There are two production processes of calcium chloride, one is acid method and the other is alkali method.
The acid method is mainly prepared by chemical reaction of limestone and hydrochloric acid. About 22% dilute hydrochloric acid is used to react with limestone (containing about 52% calcium) to produce 27% liquid calcium chloride. After filtration and separation, the filter residue is discarded. The filtrate is neutralized with lime milk to adjust pH = 8.9-9. Impurities in the calcium chloride solution such as me, Fe, al1, etc. form insoluble me (OH) 2, Fe (OH) 3, A1 (OH) 3, etc. to precipitate. The filter cake is solid waste, The filtrate is subjected to three-effect forced circulation vacuum evaporation to concentrate 27% calcium chloride solution to 68-69%, and then it is fed into the flaker for production. The flake calcium chloride is dried in the fluidized bed to produce 74% calcium chloride dihydrate
Alkali method produce calcium chloride: 1. Direct evaporation process of calcium chloride: generally, the content of calcium chloride in the waste liquor of soda ash is 76.8g/l. After purification, it is first concentrated, separated out useless crystals, and then concentrated to obtain calcium chloride.
2. Calcium chloride salt field pre evaporation process: generally, salt field spreading is used to naturally evaporate the soda ash waste liquid. The salt in the waste liquid is settled, and the salt in the waste liquid will be precipitated first. With the increase of evaporation, more salt will be precipitated. The remaining calcium chloride liquid will be collected into the equipment for evaporation, and calcium chloride will be obtained.
The difference between the two production processes is that the hardness of calcium chloride produced by the acid method is higher than that by the alkali method, but there are more impurities, unstable color and flavor, and the acid method is cheaper than the alkali method. Calcium chloride tablets obtained by alkali process are thin and fragile, with high purity, few impurities and very white color
Post time: Aug-09-2022