Method for the removal of chloride from zinc sulphate solution

1. A method for removing chloride from concentrated zinc sulphate solution with copper(I) oxide, whereby a sidestream is taken from the zinc sulphate solution, which is cooled and routed to a chloride removal stage, wherein chloride removal is performed with copper(I) oxide, which is produced in a separate copper(I) oxide formation stage by reducing the copper sulphate contained in the zinc sulphate solution fed into the copper(I) oxide formation stage and the copper sulphate additionally fed into the copper(I) oxide formation stage into copper(I) oxide with zinc powder, said reducing the copper sulphate being conducted at a pH in the range of 4.5-5.

2. A method according to claim 1 , wherein the solution exiting the chloride removal stage is subjected to liquid/solids separation and that the copper chloride residue formed is routed to hydroxide washing in order to form sodium chloride solution and a precipitate containing copper(I) oxide and metallic copper.

3. A method according to claim 2 , wherein the precipitate exiting hydroxide washing is leached in a copper leaching stage with sulphuric acid and oxygen-containing gas and that the acidic copper sulphate solution that is formed is routed either wholly or partly to the chloride removal stage.

4. A method according to claim 3 , wherein part of the copper sulphate solution formed in the copper leaching stage is routed to the copper(I) oxide formation stage.

5. A method according to claim 2 , wherein part of the precipitate exiting hydroxide washing is routed to the copper(I) oxide formation stage.

6. A method according to claim 1 , wherein the pH of the copper(I) oxide formation stage is regulated with sodium hydroxide.