Patent ID: 6241958
Filing Date: 2001-06-05
Classification: C01F,C01P,C02F

Abstract:
A process of preparing a solution of basic sulfate-containing polyaluminum chloride, said process comprising the steps of:a. digesting an aluminum-containing substance with hydrochloric acid to form a resulting solution and an insoluble residue;b. filtering said resulting solution formed in step a) to separate said insoluble residue therefrom and to form a solids-free solution;c. concentrating said solids-free solution formed in step b) by evaporation to form a concentrated solution having an AlCl.sub.3 content of about 30 percent by weight;d. recovering AlCl.sub.3.6H.sub.2 O from said concentrated solution formed in step c) by crystallization;e. thermally decomposing said AlCl.sub.3.6H.sub.2 O formed in step d) to form a solid basic aluminum chloride by heating at temperatures from 150 to 200.degree. C. so that said solid basic aluminum chloride contains Al and OH in a molar ratio of OH/Al of from 1.35:1 to 2.25:1;f. feeding the solid basic aluminum chloride formed in step e) into an aqueous sulfuric acid solution and dissolving said solid basic aluminum chloride therein to form another solution; andg. subsequently to step f), heat-treating said another solution at temperatures of 40.degree. C. to 70.degree. C. for 1 to 3 hours to form a solution of basic sulfate-containing polyaluminum chloride having a sulfate content of 1 to 6 percent by weight and an aluminum concentration of 3 to 10 percent by weight, wherein said molar ratio of OH/Al in said solution of said basic sulfate-containing polyaluminum chloride is from 1.05:1 to 1.95:1.