Patent ID: 6406676
Filing Date: 2002-06-18
Classification: C22B,Y02P

Abstract:
A method of purifying an acid leaching solution obtained when working-up hydrometallurgically material that contains valuable metals, said solution also containing Fe3+ and Fe2+ and arsenic, said method comprising adding a pH-elevating agent to the leaching solution so as to raise the pH to a value within the range of 2.2 to 2.8 and to precipitate the majority of the Fe3+ and the arsenic from said solution in a first precipitation stage; separating the precipitate formed in the first precipitation stage from the solution; adding a further pH-elevating agent to the solution in a further precipitation stage; oxidizing Fe2+ to Fe3+ and precipitating the resulting Fe3+ in the further precipitation stage; separating the resultant precipitate and any residual solid pH-elevating agent from the solution in the further precipitation stage and returning at least part of said resultant precipitate and any residual solid pH-elevating agent to the leaching solution prior to the first precipitation stage; and thereafter winning the valuable metal content from the thus purified solution.