Treating granular sulphidic ores containing gold and/or silver

摘要

Process for treating granular sulphidic ores containing gold and silver as well as iron, comprises producing a solid mixture containing metal oxide, and a flue gas containing SO2 by roasting at temperatures of 500-900 deg C with addition of gas containing free oxygen. The solid mixture is cooled, in which the temperature drops by around 50 deg C, and the cooled mixture is added to a fluidised bed reactor and SO2-containing flue gas fed into the reactor. Metal sulphate is produced in the solid mixture and at least 10% of the sulphur content in the flue gas binds in the form of metal sulphate. The mixture containing the metal sulphate is removed from the reactor, and stirred with an aqueous acidic solution to dissolve the metal sulphate so that the solids are removed from the solution and gold and/or silver recovered.