Method for deeply purifying cadmium ions in production process of battery-grade cobalt sulfate

The invention discloses a method for deeply purifying cadmium ions in the production process of battery-grade cobalt sulfate. The method comprises the following steps: firstly, adding coarse zinc powder into a cobaltous sulfate solution produced by utilizing zinc smelting purification slag for reaction, and after the reaction, carrying out filter pressing on an obtained reactant to filter out filter residues, so as to obtain a cadmium-poor cobaltous sulfate solution; the cadmium-poor cobalt sulfate solution enters an extraction system to be extracted, and raffinate meeting the production requirement of battery-grade cobalt sulfate is obtained after extraction. According to the technical scheme, in the process of producing the battery-grade cobalt sulfate by using the zinc smelting purification slag, two-stage purification and cadmium removal are adopted, the cadmium ion concentration can be reduced to 0.001 g/L or below, the production requirement of the battery-grade cobalt sulfate is met, the recovery rate