The raw materials are sieved with a water-washed drum and removed from mud impurities. After drying, they are graded on a vibrating screen as needed, and then they are magnetically sorted to remove the silicon, so that the chromium content reaches more than 46% and the silicon content is less than 1%. Finally, the finished product is packaged according to the particle size requirements. The particle size and composition indicators must be strictly monitored throughout the process.