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Continuous preparation method of ammonium heptamolybdate

A technology of ammonium heptamolybdate and ammonium molybdate, which is applied in the field of continuous preparation of ammonium heptamolybdate, can solve the problems of unstable quality, low purity and poor solubility of ammonium heptamolybdate products, and achieve good fluidity and high product quality. Stable quality and good solubility

Active Publication Date: 2020-02-18
JINDUICHENG MOLYBDENUM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a continuous preparation method of ammonium heptamolybdate, which solves the problems of low purity, poor solubility and unstable quality of the ammonium heptamolybdate product obtained by the existing intermittent production process

Method used

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Examples

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preparation example Construction

[0022] The invention provides a kind of continuous preparation method of ammonium heptamolybdate, comprising the following steps:

[0023] Step 1, dissolving: get the ammonium dimolybdate aqueous solution with the mass ratio of ammonium dimolybdate: deionized water=1:1, wherein the mass percentage of molybdenum in the ammonium dimolybdate is not less than 56%; to the ammonium dimolybdate aqueous solution Add ammonia water with a concentration of 25%, the reaction temperature is 70°C, and the pH is 6.8-7.2 to obtain an ammonium molybdate solution;

[0024] Step 2, concentration: the ammonium molybdate solution obtained in step 1 is evaporated and concentrated, and the density of the ammonium molybdate solution is controlled to be 1.36-1.4g / cm 3 , pH is 6.3-6.8, obtains ammonium heptamolybdate solution;

[0025] Step 3, filtering: the ammonium heptamolybdate solution obtained in step 2 is filtered to remove impurities;

[0026] Step 4, crystallization by cooling: inject the am...

Embodiment 1

[0029] Get the mass ratio as ammonium dimolybdate: deionized water=1:1 ammonium dimolybdate aqueous solution, wherein the mass percentage of molybdenum in ammonium dimolybdate is 56.23%; add concentration to be 25% ammoniacal liquor in the ammonium dimolybdate aqueous solution , the reaction temperature is 70°C, the pH is 6.8, and the ammonium molybdate solution is obtained; the ammonium molybdate solution is evaporated and concentrated, and the density of the ammonium molybdate solution is controlled to be 1.36g / cm 3 , pH is 6.3, obtains ammonium heptamolybdate solution; The ammonium heptamolybdate solution is filtered to remove impurities; The ammonium heptamolybdate solution after filtering and removing impurities is injected into the cooling crystallizer for cooling crystallization, and the injection volume is cooling crystallizer 75% of the full liquid level, control the stirring speed to 120r / min during the cooling and crystallization process, and the crystallization temp...

Embodiment 2

[0032] Take the mass ratio as ammonium dimolybdate: deionized water=1:1 ammonium dimolybdate aqueous solution, wherein the mass percentage of molybdenum in ammonium dimolybdate is 56.21%; add concentration to be 25% ammoniacal liquor in the ammonium dimolybdate aqueous solution , the reaction temperature is 70°C, the pH is 7.2, and the ammonium molybdate solution is obtained; the ammonium molybdate solution is evaporated and concentrated, and the density of the ammonium molybdate solution is controlled to be 1.4g / cm 3 , pH is 6.8, obtains ammonium heptamolybdate solution; The ammonium heptamolybdate solution is filtered to remove impurities; The ammonium heptamolybdate solution after filtering and removing impurities is injected into the cooling crystallizer for cooling crystallization, and the injection volume is cooling crystallizer 80% of the full liquid level, control the stirring speed to 130r / min during the cooling and crystallization process, and the crystallization temp...

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Abstract

The invention discloses a continuous preparation method of ammonium heptamolybdate, and the method comprises the following steps: adding ammonia water into an ammonium dimolybdate water solution to obtain an ammonium molybdate solution; evaporating and concentrating the ammonium molybdate solution to obtain an ammonium heptamolybdate solution; filtering the ammonium heptamolybdate solution to remove impurities; injecting the ammonium heptamolybdate solution subjected to filtering and impurity removal into a cooling crystallizer for cooling crystallization, starting to continuously feed and discharge at intervals after crystals are separated out, filtering the discharge liquid to obtain a crystallized filter cake, and sequentially performing centrifugal spin-drying and drying on the crystallized filter cake to obtain an ammonium heptamolybdate product. According to the continuous preparation method of the ammonium heptamolybdate disclosed by the invention, the ammonium heptamolybdate product obtained in a continuous feeding and interval discharging manner is stable in quality and good in flowability; the nitrate impurity content of the ammonium heptamolybdate product obtained by taking ammonium dimolybdate as a raw material is less than 20ppm, the solubility of the ammonium heptamolybdate product in pure water at 25 DEG C is more than 60g / 100ml, the product purity is high, and the solubility is good.

Description

technical field [0001] The invention belongs to the technical field of molybdenum chemical production technology, and in particular relates to a continuous preparation method of ammonium heptamolybdate. Background technique [0002] Ammonium heptamolybdate is one of the earliest ammonium molybdate products. It has large particle size and good water solubility. It is mainly used in industries such as chemical and petroleum catalysts, dyes, pigments and micro-fertilizers. It is also used in the molybdenum metal processing industry. It has been used abroad. Ammonium molybdate is used as a raw material for catalysts such as coke oven gas hydrogenation and methanol oxidation. However, domestic ammonium heptamolybdate mostly adopts a batch process, and the product has low purity, poor solubility, and unstable quality, which makes it difficult to meet the needs of foreign catalyst industries. [0003] The intermittent production process is complicated, the equipment is outdated, th...

Claims

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Application Information

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IPC IPC(8): C01G39/00
CPCC01G39/00C01P2004/62C01P2006/80
Inventor 郭军刚刘东新姚成唐丽霞李旺
Owner JINDUICHENG MOLYBDENUM CO LTD