Page 187 - Chemical and process design handbook

Speight_Part II_C 11/7/01 3:08 PM Page 2.128

CALCIUM HYPOCHLORITE

Calcium hypochlorite is manufactured by chlorination of calcium hydrox-
ide [CaOH) ] followed by the separation of the calcium hypochlorite
2
[Ca(OCl) ] through salting out from solution with sodium chloride.
2
2Ca(OH) + 2Cl → Ca(OCl) + CaCl + H O
2 2 2 2 2
Calcium hypochlorite is also manufactured by the formation under
.
.
refrigeration of the complex salt Ca(OCl) NaOCl NaCl 12H O, which is
2 2
prepared by the chlorination of a mixture of sodium hydroxide and calcium
hydroxide. The salt is reacted with a chlorinated lime slurry, filtered to
remove salt, and dried, resulting finally in a stable product containing 65
to 70% calcium hypochlorite.
The great advantage of calcium hypochlorite is that it does not decom-
pose on standing as does bleaching powder. It is also twice as strong as
ordinary bleaching powder and is not hygroscopic.

2.128