Method for removing sulfate radicals and hydrogen sulfate radicals when preparing sodium molybdate from molybdenum-containing waste catalyst through tertiary amine extraction method

Abstract

The invention relates to a method for removing sulfate radicals and hydrogen sulfate radicals when preparing sodium molybdate from a molybdenum-containing waste catalyst through a tertiary amine extraction method. The method comprises the following steps that alkalified oxidation roasting, water leaching filtration, phosphorous removal by a chemical precipitation method, tertiary amine and a kerosene solution are adopted to treat the molybdenum-containing waste catalyst under a faintly acid condition to extract a molybdenum-sodium hydroxide solution and re-extract and concentrate crystal sodium molybdate product. According to the method, a dilute sodium hydroxide solution is used for eluting a molybdenum-loaded organic phase, which can reduce the sulfate radicals of the molybdenum-loaded organic phase to 1.96 g / L from 10.82 g / L before elution with the elution rate of 81.88%. After the molybdenum-loaded organic phase is diluted through a dilute alkali liquor, an alkali liquor is used for reextraction to obtain a high-concentration sodium molybdate solution with Mo / SO4<2-> larger than 100 and SO4<2-> content less than 2g / L, and the crystal is concentrated to obtain the sodium molybdate product with the SO4<2-> less than or equal to 0.05%, which meets the requirements of industrial first-class products.

Description

technical field [0001] The invention relates to a method for removing sulfate radicals and hydrogen sulfate radicals when preparing sodium molybdate from molybdenum-containing waste catalysts by a tertiary amine extraction method. Background technique [0002] The method of extracting molybdenum from the molybdenum-containing waste catalyst molybdenum to prepare sodium molybdate includes ① using concentrated precipitated molybdic acid-sodium hydroxide to dissolve-concentrated crystallization, due to the low concentration of molybdenum, high energy consumption and low metal yield; ② solvent extraction method, using Acidic extraction of molybdenum with tertiary amine kerosene solution-NaOH stripping-precipitation of molybdic acid-NaOH dissolution-concentration and crystallization to obtain sodium molybdate; this method has disadvantages such as long process flow, high reagent consumption, and more process wastewater; ③Ion exchange Method, adopts weakly basic anion exchange res...

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Problems solved by technology

[0005] It can be seen from the reaction formula that during extraction, the polymolybdate anion is exchanged with the sulfuric acid (hydrogen) ion in the extractant after transformation, because the working capacity cannot reach the saturation capacity during extraction, that is to say, the sulfuric acid (hydrogen) in the extractant cannot be The molybdenum ions are all replaced, so the molybdenum-loaded organic phase still contains a certain amount of sulfate (hydrogen) ions. After the molybdenum is extracted with 10% (V / V) trioctylamine kerosene solution, the composition is: Mo 18g / L~22g / L, SO 4 2- 10g / L~12g / L, they are stripped together during the stripping of sodium hydroxide, seriously affecting the quality of sodium molybdate