Preparation of anhydrous calcium chloride

Anhydrous calcium chloride (CaCl2) is a white or off-white solid (granular, blocky, or powder) with a slightly bitter taste and no odor. It is easily soluble in water and gives off a lot of heat when dissolved in water.It has strong hygroscopicity, and is easy to delighting in air.

1. Preparation of calcium chloride dihydrate (CaCl2· 2H2O) : mix hydrochloric acid (31%) and limestone powder into the reaction cylinder at a ratio of 2.2:1, react under agitation, and produce an acidic calcium chloride solution, which is transferred into the clarification tank.Add lime milk, adjust the pH value of the solution to 8.9 ~ 9, then iron hydroxide, magnesium hydroxide precipitation out.After clarification and filtration, the filtrate was heated in the evaporating dish to 172 ~ 174℃ to evaporate. After crystallization, the filtrate was dried and dehydrated at 200 ~ 240℃ to obtain calcium chloride dihydrate.   

2. Preparation of anhydrous calcium chloride: reheat calcium chloride dihydrate to 260 ~ 300℃, dry and dehydrate, that is, turn into white anhydrous calcium chloride.