A Comparison of Dry and Wet Milling Processes for Mica

Once ground, mica powder is widely used as a functional filler in various industrial sectors, including construction, plastics and rubber. Due to its abundant reserves, wide range of applications and ease of extraction, mica powder has excellent market prospects. Depending on the production process, mica powder is primarily produced using either dry or wet milling methods, which differ significantly in terms of characteristics, applications, and advantages and disadvantages.

Dry-ground mica powder is produced by crushing, grinding and classifying flake and fragmentary mica. Its key characteristics are low purity and a low aspect ratio. The dry-grinding process tends to damage the crystal structure and layered architecture of the mica, and product quality is highly susceptible to the quality of the raw ore and climatic conditions, making it difficult to control. The dry-milling process requires no complex equipment, water or heat, and has low energy demands, resulting in a product with a high cost-performance ratio. It is suitable for non-functional applications with modest requirements, primarily used in cattle felt, welding rods and drilling mud, and is unsuitable as a functional filler; however, it suffers from disadvantages such as a low aspect ratio, high impurity content and severe dust pollution, rendering it unsuitable for high-end applications.

Wet-ground mica powder is produced using water as a medium through multiple precision processing steps. It offers higher purity and aspect ratio, a smooth surface, and excellent binding, dispersion and adhesion properties. Its quality is less affected by the raw ore and climatic conditions, making it easier to control and suitable for a wider range of applications. It is primarily used in high-end sectors such as mica pearlescent pigments, high-grade coatings and engineering plastics, and can also be applied in industries such as household chemicals and pharmaceuticals; The advantages include uniform particle size, a high aspect ratio and extremely low impurity content. The disadvantages are high energy consumption, low production efficiency, high cost, a complex production process and a strong reliance on experience.

When grinding mica, it is important to note that its Bond work index reaches 148, making it difficult to grind; even after ultra-fine grinding, the particles remain flake-like, and the higher the aspect ratio, the greater the product value. In wet grinding, care must be taken to avoid scratching the mica surface, as this can reduce lustre and affect competitiveness.