Cominco, Ltd.

Sherritt Gordon Mines Limited

Comino Ltd.

Cominco Electronic Materials Inc.

Edward Francis Milner

Godefridus M Swinkels

Roman M Genik-Sas-Berezowsky

John Alden Dunlop

Gerald W Toop

Robert W Smyth

Charles Ray Kirby

Robert Arthur Furber

Ernest G Parker

David L Jones

Copper arsenate, substantially free from impurities that form sludge in wood preservatives such as chromated copper arsenate, is prepared by adding a solution of soluble arsenate to copper sulfate solution, either or both solutions containing sludge-forming impurities, to form a copper and arsenic-containing solution without precipitating copper arsenate. The pH during the adding is controlled at a value in the range of 1.8 to 2.2 to precipitate impurities. Precipitated impurities are removed, and the copper and arsenic-containing solution is neutralized with a suitable alkaline substance to pH 3.5 to 5.0 to precipitate copper arsenate. Arsenate solution is derived from arsenic oxides, soluble arsenic salts and compounds and metallurgical materials capable of yielding water-soluble arsenate. Copper sulfate solution is derived from crystals and compounds and metallurgical materials cable of yielding copper sulfate. In a preferred embodiment, sodium arsenate is derived by aqueous caustic oxidative pressure leaching of flue dusts and copper sulfate is derived by aqueous acid oxidative pressure leaching of copper matte.

Method for the preparation of copper arsenate

Lead with a low alpha particle emission is produced by selecting an orebody wherein lead mineral is present in a coarsely disseminated form and substantially free of impurities. The ore is selected from a host rock that is relatively low in alpha emitters, such as a carbonate rock. The ore is mined and is milled such that the lead mineral can be separated from the host rock and any other minerals. The ground ore may be screened into one or more fractions having a narrow range of particle sizes. Each fraction is formed into a fluid suspension, and each suspension is subjected to gravity separation to remove the host rock and any other minerals which substantially contain the alpha particle-emitting substances, and to recover the lead mineral as a concentrate with a low alpha count. The lead concentrate is subjected to a suitable reduction operation that may include a conversion of the concentrate into a reducible form, without the introduction of alpha emitters, for the recovery of a low alpha lead. When the lead mineral is galena, suitable reductions include the smelting with sodiuim carbonate with or without an oxygen-bearing gas and electrolytic reduction in a molten bath of lead chloride. The low alpha lead recovered from these operations has an alpha count of about 0.02 alpha particle per cm.sup.2 per hour or less, and the count does not substantially increase with time. The recovered low alpha lead may be further purified by electro-refining.

Method for making low alpha count lead

Lead with a low alpha particle emission is produced by selecting an orebody wherein lead mineral is present in a coarsely disseminated form and substantially free of impurities. The ore is selected from a host rock that is relatively low in alpha emitters, such as a carbonate rock. The ore is mined and is milled such that the lead mineral can be separated from the host rock and any other minerals. The ground ore may be screened into one or more fractions having a narrow range of particle sizes. Each fraction is formed into a fluid suspension, and each suspension is subjected to gravity separation to remove the host rock and any other minerals which substantially contain the alpha particle-emitting substances, and to recover the lead mineral as a concentrate with a low alpha count. The lead concentrate is subjected to a suitable reduction operation that may include a conversion of the concentrate into a reducible form, without the introduction of alpha emitters, for the recovery of a low alpha lead. When the lead mineral is galena, suitable reductions include the smelting with sodium carbonate with or without an oxygen-bearing gas and electrolytic reduction in a molten bath of lead chloride. The low alpha lead recovered from these operations has an alpha count of about 0.02 alpha particle per cm.sup.2 per hour or less, and the count does not substantially increase with time. The recovered low alpha lead may be further purified by electro-refining.

