A method for preparing tungsten oxide and tungsten powder from scheelite

Abstract

The present invention relates to a method for preparing tungsten oxide and tungsten powder from scheelite. The method uses the scheelite as a raw material and comprises the following steps: (1) conducting leaching reaction; (2) conducting filtering and washing; (3) conducting hydrogen peroxide extraction-decomposition to extract tungsten; (4) conducting hydrogen peroxide multiple dissolution-decomposition to purify tungstic acid; (5) pure tungstic acid calcination to prepare tungsten trioxide; and (6) conducting peroxotungstic acid solution spraying pyrolysis to prepare tungsten oxide and tungsten powder. The method only consumes cheap and easily available sulfuric acid, greatly reduces the decomposition cost of the scheelite and uses sulfuric acid to decompose; decomposed residues are gypsum; the gypsum can be used as building materials; the method does not produce dangerous waste alkali cooking residues, greatly reduces production and operation costs of enterprises, uses hydrogen peroxide as an extractant of tungstic acid, does not produce ammonia nitrogen wastewater, eliminates the technology of producing the ammonia nitrogen wastewater for many years in tungsten smelting, greatly reduces environmental protection costs, directly produces various tungsten end products and tungsten powder, and improves added value of products of the tungsten smelting enterprises.

Description

technical field [0001] The invention relates to the field of chemical production, in particular to a method for preparing tungsten oxide and tungsten powder from scheelite. Background technique [0002] At present, the mainstream technology for processing scheelite in industry is to first use alkaline reagents such as sodium hydroxide or sodium carbonate to obtain crude sodium tungstate solution and alkali cooking residue by pressure cooking. Crude sodium tungstate solution is converted into ammonium tungstate solution by ion exchange technology after being diluted with a large amount of water, and is also transformed into ammonium tungstate solution by solvent extraction. This mainstream technology is currently facing several serious problems: First, alkaline pressure cooking needs to consume alkali such as sodium hydroxide or sodium carbonate. The cost of scheelite decomposition is very high; secondly, alkali pressure cooking will produce alkali cooking slag, which has be...

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Problems solved by technology

This mainstream technology is currently facing several serious problems: First, alkaline pressure cooking needs to consume alkali such as sodium hydroxide or sodium carbonate. The cost of scheelite decomposition is very high; secondly, alkali pressure cooking will produce alkali cooking slag, which has been listed in the national hazardous waste catalogue, and tungsten smelting enterprises are not allowed to dispose of it at will, and must be handed over to qualified enterprises for paid treatment, and The state also charges an environmental protection tax of 2,000 yuan / ton for the hazardous waste alkali cooking slag, which greatly increases the cost of tungsten smelting; third, in order to produce tungsten products with qualified impurity content, the current tungsten smelting process must also Ammonium reagents such as ammonia water or ammonium chloride are used as transformation reagents, so a large amount of ammonia nitrogen wastewater will inevitably be generated during the production process, resulting in environmental pollution

Moreover, the main purpose of its invention is to separate tungsten and molybdenum according to the stability difference between peroxytungstic acid and peroxymolybdic acid in acidic solution, and does not involve the purification method of tungsten

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