Process for producing scorodite and recycling the post-scorodite-synthesis solution

1. A process for recycling a post-scorodite-synthesis solution, comprising the steps of:

(1) conducting a sulfuric acid leaching by feeding an oxygen-containing gas into an electrolytically precipitated copper in an acidic aqueous solution of sulfuric acid, while stirring the solution at a temperature and for a time sufficient for oxidizing As component contained in the electrolytically precipitated copper to pentavalent, followed by solid-liquid-separation of the solution into a post-leaching residue and a sulfuric acid-leached solution containing the pentavalent As component,

(2) adding ferric sulfate into said sulfuric acid-leached solution so that the molar ratio of trivalent Fe to pentavalent As may be equal to or more than 0.9 and equal to or less than 1.1 to prepare a reaction solution, followed by synthesis of a crystalline scorodite,

(3) after the synthesis of the scorodite, conducting solid-liquid-separation of the reaction solution into a post-scorodite-synthesis solution and a scorodite crystal, and

(4) using the post-scorodite-synthesis solution directly as an electrolyte solution used in electrolytic refining of copper.

2. The process according to claim 1 , further comprising the steps of:

(1)′ adding water to the post-leaching residue in step (1) for dissolving copper sulfate, followed by solid-liquid separation of a copper sulfate solution from the post-leaching residue, and

(3) adding said copper sulfate solution to the post-scorodite-synthesis solution obtained in Step (3) between Step (3) and Step (4).