Cominco, Ltd.

Donald Roderick McKay

Ernest G Parker

Charles Ray Kirby

Louis Landucci

A method for the removal of moisture associated with sulfur and for the melting of solid sulfur. A flow of molten sulfur is circulated through a mixing device in a substantially spiral flow wherein the circulating molten sulfur forms a continuous vortex of molten sulfur. Particulate solid sulfur with or without associated moisture, either as such or in the form of an aqueous slurry or moisture-containing liquid sulfur is fed into the vortex of circulating molten sulfur. Sulfur is discharged from the mixing device and any associated moisture is evaporated and separates from the sulfur. Molten sulfur substantially free of moisture is recovered.

Process for the melting of sulfur

This invention relates to a process for hydrometallurgical treatment of concentrates of sulphides of copper, nickel, cobalt, lead and iron and copper-containing mattes. A first embodiment of the process includes subjecting a finely ground slurry of a sulphide concentrate to an oxidation leach at elevated temperature and pressure in the presence of an oxygen-bearing gas to preferentially leach cobalt and nickel and to convert galena to lead sulphate. The reaction mixture is heated to a further elevated temperature, in the absence of oxygen, to convert a portion of chalcopyrite to insoluble simple copper sulphides and ferrous sulphate solution and to decompose complex insoluble ferric compounds. The resulting mixture is subjected to differential flotation whereby a lead concentrate and a copper concentrate are obtained. The solution is reduced in acid content by addition of limestone, the iron is precipitated and removed, and nickel and cobalt are precipitated in the remaining solution as sulphides and recovered as a concentrate. The second embodiment of the process includes subjecting a copper-containing matte to an oxidation leach at elevated temperature and under pressure of an oxygen-bearing gas whereby a copper sulphate-containing solution is formed for use in the process of the first embodiment and solids residue is recovered as a concentrate.

Process for hydrometallurgical upgrading

A process for the treatment of zinc plant residue formed on leaching zinc calcine with sulphuric acid in which the residue is leached in a first leaching step with a sulphuric acid solution at atmospheric pressure, and a temperature above about 60.degree.C, in the presence of excess zinc sulphide reductant whereby ferric iron in the residue is reduced to the ferrous state, thereby forming a zinc sulphate solution containing excess acid, ferrous iron and other dissolved impurities such as germanium, indium, gallium, antimony and arsenic nd a mixture of solids containing undigested zinc residue, lead residue, and unreacted zinc sulphide. Clarified solution is separated, preferably by thickening, from the mixture of solids. The mixture of solids is leached in a second residue leaching step at atmospheric pressure and at a temperature above about 60.degree.C in a solution which is substantially higher in acid than the solution in the first leaching step, unreacted zinc sulphide from the first residue leaching step providing reducing conditions in the second residue leaching step. Slurry from the second residue leaching step is treated by flotation to separate a froth product comprising unreacted zinc sulphide and elemental sulphur, a tailings product containing gangue and a lead residue, and an acidic solution which is recycled to the first residue leaching step. A portion of the clarified zinc sulphate solution from the first residue leaching step is treated by oxidizing a small part of the ferrous iron contained therein, and neutralizing this portion of the solution with limerock to precipitate solids containing oxidized iron, gypsum, and the other impurities. These precipitated solids are separated and this portion of the solution is combined with the remainder of the clarified zinc sulphate solution. Ferrous iron in the combined solution is oxidized to precipitate ferric iron compounds which are separated from the solution to provide purified zinc sulphate solution which is recovered.

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Rossland, Canada

Donald Roderick McKay