NITRIC ACID LEACHING PROCESS FOR THE RECOVERY OF COPPER, SILVER AND NICKEL FROM POLYSULFIDE ORES OF THE SAME

摘要

Ni, Ag, Cu etc., may be very efficiently extracted from untreated sulphide ores and concentrates by subjecting to a pressure leaching process in which molten sulphur is formed as a separate fluid layer. This is then removed via a flash-tank and purified if necessary. Typical conditions using a 30-50% HNO3 leach soln. are 115-125 degrees C at 3.52-8.44 ats. gas (usually air or gas e.g., N2) pressure. Reaction time is 30-60 mins. with high efficiency i.e. 99.9%. NHO3 can be regenerated from nitrous fumes and returned to the closed system or converted to NH4NO3.