An innovative strategy for deeply separating macro amounts of molybdenum from tungstate solutions via vulcanization step-by-step and microbubble floating-extraction: Theoretical and experimental investigation

Abstract

The gradually increasing demand for high-purity tungsten products has become a key challenge and attracted considerable attention in chemical industry, the premise of which is to achieve the deep separation of molybdenum impurities from tungstate solutions. An innovative separation of molybdenum impurity from tungstate solutions were systematically investigated in this work. On the foundation of the theoretical analysis, a novel strategy named vulcanization step-by-step and the vulcanized trajectory of which were proposed. It was found that the thiomolybdate method is still suitable to separate molybdenum from tungstate solutions (Mo/WO3 > 2 wt%) based on the vulcanization step-by-step, and satisfactory separation results were obtained by microbubble floating-extraction. Under optimized conditions, the separation efficiency of molybdenum can reach over 99 %, and the loss of tungsten is approximately 2 %. As a results, the tungstate solutions with Mo/WO3 less than 2 × 10−6 was obtained. Subsequently, the tungsten products (WO3) with a purity greater than 99.99 % was prepared from purified tungstate solutions. Ultimately, the microbubble floating-extraction mechanisms including the mineralization behaviors of target component, the attachment behaviors of hydrophobic complexes on the surface of rising microbubbles and the mass transfer process at the oil–water phase were comprehensively interpreted at the molecular level. This work can provide an important technical support for the preparation of high-purity tungsten products from tungstate solutions containing macro amount of molybdenum.