Non-Metallic Mineral Mini Encyclopedia — Magnesite

Magnesite, also known as magnesium carbonate (chemical formula: MgCO₃), is an important non-metallic mineral resource rich in magnesium. Natural magnesite often contains impurities such as calcium, manganese, and iron. When FeO content is around 9%, it is called ferroan magnesite; with higher Fe content, it is referred to as magnesioferrite, and when nickel is present, it is known as breunnerite.

Magnesite can be calcined at different temperatures to produce caustic magnesia (light-burned magnesia), dead-burned magnesia, and fused magnesia, each exhibiting distinct physical and chemical properties. High-temperature MgO is characterized by high hardness, strong chemical resistance, and high electrical resistivity, making it an excellent industrial material.

Industrial Applications

Magnesite has a wide range of uses. In most cases, it is calcined before processing, while only a small portion is used directly in its natural form. Today, it serves as an important raw material in metallurgy, construction, chemicals, rubber, magnesium extraction, pharmaceuticals, agriculture, and defense industries.

Metallurgical Industry

Approximately 90% of magnesite is used for refractory materials, applied in converters, open-hearth furnaces, electric furnaces, and metallurgical kilns for lining the bottom, walls, and hearths. The resulting refractory materials exhibit excellent thermal stability and corrosion resistance.

Construction Industry

Light-burned magnesia serves as a binding material for magnesium-based cements, offering good sound insulation, heat resistance, and wear resistance. When combined with other raw materials, it can form construction and decorative materials. When mixed with asbestos, it produces thermal and acoustic insulation materials. These materials are widely used in buildings, boilers, cylinders, and steam pipelines.

Chemical Industry

Magnesite and its derivatives can produce magnesium sulfate and various magnesium compounds. Light-burned magnesia is also an important raw material for synthetic fibers, plastics, cosmetics, and specialty glass, and serves as a mordant, desiccant, decolorizer, neutralizer, and adsorbent in chemical processes.

Other Applications

Chemically treated caustic magnesia can produce high-purity magnesium compounds for use in medicine, as a vulcanization accelerator and filler in rubber, and as a purifying agent in sugar production. In papermaking, it is used for sulfation treatment. In agriculture, light-burned magnesite serves as a feed additive and fertilizer, and it is also the primary raw material for metallic magnesium extraction.

Fine Processing of Magnesite: Ball Mill and Grinding

Whether to improve calcination efficiency or to utilize calcined magnesia in high-performance slurries, refractory bricks, or rubber fillers, grinding and ultrafine processing are indispensable steps in the magnesite industrial chain.

Ball milling is one of the most efficient methods for grinding magnesite, whether from raw ore or calcined magnesia.

Purpose and Challenges:
Magnesite has moderate Mohs hardness. However, sintered (dead-burned) magnesia or fused MgO is extremely hard and dense. This poses significant challenges to equipment wear resistance and grinding efficiency. The goal of ball milling is to reduce particle size to micron or even submicron levels. This ensures uniformity and reactivity in subsequent formulations.

Process Applications:
Large ball mills (continuous or batch types) are loaded with high-hardness grinding media such as high-chrome steel balls, alumina balls, or zirconia beads. As the mill rotates, the media apply strong impact, grinding, and compression forces to the material, achieving efficient size reduction.

Ultrafine Requirements:
For high-quality refractory materials or specialty chemical products, further ultrafine grinding (e.g., using stirred mills or vibration mills) is needed. The milled powder is then processed through air classifiers for precise particle size separation.

Key Role:
Fine ball milling of magnesite significantly increases the specific surface area of magnesia, ensuring uniform density and packing during mixing and sintering, and enhancing reactivity and filler dispersion in chemical and rubber applications. It is a critical technology to guarantee high performance of the final products.

Conclusion

The high-performance applications of magnesite depend on its fine processing capability. However traditional grinding methods can no longer meet modern industry requirements for ultrafine, high-purity, and uniform particle size powders.

The modern Epic Powder ball mill and air classifier production line integrates high-efficiency grinding with precise air classification technology. It can stably process hard magnesia into micron or even submicron sizes. Through precise control, the system ensures an extremely narrow particle size distribution and excellent dispersion. It provides high-quality deep-processed magnesite products for metallurgy, building materials, and fine chemical industries. This promotes continuous upgrading of magnesite applications.