Get MgO Ceramic Raw Material Wollastonite

Wollastonite (chemical formula CaSiO₃ or Ca₃Si₃O₉) is a natural calcium metasilicate mineral. Due to its unique needle-like structure, high whiteness, high-temperature resistance and chemical stability, it is widely used in industries such as ceramics, plastics, coatings and metallurgy. The following is a detailed introduction to wollastonite products: 

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### **I. Basic Characteristics**

1. **Physical Properties**

- **Form**: Natural wollastonite often occurs as needle-like, fibrous or radiating aggregates, with white being the dominant color, occasionally with a light gray or light red tint.

- **Hardness and Density**: Mohs hardness 4.5 to 5.5, density 2.75 to 3.10 g/cm³, melting point approximately 1540°C.

- **Chemical Stability**: Resistant to acids, alkalis, and corrosion, with low moisture absorption (<4%), low electrical conductivity, and excellent insulation properties. 

2. **Chemical Composition**

- The main components are SiO₂ (40% - 50%) and CaO (45% - 50%), with trace amounts of elements such as Fe, Mn, and Mg. 

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### **II. Product Classification and Processing Techniques**

Wollastonite products can be classified into the following categories based on processing methods and applications:

1. **Common Powder**

- With relatively coarse particle size, it is mainly used in ceramic glazes, metallurgical protective slag, and welding rods.

2. **Ultrafine Powder (3000-6000 Mesh)**

- Produced through mechanical grinding or air jet milling, it is applied in plastics, rubber, and coatings, significantly enhancing the mechanical properties and thermal stability of materials.

3. **Needle-like Powder (Aspect Ratio > 10:1)**

- Retaining its natural needle-like structure, it serves as an enhancing filler in friction materials (such as brake pads) and engineering plastics, replacing asbestos or glass fibers.

4. **Modified Powder**

- Treated with surface modifiers like silane coupling agents to improve compatibility with organic matrices, it is used in high-end plastics and electronic packaging materials. 

**Production process**: It includes flotation, magnetic separation, ultrafine grinding and surface modification, etc. For instance, the Fengjiashan mining area in Hubei Province adopts a combined process of "magnetic separation - flotation - gravity separation" for purification, and the grade of wollastonite concentrate reaches 53.87% SiO₂ and 44.48% CaO. 

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### **III. Main Application Areas**

1. **Ceramic Industry (Approximately 50%)**

- The addition of wollastonite can lower the firing temperature by about 100 to 200 degrees Celsius, shorten the firing time, and reduce fuel consumption; at the same time, it enhances the glossiness of the glaze surface, increases the strength of the body, and reduces warping and cracking of the products. 

2. **Plastics and Rubber**

- As reinforcing fillers, they can enhance the tensile strength, impact strength and dimensional stability of products. For instance, when wollastonite masterbatches are added to nylon, the molding shrinkage rate can be reduced from 1.16% to 0.34%. 

3. **Coatings and Inks**

- As a reinforcing pigment, it can replace part of titanium dioxide, reducing costs while enhancing the wear resistance, corrosion resistance and covering power of the paint film. 

4. **Metallurgical Industry**

- It is used as a raw material for continuous casting protective slag. Its low Al₂O₃ content can effectively adsorb impurities in molten steel, improving the quality of the cast billet. 

5. **Environmental Protection and Building Materials**

- It can be used as an alternative to asbestos in fireproof boards, calcium silicate boards and other environmentally friendly building materials, with both impact resistance and heat resistance; it can also be made into an adsorbent to treat wastewater. 

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### **IV. Market and Industry Development**

- **Resource Distribution**: The global reserves of wollastonite are approximately 500 million tons, with China having the largest reserves (for instance, the proven resources in Xinyu, Jiangxi amount to 117 million tons). Other major production areas include the United States, India, etc.

- **High-Value Trend**: Through deep processing, the value of wollastonite can increase nearly 30 times. For example, the price of ultrafine needle-shaped powder (6000 mesh) can reach 7,000 to 8,000 yuan per ton, which is much higher than that of raw ore (several hundred yuan per ton).

- **Export and Emerging Applications**: 60% of China's wollastonite is exported to the countries along the Belt and Road Initiative, and it is gradually expanding into high-end fields such as new energy vehicles and thermosetting plastics. 

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### **V. Future Development Directions**

1. **Refinement and Functionalization**: Develop nano-scale wollastonite and high aspect ratio fibers to meet the demands of high-end composite materials.

2. **Green and Environmentally Friendly Applications**: Replace asbestos and reduce the use of synthetic fibers in plastics to promote sustainable development.

3. **Cross-industry Innovation**: Explore application potential in emerging fields such as bio-ceramics and electronic packaging.