Continuous process for obtaining aluminium fluoride by reacting fluosilicic acid with an aluminous material

Claim 1

Continuous process for obtaining aluminum fluoride by reacting fluosiliCic acid with an aluminous material, forming a suspension of insoluble silica hydrate and a supersaturated solution of Alpha -allotropic aluminum fluoride, which reaction is carried out by using fluosilicic acid having a concentration of 5 to 25%, previously heated to approximately 60* to 95*C, and finely pulverized alumina or bauxite hydrate high in silica; the reaction mixture being maintained at a temperature above 90*C, for a reaction time from 5 to 60 minutes, the process being carried out continuously in a battery of reactors arranged in cascade, the reaction being effected progressively from the first to the last reactor; the reaction flow being uniform; and the reactants being continuously introduced through the first reactor uniformly and continuously in such amount that the suspension emerging from the last reactor is maintained at a pH between 1 and 3, the insoluble silica hydrate being separated from said suspension which emerges from the last reactor, while said supersaturated Alpha -allotropic aluminum fluoride solution obtained is lead to a battery of crystallizers, arranged in cascade, where the Alpha -aluminum fluoride is continuously converted to its insoluble Beta -allotropic state.