University of Alberta

Other

Thomas H Etsell

Wasyl Kunda

William B Moure, Jr

A method and apparatus for recovering lead from scrap lead/acid batteries involves first mechanically breaking up the batteries into small pieces, then feeding the small pieces into a substantially vertical, upwardly diverging separation/leaching column through which ammoniacal ammonium sulphate solution (AAS) passes upwardly at a speed that allows the removal of metallic lead and lead alloys as sinks from the bottom of the column, with comminuted case material floating up and out of the column, while the lead compounds remain in suspension in the column for lead sulphate dissolution. The insoluble lead dirxide from the pastes is removed from the AAS downstream of the column and is slurried with sulphuric acid to convert the lead dioxide to lead sulphate, which is then returned to the separation/leaching column. The clarified AAS is fed to an electrowinning tank where metallic lead is plated out. Make-up anhydrous ammonia is fed into the bottom of the column, while ammonium sulphate being produced from sulphuric acid neutralization and lead sulphate reduction is recovered for fertilizer.

Method for recovering lead from batteries

A process is disclosed for recovering silver sulfide from a spent photographic fixer solution, which contains silver. The process is particularly suited for treating the fixer solution in a manner which enables recycling of the solution giving rise to considerable reduction in cost of fixer solution and reduced environmental pollution. The process comprises introducing a hydrosulfide reagent into the fixer solution, which contains silver, to precipitate silver sulfide while maintaining pH and thiosulfate levels in the fixer to allow for reuse. The precipitate is isolated from the fixer solution to remove silver thereby and hence enable recycling of the fixer solution.

Photographic fixer regeneration

In a process for recovering silver from spent photographic treatment solution comprises mixing nitric acid with a quantity of the treatment solution to precipitate from the solution silver sulfide. The silver sulfide may be then converted to pure silver. The improvement comprises mixing less than two parts of concentrated nitric acid solution with more than ten parts of the treatment solution to precipitate out of solution silver sulfide. The solution is filtered to remove the silver sulfide precipitate from the solution to yield a solid residue which includes silver sulfide.

Growing community of inventors

Edmonton, Canada

Thomas H Etsell