Wollastonite potentialin carbon emissions reduction technology

A beautiful outlook? A new wollastonite mine has been identified in the Adirondack Forest Preserve of New York iStock

Most, if not all, of the wollastonite market is comprised of ground wollastonite in the form of powders that are added to ceramics (frits, sanitaryware, and tile), friction products (primarily brake linings), metallurgical applications (flux and conditioner), paint (architectural and industrial paints), plastics and rubber markets (thermoplastic and thermoset resins and elastomer compounds) and some miscellaneous uses (including adhesives, concrete, glass, and sealants).

SUPPLY SECURITY

The global leader in wollastonite production is China with an estimated 1.1 million tonnes in 2017 – up from 750,000 in 2013, according to World Mineral Production 2013-17, published by the British Geological Survey. India followed with 153,049 tonnes (a fall from its 2013 total of 192,712) and the United States with an estimated 50,000 tonnes.

Data for 2017 and 2018 from the US Geological Survey (USGS) is similar, although it says Chinese output was a lot lower than the British figure – 500,000 tonnes – rising to 530,000 tonnes last year. It also estimated Indian production at 150,000 tonnes last year, down from 156,000 in 2017. USGS lists Mexico as producing 90,000 tonnes, up from 88,000 tonnes in 2017; Finland at 11,000 tonnes in 2018 and 10,000 tonnes in 2017; Canada at 10,000 tonnes last year, down from 11,000 in 2017; and "other countries" contributing 6,000 tonnes, giving a total of 800,000 tonnes – up from 770,000 tonnes in 2017.  

What is missing from the USGS data is a figure for American output – the USGS Mineral Commodity Summaries, February 2019, said no US production data had been recorded since 2009 "to avoid disclosing company proprietary data." A USGS official said only two American companies, both in New York state, mined wollastonite in 2018 - Imerys and Vanderbilt Minerals - and the survey’s proprietary data guidelines state that there must be three or more companies contributing to an aggregated statistic for it to be published unless the businesses supplying information gives permission for data to be released – which by implication did not happen here.

Global wollastonite reserves are said to exceed 100 million tonnes. Canada Wollastonite

The 2016 USGS yearbook cites US-mined wollastonite as being exported to Argentina, Belgium, Brazil, Britain, China, Colombia, the Dominican Republic, Germany, Hong Kong, India, Italy, the Netherlands and Portugal.

Reliable estimates of wollastonite resources do not exist for most countries, according to the USGS, but "large deposits" have been identified in China, Finland, India, Mexico, and the US. "Smaller, but significant, deposits" have been identified in Canada, Chile, Kenya, Namibia, South Africa, Spain, Sudan, Tajikistan, Turkey, and Uzbekistan, its 2019 survey revealed, noting that world reserves "exceed 100 million tonnes."

Finland calling

Another potential source of the mineral that is looking at expansion is Finland, which is mined at Nordkalk’s Ihalainen limestone quarry near Lappeenranta, close to the Russian border. Nordkalk’s output was an estimated at 11,000 tonnes in 2018, and the mineral is processed on site, being purified by flotation and further refined into end products by microgrinding and surface treatment. Nordkalk produces micronized low and high aspect ratio wollastonite grades, with high end applications including functional fillers in plastics and coatings. Plastic compounds for vehicle interiors, exteriors and engine compartments plus electrical insulation plastics contain Nordkalk wollastonite, which improves corrosion resistance, strengthening plastic films. Nordkalk sells most of its wollastonite W-Series in Europe, but also exports elsewhere.

MARKET DEMAND

The major drivers of growth for the market are increasing building and construction activities and growth in automotive production, in which the mineral used in sealants, wallboards, adhesives, stucco, paint and roofing materials, as well as brake manufacture. 

Asia Pacific is expected to remain the largest region by sales value and volume and is expected to record the highest growth over the forecast period due to growth in ceramic products, such as wall and floor tiles and sanitary wares in the construction industry, the Lucintel report said.

Transparency Market Research (see below) meanwhile described wollastonite as having "several exclusive characteristics" which make it "one of the most versatile functional filler and reinforcement agents." 

Since 2001, its report said, ceramic applications have accounted for more than 50% of wollastonite sales worldwide, followed by polymers at around 25%, and coatings at nearly 15%. The remaining revenue was generated through construction, friction products, and metallurgical applications. The global wollastonite market is driven by increasing demand from the construction industry, the report said, and an increase in building projects in developing countries such as China, India, and Brazil are also boosting the wollastonite market. 

