Abstract: A process for the extraction of a base metal such as Ni, Co or Zn, from suiphide ore or concentrate containing copper and the base metal comprises the step of subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halide and sulphate ions to produce a product solution containing copper and the base metal. The product solution is subjected to a copper extraction process for recovering copper from the solution and the product solution containing the base metal after copper recovery is recirculated for recycled to the pressure oxidation to effect build-up of the base metal in the product solution. Preferably, a stream which is split from the product solution is treated for the recovery of the base metal.

Abstract: A method of treatment or purification of a molybdenum concentrate also containing copper, comprises the step of subjecting the molybdenum concentrate to pressure oxidation in the presence of oxygen and a feed solution containing copper (e.g. CuSO4) and halide (e.g. CuCl2) to produce a pressure oxidation solution containing copper and a solid residue containing molybdenum. The pressure oxidation solution may be combined with feed solution to a second pressure oxidation in which a copper concentrate is treated for the recovery of copper therefrom.

Abstract: A Process for the treatment or removal of impurities, such as arsenic, antimony or bismuth, generated as by-products during smelting and refining of copper concentrates, comprises subjecting the by-products to pressure oxidation along with a copper concentrate in a hydrometallurgical copper extraction process or the treatment of impurities when present in a concentrate by subjecting the concentrate to a hydrometallurgical extraction process.

Abstract: A Process for the treatment or removal of impurities, such as arsenic, antimony or bismuth, generated as by-products during smelting and refining of copper concentrates, comprises subjecting the by-products to pressure oxidation along with a copper concentrate in a hydrometallurgical copper extraction process or the treatment of impurities when present in a concentrate by subjecting the concentrate to a hydrometallurgical extraction process.

Abstract: A method of treatment or purification of a molybdenum concentrate also containing copper, comprises the step of subjecting the molybdenum concentrate to pressure oxidation in the presence of oxygen and a feed solution containing copper (e.g. CuSO4) and halide (e.g. CuCl2) to produce a pressure oxidation solution containing copper and a solid residue containing molybdenum. The pressure oxidation solution may be combined with feed solution to a second pressure oxidation in which a copper concentrate is treated for the recovery of copper therefrom.

Abstract: A processs for the recovery of zinc from a zinc sulphide ore or concentrate comprises the steps of subjecting the concentrate to pressure leaching with an acidic solution containing at least about 15 g/L iron in solution to produce a zinc solution and a solid leach residue containing iron. The zinc solution is subjected to zinc solvent extraction to produce a raffinate and a pregnant zinc solution. A method of removing ion from an iron bearing raffinate is also provided which comprises pressure leaching a zinc sulphide ore with the iron bearing raffinate to produce a solid leach residue containing iron and a zinc solution.

Abstract: A process for the extraction of copper from a sulphide ore or concentrate comprises the steps of subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halide and sulphate ions to obtain a resulting pressure oxidation slurry. The slurry is subjected to a liquid/solid separation step to obtain a resulting pressure oxidation filtrate and a solid residue containing an insoluble basic metal sulphate salt. The basic metal sulphate salt is leached in a second leaching with an acidic sulphate solution to dissolve the basic metal salt to produce a leach liquor containing a metal sulphate, e.g. copper sulphate, in solution and a resulting solid residue. The leach liquor is separated from the solid residue and subjected to a solvent extraction process to produce metal concentrate solution and a metal depleted raffinate. At least a portion of the raffinate is recycled to the pressure oxidation after being subjected to evaporation.

Abstract: A process for the recovery of nickel and/or cobalt values from a concentrate containing nickel or cobalt hydroxide comprises the steps of subjecting the concentrate to a leaching stage with an ammonium solution to produce a leach solution containing nickel and/or cobalt values and a residue. The nickel concentration in the leach solution is controlled to a maximum value of about 3 to 25 g/l, preferably 8 to 15 g/l and more preferably 10 g/l.

Abstract: A process for the extraction of metal from an ore or concentrate which contains nickel and/or cobalt values and other metals, comprises subjecting the ore or concentrate to acid leaching under pressure at pH≦2 to obtain a liquor containing nickel and/or cobalt values, subjecting the liquor to a first precipitation stage at pH of about 5 to 6 to produce a solid containing non nickel and non cobalt metals and a resultant solution containing the nickel and/or cobalt values and subjecting the resultant solution to a second precipitation stage at a pH of about 7 to 8 to produce a solid containing nickel and/or cobalt.

Abstract: A process for the extraction of nickel and/or cobalt values from a solution comprises the steps of effecting a cobalt solvent extraction in the presence of magnesium ions with a cobalt extractant to produce a cobalt extractant loaded with cobalt ions and a first raffinate containing nickel and magnesium ions in solution. The first raffinate is subjected to magnesium solvent extraction with a magnesium extractant to produce a magnesium extractant loaded with magnesium and cobalt ions and a second raffinate. The second raffinate is subjected to nickel solvent extraction with a nickel extractant to produce a nickel loaded extractant and a third raffinate.

Abstract: A process for the extraction of precious metals from a copper sulphide ore or concentrate, by treating a leach residue of the ore or concentrate, includes the steps of removing elemental sulphur from the leach residue to obtain a low sulphur residue and subjecting the low sulphur residue to an oxidative leach at elevated temperature and pressure to oxidize sulphur and precious metal compounds present in the low sulphur residue to produce a residue for the extraction of the precious metals therefrom.

