Wollastonite is widely used in ceramics, plastics, asbestos substitutes, metallurgy, coatings and other sectors due to its low water absorption, thermal stability, conductivity and chemical inertia. At present, the annual consumption of wollastonite in the world is about 600000 tons, with ceramics accounting for 40%~50%, plastics 20%~25%, asbestos substitutes 20%~25%, metallurgy 10%, pigments and others 5%. Wollastonite with high aspect ratio (15 ∶ 1~20 ∶ 1) is mainly used as a functional filler in coatings, plastics and rubber to improve hardness, bending strength and impact resistance. It can also improve the electrical properties of plastics, improve their thermal stability, enhance corrosion resistance and improve wear resistance; It can also be used to replace asbestos in the manufacture of friction materials, insulating materials and flame retardants. Grind grade wollastonite (wollastonite with low aspect ratio of 3 ∶ 1 ～ 5 ∶ 1) is mainly used as raw material of CaO and SiO2 in ceramic and glass manufacturing process and as low-temperature flux in metallurgical industry.
Nowadays, wollastonite is mainly used as functional filler in ceramic industry and plastic rubber paint coating. As the largest consumption field of wollastonite, ceramics are consumed by nearly half of the world's output every year. Wollastonite as ceramic raw material can increase the strength of ceramic body and ceramic products, reduce ceramic fragmentation and glaze spots, increase the luster of glaze surface, and reduce fuel consumption (60% of fuel can be saved). Therefore, wollastonite is a promising energy-saving ceramic material. Some experts predict that the demand for wollastonite for ceramic industry will increase by about 5% year by year. Acicular wollastonite powder is used for special ceramics.
The needle like wollastonite powder, with needle like structure and non-toxic and harmless, can partially replace asbestos, glass fiber, paper pulp, etc., and is relatively cheap. Because asbestos will pollute the environment when it is exposed to the air for a long time, many countries in the world have formulated laws and regulations to restrict or prohibit the use of asbestos. Wollastonite has become the best substitute for asbestos because of its thermal stability, various reinforcement properties and innocuity. In recent years, the use of wollastonite as a substitute for short fiber asbestos has grown rapidly. Every year, 35000~40000 t high length diameter ratio wollastonite is consumed in building materials, insulators and other industries. It is mainly used in firewall plates, cement materials and friction materials. Other applications include interior wall panels, roof tiles, high temperature insulating bricks and panels. The original asbestos friction material is replaced by needle like wollastonite with high friction level, mainly including brake pads, valve plugs and automobile clutches. At present, this market is growing steadily in many regions of the world.
The fastest growing consumption area of wollastonite is the plastic industry. Adding wollastonite powder to plastics can improve the tensile strength and flexural strength of plastic products, reduce the amount of resin used, and improve the thermal stability and shape stability of plastics at high temperatures. The surface treatment of needle shaped wollastonite powder can improve the adsorption strength of wollastonite and organic polymers, and improve the properties of molded products. It is widely used in automotive plastics, PP, PV, PVC and other plastic products. At present, The automotive plastics market has become the fastest growing consumption area of wollastonite.
High purity wollastonite powder, as an inorganic white pigment, is widely used in coatings and can replace expensive titanium dioxide; It can also replace part of the anatase titanium dioxide in light colored rubber products, and the price is only one tenth of that of titanium dioxide.
Wollastonite is mainly consumed in Europe, the United States, Japan, India, Mexico and China. Wollastonite in North America is mainly consumed in the ceramic industry, but the per capita ceramic tile consumption is lower than that in Asia and Europe. Wollastonite consumption in Europe is mainly used in ceramics and metallurgy industry, while that in India is mainly used in ceramics and coatings industry. Wollastonite in China is mainly consumed in glazed tiles and ceramic blanks, accounting for more than 50% of the total consumption of wollastonite; Other consumption fields include plastics, rubber, coatings, metallurgy, construction and asbestos substitutes. At present, the annual consumption of wollastonite in China is about 100000 tons. The main consumption area is ceramics, accounting for 55%; Metallurgy, accounting for about 30%; Others (plastic, rubber, paper making, coating, welding electrode, etc.) account for about 15%.
The United States is an important wollastonite consumer in the world. The domestic sales volume of wollastonite in 2002 was basically the same as that in 2001. The sales volume of plastic consumption increased, while that of other consumption areas remained unchanged or decreased slightly. From the perspective of product types, due to the slowing down of American economic growth and the competition of foreign wollastonite prices, the sales volume of low value wollastonite products in the United States declined in 2002. Although the sales volume of high-value wollastonite products increased, the total volume was small, which had little impact on the total domestic sales volume of wollastonite. Wollastonite consumption in the United States is mainly in ceramic, metallurgy, coating, plastic and other industrial sectors. The main consumption structure of wollastonite in recent years is roughly as follows: 37% for plastics, 28% for ceramics, 10% for metallurgy, 10% for coatings, 9% for friction products and 6% for others.