Production process of anhydrous calcium chloride.
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Anhydrous calcium chloride can be used as desiccant, dehydrator, refrigerant, antifreeze for aviation and automobile internal combustion engine, coagulant antifreeze, fabric fire retardant, food preservative, etc. The color of anhydrous calcium chloride is white or gray white, which is easy to dissolve in water. When dissolving in water, it can release a lot of heat and has hygroscopicity, but it is easy to be deliquesced in air, so it should be sealed for storage. Let's briefly understand the production process of anhydrous calcium chloride:
I. production principle
It can be prepared by reaction of limestone and hydrochloric acid. The main chemical reactions are as follows:
CaCO3+2HCl→CaCl2+H2O+CO2↑
II. Operation process
1. Preparation of calcium chloride dihydrate (CaCl2 · 2H2O): hydrochloric acid (31%) and limestone powder are put into the reaction tank according to the ratio of 2.2:1, and the reaction takes place under agitation to generate acid calcium chloride solution, which is transferred into the clarification tank. Add lime milk, adjust the pH value of the solution to 8.9-9, and then iron hydroxide and magnesium hydroxide precipitate. After clarification and filtration, the filtrate is transferred into an evaporating dish and heated to 172-174 ℃ for evaporation. After crystallization and separation, it is dried and dehydrated at 200-240 ℃ to obtain calcium chloride dihydrate.
2. Preparation of anhydrous calcium chloride: reheat the anhydrous calcium chloride dihydrate to 260-300 ℃, dry and dehydrate, i.e. turn into white anhydrous calcium chloride.