PROCESS FOR THE RECOVERY OF RESIDUAL METAL VALUES FROM SMELTER WASTE SLAGS, AND FROM CONVERTER SLAGS

摘要

This invention provides a process for economical extraction of residual base metal values in furnace slags, by utilizing smelter by-product sulphuri c acid for the pressure leaching of such stags after sufficient initial slow- solidification to induce crystallization. After final solidification and cooling the slags are ground and pulped, mixed with sulphuric acid in an autoclave, and reacted at temperatures up to 275.degree.C and pressures up to about 940psi when applyi ng an oxygen over-pressure of up to 75psi, for up to 2 hours. High degrees of extraction of contained nickel, copper, cobalt and zinc if present, are achieved which are subsequently recovered from the leachate. Whereas the furnace slag s, as produced and untreated, present a potential long term environmental hazar d, after extraction of their base metal values they are rendered virtually beni gn vis- à-vis the environment. This method of pressure leaching can be applied to crystallized converter slags enriched in cobalt during the smelting of metal and copper sulphide ores.