EN
Wollastonite powder is an inorganic mineral powder produced from natural needle-shaped wollastonite ore through crushing, grinding, purification, and grading. Its main chemical component is calcium metasilicate (CaSiO₃). Typical crystals are needle-shaped or fibrous, and aggregates often exhibit fan-shaped or radial structures. With its unique needle-like crystal form, high chemical stability, low oil absorption, low moisture absorption, excellent insulation, and high-temperature resistance, wollastonite powder has become an indispensable functional filler and reinforcing material in industries such as ceramics, metallurgy, coatings, plastics, rubber, friction materials, papermaking, and building materials, demonstrating broad application potential in high-end manufacturing and green industry.
I. Mineral Structure and Core Physicochemical Properties
The most prominent feature of wollastonite powder is its natural needle-like/fibrous crystal structure, with an aspect ratio ranging from 3:1 to 20:1, giving it multiple superior properties:
Stable Chemical Composition: SiO₂ content approximately 43%–52%, CaO approximately 38%–46%, low impurity content, non-toxic, acid and alkali resistant, low electrical conductivity, and outstanding insulation.
Excellent Thermal Stability: Melting point approximately 1450℃, low coefficient of thermal expansion, not easily decomposed or discolored at high temperatures, suitable for high-temperature firing and molding processes.
Low Oil and Moisture Absorption: Oil absorption value 20–50g/100g, low moisture absorption, outstanding thickening and anti-settling effects in coatings and adhesives, sedimentation value >45.
Excellent Whiteness and Appearance: High-quality products have a whiteness of 83–90, ordinary products 70–80, appearing as a bright white powder with good dispersibility and a smooth feel.
Loss on ignition is controllable: typically between 1.5% and 3.0%. The ceramics industry has strict requirements for loss on ignition; products with lower loss on ignition are of higher quality and more competitively priced.
II. Processing Technology and Product Specifications
Wollastonite powder is processed using physical methods, without altering the mineral crystal form throughout the process. The core processes include:
Mineral Processing and Purification: Removing associated impurities such as quartz and calcite to improve purity and whiteness;
Crushing: From coarse to fine crushing using jaw crushers and impact crushers;
Grinding and Classification: Primarily using Raymond mills and ball mills to produce products with various mesh sizes, with 325 mesh being the mainstream and most widely used, and 1250 mesh being a high-end ultrafine product;
Drying and Packaging:Shipped in 50kg bags, ton bags, or bulk to meet domestic distribution and export needs.
Mainstream Specifications and Characteristics:
325 mesh: Mainstream specification for ceramic glazes, metallurgical protective slags, and glass fiber; offers the best cost-performance ratio.
1250 mesh: Used in coatings, plastic reinforcement, adhesives, and high-end ceramics; high fineness and excellent reinforcing effect.
60 mesh particles: Highest aspect ratio (approximately 20:1); used in metallurgy, refractories, and friction materials.
III. Mainstream Application Areas
1. Ceramics and Metallurgy (Largest Usage)
Ceramic glazes/body: Reduces firing temperature, minimizes shrinkage deformation, and improves whiteness and strength; strict requirements for loss on ignition.
Metallurgical protective slag: Added up to 40%; 20%–50% added to continuously cast steel; provides melting, insulation, oxidation prevention, and lubrication.
2. Glass Fiber and Refractory Materials
The glass fiber industry extensively uses 325 mesh products to improve fiber strength and temperature resistance.
Refractory materials must use high-purity wollastonite to ensure high-temperature strength and thermal shock resistance.
3. Coatings and Building Materials: Thickens and prevents settling; improves wear resistance, corrosion resistance, heat insulation, and crack resistance; partially replaces calcium carbonate and talc.
Add 5%–15% to ordinary coatings, 10%–30% to functional coatings, and up to 20%–40% to high-temperature coatings.
4. Plastics, Rubber, and Friction Materials: Needle-like structure significantly enhances rigidity, toughness, and dimensional stability; used in pipes, sheets, cable sheaths, brake pads, etc.
Provides a stable coefficient of friction, high-temperature resistance, low noise, and low wear in friction materials; a key material for green asbestos substitution.
5. Papermaking, Adhesives, and Calcium Silicate Boards: Improves smoothness, whiteness, and printability in papermaking. Enhances strength, heat insulation, fire resistance, and weather resistance in calcium silicate boards and waterproofing materials.
IV. Alternative Solutions and Cost Advantages
Wollastonite powder can be replaced with alternative materials depending on the application scenario to optimize costs:
Ordinary coatings and waterproofing: Calcium powder can be used as a substitute ;
High silicon content requirements: Talc powder can be used as a substitute (length-to-diameter ratio 1:3);
Porous ceramics: 1250 mesh quartz powder can be used as a substitute;
High-end fields (papermaking, ceramics, coating reinforcement): Genuine wollastonite powder must be used to ensure stable performance.
V. Market Structure and Price Reference
China is a major global producer of wollastonite, primarily through underground mining. Wollastonite and calcium carbonate are often found together, resulting in concentrated resources and a mature industrial chain.
Conclusion
Acicular wollastonite powder, with its unique crystal form, stable performance, green and non-toxic nature, and controllable cost, has become a high-performance mineral material with a wide range of applications in the industrial sector. From traditional ceramics and metallurgy to high-end coatings and plastics, from building materials to new energy composite materials, it continuously improves quality and reduces costs for various industries through multiple functions such as reinforcement, thickening, heat insulation, and corrosion protection. With the rapid development of high-end manufacturing and green industries, the demand for high aspect ratio, ultrafine, and modified wollastonite powder will continue to increase, and the market prospects are broad. It is one of the non-metallic mineral materials with the greatest growth potential in the future.