METHOD FOR PURIFYING WATER CONTAINING CALCIUM SULPHATE BY PRECIPITATION OF A CRYSTALLINE SULPHOALUMINATE USABLE AS CHARGE

摘要

Method for purification of water containing dissolved calcium sulphate to be eliminated, by precipitation producing crystalline calcium sulphoaluminate, which is valuable or which may be recycled, method being characterized in that; a) there is created in the waters to be treated a reaction system by introduction of at least a couple of treatment agents, one of which bringing the calcium element and the other one bringing at least one element M, alcaline and/or equivalent, and selected in the group comprised of lithium, sodium, potassium and ammonium such that the molar ratio of initially present ions in solution and introduced treatment agents Al/SO4?Ca?M is comprised between 2/1/2/0.08 and 2/2.5/5/4; b) the couple of treatment agents providing the calcium and at least one alkaline and/or equivalent element M is selected in the group including aluminates and hydroxydes such that: when the alkaline and/or equivalent element M is introduced in the form of aluminate, the calcium element is introduced in the form of hydroxyde ; when the alkaline and/or equivalent element M is introduced in the form of hydroxyde, calcium element is introduced in the form of aluminate. The crystalline structures collected at the end of the purification are exploited as charge in various application fields such as the paper making industry, paint, plastic materials.