Provided is a method for processing a gold-bearing sulfide ore which involves maintaining the ore in a substantially oxygen free environment, preferably beginning with comminution of the ore and ending when a desired final concentrate, enriched in sulfide minerals, is obtained by flotation. In one embodiment, nitrogen gas is used to substantially prevent contact between the ore and air during comminution of the ore and during flotation operations. It is believed that oxygen gas present in air detrimentally affects the recovery of sulfide minerals in a flotation concentrate through surface oxidation of sulfide mineral particles. The use of a gas such as nitrogen can significantly reduce the potential for such surface oxidation. Additionally, gases separated from an oxygen plant may be beneficially used, with an oxygen gas stream being used, for example, for pressure oxidation of sulfide mineral materials, and with a nitrogen gas stream being used in comminution and/or flotation operations, resulting in advantageous use of a nitrogen gas by-product stream which has previously been vented to the atmosphere as waste.