Method for crystallizing ammonium molybdate

Abstract

A method for crystallizing ammonium molybdate relates to that field of ammonium molybdate preparation, in particular comprises the follow steps: ammonia leaching is carried out after molybdenum calcine is pickled to obtain ammonia leaching solution; ammonia leaching solution enters into a cationic exchange resin to remove calcium, magnesium, aluminum, iron and copper and other metal ions; the treated liquid enters a cross-flow three-effect evaporation crystallization system and crystallizes continuously to obtain ammonium dimolybdate; centrifugal drying and screening are performed to obtain ammonium dimolybdate finished product. The ammonium molybdate crystallization method uses the ion exchange resin to remove impurity from ammonia leaching solution, the liquid directly enters the evaporation crystallization system, continuously crystallizes to obtain ammonium dimolybdate product, eliminates the acid precipitation crystallization step in the traditional process, simplifies the processflow, simultaneously reduces the use of acid solution, reduces the environmental pollution, and uses the ion exchange resin impurity removing step to compound the evaporation crystallization purification step to obtain the product with high purity.

Description

technical field [0001] The invention relates to the field of crystallization methods of compounds, in particular to the crystallization method of ammonium molybdate. Background technique [0002] Ammonium molybdate is mainly used for smelting ferromolybdenum and producing molybdenum trioxide. Metal molybdenum powder is used as raw material for tungsten-molybdenum alloy and molybdenum wire; secondly, it is used as a catalyst for chemical industry, and a small amount is used as agricultural molybdenum fertilizer; a very small amount is used for medicine. , as a component of various enzymes, the lack of molybdenum can lead to dental caries, kidney stones, Keshan disease, Kashin-Beck disease, esophageal cancer and other diseases, mainly for patients who rely on intravenous hypertrophy for a long time. Among them, ammonium dimolybdate is mainly used in chemical and petroleum catalysts, dyes, pigments and micro-fertilizers, and is an important molybdate. [0003] The traditional ...

AI Technical Summary

Problems solved by technology

When using nitric acid acid precipitation in the traditional process, a large amount of acidic waste liquid will be produced, causing environmental pollution. At the same time, the post-treatment of the acidic waste liquid also requires a lot of manpower and material resources

[0004] Chinese patent CN201710765989.9 discloses a method for preparing ammonium molybdate, specifically: step 1, prepare a certain amount of molybdenum ammonia immersion solution or ammonium molybdate crystallization mother liquor, and then add ammonia water to adjust the pH; step 2, after the steps 1. Add the hydrogen peroxide with a mass fraction of 30% to the molybdenum ammonia immersion solution or the ammonium molybdate crystallization mother solution to adjust the pH, stir and mix evenly to obtain the mixed solution 3; step 3, add methanol or ethanol or ethanol to the mixed solution A obtained in step 2 NMP, stir and mix evenly to obtain mixed solution B; step 4, filter the mixed solution B obtained in step 3, and dry the solid obtained by filtering to obtain ammonium dimolybdate or ammonium heptamolybdate; the preparation of the ammonium molybdate The method saves the steps of acid precipitation and crystallization, and solves the problem that a large amount of acidic waste liquid will be generated when nitric acid precipitation is used, causing environmental pollution, and the process flow is simple and easy to operate. The ammonium molybdate product is removed from impurities, so that the purity of the finished product is relatively low

Images