Removing calcium impurity from strontium sulphate - or barium sulphate - by leaching with an ammonium

摘要

Removal of Ca impurity from e.g. celestite is carried out by leaching with an aq. soln. contg. pref. 5 wt.% of an ammonium salt, such as nitrate, chloride or acetate, and opt. =15 wt.% of a mineral acid, such as HCl or HNO3. The soln. can be regenerated by treatment with an ammonium slt whose anion is capable of pptg. Ca, e.g. (NH4)2CO3. The products can be used in pyrotechnical applications.