Method and equipment for purifying zinc sulfate solution

Abstract

The invention discloses a method and equipment for purifying a zinc sulfate solution. The method comprises the following steps of: adding zinc powder into the zinc sulfate solution for purifying; and after the zinc powder is added, adjusting the acidity of the zinc sulfate solution, namely a) detecting a BT value of the zinc sulfate solution into which the zinc powder is added; b) adding an acid solution into the zinc sulfate solution according to the BT value in the step of a); and c) repeating the step a) to the step b) until the BT value of the zinc sulfate solution is between 1.2 and 2.0.According to the method, the acidity of the zinc sulfate solution is controlled by detecting the BT value of the zinc sulfate solution to destroy an oxidation film on the outer surface of the added zinc powder, and the generation of high-quality seed crystals is ensured on the basis of reducing the addition amount of the zinc powder and improving the activity of the zinc powder, so that the aims of improving the purification quality and reducing the consumption of the zinc powder are fulfilled.

Description

technical field [0001] The invention relates to the field of zinc smelting, in particular to a method and equipment for purifying a zinc sulfate solution. Background technique [0002] At present, in the purification process of zinc sulfate solution in zinc hydrometallurgy, zinc powder is usually used as an additive. During the production and transportation of zinc powder, part of the surface will be oxidized due to the contact with outside air, and a certain amount of oxide film will be produced. , this part of the oxide film wraps the zinc powder inside, which seriously affects the activity of the zinc powder, which causes a substantial increase in the amount of zinc powder used in the purification process of the zinc sulfate solution, wasting a lot of zinc resources. [0003] In the prior art, in order to reduce the waste of zinc powder, the commonly used method is to add an appropriate amount of waste acid to adjust the acidity of the solution during the purification pro...

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Problems solved by technology

[0006] It can be seen from the above reaction formula that an acid release reaction will occur in the zinc sulfate solution during the purification process to generate basic zinc sulfate. This reaction will cause an increase in the acidity of the solution and a decrease in the pH value, and the H + It cannot react with zinc oxide, which causes the measurement data of PH value to not truly reflect the acidity of the solution, and cannot effectively control the acidity of the zinc sulfate solution, and cannot effectively destroy the oxide film on the surface of the zinc powder

[0007] At the same time, basic zinc sulfate is a kind of fine solid particles. After the purification operation of the zinc sulfate solution is completed, it is necessary to perform a press filter operation to separate the liquid from the solid. Such fine particles can easily block the capillary pores of the filter cloth, resulting in Serious restrictions on the filter press operation; in addition, the purification slag formed in the purification process needs to be returned to the purification operation as crystal seeds to reduce the consumption of zinc powder in the purification process. However, if there is a large amount of basic zinc sulfate in the system solution, it will It is wrapped inside the seed crystal and forms an unstable seed crystal structure. This unstable seed crystal will produce back-dissolving phenomenon when it returns to the purification operation, that is, the harmful components in the purification slag re-dissolve into the solution, thereby affecting the purification quality

This makes basic zinc sulfate also cause great harm to purification operations.

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