Sherritt Gordon Mines Limited

University of Alberta

Wasyl Kunda

Thomas H Etsell

Winfried J Huppmann

Herbert Veltman

Michael Kohut

Boris Rudyk

Roderick H Hitesman

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.

Method for recovering silver from waste solutions containing thiosulfate

A process for the production of elemental silver from silver chloride, silver sulphate or silver sulphide includes mixing the silver salt with sodium carbonate, and heating the mixture at a temperature in the range of from about 500.degree. C. to about 650.degree. C. to produce a product mixture comprising elemental silver powder and a product sodium salt selected from the group consisting of sodium chloride and sodium sulphate. The product mixture is then cooled, and the product sodium salt and any unreacted sodium carbonate removal from the elemental silver powder by washing with water.

Process for the production of silver powder from silver chloride,

A process for the recovery of silver values from silver-containing material which also contains iron and arsenic includes leaching the material under oxidizing conditions at elevated temperature and pressure in aqueous nitric acid solution to dissolve a substantial amount of silver together with substantial amounts of arsenic, iron and other metals if present. The resultant leach solution is separated from undissolved leach residue and treated with a solution containing chloride ions to selectively precipitate substantially all dissolved silver as silver chloride without significant co-precipitation of other dissolved metals. The silver chloride precipitate is then separated from the remaining solution.

Process for the recovery of silver values from silver-containing

A process for the production of elemental silver from silver chloride or silver sulphate includes mixing the silver salt with sodium carbonate, and heating the mixture at a temperature in the range of from about 500.degree. C. to about 650.degree. C. to produce elemental silver powder.

Process for the production of elemental silver from silver chloride or

Ammonium jarosite is converted to hematite or magnetite and ammonium sulphate. The invention can be used for removing iron from a feed solution containing dissolved ferrous sulphate. The feed solution is treated with ammonium sulphate and oxygen to precipitate ammonium jarosite which is then separated from the treated solution to produce an ammonium jarosite slurry and a separated solution containing sulphate ions. The ammonium jarosite slurry is treated with ammonia to convert the ammonium jarosite to hematite or magnetite and ammonium sulphate solution. The ammonium sulphate solution is separated from the hematite or magnetite, and a portion of the separated ammonium sulphate solution is recycled to the ammonium jarosite precipitation step, the remaining portion of the separated ammonium sulphate solution being recovered.

Recovering magnetite and ammonium sulphate from ammonium jarosite

Silver is precipitated from an aqueous sulphate solution containing dissolved silver and other metals at a temperature between about 60.degree. C. and about 125.degree. C. by hydrogen gas at a partial pressure between about 2 and about 5 kg/cm.sup.2.

Recovery of silver from silver containing solutions

A process is described for producing cobalt powder having a particle size of about 2 microns or smaller. The process involves two basic operations: Firstly, finely divided cobaltous carbonate is prepared by precipitation from a cobaltous ammine-ammonium sulphate solution by reacting the solution with carbon dioxide. Secondly, the cobalt carbonate precipitate is separated from the solution and is dry-reduced with hydrogen under controlled conditions of time and temperature to produce finely divided elemental cobalt powder. Cobalt powders produced in accordance with the invention are particularly suitable for manufacture of sintered carbide products as well as for use in magnetic products such as magnetic inks and tapes.

Process for the production of finely divided cobalt powders

The process involves subjecting finely divided particles of copper-bearing mineral sulphide ores or concentrates to a first stage leach in which the particles are leached in an aqueous ammoniacal ammonium carbonate solution in the presence of free oxygen to provide a first stage leach slurry which contains dissolved copper values. Residue is separated from the first stage leach slurry and is subjected to attrition in order to rub off an outer layer therefrom and expose surfaces of the residue beneath the layer. The resulting residue is passed to a second stage leach which is carried out in the same way as the first leach. Solution is removed from the second leach stage and is recycled to the first leach stage. The first stage leach solution is further treated for recovery of copper and ammonium sulphate.

Process for the recovery of copper and ammonium sulphate from

A cobalt powder product is described which is composed of cobalt particles about 0.8 microns or smaller in size and have refractory oxide particles fixed on the surfaces thereof. The powder is particularly suitable for manufacture of sintered carbide products as well as for use in magnetic products such as magnetic inks and tapes.

Growing community of inventors

Edmonton, Canada

Wasyl Kunda