Abstract: A process for recovering zinc from zinc containing sulphidic material which also contains iron together with lead and/or silver includes leaching the material under oxidizing conditions at a temperature in the range of from about 130.degree. to about 170.degree. C. in aqueous sulphuric acid solution with a stoichiometric excess of sulphuric acid relative to the zinc content of the material of from about 40 to about 100% to produce an undissolved residue containing a major proportion of lead and/or silver and a leach solution containing a major proportion of the zinc and iron. The residue is separated from the leach solution and treated to recover lead and/or silver values. The leach solution is treated to recover zinc by feeding the solution to another process in which zinc-containing material is treated to recover zinc and which includes an iron-precipitation step.

Abstract: A process for removing radium from a radium-containing aqueous sulphate solution also containing dissolved magnesium at a pH not greater than about 10 comprises treating the solution with a soluble barium salt to precipitate radium as barium radium sulphate. The pH of the solution is raised to at least about 11 to precipitate an insoluble magnesium compound which collects the barium radium sulphate precipitate, and substantially all of the precipitates are separated from the solution.

Abstract: A process for the recovery of uranium values from uranium-containing material which also contains iron, arsenic and siliceous matter, includes leaching the uranium-containing material in aqueous sulphuric acid solution under conditions to provide dissolved iron present in the resultant leach solution as predominantly ferrous iron rather than ferric iron and/or to provide a sulphuric acid concentration in the leach solution sufficiently high to substantially prevent the precipitation of arsenates. Uranium values are recovered from the leach solution by solvent extraction agent which has little affinity for arsenic.

Abstract: A process for selectively removing ions of copper and/or cadmium from a sulphate solution containing nickel and/or cobalt values. The solution is treated at a temperature in the range of from about 85.degree. to about 95.degree. C. and at a pH in the range of from about 4.5 to about 5.5 with hydrogen sulphide to precipitate copper and/or cadmium ions as copper and/or cadmium sulphide, and the precipitated copper and/or cadmium sulphide is separated from the solution.

Abstract: A process for recovering uranium values from a sulphate solution containing dissolved uranium and molybdenum and with a pH not exceeding about 5.5, includes reacting the solution with ammonia at a pH in the range of from about 8 to about 10, without the solution existing for any significant time at a pH of around 7, with resultant precipitation of uranium values relatively uncontaminated by molybdenum. The uranium containing precipitate is separated from the remaining solution while maintaining the pH of the remaining solution within the same range.

Abstract: 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.

Abstract: A process for removing manganese and chloride ions from an aqueous acidic sulphate solution containing zinc, manganese and chloride ions without removing a substantial amount of zinc ions from the solution includes adjusting the free acidity of the solution if necessary to at least about 0.1 molar. The solution is then treated with ozone to oxidize manganese ions to manganese dioxide, and the ozone treatment is continued after the manganese concentration has fallen to a low level to oxidize chloride ions to chlorine gas. The precipitated manganese dioxide is removed from the solution.

Abstract: Dissolved selenium values are removed from an acidic aqueous copper sulphate solution by treating the solution at a temperature of at least about 140.degree. C. with a stoichiometric excess relative to the dissolved selenium of sulphur dioxide or a sulphite solution to produce a selenium-containing precipitate and dissolved cuprous copper. The temperature of the treated solution is maintained at at least about 140.degree. C. and an oxygen containing gas is passed into the treated solution under a pressure of at least about 350 kPa to oxidize dissolved cuprous copper to dissolved cupric copper.

Abstract: Selenium (IV) and selenium (VI) are removed from acidic copper-nickel sulphate solutions in a two-stage process by adjusting and maintaining the sulphuric acid content of the solution in a range of 10 to 50 g/L and, in a first stage, contacting the solution with sulphur dioxide or a sulphite-containing solution at an elevated temperature in the range of about 140.degree. to 175.degree. C. and, in a second stage, maintaining the said solution at an elevated temperature in the range of about 140.degree. to 200.degree. C. and pressure within the range of about 400 to 1750 kPa in an essentially oxygen-free atmosphere for a sufficient retention time to reduce and precipitate selenium (VI) as cuprous selenide.

