With the continuous development of China's economy, the agricultural development under the new normal is also deeply concerned by people. At present, while developing phosphate fertilizer production, one of the important tasks of phosphate fertilizer industry is to treat fluorine-containing waste gas and wastewater, make comprehensive utilization of fluorine resources and actively develop cryolite. Cryolite is an important raw material for aluminum smelting industry. At present, the vast majority of cryolite production takes fluorite as raw material. As an important strategic resource for the development of atomic energy industry, fluorite has limited reserves. Countries all over the world attach great importance to the protection of fluorite resources and affect their development and utilization.
Industrial production of cryolite is divided into high mass ratio cryolite and low mass ratio cryolite according to the mass ratio of sodium fluoride to aluminum fluoride. The higher the molecular ratio, the higher the current efficiency of electrolytic aluminum smelting, the less fluorine loss, and the less environmental pollution will be caused. Moreover, cryolite with high molecular ratio is more suitable for other industries other than aluminum smelting. The cryolite with high molecular ratio is prepared from fluosilicic acid discharged from recycled phosphate fertilizer plant. Compared with sodium fluosilicate method, the raw materials are different and the preparation process is also different.
The process can achieve the following purposes: fluorine and silicon in fluorosilicic acid are used, fluorine is in the product cryolite, silicon is in the by-product white carbon black, and ammonium sulfate is also a by-product. There is no pollution emission in the process, and all raw materials are comprehensively utilized, which greatly improves the economic benefit. The preparation of cryolite by recovering fluorosilicic acid, a by-product of phosphate fertilizer, protects fluorine resources and prevents fluorine pollution. It has great advantages in raw material source, process flow, product quality and production cost, and will gradually replace the existing fluorite method.
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