Treatment of Ammoniacal Leach Liquor from Reduction Roast-Leach Route of Sea Nodules by Solvent Extraction

Abstract

The NML is currently engaged in developing processes for recovery of valuable metals from the polymetallic sea nodules of Indian Ocean. In this endeavour,the solutions generated in the leaching of the sea nodules by reduction roast-ammonia leaching route, were processed for the recovery of nickel, copper and cobalt by solvent extraction-electrowinning technique. A 40% LIX-64N in kerosene co-extracts copper and nickel from the leach liquor leaving cobalt in the raffinate. The loaded organic after scrubbing ammonia was selectively stripped off nickel with dilute sulphuric acid whereas concentrated sulphuric acid (180 gpl) stripped copper thereby generating solvent for reuse. Parameters for extraction, stripping and electrowinning of the pregnant electrolytes of the metals have been optimized. Cobalt recovery from the raffinate has also been studied.