Abstract: A process for the extraction of a metal from an ore or concentrate comprises subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halogen ions and a source of bisulphate or sulphate ions, such as H.sub.2 SO.sub.4. The metals which can be extracted by the process comprises copper, as well as non-cuprous metals, such as zinc, and precious metals, such as gold and silver.

Abstract: A process for the extraction of zinc from a sulphide ore or concentrate containing copper and zinc includes subjecting the concentrate to pressure oxidation in the presence of oxygen and an acidic halide solution to obtain a resulting pressure oxidation slurry and subjecting the slurry to a liquid/solid separation step to produce a liquor containing copper and zinc in solution. The liquor containing the copper and zinc is subjected to a first solvent extraction with a copper extractant to remove copper from the solution and to produce a copper depleted raffinate. The copper depleted raffinate is subjected to a second solid extraction with a zinc extractant to produce a zinc depleted raffinate and the zinc depleted raffinate is recycled to the pressure oxidation step.

Abstract: A heat exchanger 10 comprises a pressure vessel 14 having a feed inlet 11 in an upper part thereof for particulate material to be subjected to heat exchange and an outlet 13 at a lower part thereof for the outflow of particulate material from the vessel 14. A plurality of heat exchange elements, such as heat exchange plates 12, arranged in spaced relationship inside the pressure vessel 14 to define flow passages between adjacent heat exchange elements 12 is provided for particulate material to flow therethrough under the force of gravity. The pressure vessel 14 has an inside wall extending around the heat exchange elements 12 and further comprises a trap, such as a baffle 22, between the heat exchange elements 12 and the inside wall for trapping particulate material leaking from the flow passages between the heat exchange elements 12 to form a gas barrier 26 between the heat exchange elements 12 and the pressure vessel 14.

Abstract: A process for the extraction of Ni/Co values from an ore or concentrate comprises the steps of subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halide, copper and sulphate ions to obtain a liquor containing Ni/Co values from the resultant pressure oxidation slurry. The liquor is subjected to a selective precipitation treatment to obtain a solid containing Ni/Co hydroxide. The solid is subjected to a Ni/Co leaching stage with an ammonium solution to produce a leach solution containing Ni/Co values and a residue. The Ni/Co values are separated by solvent extraction to produce solutions suitable for electrowinning of Ni and Co. The process also provides for the recovery of precious metals and other metals such as copper.

Abstract: Flotation apparatus (10) for removing finely divided bodies of an insoluble substance dispersed in an aqueous medium, such as oil and solids dispersed in water, comprises a vertical flotation column (12) having a feed inlet (14) and an outlet (22) for the aqueous medium, a sparging system (16) for generating gas bubbles rising upwardly in the aqueous medium to capture and raise the finely divided bodies of the insoluble substance to the surface of the aqueous medium in the column to form a layer (31) of the insoluble substance on the surface of the aqueous medium, a launder (18) for receiving an overflow of the insoluble substance and an outlet (20) for the insoluble substance in the launder. The apparatus (10) can be used in both countercurrent and co-current fashion. In a particular embodiment, the apparatus includes a mechanism for the intermittent dumping of the layer (31) of insoluble substance from the column (12).

Abstract: A sparger (100) for producing gas bubbles in a liquid comprises a body member (102) having a gas inlet (105) and an outlet portion (106) provided with a gas outlet (108). The outlet portion (106) has an internal bore (110) which is in communication with the gas inlet (105) and the gas outlet (108). The bore (110) has opposite sides which converge in the direction of the outlet (108) to form a tapered region (112) in the bore (110). The bore (110) has a substantially constant diameter along at least a part of its length in an area between the tapered region (112) and the outlet (108). The sparger (100) further comprises a valve member (114) which is moveable into said tapered region (112) towards the outlet (108) for controlling the flow of gas through the outlet (108).

Abstract: A process for the extraction of a metal from an ore or concentrate comprises subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halogen ions and a source of bisulphate or sulphate ions, such as H.sub.2 SO.sub.4. The metals which can be extracted by the process comprises copper as well as non-cuprous metals such as zinc, nickel and cobalt. During pressure oxidation the metal may be precipitated as an insoluble basic salt, such as basic copper sulphate, or substantially completely solubilized and precipitated later as the basic metal salt.

Abstract: A process for the extraction of copper from a sulphide copper ore or concentrate comprises subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic chloride solution to obtain a resulting pressure oxidation filtrate and an insoluble basic copper sulphate salt. The pressure oxidation is conducted in the presence of a source of bisulphate or sulphate ions, such as sulphuric acid. The amount of the sulphate source added contains at least the stoichiometric amount of sulphate ions required to produce the basic copper sulphate salt less the amount of sulphate generated in situ in the pressure oxidation. In a particular embodiment, the pressure oxidation is carried out at a predetermined H.sup.+ /Cu ratio so that the pressure oxidation filtrate contains a major portion of the copper in the ore or concentrate and the basic copper salt contains a minor portion of the copper in the concentrate. The invention further provides for the selection of the H.sup.

Abstract: A process for the extraction of a metal from an ore or concentrate comprises subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halogen ions and a source of bisulphate or sulphate ions, such as H2SO4. The metals which can be extracted by the process comprises copper as well as non-cuprous metals such as zinc, nickel and cobalt. During pressure oxidation the metal may be precipitated as an insoluble basic salt, such as basic copper sulphate, or substantially completely solubilized and precipitated later as the basic metal salt.