,
if one looks at the price development of andalusite versus
bauxite for instance, it needs to be noted that bauxite has
more than quadrupled in price over the last 5-6 years, while
andalusites price levels have only increased by about
20-30% over the same time period. said Pabst
It appears that although there is
much interest in andalusites potential as a refractory
raw material, particularly with regard to the bauxite supply
situation, only a few consumers seem willing to test to the
For its part, Andalusite Resources,
in co-operation with its chief marketing agent Cofermin
Rohstoffe GmbH is looking into commissioning more research into
the technical aspects of andalusite replacing bauxite, and thus
expanding its market share.
Pabst concluded: This
expansion [at Maroeloesfontein] will depend very much on the
market situation of steel, ceramics, refractories, and bauxite;
but from our point of view we believe strongly in the long term
growth and viability of the andalusite market.
Indeed, another keen observer of
the market is emerging new producer Andalucita SA of Peru.
Carlos De Ferrari, Andalucita SA, recognises the interest in
andalusite from the refractories market and is hopeful.
On a steel production comparative basis, the western
hemisphere consumes roughly 20% of the andalusite refractories
used in Europe. Based on the above, the western hemisphere
industrial world could be consuming at minimumÊ100,000
tpa of Peruvian quality andalusite.
For Brazilian refractories producer
Togni SA, the bauxite issue has played an important role in its
development. It forced us to find viable alternatives; we
can now produce synthetic bauxite in our Plant 3 with a
Brazilian source of raw materials without depending on imports
anymore, especially with the monopoly that is being created by
the Chinese suppliers. For synthetic bauxite, we use some
synthetic additions, decreasing the amount of iron oxide to
0.8% and the alkalis to very low amounts, with improved
physical properties, giving us a much better product compared
to natural calcined bauxite. said Livio Togni, operation
vice president, Togni.
Togni also underlined that Brazil
is a very rich country regarding aluminosilicate minerals
which gives us some good possibilities to supply
Certain high grade sillimanites
remain largely unaffected by the bauxite debate. Sintered and
fused mullites made from higher purity raw materials mean
predominately higher application temperatures and longer life
cycles of refractories ie. very specific niche market
Jan Kupfer, director Business
Division Technical Ceramics, Nabaltec AG, told
IM: Thats basically the reason why
Nabaltec expects a further increase in demand and consumption
for its synthetic sintered mullites in the future.
Symulox® products find application mainly in
high alumina refractory products, typically in steel and glass
manufacture, incinerator linings, and kiln furniture
production. Due to their high purity, M72 and Z72
products are used rather in high performance refractories, than
as a substitute for refractory bauxite. Nabaltec does not
expect any significant impact from the shortage of these
minerals on its own business. said Kupfer.
In conclusion, with the future of
Chinese bauxite supply very much in doubt, and already emerging
trends of increasing sillimanite mineral use in certain
refractory applications, it would appear that there are good
prospects for market penetration for these minerals.
The next bridge to cross, given market recovery continues,
will be to reassure consumers of a quality consistent, stable
supply of high quality sillimanite minerals at attractive
prices. (see p42-43 for producer tables).
World production of
andalusite, kyanite, sillimanite & mullite
M: mullite, ie.
synthetic: fused & sintered
cap. estimated production capacity
where production unknown
Note: figures are in tonnes, and refer to most recent
production estimates, usually 2008; planned production for 2010
only indicated, see producers table for post-2010
Sillimanite minerals in
Andalusite, kyanite, sillimanite,
and mullite are all aluminium silicate, or aluminosilicate
minerals, typically occuring in metamorphic rocks such as
gneiss or schist, and their weathered derivatives, including
some mineral sand deposits.
They are also referred to as the
sillimanite group of minerals, since supply was originally
dominated by Indian sillimanite output. In the USA, owing to
kyanites predominance, the group is referred to as
kyanite and related minerals.
