PURPOSE: To prepare calcium hydroxide of high purity at a low cost, by reacting calcium chloride with calcium hydroxide and/or calcium oxide, and decomposing only the resultant coarse particulate part of the calcium oxychloride.
CONSTITUTION: Calcium oxychloride is crystallized from calcium chloride and calcium hydroxide and/or calcium oxide in an aqueous solution, and classified to give coarse particulate calcium oxychloride, which is then decomposed to prepare calcium hydroxide of high purity at a low cost without the influence of the variation in the kinds and content of impurities in the raw material. The calcium hydroxide or calcium oxide is preferably formed with water into a calcium hydroxide slurry, which is then classified to remove coarse sand, etc. and use only the coarse particulate part. Preferably, the calcium oxychloride is prepared by crystallizing as tribasic calcium chloride hydrate capable of easily forming coarse crystals containing no impurity.
HIRAGA YOUICHI
KAWAMOTO TAIZOU
