Patent ID: 6132696
Filing Date: 2000-10-17
Classification: C01F,C01P

Abstract:
A method for the manufacture of precipitated calcium carbonate from impure calcium oxide, comprising:(a) admixing said impure calcium oxide with an aqueous solution consisting essentially of a salt of at least one compound selected from the group consisting of organic amines of the formula RNH.sub.2 and alkanolamines of the formula NH.sub.2 (R.sup.1 OH), where R and R.sup.1 are alkyl groups of 1-4 carbon atoms, and hydrochloric or nitric acid, said salt being used in at least the stoichiometric amount to dissolve the calcium oxide;(b) separating the solution so obtained from insoluble matter therein; and(c) treating the solution at a temperature of at least 50.degree. C. with (i) carbon dioxide or (ii) the carbonate of said amine or alkanolamine of step (a),said process additionally comprising the step of adding a solution of a reducing agent subsequent to step (b).