Method for decomposing scheelite

Abstract

The invention provides a method for decomposing scheelite. The scheelite is decomposed by employing nitric acid, so that Ca in the scheelite can enter the solution in a form of soluble calcium nitrate; meanwhile, phosphoric acid or phosphorite (the phosphorite is decomposed into phosphoric acid through the nitric acid) serve as a tungsten complexing agent, so that WO3 in the scheelite enters the solution in a form of soluble phosphotungstic acid, the generation of solid tungstic acid membrane and slightly soluble calcium salt is avoided in the whole decomposition process, the calcium nitrate solution containing phosphotungstic acid, which is generated after decomposition, is extracted by employing a solvent and is subjected to ion exchange or ammonium salt precipitation method so that the phosphotungstic acid is recovered from the calcium nitrate solution; and sulfuric acid is added into the calcium nitrate solution from which tungsten is extracted and is combined with calcium ion in the solution so as to generate slightly soluble calcium sulfate precipitate, so that the nitric acid is regenerated; and the regenerated nitric acid return to a new round of mineral leaching process. The method has the advantages that tungsten in the tungsten mineral can be completely decomposed; the regenerated nitric acid is recycled, and the leaching cost and wastewater discharge are greatly reduced; and moreover, the treatment equipment is simple, the operation is convenient, and industrialization is easily realized.

Description

technical field [0001] The invention relates to the extraction process of tungsten in the field of hydrometallurgy, in particular to a method for decomposing scheelite. Background technique [0002] Tungsten and its alloys are widely used in various fields such as national defense and military industry, machining, and electronics industry due to their excellent physical and chemical properties, and have become important strategic materials. The tungsten industry is a dominant industry in my country, and its resource reserves, output and export volume all rank first in the world. More than 2 / 3 of the basic reserves of tungsten ore in my country are scheelite resources, forming an absolute advantage. [0003] At present, the mainstream process for processing scheelite is based on the alkaline process that generates insoluble calcium salts. For example, Na 2 CO 3 Pressure cooking process is used to decompose scheelite, while in China, the treatment technology of wolframite N...

AI Technical Summary

Problems solved by technology

[0007] This type of method has achieved satisfactory results in the treatment of minerals such as scheelite concentrate, high-phosphorus scheelite, and high-molybdenum scheelite. However, the control requirements for the decomposition process conditions are strict, and a little carelessness may lead to sulfuric acid The calcium crystallization environment deteriorates, thus forming a dense package on the undecomposed scheelite, resulting in the slag containing WO 3 the rapid rise of

Therefore, this method can not thoroughly solve the problem that solid product calcium sulfate wraps

In addition, the phosphotungstic acid in the leaching solution has strong oxidizing properties, and will react with the remaining reducing flotation reagents in the scheelite concentrate to produce tungsten blue, which will affect the extraction of tungsten in the subsequent process.