Their commercial development is
limited to just a few producers worldwide (see map and
In the case of mullite, natural
occurrences are uneconomic to mine and thus all commercially
produced mullite is synthetic, ie. produced from natural
minerals by calcination and fusion (see Mullite
With the exception of mullite,
these minerals are mined using open pit methods. Drilling and
blasting for hard rock deposits, followed by primary and
secondary crushing, high intensity dry or wet magnetic
separation, sometimes heavy media separation, possibly
flotation and gravity separation, and acid leaching for
Kyanite and sillimanite are also
produced as by-products from mining of certain mineral
When these minerals are subject to high temperatures they
undergo mullitisation, a chemical reaction of their consituents
to form a mullite phase. The mullite imparts superior
refractory properties and high strength. Thus, the main market
applications for these mineral are in refractories, ceramics,
abrasives, and foundries.
|Density post calcination (g/cm3)
|Temperature of mullitisation (ºC)
||(melts at 1,840ºC)
|Volume change during calcination
||Very slight increase
||Stable at high temperatures
Mullite is rare in nature, and is
named from one locality on the Isle of Mull, Scotland, where
argillaceous sediments have been fused by igneous
3Al2O3-2SiO2, is a mineral
phase much sought after as a major constituent of refractory
and ceramic products owing to its extremely high refractoriness
and strength (the latter owing to the interlocking of its
needle-like crystals). Mullite is very refractory, breaking up
into corundum and liquid silica at 1,810ºC.
Since mullite does not naturally
occur in deposits of commercial value, the mineral is produced
synthetically by either sintering or fusing carefully selected
aluminosilicate raw materials.
Sintered mullite maybe produced by
calcining kyanite (as produced by KMC), calcining a bauxitic
kaolin (as produced by C-E Minerals), or by calcining carefully
selected blends of alumina, kaolin, and bauxite (as in
Commercial sintered mullite grades
have alumina contents in the 45-50%, 60%, and 70+%
Al2O3 categories. Other important
properties are low iron (<1% Fe2O3)
and low cristobalite, and of course, the all important mullite
phase, which can range from 65-90%.
Fused mullite grades, which include
so-called white fused mullite grades, can be produced from
fusing Bayer process alumina and high purity silica (eg.
Washington Mills), or by fusing certain blends of bauxite,
aluminas, and refractory kaolins (eg. in China).
There are a range of commercial
grades of sintered and fused mullite on offer. A typical
analysis would be: 71.7-76.2% Al2O3,
23.0-23.6% SiO2, 0.11-3.0%, TiO2,
0.13-1.17% Fe2O3, 0.04-0.06% CaO,
0.05-0.06% MgO, 0.05-0.44% alkalies.
Mullite has a melting point of
1,810¡C, softens at 1,650ºC, and has a specific
gravity of 3.156.
Fused zirconia mullite, with a
melting point of 1,750¡C and specific gravity of 3.5-3.6
is produced by fusing calcined alumina and zircon sand. During
melting, the zircon and alumina react to yield a mixture of
mullite and zirconia.
Fused zirconia mullite is composed of large, needle-like
mullite crystals, containing co-precipitated monoclinic
zirconia. Average crystal width is 100 microns, with an average
length of 10,000 microns. Traces of dendritic, monoclinic
zirconia and about 5% glass is present in the interstices
between the mullite crystals.
Fused zirconia mullite provides high resistance
to environmental corrosion and a low coefficient
of thermal expansion, and is used in steel and
glass refractories, also ceramic pressure casting
tubes and ceramic rollers. Courtesy Washington
Mills Electro Minerals Corp.
Sillimanite minerals in
Thermal stability Flow resistance
Hot load and hot strength
Mullite 47 (M47) in blast furnace tap-hole clays
Chamotte/M47 and Mullite 60 (M60) in tundish backup
M60 and Mullite 70 (M70) used in steel lances
M60 and M70 in electric arc furnace delta sections
M60 and M70 in slide gate formulations
M60 in construction grade plastics
M47-70 used to replace fine grain calcined bauxite in mortars,
plaster, and plastics
M60 in iron runners
M60 grain of choice in torpedo ladle applications
M70 and M60 in various pressed brick shapes.
