Because of their specific mineral
properties, both perlite and vermiculite lend themselves to a
variety of commercial applications, such as in construction and
packaging. One niche use is the application of perlite and
vermiculite in horticulture, owing to the structure of both
minerals, which allows them to control soil moisture and host
mineral fertiliser.
Vermiculite is a hydrated
magnesium-aluminium silicate, with typical composition being
38% to 46% silica (SiO2), 10% to 16% alumina
(Al2O3), 16% to 35% magnesia (MgO), and
other compounds such as calcium, iron, potassium and titanium
oxide.
Owing to its lamellar structure,
similar to that of mica, vermiculite expands 6 to 30 times the
original volume of vermiculite concentrate when heated above
870¡ C through a process called exfoliation.
Exfoliated vermiculite is
chemically inert, with a melting temperature of between
1200¡ C and 1320¡ C, non-combustible and a good
insulator of electricity, heat and sound.
Horticulture accounts for at least
50% of vermiculite’s end market. Other market applications
include building plaster; fire protection; refractory; friction
linings; special coatings; animal feed; and packaging.
“The end use diversity of
vermiculite does ensure some stability from a sales point of
view. The agriculture and horticulture markets continue to
perform very well,” Richard Knight, business manager at
Palabora Mining Co.’s subsidiary, Palabora Europe Ltd,
told IM.
In horticulture and agriculture,
vermiculite is used for different purposes. It is used in the
retention of soil moisture; acting as cation exchanger; and
hosting a number of mineral fertilisers such as ammonium,
potassium, calcium and magnesium.
When combined with peat,
vermiculite promotes faster root growth in plants, controls the
delivery of fertilisers, herbicides and insecticides, and
protects plants from cold and drought.
At the beginning of 2014, the
All-Russian Rapeseed Research Institute (ARRI) developed a new
vermiculite, sodium carboxymethylcellulose (NaKMC)
bio-nano-chip, to enhance soy-bean germination capacity from 92
to 99% with half the normal amount of protective fungicide,
Topsin-M.
Substitutes for vermiculite in the
horticulture market are perlite, peat, sawdust, pine bark and
synthetic soil conditioners.
While perlite has a stable neutral
pH, vermiculite’s pH can vary from 6 to 9, from neutral to
slightly alkaline, owing to the presence of carbonate compounds
associated with the mineral ore.
In the last four years, the
vermiculite market suffered a contraction, because of rising
vermiculite prices, as reported by the Canadian processing
company, Perlite Canada Inc., in 2013.
Knight told IM
that horticulture and agriculture markets continue to be strong
and will see a growth in vermiculite demand. Ê
“The horticulture market is an
exciting opportunity for Palabora vermiculite, which seems very
well suited for this application and we are seeing increased
growth in this area especially in the warmer countries where
the climate is suited for greenhouses,” Knight said.
Jose Luis Fernandes, technical and
sales manager at Brasil Minerios, told IM that
the size of the market remained unchanged in the last three
years, with 40% consumption in the horticulture/agriculture
market and 40% in the building board market. He added that in
the international markets, consumption was for the 40% coarse
grade and 60% fine grade.
Brasil Minerios said that the
economic crisis caused a 15% to 20% contraction in vermiculite
demand in the last three years compared to 2007 and 2008.
According to Fernandes, the
vermiculite market in Brazil and worldwide will increase at low
rates. In Brazil, the construction market will be predominant,
while the agricultural markets will see a moderate growth in
demand, predominantly in fine grades.
New markets for fine grades of
vermiculite are in water absorption and air pollution control
in mines, used in ion-exchange columns, purification of waste
water as well as for nuclear waste containment and
removal.
Vermiculite prices
In the US, vermiculite prices
ranged between $115/tonne and $460/tonne in 2011, depending on
grade; according to the US Geological Survey (USGS). Prices
increased to $145-525/tonne in 2012 and to $150-550/tonne in
2013, due to a difficulty in supply meeting increasing demand
for coarse grades vermiculite.
Average prices of vermiculite sold
by Palabora Mining Co., calculated from the ratio of total
sales values and volumes, amounted to $326/tonne in 2012 and
increased to $357.6/tonne in 2013.
