New Materials, Compounds and Applications

The recycling of tungsten waste is now a critical concern. The industry now recycles waste from hard alloys and metallic tungsten, but seldom recycles trash from tungsten-containing molybdenum. This discrepancy arises from the challenge of distinguishing these two components. Furthermore, the SPA (Scientific and Productive Association) JSC Almalyk MMC did not engineer a system for purifying tungstate solutions from molybdenum and until recently, no technology existed for such purification. This article discusses theoretical concerns in the chemistry of tungsten and molybdenum. It also discusses a method for purifying mother liquors that have crystallized from molybdenum ammonium vapour tungstate. At SPA JSC Almalyk MMC, a process chain was established, enabling the company to manufacture tungsten products with a high molybdenum content this year. Pure metallic tungsten, devoid of molybdenum contaminants, has enhanced physical and thermoionic characteristics. Processing metallic molybdenum devoid of tungsten is more straightforward. The conversion of oxides into metal does not separate tungsten from molybdenum, hence requiring the separation of pure oxides. Tungsten and molybdenum exhibit identical configurations of outer electron shells, nearly equivalent atomic radii (Mo-1.36 A₀, W-1.37 A₀) and matching ionic radii (Mo⁴⁺ - 0.68 A₀, W⁴⁺ - 0.68 A₀); this similarity accounts for their comparable physical, mechanical and chemical properties, their concurrent occurrence in ore materials and the significant challenge of achieving complete separation.