Radiological Waste Processing for the Recovery of Silver through Cementation with Zinc Powder

Abstract

The recovery of silver from silver-thiosulphate-fixer solutions of radiological wastes has been studied by cementation in batch-stirred reactors using zinc powder as the cementing agent. Silver is efficiently recovered from the solutions. The silver recovery rate and the total silver recovery increased with pH. Metallic silver was the product for cementation in deoxygenated solutions at all pH studied. With non-deoxygenated solutions and at low pH values, metallic silver cemented first, followed by silver sulfide. At high pH values, metallic silver was the cementation product. Electrochemical reactions are proposed for the cementation process in the presence and absence of oxygen.

Keywords:

• Radiological waste
• silver recovery
• thiosulphate
• water remediation
• zinc powder

ACKNOWLEDGEMENTS

The authors thank PROMEP-SEP for the financial support to this project and for the fellowship to V. Ibarra Galvan to carry out this investigation.