Average prices of exported
vermiculite in South Africa amounted to $186.7/tonne in 2011,
according to data from the Department of Mineral Resources and
Statistics of South Africa (DMRS); prices calculated from the
ratio between total sales values and volumes.
Indian vermiculite exports were at
$116.3/tonne in 2011 and increased to $140.7/tonne in 2012;
calculated from the ratio between export values and export
volumes reported by the IBM.
IBM data suggest that average
vermiculite import prices from South Africa to India decreased
from $289.8/tonne in 2011 to $240/tonne in 2012.
Fernandes said that prices of fine
grades dropped by almost 20% compared to 2010, probably due to
overproduction, while prices of coarse grades have shown little
variation.
According to the USGS, after a
ramp-up in the last few years, vermiculite prices are expected
to stabilise in 2014.
“The price of vermiculite has
been affected by the supply and demand scenario. We have seen
increases of around 40% for some grades of vermiculite. Prices
have reduced and stabilised to reflect the competitive
environment,” Knight said.
Global vermiculite
production
In the last few years, the
vermiculite market has recorded several changes among global
producers, with an increasing demand of coarse grade and an
oversupply of fine grades, partly due to a downturn in the
building sector over the last two years.
“The building sector is an
important end use market for Palabora vermiculite and the
downturn of this industry in the last couple of years has
impacted on our sales,” Knight told
IM.
According to the USGS, the
estimated global production of vermiculite increased by 10.5%
in 2013, reaching 420,000 tonnes from 380,000 tonnes in
2012.
The figures are still lower than
those in 2011, when total production amounted to 542,000
tonnes.
South Africa
South Africa-based Palabora Mining
Co. Ltd is one of the world-leading producers of vermiculite
concentrate, with 133,000 tonnes produced in 2012 from its
vermiculite mine in Limpopo.
The major producing country is
South Africa, accounting for 31% of world production in 2013,
with estimated reserves of 14m tonnes of vermiculite, according
to USGS data.
Knight said that production in 2013
amounted to 130,000 tonnes, less than Palabora’s optimal
plant capacity.
“Improved mine planning and
more efficient recovery is giving us the right quantity of
grades for the market. Our business plan is to be back to
producing 150,000 tonnes in the next 18 months,” Knight
told IM.
The company sold about 121,500
tonnes of vermiculite in 2013, compared to 115,000 tonnes in
2012.
Knight added that production
capacity is around 200,000 tonnes and expansion of mining
operations will extend the mine lifetime over 24 years.
“The European vermiculite
market still remains a key market for Palabora with Asia and
America markets still having opportunities for growth,”
Knight told IM.
In December 2012, Anglo-Australian
mining companies, Rio Tinto and Anglo American PLC, sold their
respective 57.7% and 16% interests in Palabora Mining to
state-owned Industrial Development Corp. of South Africa and a
Chinese consortium, including private-owned Hebei Iron Steel
Group, state-owned Tewoo Group Co. Ltd and private-owned
General Nice Development Ltd.
According to the USGS,
Palabora’s production of sufficient quantities of
coarse-grained grades became increasingly challenging to meet a
substantially increasing world demand in 2011.
Knight told IM
that more efficient mining in the last few years has resulted
in producing more medium and fine grades.
“In recent years, both these
grades have been in short supply and our ability to now supply
will definitely benefit our business,” he said.
Zimbabwe
Zimbabwe is another important
producer of vermiculite in Africa from the Shawa mine, near the
town of Dorowa, owned by the French mining company, Imerys
SA.
The deposit, which extends over an
area of 5.5km in radius, has an estimated lifetime of 30 years,
with a processing plant production capacity of 50,000 tpa.
Imerys also owns a vermiculite
deposit in Australia with an estimated minelife of 20
years.
Uganda
Uganda is the third major producer
of vermiculite in Africa, with its East African Namekara mine
hosting inferred mineral resources for 55m tonnes, 60% of which
includes significant coarse and medium grades of vermiculite,
according to the IBM.
Australian mining company, Gulf
Industrials Ltd, increased its production capacity at Namekara
from 4,000 tpa raw concentrate in 2010 to 30,000 tpa in 2012.
