Method for the removal of copper from a zinc sulphate solution
AssigneeOutotec Oyj
InventorsLeena Lehtinen, Marko Lahtinen, Marika Jyrälä, Matti Vuokko
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Abstract
The purpose of the invention is to remove copper selectively from a concentrated zinc sulphate solution by ion exchange. The method enables a significant reduction in the use of zinc powder during the solution purification of zinc sulphate solution and makes possible to avoid usage of arsenic or antimony trioxides as a precipitation chemical. The method is to be combined with the chloride removal that occurs as a sub-stage of solution purification.
Claims26
A method for the removal of copper from a concentrated chloride-containing zinc sulphate solution known as raw solution that is going to an electrolytic preparation of zinc, using an ion exchanger, comprising:
- routing at least some of the raw solution to an ion exchange stage for copper removal, wherein the copper removal takes place using a chelating alkyl-silylated silica-based ion exchanger, of which a functional group is a polymeric amine and which does not remove zinc from the raw solution, and
- routing the raw solution from which the copper has been removed to a subsequent stage of solution purification.
A method for the removal of copper and chloride from a chloride-containing concentrated zinc sulphate solution known as raw solution that is going to an electrolytic preparation of zinc, comprising:
- routing at least some of the raw solution to cooling, where the raw solution is cooled to a temperature of 30-45° C. and the pH is adjusted to the range 1.5-3.9,
- subsequently routing the raw solution which has been cooled to chloride removal, which is performed with cuprous oxide whereby the chloride in the raw solution is precipitated as copper chloride;
- separating the copper chloride from the raw solution
- routing the raw solution at least partially to an ion exchange step for copper removal, wherein the copper removal occurs using a chelating alkyl-silylated silica-based ion exchanger, of which a polymeric amine acts as a functional group and which does not remove zinc from the raw solution, and where the ion exchange step comprises an alkaline pretreatment of the ion exchanger, treatment with copper-free zinc sulphate solution, copper removal, a regeneration of the ion exchanger and a separation of copper from the regeneration solution, and
- routing the raw solution from which chloride and copper have been removed to a following stage of solution purification.
Dependencies are inferred from the claim text.