in steel ladles
in hot stove bricks
in bricks for cement rotary kilns
Andalusite-SiC in iron ladles
Aluminosilicate raw materials in refractories
||Alumina content (%)
||Max. service temperature (°C)
||Steel (continuous casting)
|White fused alumina
||Steel (continuous casting)
|Brown fused alumina
||Blast furnace (runners)
||General heat containment
|(steel and industrial boilers)
||General heat containment
||General heat containment
Source: Bernd Durstberger, former Head of Minerals for
Refractories Division, Imerys, presentation Alternative
solutions to non-metallurgical metallurgical bauxite and
alumina in a tight supply scenario, 15th
International Bauxite & Alumina Seminar, 11-13 February
2009, Montego Bay.
|55-59% Al2O3, FOB European port,
|57-58% Al2O3, 2,000 tonne bulk, FCA mine South
|Shanxi rotary kiln 87% Al2O3/1.8% Fe2O3/BD 3.20+, FOB
|Guizhou round kiln 87% Al2O3/2.0% Fe2O3/BD 3.20, FOB
|Kyanite, crude, ex-works USA, 55-60% Al2O3
|Calcined kyanite, ex-works USA, 55-60% Al2O3, 22 ton
|Sintered mullite, 47% -70% Al2O3 (sized in bulk
bags), FOB USA
Source: Industrial Minerals
Major natural sillimanite
||Capacity (unless otherwise stated)/remarks
|Togni S/A Materiais Refratários**
||Pocos de Caldas, Minas Gerais ; concentration
||several kyanite mines in Minas Gerais, 1.5m. tonnes
reserves; captive feedstock for refractories production,
capacity 60,000 tpa both shaped and unshaped.
|Henan Mines and Refractory Corp.
||exports >100,000 tpa of range of minerals
|Imerys Yilong Andalusite Mineral Co.
|Imerys (majority shareholder)
||15,000 tpa; +25,000 tpa commissioned late 2009,
start-up after winter.
||raw kyanite from own mines for sintered mullite
|Indian Rare Earths Ltd
|Chatrapur (Oscom), Orissa
||By-product of titanium, zircon, and rare
earth mineral sands production; total combined mineral
prod. cap.: 200,000 tpa Chavara; 500,000 tpa Oscom.
|Refractarios Peruanos SA
||40,000 tpa 0.6-4mm planned as initial production
mid-2010; 2007 reserve estimates indicate primary grade
exceeds 10m. tonnes 58-60% Al2O3 low iron finished
|Andalusite Resources (Pty) Ltd
||Maroeloesfontein, Thabazimbi, Limpopo
||50,000 tpa; min. 57% Al2O3, max. 1% Fe2O3, 1-3mm,
0.5-1.5mm, 0-1mm, 100#, 200# other sizes upon request;
licence to mine north of site, proven reserves = 70 year
mine life at current rate; plans to increase to
80-100,000 tpa by 2012.
|Samrec Pty Ltd
||4 mine/plant sites:
|Annesley, Penge, Limpopo
|Havercroft, Burgersfort, Limpopo
|Rhino, Thabazimbi, Limpopo
|Krugerpost, Lydenburg, Mpumulanga
||195,000 tpa combined; debottlenecking at
Thabazimbi (adding 20,000 tpa) and Krugerpost (10,000
tpa) will be fully commissioned during Q1 2010; ongoing
project to develop mine at Segorong (85,000 tpa) by 2014;
Annesley and Havercroft (60,000 tpa combined) expected to
in line with Segorong start-up total prod. cap. est.
250,000 tpa by 2014.
|Ukraine Minerals Ltd (Umin)
||Vilnohirsk, processing plant
||25,000 tpa concentrate 57-58% Al2O3 processed from
tailings from Vilnohirsk Mining & Metallurgical Plant
operation; owns 2m. tonnes reserves; planning to expand
plant and develop kyanite mine and plant at
|Vilnohirsk Mining & Metallurgical
||Vilnohirsk, mine and plant
||Large open pit mining and processing operation
exploiting ilmenite, rutile, zircon with kyanite,
staurolite, quartz by-products.
|Kyanite Mining Corp.**
||Dillwyn, Virginia; mine sites, Willis Mt. and East
Ridge; 3 plants, 1 calcines Virginia Kyanite into
Virginia Mullite, 2 grind, bag, and inventory Virginia
Kyanite and Virginia Mullite.
||130,000 s.tpa kyanite (55-60% Al2O3); can expand by
20% by increasing to 7-day shift from 5-day;
|division of Resco Products Inc.
