1. Mineral beneficiation processing method of crystalline graphite
Crystalline graphite is naturally more floatable, and flotation is basically used for mineral processing in China. Since the size of graphite flakes is one of its most important quality indicators, multi-stage grinding and multiple sorting processes are used in the selection method to select large flake graphite as early as possible. The commonly used collectors for flotation are kerosene, diesel, etc., the frothers are No. 2 oil, No. 4 oil, etc., the regulators are lime and sodium carbonate, and the inhibitors are water glass.
2. Cryptocrystalline graphite beneficiation processing method
Cryptocrystalline graphite crystals are extremely small, so they are also called microcrystalline graphite. Graphite particles are often embedded in clay, making separation difficult. . Due to the high grade of raw ore (generally containing 60% to 80% carbon), many graphite mines directly crush the mined ore and sell graphite powder products. Hunan Lutang Graphite Mine once established a flotation plant to flotate microcrystalline graphite in the 1950s, but production was discontinued due to high costs. At present, some units are still conducting research on new microcrystalline graphite flotation processes (such as oil agglomeration flotation, etc.).
3. Purification and processing of graphite products
Modern industry’s requirements for graphite products are developing in two aspects: one is to require large crystal flakes to achieve high purity, and the other is to require graphite product particles to be ultra-pure. Fine (such as less than 1μm or 0.5μm). China has established graphite purification and fine powder processing production lines in Nanshu, Beisu, Liumao, Xinghe and other graphite concentrators. The purification method is mainly chemical purification. The most mature process for chemical purification of graphite is to use caustic alkali and graphite to melt at 700°C, then wash them to neutrality, then add hydrochloric acid treatment and washing, so that the carbon content of the graphite reaches 98% to 99%. There are also manufacturers that use hydrofluoric acid treatment to produce high-purity graphite.