Mineral beneficiation * crystalline graphite method: crystalline graphite has good natural buoyancy, and the flotation method is used in domestic beneficiation. Since the size of flake graphite is one of its most important quality indicators, the sorting method adopts multi-stage grinding and multi-channel separation processes to select large flakes of graphite as early as possible. Collectors commonly used in flotation include kerosene, diesel oil, etc., foaming agents include No. 2 oil, No. 4 oil, etc., regulators include lime and sodium carbonate, and corrosion inhibitors include water glass. Aphanitic graphite beneficiation method *: aphanitic graphite crystals are extremely small, so it is also called microcrystalline graphite. Graphite particles are often embedded in clay and are difficult to separate. Due to the high grade of raw ore (generally 60% to 80% carbon content), many graphite mines directly crush the mined ore to produce graphite powder products. The Lutang Graphite Mine in Hunan once established a flotation plant in the 1950s to flotation microcrystalline graphite, but production was discontinued due to high costs. At present, some units are still conducting research on new microcrystalline graphite flotation technologies (such as oil agglomeration flotation, etc.). Purification of graphite products*: Modern industry requires graphite products to develop in two aspects. One is to require large-scale crystals and high purity, and the other is to require ultra-fine particles of graphite products (such as less than 1 μm or 0.5 μm). China has established graphite purification and fine powder production lines in graphite processing plants such as Nanshu, Beishu, Liumao, and Xinghe. The purification method is mainly chemical purification. The most mature process of chemical purification of graphite is to melt caustic soda and graphite at 700°C, wash to neutrality, and then add salt* to wash so that the carbon content of graphite reaches 98% to 99%. It can also be treated with hydrofluoric acid* to produce high-purity graphite.
