Abstract: The roasting temperature of ore, such as sulfide concentrate, is controlled by feeding water and air under pressure to at least one spray nozzle located relative to a roasting zone containing the ore, means being employed for selectively varying the ratio of water and air fed to the nozzle in accordance with the temperature to be desired and maintained in the roasting zone.

Abstract: A method is provided for producing blister copper from calcined copper-iron concentrates wherein the calcine containing copper ferrite is mixed with particulate carbonaceous reducing agent and charged into a rotary furnace, slag-forming ingredients being also added to slag off iron oxide. The charge is heated to a smelting temperature above the melting point of copper by directing a combusting stream of oxygen and hydrocarbon fuel axially into the rotatable furnace while causing said charge to cascade by rotating the furnace, the ratio of oxygen to the fuel being sufficient to effect substantially complete combustion and provide excess oxygen. Following reduction of the copper to molten blister copper, it is separated from the slag for further purification treatment, the slag being further treated when necessary to recover contained copper therefrom.

Abstract: Process and means are provided for reducing the viscosity of a work hardened slurry of finely divided ore having a pulp density of at least 15% by weight of solids, the process comprising, gently mechanically agitating a mass of said work hardened slurry confined in a container whereby to cause relative movement between said mass and a contacting surface such that said mass is subjected to shear forces, the relative movement being at a linear velocity sufficient to provide shear forces in said agitated mass in contact with the surface effective for reducing the viscosity to a desired level more than 50% below the original viscosity, and continuing said agitation at substantially said linear velocity until the viscosity has been reduced to said desired level. A rotating drum or a container with a stirring device may be employed for carrying out the invention.

Abstract: The leaching efficiency of nickeliferous lateritic ore is optimized by scalping the ore to remove a coarse low-nickel fraction and provide a fine nickel-rich fraction which is then high pressure leached in a sulfuric acid solution by controlling the parameters temperature, pulp density, the rate of acid addition, leaching time, agitation rate, etc., whereby a pregnant solution is obtained with the nickel to (Fe+Al+Cr) ratio exceeding about 2.

Abstract: The roasting temperature of ore, such as sulfide concentrate, is controlled by feeding water and air under pressure to at least one spray nozzle located relative to a roasting zone containing the ore, means being employed for selectively varying the ratio of water and air fed to the nozzle in accordance with the temperature to be desired and maintained in the roasting zone.

Abstract: A method is provided for separating cobalt from a nickel solution containing cobalt in the cobaltous state and an ammonium salt comprising subjecting said solution containing at least 0.2 grams per liter of ammonium ion to ozonation while maintaining the pH thereof from about 4.5 to 6, until said cobalt has been oxidized to the cobaltic state and simultaneously precipitating said cobalt in the cobaltic state at a temperature ranging from about 10.degree. to 90.degree. C.

Abstract: Selenium is removed from copper electrolytes by adding a substance selected from the group consisting of metals above copper in the electromotive series, excluding alkali metals, such as nickel powder, cobalt powder and iron powder. Sodium sulfide can also be used along with a subsequent addition of ferric sulfate. The amount of the reactive substance added should be sufficient to reduce the selenium content to below 2 ppm.

Abstract: A method is provided for treating industrial waste water, such as aqueous effluents obtained in the hydrometallurgy of zinc to remove metal ion impurities therefrom, the method comprising, neutralizing the waste water with slaked lime to provide a final pH of at least 8.5 to precipitate hydroxides of metals which form precipitatable hydroxides at said pH and provide an aqueous effluent containing residual quantities of metal ions such as cadmium and manganese, capable of being removed from solution by the addition of a soluble silicate solution, separating the aqueous effluent from the hydroxide precipitate, adding to the effluent a soluble silicate solution in an amount at least sufficient to remove the residual metal ions from solution, and then separating the treated effluent from said precipitate.

Abstract: A method is provided for separating chromium from lateritic ore. The ore which generally also contains nickel and cobalt along with other metal values is leached with a strong sulfuric acid solution of about 10 to 30 normal concentration at an acid to ore ratio of at least 3:1 by weight. The leaching is carried out at a temperature of at least 100.degree. C ranging as high as about 300.degree. C at above atmospheric pressure. An oxidant, such as manganese dioxide, is preferably added to oxidize the chromium to the hexavalent state, the manganese dioxide, or its equivalent, being advantageous in improving the chromium yield at the lower end of the leaching temperature range.

Abstract: A high efficiency aluminum scrap melting system is provided in which a portion of the hot combustion gases employed to melt the aluminum in a hearth is recycled through scrap-receiving preheat compartments to preheat scrap and volatilize contaminants as the scrap is fed to the hearth, the remainder of the hot combustion gases leaving the hearth as hot exhaust gases being optionally employed through a recuperator to preheat air which is fed to a combustion burner system used to burn hydrocarbon fuel and provide heat for the overall system. Energy available in the contaminants also supplements the energy supply to the system.

Abstract: A method is provided for producing blister copper from calcined copper-iron sulfide concentrates wherein the calcine containing copper ferrite is mixed with particulate carbonaceous reducing agent and charged into a smelting furnace, slag-forming ingredients being also added to slag off iron oxide. The charge, in the form of a shallow bed, is smelted by applying heat whereby the temperature is raised to above the melting point of copper, the copper oxide being selectively reduced to form blister copper, the iron oxide being reduced to form substantial amounts of ferrous oxide, the iron oxide combining with SiO.sub.2 present in the charge to form a slag and assure a low-iron copper product. Following reduction of the copper to molten blister copper, it is separated from the slag for further purification treatment, the slag being further treated when necessary to recover contained copper therefrom.

