A method for continuously leaching scheelite

Abstract

The invention relates to a method for continuously leaching scheelite. The method comprises the following steps: 1) adding scheelite powder to a phosphoric acid solution in a pre-reaction tank for reacting for 3-5 hours and then going into a phosphoric acid regeneration tank; 2) phosphoric acid regeneration, namely continuously replenishing sulfuric acid to the phosphoric acid regeneration tank and reacting for 3-5 hours before going into an aging desulfurizer; and 3) performing aging sulfur control and ore pulp reflux, namely continuing reacting the ore pulp in the aging desulfurizer for 3-5 hours, refluxing partial ore pulp to the pre-reaction tank, filtering the rest ore pulp to obtain gypsum slag, and guiding the filtrate back into the pre-reaction tank after tungsten extraction. The method for continuously leaching the scheelite, namely a continuous decomposition method, realizes stable and efficient decomposition of the scheelite, and the decomposition rate is above 99%; in addition, the sulfuric acid concentration in the system is reduced to the range of 30-50g / L and the stress of the subsequent treatment is reduced; the method for continuously decomposing the scheelite achieves the purposes of continuous leaching, simplicity in operation and leaching agent recycling.

Description

technical field [0001] The invention relates to a method for continuously leaching scheelite, belonging to the technical field of hydrometallurgy. Background technique [0002] Tungsten resources are mainly scheelite, which accounts for more than 2 / 3 of the world's total reserves. my country's tungsten resource reserves rank first in the world, and scheelite is the main source, accounting for more than 2 / 3 of the tungsten resource reserves. Therefore, the development of efficient scheelite smelting process has become an important topic of tungsten metallurgy. [0003] In the prior art, more in-depth research has been carried out for this purpose, such as ZL201010605095.1 discloses that the supersaturation of calcium sulfate in the solution is reduced by increasing the concentration of phosphoric acid in sulfur-phosphorus mixed acid, in order to obtain coarse and regular calcium sulfate crystals, and avoid Form a package on scheelite to realize the decomposition of scheelit...

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Problems solved by technology

In addition, the violent reaction also leads to excessive local temperature, which affects the crystal form control of calcium sulfate

These problems are more prominent when dealing with low-grade tungsten ore with a large amount of calcium-containing gangue, which often makes the leaching process deviate from the optimal working conditions, resulting in agglomeration in the slurry, making the decomposition effect unsatisfactory; (2) the acid concentration is in the It is high at the beginning of each leaching cycle, but it continues to decrease with the consumption of the reaction. It is difficult to provide a stable physical and chemical environment for calcium sulfate crystallization, thereby affecting the leaching

If the reaction liquid-solid ratio is increased, the acid concentration can be stabilized to a certain extent, but the processing capacity of the equipment is greatly reduced; (3) the seed crystals added for improving the crystallization behavior of calcium sulfate need to be specially prepared, and the prepared crystal seeds also need to be specially prepared. Careful filtration and washing are required to avoid agglomeration and affect the effect, which makes the process complicated and lengthy, and sometimes it is difficult to achieve a good leaching effect

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