However, the company suspended production for ‘care and
maintenance’ operations since October 2012.
According to the USGS, the company
is planning to increase its capacity up to 50,000 tpa in
2014.
China
China is another producer of
vermiculite, with 50,000 tonnes produced in 2013, accounting
for 12% of global production, according to USGS data. Xinjiang
Weili Xinlong Vermiculite Co. Ltd is the main producer in the
country.
US
The US is the second largest
producer worldwide, with 100,000 tonnes of concentrate produced
in 2013 and reserves of up to 25m tonnes.
The country consumed 140,000 tonnes
vermiculite concentrate in 2013, down 12.5% year-on-year,
according to the USGS.
Imports, which were mainly from
South Africa and China, increased from 53,000 to 57,000 tonnes
in 2012, but decreased by 26.4%, to 42,000 tonnes in 2013.
WR Grace, one of the major US
producers, sold its vermiculite mine in Enoree, near the city
of Woodruff, South Carolina, to its subsidiary Specialty
Vermiculite Corp.
The company previously ran the
biggest US vermiculite mine in Libby, Montana, until 1990, when
it closed operations owing to asbestos contamination in the
area. The company filed for reorganisation under Chapter 11 of
the US bankruptcy code in 2011 to resolve its asbestos-related
liabilities and emerged from bankruptcy at the beginning of
2014.
Virginia Vermiculite LLC mines
vermiculite in Louisa County, Virginia, with an average
production between 35,000 and 40,000 tpa, according to the
Virginia Department of Mines, Minerals and Energy.
Brazil
Brazil is also an emerging producer
of vermiculite resources, with estimated reserves of up to 16m
tonnes, according to the USGS.
In 2011, Brazil accounted for 9.3%
of global production, with about 55,000 tonnes, according to
the National Department of Mineral Production (DNPM).
Production was concentrated in the state of Goias (84%),
followed by Pernambuco (8.2%), Paraiba (6.7%) and Bahia
(1.1%).
Brasil Minerios is the main
vermiculite producing company in Brazil, with mineral reserves
in Sao Luis, Goias, amounting to 4m tonnes, of which 1.2m
tonnes are vermiculite ore.
With the development of its second
vermiculite deposit at the Catalao project, near the state of
Minha Gerais, the company will reach estimated mineral
resources up to 20m tonnes.
Jose Luis Fernandes, technical and
sales manager at Brasil Minerios, told IM that
vermiculite production at Morro Pelado mine in Sao Luis in 2013
amounted to 60,000 tonnes, of which 40,000 m3 was
expanded vermiculite. Vermiculite products were 50% coarse and
50% fine grades, with sales in America (50%), Europe (35%) and
Asia (15%).
With the additional development of
its Catalao project, Brasil Minerios aims to expand its
production capacity to 200,000 tpa in 2016, when production
will start at Catalao.
Processing
improvements
Exfoliation of vermiculite
concentrate traditionally takes place in a blast furnace,
through an energetically intensive process, with waste being up
to 8% of product not completely exfoliated.
In 2012, Brasil Minerios developed
a unique hybrid wash screen-dry winnower method, which leads to
high quality products and cost-effective improvements in
exfoliation.
“These beneficiation
techniques were developed to process our kind of raw material
using natural resources, like sunlight and water,”
Fernandes told IM.
New advanced exfoliation methods
are based on microwave power, reducing energy costs and
guaranteeing a more uniform heating of all concentrate
flakes.
UK-based technology solution
provider, E2V Technologies, in collaboration with the National
Centre for Industrial Microwave Processing at Nottingham,
developed a microwave-based process to exfoliate vermiculite,
Prowave, which achieves yields of 80g/litre bulk density,
compared to 110g/litre in blast furnaces.
Prowave can produce up to
12.5m3/tonne exfoliated vermiculite, compared with
9.1m3/tonne generated in blast furnace.
As vermiculite is transparent to
microwaves, the final product is cooler (150¡C) than that
processed in a furnace, it can be packaged almost
immediately.
According to the E2V, the microwave
method can reduce energy consumption by 90% and cut carbon
dioxide emissions by 85%.
