Dechlorination method of zinc sulfate solution

Abstract

The invention discloses a dechlorination method of a zinc sulfate solution, which comprises the steps that sulfuric acid is added to a zinc sulfate solution containing 100-150g / L zinc and 0.5-5.0g / L chlorine; an acid solution with the sulfuric acid concentration of 20-75g / L is obtained; the acid solution is subjected to selective electrodialysis in four diaphragm electrolytic cells at a room temperature and at the current density of 50-200A / m<2>; a low-chlorine solution containing 0.1-0.3g / L chlorine and a high-chlorine solution containing 5-20g / L chlorine are obtained; the low-chlorine solution is used for producing electric zinc; the high-chlorine solution is subjected to chlorine precipitation by a cuprous chloride method; a chlorine precipitation solution containing 0.4-1.0g / L chlorine is obtained; zinc powder is added to the chlorine precipitation solution for replacing and removing copper; a copper removal solution containing 0.4-1.0g / L chlorine is produced; the copper removal solution is returned for acid addition, and subjected to the selective electrodialysis. With the adoption of the method, chloride ions in the zinc sulfate solution can be removed at low cost and high efficiency.

Description

technical field [0001] The invention relates to the field of nonferrous metal hydrometallurgy, in particular to a method for dechlorination of zinc sulfate solution. Background technique [0002] In the rigid regulations on the production of zinc metal, more than 75% of the total zinc metal is produced by wet method. The general process of wet production of zinc metal is: desulfurization and roasting of zinc concentrate to produce calcined sand - leaching of calcined sand with sulfuric acid to produce zinc sulfate solution - purifying and removing impurities from zinc sulfate solution to produce zinc sulfate purification solution ---- Zinc sulfate purification solution electrolysis to produce cathode zinc flakes ---- Cathode zinc flakes are melted and cast to obtain zinc ingot products. [0003] In the process of wet production of zinc metal, the purification and removal of impurities in zinc sulfate solution is a very important process. In this process, the impurity elemen...

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Problems solved by technology

[0004] (1) Silver chloride precipitation method: This method uses the reaction of silver ions and chloride ions to form silver chloride precipitates with low solubility and good stability. This method has the advantages of fast reaction speed and high degree of dechlorination , its disadvantage is that the production cost is very high, and it cannot be popularized and applied in industrial production at all.

[0005] (2) Cuprous chloride precipitation method: This method uses the joint action of copper ions, copper elemental substances and chloride ions to generate cuprous chloride precipitates with low solubility and poor stability. This method has low production costs Advantages, suitable for treating solutions with higher chlorine content, but its disadvantages are poor dechlorination degree, unstable dechlorination products, and dechlorination solution needs to remove copper, so it is not suitable for treating solutions with lower chlorine content

[0006] (3), goethite co-precipitation method: this method is to use the process of iron precipitation in the solution, when the goethite precipitate is generated, part of the chloride ions replace and replace the hydroxide ions in the goethite molecule, and combine with the goethite ore together to form co-precipitation. This method has the advantages of low production cost and stable product. It is suitable for processing solutions with high iron content and low chlorine content. The disadvantage is that the processed solution requires a higher iron content, and The dechlorination efficiency is not high, so it is not suitable to deal with low iron content solution

This method has the advantages of low production cost, large processing capacity, and small metal loss.

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