||Hillsborough, North Carolina
||Captive feedstock for refractories production; the
only andalusite deposit mined in the USA, the ore is a
mixture of pyrophyllite and andalusite.
ie. andalusite, kyanite, and sillimanite not synthetic
** see also mullite producer table
Major mullite producers
(fused & sintered)
||Capacity if known (unless otherwise
|Elfusa Geral de Eletrofusão
||São João da Boa Vista, São
||120,000 tpa combined total prod. cap. of range of
fused minerals incl. white fused mullite, fused ZrO2
|Togni S/A Materiais Refratários
||Sacramento, Minas Gerais
||15,000 tpa; based on 72% Al2O3 gibbsitic clays;
plant has high temperature rotary kiln,
grinding, and concentration facility with two 120x120x110
|Treibacher Schleifmittel Brazil Ltda
||Salto, Sao Paulo
|Datong Alumina-Silicate Refractory Co.
|Pleiade International Merchandise (Tianjin) Co.
||Xing Pingwang, Datong, Shanxi
||80,000 tpa total combined cap. incl. calcined
bauxite, kaolin; 60%, 70% Al2O3 grades
|Henan Mianchi Great Wall Corundum Co. Ltd
||6,000 tpa; 3,000 tpa ZrO2 mullite
|Henan Mines and Refractory Corp.
||exports >100,000 tpa of range of minerals
|Huang He Minerals Co. Ltd
||20,000 tpa 45%, 60%, 70% Al2O3 grades plus ZrO2
|Hunan Chenxi Huazhong Mullite Co. Ltd
||5,000 tpa fused (70% Al2O3), 30,000 tpa sintered (60,
70% Al2O3); owns 3 bauxite mines.
|Inner Mongolia Sanhe Calcined Kaolin Ltd Co.
||Eerduosi, Inner Mongolia
|Jie Xiu Bauxite Plant
||Jie Xiu, Shanxi
||Rotary kiln producing sintered mullite
|Jungar Mengsheng New Materials Co. Ltd
||Jungar, Inner Mongolia
||75,000 tpa rotary kiln capacity; 47.5%, 60%, and 70%
|Shanxi Diversified Industrial Corp.
|CMP-Shaowu Haisheng Minerals Co.-Zhongtian Weitu
Trading Co. j-v
||100,000 tpa, 45%, 47%, and 60% Al2O3 grades
||10,000 tpa, 72% Al2O3, also incl. ZrO2 mullite
|Treibacher Schleifmittel Zschornewitz
||8,000 tpa fused ZrO2 mullite, 23,000 tpa white fused
mullite; incl. new white fused alumina kiln cap.
|Motim Electrocorundum Ltd
||5,000 tpa white fused mullite; 2,000 tpa fused ZrO2
||12,000 tpa, 60% Al2O3, from calcined kyanite
|Carborundum Universal Ltd (CUMI)
||Kalamassery, Kochi, Kerala
||1,000 tpa 78% Al2O3
|Orient Abrasives Ltd
||white fused mullite 73-77% Al2O3, also fused ZrO2
mullite; total fused minerals cap. 21,000 tpa, total
calcined minerals cap. 74,250 tpa
|Itochu Ceratech Corp.
||Seto City, Aichi
||10,000 tpa, 70-76% Al2O3 grades
|Showa Denko KK
||10,000 tpa total prod. cap combined fused minerals
incl. fused mullite (76% Al2O3) and fused ZrO2
||10,000 tpa total mineral cap., incl. white fused
|DSF Refractories & Minerals Ltd
||produced by firing andalusite and alumina; June 2009
$1.17m. expansion of mullite capacity by 50%; total
mineral processing capacity 50,000 tpa
||700,000 s.tpa incl. 70,000 tpa kiln added Feb. 2009;
also distributes fused mullite produced by Triebacher in
Brazil and Germany
|Kyanite Mining Corp.
||two kilns; ability to convert 40,000 s.tpa of
Virginia Kyanite into Virginia Mullite 57% Al2O3,
0.5% Fe2O3; current capacity utilisation is about
|Washington Mills Electro Minerals Corp.
||Niagara Falls, New York
||10,000 tpa fused mullite; 10,000 tpa fused ZrO2