Fluorgypsum, also known as fluorspar, is a by-product of anhydrous calcium sulfate, which is obtained from hydrofluoride produced by hydrofluorite hydrolysis with sulfuric acid. Almost all the by-production gypsum is dihydrous gypsum, only the by-production of fluoro-gypsum is anhydrous gypsum.
Hydrogen fluoride is the main raw material for the preparation of fluorine elements, inorganic fluoride (aluminum fluoride, sodium fluoride, synthetic cryonite, sodium difluoride, borate fluoride, etc.) and organic fluoride (Freon, polytetrafluoroethylene and other fluorinated plastics).
At present, the main method of hydrogen fluoride production in the world is the hydrolysis of fluorite with sulfuric acid. According to the reaction calculation, the production of 1t hydrogen fluoride can theoretically produce 3.4t fluoropressum.
The emission of fluoro-gypsum is closely related to the production of hydrogen fluoride. China has large reserves of fluorite in the world, and proved reserves have taken up one third of the total reserves of the world. In recent years, the production of fluorite in China has increased rapidly, accounting for more than 50% of the global total. Because of rich resources, in recent years, the rapid growth of hydrogen fluoride production in China, gypsum production equipment to 2005 annual output of hydrogen fluoride 560 thousand t; In addition, the metallurgical industry produces about 60,000 t of hydrogen fluoride for metallurgy, with a total annual output of 620,000 t. According to the discharge of 3.4t of gypsum fluoride per ton of hydrogen fluoride, China's annual discharge of gypsum fluoride amounted to 2.11 million t.
At present, there are about 50 enterprises producing hydrogen fluoride in our country, among which about 30 enterprises with a large scale of production. The production of hydrogen fluoride is mainly concentrated in Zhejiang, Fujian, Jiangsu, Shandong and other provinces where fluorite resources and downstream products are available. Therefore, at present, there are about 50 hydrogen fluoride production enterprises in China, among which about 30 are large-scale production enterprises of gypsum powder processing equipment. The production of hydrogen fluoride is mainly concentrated in Zhejiang, Fujian, Jiangsu and Shandong provinces where fluorite resources and downstream products are available. Therefore, the emission of fluoro-gypsum is also mainly concentrated here. The emission of the main provinces is shown in Table 1-2-29.
Due to the export control of fluorite resources in China, foreign countries will import fluorite from China to import hydrogen fluoride. Coupled with the development of fluorine chemical industry in China, it is predicted that China's hydrogen fluoride industry will continue to develop in the future, and the annual emission of fluoropressum will also increase.
