CHROME RECOVERY FROM FERRIC CHROMIC HYDROXIDE BY OXIDATION TO DICHROMATE

摘要

CHROMATE RECOVERY PROCESS A process for recovering and recycling chromium from chromium-iron hydroxide sludge for use in cooling tower make up water and plating solution is disclosed. The process comprises separating chromium from the sludge by electrolytically forming iron-chromium compound or complex and selectively oxidizing the trivalent chromium precipitate to soluble hexavalent chromium with a strong oxidizing agent such as chlorine gas, in alkaline medium. The hexavalent chromium ions then enter solution and are thereafter separated from the iron hydroxide precipitate as the sludge is dewatered. There is also included an anode of iron, iron alloy or insoluble iron compound and a cathode, so that an insoluble iron compound or complex is produced in aqueous medium.