Recovery of non-ferrous metals by thermal treatment of solutions containing non-ferrous and iron sulphates

摘要

The specification discloses a method for recovering non-ferrous metals such as zinc or copper iron from their concentrates, ores or any other metal containing materials into a solution containing these non-ferrous metals as sulphates and a minimal amount of dissolved iron. The resultant solution is suited without or with minimum pre-purification treatment for conventional electrowinning processes to recover such non-ferrous metals with less difficulties than the previous methods involving complex iron-removal processing. There is disclosed a method for recovering at least one non-ferrous metal soluble in sulphuric acid from a strong sulphuric acid solution containing said metal and iron as sulphates, said method comprising the following consecutive steps: subjecting said solution in a sub-divided form to thermal decomposition in a fluidized bed reactor at a temperature of from 600 DEG to 750 DEG C. with 20-150% excess air for an average retention time of 1-12 hours to obtain calcine containing ferric oxide and the sulphate of said non-ferrous metal; leaching said non-ferrous metal sulphate out from said calcine with water or dilute sulphuric acid solutions; separating said leach solution containing said non-ferrous metal sulphate from the residue; and recovering said non-ferrous metal from said leach solution, via electrolysis or any other method.