Process for extracting potassium from lithium sulfate slag

The invention relates to the field of environmental protection, in particular to a process for extracting potassium from lithium sulfate slag. The method comprises the following steps: dissolving lithium sulfate slag into metal salt by hydrofluoric acid, adding calcium hydroxide, and removing Si, Al, Fe and F; adding sodium carbonate, introducing carbon dioxide, and further removing insoluble substances in the form of metal carbonate; the preparation method comprises the following steps: adding a high-efficiency coagulant, carrying out amino addition reaction on amino di (methylene phosphate) magnesium salt and methyl allyl tri-n-butyltin, carrying out amino addition reaction with N, N-methylene bisacrylamide, and polymerizing excessive carbon-carbon double bonds to obtain the high-efficiency coagulant, so that fine metal salt suspended matters can be removed; the recovery rate of potassium reaches up to 88.9%, and the recycling rate of potassium resources is greatly increased; the method is simple in process