It is probably wollastonite’s ability to reduce carbon and other greenhouse gas emissions that will really underpin future growth. This is especially given how legislation and incentives designed to limit climate change, such as CO2 taxes and quarrying and extraction tax, have increased demand for the mineral, according to Chatham House report 'Making Concrete Changes: Innovation in Low Carbon Cement and Concrete’, published in June 2018. 

Population growth and industrialization is putting pressure on developing countries to find technical solutions to reduce greenhouse gas emissions, and wollastonite delivers one choice. As a result, Transparency Market Research projects a three-to-fourfold increase in demand for wollastonite by 2050 in Latin America, Africa, the Middle East, and Asia.

Canada Wollastonite research

Research by Canadian Wollastonite, which has Canada’s only wollastonite mine northeast of Kingston, in Ontario, mining the Saint Lawrence Wollastonite Deposit (SLWD), has demonstrated how this carbon sequestration can work.

With Ontario’s University of Guelph, the company has been evaluating the potential of the mineral to sequester carbon dioxide into Ontario soils. Applying wollastonite to agricultural soils, said a company note, shows that when wollastonite is broken down in soil, it releases calcium - carbon dioxide can bind to the calcium to form calcium carbonate, a stable form of carbon in agricultural land which will remain in the soil, close to the plant’s roots as a pebble coating or in grains. "An additional benefit of this reaction is the release of plant available silicon for plant uptake which has been shown to increase yields and crop tolerance to pests and disease," the company said in a note.

In an article published by the American Chemical Society in January 2019, University of Guelph researchers concluded: "The co-benefits of wollastonite soil amendment (CO2 sequestration and improved crop yield) would encourage producers to effectively use this mineral to contribute toward global climate change mitigation without compromising their produce."

Canada Wollastonite also noted that the silicates in wollastonite "create unique conditions in the soil that promote the adsorption of phosphates in a form that can prevent run-off while still maintaining higher levels of plant availability".

Wollastonite has proven effective at mitigating algal blooms induced by fertilizer runoff and binds heavy metals, being used to treat both municipal wastewater and in mining site reclamation projects, it added.

Also, where the mineral is used in capturing phosphorus in human and animal treatment plants, it can be recycled back onto farms as a pH balancer rich in calcium and adsorbed phosphorous, the company said. Agricultural waste management costs are reduced by the low cost of the mineral, and the fact that the resulting product has economic value.

Other research being undertaken by the Canadian company includes potential uses as a low-CO2 alternative for slag conditioning in steel manufacturing, naturally-occurring products for phosphorus sequestration in bodies of water, and low CO2 and energy-saving alternative ingredients in cement production.

Wollastonite stockpiled. Canada Wollastonite

Wollastonite in cement

This latter use has attracted other researchers and is potentially important. A single kilogram of cement releases more than 0.5kg of CO2 into the atmosphere, and each year more than 4 billion tonnes of cement are produced, accounting for around 8% of global CO2 emissions, according to the Chatham House report. It argued that it is "especially important to scale up clinker substitution in the near term while more radical options, such as the introduction of novel and carbon-negative cements, are still under development." 

Wollastonite can help with this. Solidia Technologies, based in Pennsylvania, US, has commercialized a cement which uses wollastonite "or, rather, a synthetic mineral blend that contains wollastonite," as an alternative to traditional Portland cement, chief technology officer Nicholas DeCristofaro told Fastmarkets IM. The mineral blend is trademarked as Solidia Cement. "The beneficial characteristic of wollastonite in a cement/concrete scenario is that it reacts with CO2 to create a cementitious effect," he said.

The only differences between Solidia Cement and Portland cement are the calcium oxide (CaO) concentration in the cement and the kiln temperature used during cement synthesis, he explained. Solidia Cement requires a lower lime concentration and a lower kiln temperature because wollastonite is in the mix. "These two advantages allow Solidia Cement to be manufactured with 30% lower CO2 emissions," he said. "While Portland cement cures via a reaction with water, Solidia Cement cures via a reaction with CO2" removing the gas form the atmosphere. "This allows a further reduction in the carbon footprint associated with cement and concrete," he said. Indeed, when reduced CO2 emissions at the kiln are coupled with the CO2 utilized during concrete curing, replacing Portland cement in concrete with Solidia Cement will reduce the carbon footprint associated with the manufacturing and use of cement by 60-70%, he claimed.

