How to prepare metallic chromium?

 Preparation of metallic chromium The main methods of producing metallic chromium are aluminothermic method and electrolytic method.

(1) Aluminothermic method: chromite is first subjected to alkaline roasting to obtain chromium salt products. After solid-liquid separation and impurity removal, the liquid is treated with sulfur and other reducing agents to obtain chromium hydroxide. The chromium hydroxide is calcined to obtain chromium oxide products. The chromium oxide is reduced by aluminum powder to obtain metallic chromium products. This method is the main method for producing metallic chromium at home and abroad. However, the metallic chromium obtained by the aluminothermic method has a low grade. Therefore, the control of impurity content in raw materials and subsequent smelting operation processes need to be further optimized.

(2) Electrolytic method: The electrolytic method can be divided into chromium ammonium alum electrolysis method, chromic anhydride electrolysis method, and molten salt electrolysis method. The most widely used method in industry is chromium ammonium alum electrolysis method. The chromium ammonium alum electrolysis method uses high-carbon ferrochrome as raw material. The chromium ammonium alum product is obtained by leaching, removing iron, and crystallizing the high-carbon ferrochrome. The chromium ammonium alum is then electrolyzed to obtain metallic chromium. The purity of metallic chromium produced by electrolysis is higher than that by aluminothermic method, and the purity of metallic chromium is about 99.2%~99.4%.

(3) Other methods, such as electrosilicon thermal method, electroaluminothermic method and vacuum reduction, provide certain reference value for the industrial application of metallic chromium production, but the purity of the metallic chromium product obtained is lower than that of electrolysis.