Recovery and refining of rhenium, tungsten and molybdenum from W-Re, Mo-Re and other alloy scraps

Abstract

The extensive use of rhenium in fabricating high temperature alloys, its use as a catalyst in a variety of applications, its high cost and its rarity are important incentives for developing techniques for its recovery. The recycling and recovery of tungsten and molybdenum is also essential because of their increasing use in high temperature alloys, metal carbides, cutting and drilling tools, and a variety of other applications. We developed a simple recovery method in which the scrap is oxidized by pure oxygen gas at 1000 °C and the resulting volatile rhenium oxide is condensed in the cooler region of the reaction chamber. This oxide is dissolved in water and treated with potassium chloride to form its potassium salt which is reduced under hydrogen gas to pure rhenium metal powder. The oxides of tungsten or molybdenum are treated with boiling water, dried and reduced under hydrogen to their respective pure metal powders. All three metal powders are of high purity and fine size. The method is simple and economical and does not generate any acid, wastes or other environmental pollutants.