Abstract: Directed to a process for producing a tungsten product of enhanced purity from ammonium paratungstate (APT) with a minimum number of processing steps which comprises mixing the APT with an ammonium solution, autoclaving the mixture at a temperature above the boiling point thereof to dissolve the APT and recrystallizing APT from the solution to yield an APT product of enhanced marketability.

Abstract: Sulfate solutions containing nickel and cobalt ions are treated by solvent extraction to provide a nickel raffinate with a high Ni:Co ratio and a cobalt raffinate with a high Co:Ni ratio and with low recycle of cobalt by treating the solution with a cobalt extractant to provide a nickel raffinate of high Ni:Co ratio and a loaded extractant, acid stripping the loaded extractant to provide a cobalt sulfate solution containing some nickel and a regenerated cobalt extractant, treating the cobalt sulfate solution with a nickel extractant to provide a cobalt raffinate with a high Co:Ni ratio and acid stripping the loaded nickel extractant to regenerate the extractant and to provide a recyclable sulfate solution containing only a small proportion of the original cobalt.

Abstract: Hexagonal cadmium sulfide, a bright yellow pigment useful in high temperature processing, is produced by reacting cadmium sulfate solution with a solution of a soluble sulfide under pressure and at a temperature of about 250.degree. C.

Abstract: Fine cobalt or nickel powder is produced by hydrogen reduction of a sulfate solution in the presence of a base and a strong reductant such as a metal borohydride wherein the base is added stagewise to the solution with the initial addition of base being sufficient to insure an essentially neutral pH at the time of reductant addition.

Abstract: A process is provided for removing hexavalent selenium from an acidic sulfate solution containing at least one metal ion from the group consisting of nickel, cobalt and copper at ambient pressure and at a temperature not exceeding the boiling point of the solution. The solution is treated with an agent from the group consisting of a compound which will produce nascent hydrogen in the solution and finely divided metal from the group consisting of nickel, cobalt and copper resulting from in situ precipitation of the metal in the acid sulfate solution. Thus, following treatment with the compound, the hexavalent selenium is reduced to a form separable from the solution by solid-liquid separation.

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 24%, over 0.5 to about 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.Nickel is selectively leached from the comminuted matte using sulfuric acid or spent copper electrolyte solution at substantially atmospheric pressure while vigorously aerating the solution, wherein the pH is raised sufficiently to produce a nickel solution with an iron content of less than about 10 ppm and a copper content of over 5 ppm, the copper being thereafter selectively removed from the nickel solution by passing the solution through an ion-exchange resin selective to the absorption of copper.

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 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 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.