Improvements in or relating to the recovery of gold from roasted pyrites

摘要

Roasted pyrites containing less than 4,5 grms. of gold per ton are subjected to a chlorinating roast, copper is removed by leaching, and the gold then recovered from the residue by leaching with known solvents, such as sodium or potassium cyanide, calcium cyanide, cyanogen bromide, or thiourea. Leaching liquids rendered strongly alkaline as by lime are preferably employed, and gold may be recovered from the solutions obtained by means of zinc dust. A 0,05 per cent solution of sodium cyanide is preferably used, leaching being effected in a number of tanks, and later fractions of the solvent used in any one tank being passed to the next tank in the series. A flow sheet illustrating the leaching step is given.ALSO:Roasted pyrites containing less than 4,5 grms. of gold per ton are subjected to a chlorinating roast, copper is removed by leaching, and the gold then recovered from the residue by leaching with known solvents such as sodium or potassium cyanide, calcium cyanide, cyanogen bromide, or thiourea. Leaching liquids rendered strongly alkaline as by lime are preferably employed, and gold may be recovered from the solutions obtained by means of zinc dust. A 0,05 per cent solution of sodium cyanide is preferably used, leaching being effected in a number of tanks, and later fractions of the solvent used in any one tank being passed to the next tank in the series. A flow sheet illustrating the leaching step is given.