Method for removing calcium-magnesium impurities from nickel sulfate solution

Abstract

The invention discloses a method for removing calcium-magnesium impurities from a nickel sulfate solution. The method comprises the following steps of: (1) heating a nickel sulfate raw material solution, concentrating, cooling and removing a precipitated solid; (2) extracting a filtrate obtained in the step (1) with a phosphorus-containing extracting agent; and adding nickel fluoride into a raffinate obtained in the step (2), heating to 60-90 DEG C for reacting, cooling and filtering to obtain a needed nickel sulfate solution. Due to the adoption of the method, the using amount of a fluorine salt and the discharge of fluorine-containing waste water are greatly reduced, and new impurity irons are not introduced, the nickel yield is high; and the method is particularly suitable for sulfate systems with high calcium content and low magnesium content.

Description

technical field [0001] The invention relates to a method for removing impurities in a nickel sulfate solution, in particular to a method for removing calcium and magnesium impurities from a nickel sulfate solution. Background technique [0002] At present, for the removal of calcium and magnesium impurities in nickel sulfate solution, chemical precipitation methods such as sodium fluoride, ammonium fluoride or hydrofluoric acid are generally used to remove them. The fluoride salt precipitation method is effective in removing calcium and magnesium, but its disadvantages are reflected in the following four aspects: [0003] 1) The addition of fluoride salts introduces new cations into the system, such as sodium ions and ammonium ions, which are difficult to remove in subsequent processes and affect the quality of nickel sulfate crystals; [0004] 2) The consumption of fluorine salt is large, the price is relatively expensive, and the cost of raw materials is high; [0005] 3...

AI Technical Summary

Problems solved by technology

[0003] 1) The addition of fluoride salts introduces new cations into the system, such as sodium ions and ammonium ions, which are difficult to remove in subsequent processes and affect the quality of nickel sulfate crystals;

[0004] 2) The consumption of fluorine salt is large, the price is relatively expensive, and the cost of raw materials is high;

[0005] 3) The reaction temperature between fluoride salt and calcium and magnesium ions is high and takes a long time. On the one hand, the energy consumption is large, and on the other hand, part of the nickel will be precipitated in the form of nickel fluoride, resulting in the loss of nickel;

[0006] 4) Due to the large excess coefficient of fluorine salt, a large amount of fluorine-containing wastewater will be generated during the treatment, which is extremely difficult to handle;

P 507 The extraction agent is expensive, has excellent selectivity to cobalt, and has certain extractability to magnesium, but if the solution does not contain cobalt, generally do not use P 507 Extraction is performed because P 507 Raw material cost is higher

And while using P 204 and P 507 Step-by-step extraction of calcium and magnesium, the entire extraction process is lengthy, increasing the difficulty and cost of extraction process control

[0008] In addition, for the system with high calcium content in the nickel sulfate solution, although the calcium and magnesium can be removed by the extraction method, there is a big problem in the back extraction, which is mainly due to the low solubility of calcium sulfate. It is easy to separate out in the medium, forming a third phase (solid phase) besides the water phase and the oil phase, which brings great inconvenience to phase separation and subsequent stripping

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