A hydrometallurgical process for the separate recovery of non-ferrous, ferrous, and precious metal values and sulfur from metal sulfide ore concentrates by leaching of metal sulfides with a lixiviant containing ferric chloride, cupric chloride and chlorine, precipitating cuprous chloride from the leach solution with butadiene, separating and decomposing the formed addition compound to recover the cuprous chloride, oxidizing and hydrolyzing the cuprous chloride to precipitate cupric oxychloride, converting the cupric oxychloride to cupric oxide, and reducing the cupric oxide with hydrogen for the recovery of copper. The leach residue is treated for the recovery of elemental sulfur and gold. Brine solution resulting from the conversion of cupric oxychloride to cupric oxide is electrolyzed for the production of sodium hydroxide for the cupric oxychloride conversion, hydrogen for the cupric oxide reduction and chlorine, which is partly used in the recovery of gold and partly recycled to the concentrate leach. Silver is recovered as silver iodide from the mother liquor from the cuprous chloride precipitation with butadiene. A portion of the solution from the silver recovery is treated for recovery of Cu, Zn, Co and Ni, and the remaining portion and residual solution from Cu, Zn, Co and Ni recovery are treated with oxygen at elevated temperature and pressure for the regeneration of ferric chloride and precipitation of excess iron as anhydrous ferric oxide.

Hydrometallurgical process for recovering copper and other metal values

A process for the treatment of complex lead sulfide-containing concentrates additionally containing at least one metal of the group consisting of iron, copper, zinc, silver, arsenic, antimony, bismuth and gold which comprises the steps of selectively leaching a concentrate with iron-containing lixiviant for converting lead sulfide in said concentrate to lead chloride and forming a leach residue and a leach solution, subjecting said lead chloride in the leach residue to a two-stage, countercurrent, hot brine leach to dissolve the lead chloride in a brine-leach solution, subjecting the brine leach solution to crystallization by evaporative cooling for the separate recovery of crystallized lead chloride, residual brine and crystallization condensate, and returning said residual brine to said brine leach, subjecting crystallized lead chloride in admixture with sodium chloride to electrolysis in a fused bath for production of lead and evolution of chlorine, absorbing chlorine in a first portion of said leach solution for the generation of ferric chloride-containing solution; and treating a second portion of said leach solution for the recovery of values. The iron-containing lixiviant comprises an aqueous solution of ferric chloride in a concentration in the range of from 100 to 200 g/l ferric ion or aqueous solutions of ferrous chloride and hydrochloric acid in concentrations in the range of 25 to 160 g/l ferrous chloride and of 60 to 120 g/l hydrochloric acid.

Hydrometallurgical process for treating metal sulfides containing lead

A process for recovery of zinc values contained in thermally activated iron containing copper and zinc sulfides in which said activated sulfides have been subjected to an acid leach in aqueous sulfuric acid to produce a solution of ferrous sulfate and a solids residue containing copper and zinc values. The solids residue containing copper and zinc values is reacted with an acidic copper sulfate solution to precipitate copper values as a simple copper sulfide with concurrent dissolution of iron and zinc values to form a solution of ferrous sulfate containing said dissolved zinc values and said solution of ferrous sulfate is separated from the simple copper sulfides and reacted with H.sub.2 S for precipitation of zinc values therefrom as zinc sulfide. Any nickel and cobalt values present in said activated sulfides is dissolved in said solution of ferrous sulfate and reacted with the H.sub.2 S at elevated temperature for selective precipitaton.

Recovery of copper and zinc as sulfides from copper-iron sulfides

A hydrometallurgical process for treating iron containing metal sulfides for rendering iron and non-ferrous metal values active and amenable for selective extraction and separate recovery. Sulfur values can be controllably produced as elemental sulfur or as sulfuric acid to supply acid requirements of the process, while substantially obviating the discharge of sulfur-containing gases to the atmosphere. Ores and concentrates of the sulfides are thermally activated by sequentially heating and reducing said sulfides in a countercurrent flow of heating and reducing gases respectively in a reactor whereby the reaction products of the reducing gas and sulfides, together with liberated labile sulfur, are controllably combusted with oxygen to satisfy heat requirements of the thermal activation process and to convert sulfur values to SO.sub.2 gas. The activated sulfides are subjected to an acid leach in aqueous sulfuric acid for production of ferrous sulfate and evolution of H.sub.2 S gas which are separated from the solid sulfide residue containing concentrated non-ferrous metal values. The ferrous sulfate is oxidized and hydrolysed to precipitate the iron, which is removed from the system, and to regenerate sulfuric acid. At least a portion of the SO.sub.2 gas from said heating step and at least a portion of the H.sub.2 S from the acid leach are converted to sulfuric acid to satisfy the acid requirements of the process, and remaining SO.sub.2 is combined and catalytically reacted with remaining H.sub.2 S to produce elemental sulfur. The solids residue from the acid leach is subsequently subjected to further treatment for recovery of metal values.

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Warfield, Canada

Edward Francis Milner