Patent ID: 6482373
Filing Date: 2002-11-19
Classification: C22B

Abstract:
A process for treating ores in the form of ore particles, having recoverable precious metal values and metal values and including arsenic-, carbon- and sulfur-containing components which comprises:roasting said ore particles in the presence of at least one substance selected from the group consisting of: i. a free oxide, carbonate, sulfate, hydroxide and chloride of calcium, magnesium, iron and barium; ii. a pyrite; and iii. iron; in an oxygen augmented atmosphere having a total initial oxygen content of less than about 65% by volume while maintaining a reaction temperature from about 475Â° C. to about 900Â° C. during said roasting, without formation of a molten phase on the surface of said ore particles and further wherein said substance is present in an amount at least 1 to 4 times the stoichiometric amount necessary, at least 3.5 times when said substance comprises iron, on mol basis, to react with arsenic in said ore to form stable arsenates; roasting said ore in presence of water vapor up to 10% by weight of said ore such that the water vapor content in an exhaust gas from said roasting is 0.5 to 10%; and recovering a thus-roasted ore as calcine whereby said calcine is amenable to recovery of precious metal values in said calcine.