Preparation method for ultrapure ammonium molybdate

Abstract

The invention provides a preparation method for ultrapure ammonium molybdate. The method comprises the following steps of: adding pure water and liquid ammonia (or ammonia water) into molybdenum oxide, ammonium dimolybdate, ammonium tetramolybdate, ammonium polymolybdate and the like serving as raw materials, dissolving ammonia at the normal temperature and stirring for uniformly mixing; extracting and purifying with a special extracting agent, and adding a super acid under the normal pressure for performing acid precipitation and crystallization; performing solid-liquid separation after acid precipitation is completed; and drying the separated ammonium molybdate till the moisture in the ammonium molybdate is lowered to be less than or equal to 1.0 g / cm<3>, wherein during ammonia dissolving burdening, the concentration of molybdenum ions in a solution main body is controlled at 50-200 g / L, and the pH is kept at 7.0-10.0; acid precipitation is performed after extraction and purification with the special extracting agent; and the pH of an acid precipitation end point is controlled at 4.5-6.5. Due to the adoption of the preparation method, the purity of an ammonium molybdate product is greatly increased, surpasses the first class of the national standard of ammonium molybdate, and meets the index requirements of the electronics industry and the catalyst industry. The preparation method disclosed by the invention is easy to operate, novel equipment is not required to be provided, the quality of the obtained ammonium molybdate product is stable, and the crystallization rate can be over 97 percent.

Description

technical field [0001] The invention relates to a preparation method of ultrapure ammonium molybdate, in particular to a preparation method of an ultrapure ammonium molybdate raw material required for producing high-purity molybdenum powder and a highly active molybdenum-based catalyst. Background technique [0002] Ammonium molybdate can be used to produce lubricants, corrosion inhibitors, flame retardants, smoke suppressants, pigments, fertilizers, catalysts; it can also be used to prepare MoO 3 And Mo powder, and then processed into molybdenum metal products such as molybdenum bars, molybdenum crucibles, molybdenum wires, molybdenum rods, molybdenum electrodes, molybdenum slabs, molybdenum alloys; in addition, it is also applied to super capacitors, nanomaterials, optoelectronic materials, superconducting materials , hydrogen storage materials, fuel cells and other industries, widely used in steel, hard alloy, metal processing, electronic components, electric light source...

AI Technical Summary

Problems solved by technology

[0010] In view of the relatively large liquid-solid ratio when ammonium polymolybdate is dissolved in ammonia, the evaporation time is too long, which will cause the ammonium molybdate solution to grow in the stainless steel reaction axe. Stirring for a long time brings some impurities (such as iron, etc.) into the ammonium molybdate. In addition, due to the temperature gradient and the imbalance of alkalinity and mass transfer, the growth rate of the ammonium molybdate tiny particles is different. Crystal entrainment occurs, which leads to entrainment of impurities and reduces the purity of ammonium molybdate products, making it difficult for the product purity to exceed the first level of the national standard for ammonium molybdate (GB / T 3460-2007), which is difficult to meet the growing electronics industry. The demand for high-purity and ultra-pure ammonium molybdate in the fields of chemical and chemical catalysis