Perlite in
horticulture
Perlite is a glassy volcanic rock
with a pearl-like sheen. The mineral is generally composed of
around 71 to 75% silicon dioxide, 12.5 to 18% alumina, 4 to 5%
potassium oxide and between 1 and 4% sodium and calcium oxides,
as well as trace amounts of metal oxides.
Because of its low density
composition and relatively low price, a variety of commercial
applications have been developed for perlite including in
construction, fillers, horticulture and filter aids. Although
it can be replaced with other competitive commodities in all
its applications, approximately 15% of perlite produced
globally is used in horticultural aggregate applications.
Functioning in the much the same
way as vermiculite in horticulture, perlite is often used as a
soil amendment owing to its high permeability and low water
retention properties.
Various materials can be added to
soil as an amendment, enhancing physical properties such as
water retention and infiltration, drainage, aeration, structure
and permeability. Perlite is particularly suited to clay soils
with low permeability, while vermiculite, with its high water
retention properties, is more suited to sandy soils, which have
low water retention attributes.
When perlite is processed, it is
heated to temperatures of around 871¡C (1600¡F),
causing the mineral to expand as its particles pop like
popcorn, leaving an extremely lightweight, snow-white material.
The expanded perlite product consists of closed air cells
covered in cavities, creating a very large surface area. It is
this property that enables the perlite particle to trap
moisture, making it readily available to plant roots when
needed. The shape of the particle also adds additional aeration
and improves drainage.
Used in both small-scale gardening
and commercial growing, perlite also lends itself well to
soilless growing thanks to its neutral pH and the fact that it
is weed free. It is also ideal for carrying fertiliser,
herbicides, pesticides and seed pelletising, as well as for
container growing.
Several other positive traits
include the fact that the mineral is organic and does not
deteriorate, it insulates against extreme soil temperature
fluctuations and it is sterile, clean and odourless.
Global perlite
production
USGS figures indicate that the US
is the leading consumer of processed crude and expanded perlite
in 2012, however new data indicates that Greece, Iran, and
Turkey have been producing more perlite that the US since
2008.
Although no reliable data is
available for China, Greece and Turkey are believed to be the
largest perlite producers, both producing around 800,000 tonnes
of perlite in 2013. The third largest perlite producer is Iran,
which produced 500,000 tonnes in 2013. Though the majority of
global production remained stable, the US saw its production
decline slightly from 396,000 tonnes in 2012, to 376,000 tonnes
in 2013.
The US imports all of its perlite
from Greece, with the majority provided by S&B Minerals.
According to the USGS, production in the US has been decreasing
since 2011, while imports have also been in decline. The
estimated value of crude perlite produced in 2013 is $21.1m,
with production from eight mines operated by six companies and
led by New Mexico.
The primary end use for perlite in
2013 was in building construction products, which consumed 53%
of all of the mineral produced in the US last year. This was
followed by fillers, accounting for 15% of consumption,
horticultural aggregate with 14% and filter aid with 10%.
Processing
perlite
Crude perlite for use in plaster
aggregates ranges from between 60 mesh to 12 mesh, while crude
perlite expanded for use in concrete aggregate applications,
ranges from between 16 mesh to 100 mesh. The majority of
perlite ore used in horticulture is greater than 20 mesh.
Perlite mining uses open-pit
methods and is transported to the plant site for crushing and
drying. A primary jaw crusher is used to reduce the diameter of
the ore, which is passed through a rotary dryer to reduce the
minerals’ moisture content to less than 1%. The material
is then passed through a secondary grinding phase using a
closed-circuit system consisting of screens, air classifiers
and hammer mills.
The mineral is subsequently stored
until it is ready to be expanded using horizontal rotary or
vertical stationary expansion furnaces. The processed ore is
preheated to around 430¡C, which reduces the amount of
fines produced at this stage of processing, or it is fed
directly into the furnace at the expansion plant, where it is
heated to around 760¡C to 980¡C.