Mr DeCristofaro added: "the detrimental aspect of wollastonite is associated with logistics. For cost reasons, cement is rarely shipped more than 150km overland (by truck or train) or over 1,500km by barge."

Despite these issues regarding cement, the generally positive market projections and research indicating the potential value of wollastonite, mineral industries worldwide are - unsurprisingly - taking a close look at expanding production. India is a case in point. The world’s second largest producer after China, the 2017 India Minerals Yearbook (released last February) said the Indian Bureau of Mines plans to encourage exports of the mineral in high aspect ratio and powdered form.

Bureau data said in the five months between April and August 2018, India produced 63,487 tonnes of wollastonite – up 1.2% year-on-year.

According to Indian Bureau of Mines, in the financial year ended March 2017, Indian exports of wollastonite were 16,699 tonnes, mainly to Belgium (53%), Japan (25%), Germany (12%) and Turkey (3%).

Singhal said: "International demand is increasing gradually and we have never seen sales drop." 

The major export markets for the company remain in Europe, Japan, Asia Pacific region and Australia, while the major international competitors are companies in China and the US, he said.

Prices

A USGS official said ex-works prices for domestic wollastonite have been reported to range from approximately $210 to $445 per tonne (quoting past Fastmarkets IM data). Free-onboard prices for wollastonite from China, which tends to be minimally refined – according to the recent USGS report, ranges from $80 to $105 per tonne.   

The average costs of producing wollastonite in India is $12 per tonne, the bureau said, giving decent margins. A senior executive of a major ceramic tiles manufacturer in Bhiwandi, Rajasthan, told Fastmarkets IM the company procures wollastonite at 2,000 rupees ($29) per tonne and higher grades used in other applications could cost four times as much.

Wollastonite constitutes 6% of the raw mixture for its ceramic tiles and it is procured directly from a manufacturer in 50kg bags, he said.

MARKET OUTLOOK

The Lucindel report estimated global market growth for the mineral, known for its properties of high brightness and whiteness, low moisture and oil absorption, and low volatile content, at a compound annual growth rate (CAGR) of 6% between 2018 and 2023. As for values, a Transparency Market Research report published last August, 'Wollastonite Market - Global Industry Analysis, Size, Share, Growth, Trends, and Forecast 2018-2026’, said the powdered wollastonite market was valued at about $180 million in 2017 and projected to expand at a CAGR of above 8.1% during the forecast period to $370 million by 2026.

The many uses of wollastonite

Wollastonite’s use in ceramics production means less shrinkage and CO2 production during the firing process and an increase in strength, with stable brightness and fewer cracks or defects in the finished fired product.

In metallurgical applications, wollastonite acts as a flux for welding, a source for calcium oxide, a slag conditioner, as well as protecting the surface of molten metal during the continuous casting of steel. 

It can be used as a paint additive, providing reinforcement and low oil absorption, preventing the breakdown of paint film due to its high pH value stabilizing acidity, improving weather resistance and it also reduces gloss and pigment consumption, and acts as a flatting and suspending.

In plastics, wollastonite improves the strength and amount of flex in a product, helps resin retention and enables it to withstand exposure to high temperatures.

It can be used as an asbestos substitute in the manufacture of floor and roofing tiles, insulating panels and board, vehicle brakes and clutches.

"The crystal structure and physical properties of wollastonite are stable to about 1,120°C, making wollastonite a substitute for asbestos in thermal insulation applications," a USGS fact sheet published in 2001 said.

A note from the Industrial Minerals Association - North America (IMA-NA) said the needle-shaped structure of wollastonite helps to improve the durability in plastic production, as well as enhancing electrical insulating properties and adding fire resistance. Its low thermal conductivity and high aspect ratio structure makes wollastonite an attractive addition for applications requiring fire resistance, the note said. Its shape and alkaline properties also make it "an ideal auxiliary pigment in industrial coatings and primers for improved corrosion resistance," it added. 

Wollastonite can also greatly improve pest and disease tolerance for many crops including cannabis, newly legalized in Canada, according to research by Vertical Exploration, a Vancouver, Canada-based mining company.