Abstract: A method is provided for extracting silver from a silver sulfate-bearing substance, such as oxide materials, metal or metal sulfate mixtures containing silver sulfate which comprises subjecting said substance to aqueous leaching to remove soluble salts therefrom and leave a residue, taking the residue containing silver sulfate and other insoluble materials, such as insoluble salts, and forming a slurry with an aqueous solution of a metal sulfate, such as calcium nitrate, the amount of calcium nitrate being at least sufficient to effect metathetical exchange with the silver sulfate and form a silver nitrate solution containing substantially the silver originally present in the silver-sulfate bearing substance, and separating the silver nitrate solution from the residue remaining, and then purifying said solution, the silver being thereafter recovered from the silver nitrate solution by hydrolytic precipitation, electrowinning or other suitable means.

Abstract: The pregnant solution obtained from high pressure and high temperature leaching of nickel-cobalt bearing low magnesium oxidic ores is neutralized at high temperature and pressure by coordinating the leaching of the low magnesium ores with the leaching of nickel-cobalt bearing high magnesium ores, the leach slurry from said low magnesium ore being neutralized by mixing it with said high magnesium ore which is simultaneously leached with said solution to produce a final pregnant solution from which metal values are subsequently recovered.

Abstract: An improved method is provided for efficiently precipitating metal powder selected from the group consisting of nickel, cobalt and copper from aqueous solutions using sulfur-free hydrogen at elevated pressure and temperature, the improvement residing in adding to the solution a small but effective amount of a catalyst as an anti-plating agent, said catalyst comprising an alkali metal or ammonium salt of a copolymer of maleic acid anhydride and an unsaturated branched chain aliphatic olefinic hydrocarbon containing 4 to 10 carbon atoms.

Abstract: A method is provided for leaching comminuted nickeliferous sulfide matte containing by weight about 20% to 75% nickel, about 5% to 50% copper, non-stoichiometric sulfur in the range of over 4% to about 20%, over 0.5% to about 15 or 20% iron, the sum of the nickel, copper and sulfur contents being at least about 80% of the matte composition, with the balance gangue or slag and incidental impurities.The matte, because of the iron content, is first granulated by quenching molten matte from a temperature at least about 10.degree.C above its solidus-liquidus temperature but below its boiling point, following which the matte is comminuted and subjected to atmospheric leaching to dissolve nickel selectively therefrom using a spent copper electrolyte solution containing sulfuric acid having a pH ranging up to about 2 while aerating said solution to cause the pH to rise to above 5 and effect substantial precipitation of copper and iron.

Abstract: A method is provided for removing trace amounts of selenium from acid leach solutions containing over 2 ppm of total selenium comprising either Se(IV) and/or Se(VI) obtained during the pressure oxidation leaching of metal sulfide concentrate comprising forming a slurry of said acid solution with comminuted metal sulfide concentrate, said slurry containing at least two grams of a metal ion as metal hydroxide per liter of solution and then subjecting said slurry to agitation at a temperature of at least about 185.degree.C at a pressure of a least about 160 psig, whereby to reduce the total selenium content of said solution to less than about 2 ppm.

Abstract: A pair of tubular air-sparging elements is provided cooperatively associated with a cathode, each of said tubular elements being disposed at opposite faces of the cathode at the bottom of said cathode and running the entire length of said bottom, each of the air-sparging elements comprising an inner tube disposed within an outer foraminous sleeve of larger diameter, said inner tube having a plurality of air emitting orifices disposed along the length thereof, such that air passing through said inner tube as coarse bubbles emerges as fine bubbles through the foraminous sleeve to form a uniform curtain of air bubbles along the plating faces of said cathode which inhibits the formation of rough surface deposits.

Abstract: The formation of acid mist or spray over electroplating tanks, such as in the electrowinning of copper, is substantially inhibited by utilizing a tank system in which the surface of the electrolyte has floating thereon a freely movable assembly of floatable elongated members arranged parallel with the electrodes therein across the surface of the electrolyte between the electrodes and extending beyond the sides of the electrodes in parallel self-locating relationship.

Abstract: A method is provided for enriching nickel in a nickel-cobalt solution to a nickel-to-cobalt ratio of over 2000:1, wherein an aliquot portion of the solution is removed, the nickel precipitated from said aliquot portion in the nickelous state, the nickelous precipitate thereafter oxidized to the nickelic state and the oxidized nickel precipitate then mixed with the remaining nickel-cobalt solution to oxidize the cobalt therein to the cobaltic state which precipitates from the solution, thereby highly enriching the solution in nickel.

Abstract: A method is provided for separating nickel and cobalt from a cobalt-nickel precipitate, the cobalt being in the cobaltic state. The method comprises dissolving the precipitate in an ammonium sulfate solution containing NH.sub.3, acidifying the solution to a pH of about 1.5 to 3.0 and then cooling the solution to produce a nickel-ammonium sulfate precipitate highly enriched in nickel. The precipitate is separated from the solution and the solution passed through an ion exchange column selective to the removal of nickel, the solution remaining containing said cobalt substantially free of nickel, the cobalt solution being then sent to cobalt recovery.