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AssigneeOronzio de Nora Impianti Elettrochimici S.p.A.
InventorsCarlo Traini, Giuseppe Bianchi, Alberto Pellegri
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A method of reducing ferric ions in a sulfuric acid ilmenite leach solution to ferrous ions comprising circulating a sulfuric acid ilmenite leach catholyte solution through the cathodic compartment of an electrolysis cell separated by a fluid-impervious anion exchange membrane from the anodic compartment, circulating a ferrous sulfate anolyte solution through the anodic compartment of the electrolysis cell and impressing an electrolysis current across the cell to reduce the ferric ions in the catholyte to ferrous ions and to oxidize a portion of the ferrous ions to ferric ions in the anolyte to prevent oxygen evolution in the anodic compartment and to an off-peak method of electrolysis operation to reduce energy consumption and to reduce or eliminate ferrous sulfate by-product.
A method of reducing ferric ions in a sulfuric acid ilmenite leach solution to ferrous ions comprising circulating a sulfuric acid ilmenite leach catholyte solution containing Ti.sub.4+ ions through the cathodic compartment of an electrolysis cell separated by a fluid impervious anion exchange membrane from the anodic compartment, circulating a ferrous sulfate anolyte solution through the anodic compartment of the electrolysis cell and impressing an electrolysis current across the cell reducing the ferric ions in the catholyte to ferrous ions and oxidizing a portion of the ferrous ions to ferric ions in the anolyte.
A method of treating a sulfuric acid leach solution of ilmenite containing iron and titanium salts comprising leaching ilmenite with an acid solution to obtain an acid leach solution containing ferric ions and titanium ions, subjecting an acid solution containing ferric ions and tetravalent titanium ions to electrolysis in the cathode compartment of an electrolysis cell to selectively reduce at the cathode at least part of tetravalent titanium ions to trivalent titanium ions and contacting the leach solution with the solution containing trivalent titanium ions to reduce the ferric ions to ferrous ions.
A method of treating sulfuric acid ilmenite leach solutions in a process for producing titanium dioxide which comprises electrolytically reducing ferric ions in the leach solution to ferrous ions by passing said solution through the cathode chamber of a first electrolysis cell separated from the anode chamber by an anion exchange membrane gathering crystallized ferrous sulphate precipitated and filtered off from the reduced titanyl and ferrous sulfate solution, gathering the liquid effluents comprised of a sulfuric acid solution of ferrous sulfate from the subsequent stages of the titanyl sulfate processing, forming a ferrous sulfate solution by dissolving said crystallized ferrous sulfate in said liquid effluents in a dissolving tank, passing a first portion of the ferrous sulphate solution through the cathode chamber of a second electrolysis cell separated from the anode chamber by an ion exchange membrane, plating out metal iron onto the cathode of the second cell and recovering it therefrom, passing a second portion of the ferrous sulfate solution through the anode chambers of the two cells and withdrawing therefrom an anolyte solution containing a major amount of ferric sulfate and a residual amount of ferrous sulfate.
Dependencies are inferred from the claim text.