Method for removing calcium and magnesium in zinc hydrometallurgy process

Abstract

The invention belongs to the technical field of metallurgy, and particularly relates to a method for removing calcium and magnesium in a zinc hydrometallurgy process. The method comprises the following steps: 1) calcium removal: adding a fresh solution, a waste electrolyte and thickener underflow containing CaSO4.2H2O crystal seeds into a crystal seed mixing tank, carrying out cooling, then feeding the above materials into a ripening tank and a thickener, allowing one half of the thickener underflow to return to the seed crystal mixing tank and the other half of the thickener underflow to enter a reaction tank No. 1, slurrying CaCO3, adding the slurried CaCO3 into the reaction tank No. 1, adjusting a pH value to 2.5-3, adding the waste electrolyte into the reaction tank No. 1, conveying the materials in the reaction tank No. 1 to a reaction tank No. 2, carrying out a reaction, conveying a reaction product to a centrifuge, and performing centrifuging to obtain a centrifuge calcium-removed filtrate and centrifuge calcium-containing filter residues; and 2) magnesium removal: adding the centrifuge filtrate into a neutralizing tank, slurrying Ca(OH)2, adding the slurried Ca(OH)2 into the neutralizing tank, adjusting a pH value to 8-9, then conveying the treated filtrate to a filter press, and conveying the obtained magnesium-containing filtrate to a sewage station for treatment. With the method, calcium and magnesium ions in a zinc hydrometallurgy system can be effectively removed and maintained at a reasonable concentration level, the power consumption of zinc electrolysis is greatly reduced, and production cost is saved.

Description

【Technical field】 [0001] The invention relates to the technical field of metallurgy, in particular to a method for removing calcium and magnesium in a zinc hydrometallurgy process. 【Background technique】 [0002] Wet zinc smelting is to use dilute sulfuric acid (ie waste electrolyte) to leach zinc roasted ore to obtain zinc sulfate solution. After purification, zinc is electrolytically separated from the solution by electrolysis. [0003] The zinc hydrometallurgy process is: roasting → leaching → purification → electrolysis → melting and casting. After roasting and leaching, Ca and Mg mainly enter the leaching supernatant solution in the form of sulfate, which is difficult to remove in the traditional purification process. As a result, calcium and magnesium are continuously cyclically enriched in the wet system, causing problems such as crystallization blockage, decreased current efficiency, and increased energy consumption to normal production, which is regarded as a major ...

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Problems solved by technology

[0003] The zinc hydrometallurgy process is: roasting → leaching → purification → electrolysis → melting and casting. After roasting and leaching, Ca and Mg mainly enter the leaching supernatant solution in the form of sulfate, which is difficult to remove in the traditional purification process. As a result, calcium and magnesium are continuously cyclically enriched in the wet system, which brings problems such as crystallization blockage, decrease in current efficiency, and increase in energy consumption to normal production, which is regarded as a major common problem in the industry

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