Method for recovering metal chlorides from silicon or ferrosilicon alloys which have been reacted with chlorinating agents.

摘要

A method for recovering iron chloride, aluminium chloride and calcium chloride from silicon and ferrosilicon or from residues which contain silicon and/or ferrosilicon and metal chlorides and optionally copper and/or copper compounds. These materials are leached with CHl or CHl + FeCl3/FeCl2 solution, whereafter the solid silicon or ferrosilicon residue is removed from the leach solution together with any copper. Fe<2><+> in the leach solution is then oxidised to Fe<3><+> whereafter the leach solution is subjected to liquid-liquid extraction by means of an organic phase containing n-tributyl phosphate dissolved in a hydrocarbon solvent in order to extract FeCl3 and at least a part of any CaCl2 from the leach solution. FeCl3 and any CaCl2 are stripped from the organic phase by water and the remaining solution is concentrated by evaporation and adding HCl gas to the solution in order to selectively precipitate AlCl3.6H2O and AlCl3.6H2O is then recovered from the solution by filtration.