Abstract: A composite powder sprayable by thermal spraying onto a substrate to form an abradable seal coating, is composed of particles each having a core of non-metallic solid material surrounded by a layer of nickel-chromium-aluminum alloy containing from about 4 to about 8% and from about 2 to about 6% aluminum.

Abstract: A process for removing arsenic from an aqueous solution containing arsenic in the form of a soluble arsenate includes adjusting the pH of the solution if necessary to at least about 10, adding a soluble barium salt to precipitate arsenic as barium arsenate, and removing the precipitated barium arsenate from the solution.

Abstract: A cross-flow nebulizer is manufactured from first and second deformable tubular members each having a substantially constant external diameter and a central passage of substantially constant diameter extending from a forward end to a rearward end. A forward end portion of each tubular member is deformed to provide the forward end with an orifice of reduced diameter of desired size, and the forward end portions of the tubular members are positioned in an angular spaced relationship with the orifices closely adjacent. The relative positions of the orifices are adjusted to provide a satisfactory spray when gas is passed through one tubular member and the other tubular member is connected to a source of liquid, and the tubular members are integrally connected to maintain the forward ends in the adjusted position.

Abstract: 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.

Abstract: A process for removing dissolved selenium IV values from an acidic aqueous copper sulphate solution includes passing the solution through a tubular member in a plug flow manner and injecting sulphur dioxide or a sulphite solution into the solution as it enters the tubular member. When the sulphate solution also contains dissolved selenium (VI) values, the ratio of dissolved selenium (IV) values to dissolved selenium (VI) values is preferably at least 3 to 1.

Abstract: A method of condensing a gaseous mixture of ammonia carbon dioxide gas and water vapor to produce an ammonium carbonate solution with minimum formation of ammonium carbamate includes passing the gaseous mixture into a condenser and cooling the condensing surface to cause the gaseous mixture to condense to form ammonium carbonate solution at a temperature at which formation of solid ammonium carbamate may occur. An aqueous liquid is discharged onto the condensing surface of the condenser, the liquid having an ammonia concentration below about 260 grams per liter to maintain the concentration of ammonia and carbon dioxide on the condensing surface below a concentration at which ammonium carbamate tends to form.

Abstract: 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.

Abstract: A process for producing cobalt-rare earth alloy powders suitable for forming into permanent magnets includes mixing cobalt powder particles having refractory oxide dispersoid powder particles fixed in the surfaces of the cobalt particles with particles of a rare earth element in a proportion corresponding to the composition of the alloy to be formed. The mixture is heated to cause the cobalt-dispersoid particles and the rare earth particles to form the desired alloy by diffusion with substantially no sintering.

Abstract: A composite powder sprayable by thermal spraying onto a substrate to form an abradable seal coating with suitable strength and erosion resistance. Each powder particle has a core of non-metallic solid material surrounded by a layer of metallic material selected from the group consisting of nickel and nickel alloys. At least about 95% of the particles have a size less than about 150 microns, at least about 50 to about 90% of the particles have a size greater than about 75 microns, and less than about 10% of the particles have a size less than about 45 microns.

Abstract: A process for removing manganese ions from aqueous acidic sulphate solutions containing zinc and manganese ions, without removing a substantial amount of zinc ions from solution, includes treating the solution with ozone to oxidize manganese ions to manganese dioxide, and removing the manganese dioxide from the solution.

Abstract: A process for the recovery of copper and zinc values from copper and zinc containing sulphidic ore includes subjecting ground ore to a flotation operation. An initial copper concentrate is floated in a first flotation step, and the initial copper concentrate is fed to a second flotation step to float a relatively zinc free copper concentrate. Remaining ore from the first flotation step is fed to a third flotation step to float an initial zinc concentrate, and remaining ore from the third flotation step is fed to a fourth flotation step to float a copper and zinc containing material. An intermediate concentrate containing from about 5 to about 25% copper and from about 2 to about 25% zinc, with a total of at least about 12% copper and zinc, is produced by selecting at least the remaining ore from the second flotation step, and a zinc concentrate containing at least about 20% zinc is produced by at least selecting a portion of the initial zinc concentrate.