Heating the perlite at high
temperatures causes the water in the mineral to be released as
steam, and allows the particles to expand by 4 to 20 times
their original size. Perlite particles are then collected from
a cyclone classifier system, which enables them to cool as they
are transported. As particles are collected, the cyclone
classifier system removes the excessive fines and discharges
gasses for air pollution control either using a baghouse or wet
scrubber.
New processing facility in
New Orleans
Despite an apparent 5% decrease of
crude perlite bought or sold in the US in 2013, Governor Bobby
Jindal and the CEO of IT Minerals LLC, Jose Domene, announced
this month that the company is to invest $4.5m in Louisiana to
establish a perlite importing, processing and exporting
facility at the Port of New Orleans.
The company produces lightweight
aggregates and fillers for polymer-based products, construction
products, insulation, filtration, textile, cryogenic,
horticulture and gardening products, and estimates that around
6,000 tonnes of product will be processed in the first year of
operation. Processing is then expected to be ramped up to
12,000 tonnes in the second year.
“As we explored our options
for setting up our new facility, we found one that offered all
the conveniences we were looking for: energy, logistics, land
and a friendly business environment,” Domene said, adding
that he expects IT Minerals’ investment in the area to
increase in the future.
The project, which will begin in
the first quarter of 2014 and is expected to be completed by
the third quarter, will enable the company to import raw
materials from igneous rock quarries in north central Mexico by
rail to Louisiana; the company already imports and processes
raw minerals from Mexico, Brazil and South Africa.
Building a new processing facility
at the Port of New Orleans will allow IT Minerals to add value
to its imported perlite ore, which will then serve US markets,
followed by the Caribbean and Central and South American
markets.
The facility will use a natural gas-fired furnace processing
method to heat and reform minerals at the plant for various
applications, which will then be stored and prepared for export
to commercial customers.
Perlite in filtration
US speciality minerals
producer, EP Minerals, produces perlite for another niche
application; the filtration market. The company commissioned a
new perlite plant in the Midwest US in early 2014, allowing it
to expand its business into new regions. In terms of sales,
perlite accounts for around 5% of EP’s business, though
its main focus is diatomite, followed by clay. The company
sources perlite from its own deposits in Nevada, and has chosen
to play a large part in a small area of perlite application,
concentrating on uses in filtration.
“In terms of our
existing plants and our new plant in Blair, it will be a
growing part of our portfolio, and also because we’re
filtration experts, perlite serves many end uses with the
biggest in construction and horticultural applications, but we
play in
a small space in perlite,
which is filtration,” Gregg Jones, president of EP
Minerals, told IM.
In some cases EP also acts as a
distributor where it buys product from factories around the
world and sells into filtration applications where the company
has the technical knowledge to help the customer with the use
of the product.
“There’s very specific
processing that needs to be done to make it suitable for the
filtration industry, so it’s fairly complex,” Jones
told IM. “But what we know about the
filtration industry gives us a unique advantage in terms of how
to manufacture the product to make it suitable for its end
use.”
In terms of the biggest demand
drivers for perlite in filtration applications, Jones said that
the mineral continues to find unique applications in the
filtration area where it adds value to the end customer. In
some more demanding filtration applications customers may opt
for diatomaceous earth, while other customers find that perlite
will add more value depending on what product is being
filtered, where the customer is located and what kind of
equipment the customer has.
“In the filtration space
it’s more of a technical solution that drives the use of
the product, and that’s where our expertise comes into
play,” he told IM.
Towards the end of 2013, EP
Minerals announced that prices of perlite and cellulose
products would be increased affecting all regions. The price
increases followed a similar announcement by fellow producer,
Imerys.
Speaking to IM
about the price increases, Jones explained: “It’s
basically inflationary costs in our business whether it’s
in the mining of the ore, just general costs, costs of energy,
all the things we mentioned in our press release, but it’s
basically just inflationary pressure we experience and we pass
through to our customers.”
In terms of the outlook for
perlite, EP Minerals expects to continue to see growth in
business, which is why it has invested in its new perlite
plant.
“Perlite is very much of a local business, meaning you
can’t ship it very far because of its light density, so
you tend to service a local market close to the expander. The
expander in the Midwest is going to give us a nice opportunity
for our business and we will continue to focus on the sale of
the product around the world,” Jones said.