Method for processing wastes resulting from production of phosphorus namely, slime and off-gases, with utilization of the resultant products

Method of modifying and refining hypereutectic silumines, which comprises melting a hypereutectic silumine at a temperature between about 820.degree.-900.degree. C. and adding thereto the solid product obtained by treating slime wastes or off-gases from the production of phosphorus with an aqueous solution of copper sulphate and separating the resulting solid product from the liquid product, said solid product containing mainly copper phosphide, chlorides and fluorides of alkali metals and silicon, and silicates of calcium and aluminum, whereby the copper phosphide reacts with the aluminum to form AlP seeds which serve as crystalization centers for silicon grains while the chlorides and fluorides of alkali metals and silicon are decomposed by the aluminum to form the corresponding aluminum and silicon fluorides and chlorides which evolve from the melt while the corresponding alkali metal fluorides and chlorides and silicon remain in the melt, the remaining components of said solid product surfacing from the melt as a slag, and recovering the thus modified and refined silumine.