A method for treating waste sodium sulphate obtained from an industrial process of battery industry, use of waste sodium sulphate obtained from an industrial process of battery industry and an industrial processing plant of battery industry

A method for treating waste sodium sulphate obtained from an industrial process of battery industry, the method comprising:

• providing a solution of waste sodium sulphate obtained from an industrial process of battery industry,
• providing potassium hydroxide and mixing with the solution of waste sodium sulphate to obtain a reaction mixture as a homogenous solution having a temperature in the range of 60-90° C. to convert the waste sodium sulphate to potassium sulphate and sodium hydroxide
• cooling the solution, or allowing the solution to cool, to 50° C. or less to obtain crystallized potassium sulphate and a solution of sodium hydroxide, and
• recovering the formed crystallized potassium sulphate and the solution of sodium hydroxide.