Method for decomposing scheelite

Abstract

The invention provides a method for decomposing scheelite. The method comprises the following steps: carrying out complexing decomposition by adopting hydrochloric acid with a certain concentration and phosphoric acid with a certain ratio; after decomposing, enabling tungsten to directly enter a decomposed solution in a manner of heteropoly acid; filtering to obtain a filtrate; extracting tungstophosphoric heteropoly acid in the filtrate by using N235; extracting and separating; carrying out stripping on a loading organic phase by using NaOH; adding calcium sulfate into raffinate; filtering to obtain the hydrochloric acid for circular utilization; circularly utilizing a stripping organic phase; acidifying a stripping solution to adjust the pH (Potential of Hydrogen); evaporating and crystallizing to obtain a sodium phosphotungstate crystal. The method for decomposing the scheelite has the advantages that a traditional scheelite single acid decomposition concept is changed, and the hydrochloric acid and the phosphoric acid are used for carrying out the complexing decomposition on the scheelite to improve the leaching efficiency of the tungsten; the scheelite decomposed solution is treated by an extraction method to improve the concentration of the tungsten and reduce the water use amount of a tungsten smelting process; the water circulation of the whole process is easy to realize; the regeneration of a decomposition reagent is realized by using the calcium sulfate and the production cost is greatly reduced; prepared heteropolyphosphotungstate has a very wide application.

Description

technical field [0001] The invention relates to the extraction of rare high melting point tungsten in the field of hydrometallurgy, in particular to a method for decomposing scheelite. Background technique [0002] my country's proven scheelite concentrate reserves are 1 million tons, and black tungsten concentrate is only about 200,000 tons. Because scheelite ore has the characteristics of complex components, low grade, associated with other metals, and difficult development and utilization, the current tungsten smelting and production industry in my country is dominated by black tungsten mineral raw materials, and wolframite reserves are increasingly exhausted. With the increasingly depleted tungsten mineral wolframite, it is imminent and significant to replace wolframite with scheelite in tungsten smelting. [0003] However, in the prior art, hydrochloric acid is directly used to decompose scheelite. During the decomposition process, a layer of tungstic acid hydrate film...

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Problems solved by technology

[0003] However, in the prior art, hydrochloric acid is directly used to decompose scheelite. During the decomposition process, a layer of tungstic acid hydrate film will be formed on the surface of scheelite particles, which will hinder the diffusion of reactant HCl to the reaction interface, which greatly slowed down the speed of reaction

[0004] When dilute ammonia water was used to back-extract the loaded organic phase, it was found that there would be precipitation, and phase separation was extremely difficult.

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