METHOD FOR REGENERATION OF WASTE ELECTROLYTES FOR POLISHING AND ETCHING CHROME-CONTAINING STEELS Russian patent published in 2001 - IPC

FIELD: regeneration of highly concentrated acidic electrolytes, possibly for selective extraction of Fe2+,Fe3+ and Cr3+,Cr6+ ions at plating processes. SUBSTANCE: method for regeneration of waste acidic solutions for chemical and electrochemical etching and polishing of chrome- containing steels after removing mechanical impurities in order to separate Cr3+, Cr6+ ions comprises steps of sorption cleaning by means of chitosan, passing solution through vessel with acid-resistant polymer preliminarily treated in mixture of sulfate and chromate; in order to extract Fe2+, Fe3+ ions, subjecting solution to electrochemical treatment including cathode reduction of Fe3+ to Fe2+ and subsequent deposition of slightly soluble monohydrate of ferrum sulfate at introducing finely crystalline potassium sulfate in quantity 0.05-0.25 mol/l and cooling; using as acid resistant polymer polyethylene, polypropylene, polystyrene, their copolymers. EFFECT: enhanced efficiency of cleaning of highly concentrated acidic electrolytes, lowered energy consumption, possibility for separating dissolved products of chrome-containing steels. 1 tbl, 5 ex