Abstract: Sulphuric acid leaching has been used in the treatment of lateritic ores for the recovery of nickel and cobalt therefrom. However, in order to obtain good extraction from these ores, prolonged treatment using acid of high strength and also using high pressures and recycling steps have been necessary. In the improved method of the invention nickel and cobalt is solubilized from high-magnesia nickeliferous serpentine ores by leaching the ore with an aqueous solution of sulphuric acid while adding to the solution a reducing agent to maintain the redox potential of the solution at a value between 200 and 400 millivolts, measured against the saturated calomel electrode. This improved procedure increases the reactivity of the serpentine and results in maximum extraction of nickel consistent with minimum extraction of iron and magnesia and minimum acid consumption.

Abstract: When the electrodeposition of nickel is carried out in the presence of sulphur, it is desirable to control the content and the distribution of the sulphur in the deposited nickel. Sulphur-bearing nickel is deposited onto a multiplicity of cathodes (12) in an electrolytic cell. The electrolyte contains nickel ions, chloride ions, and at least one thiocyanate compound. To prevent oxidation of the thiocyanate ions by the chlorine gas generated at the anode (11), the chlorine is almost completely excluded from the cathode compartment by providing a flow of electrolyte from the cathode (12) to the anode (11) and by continuously removing chlorine and chlorine-containing electrolyte from the anode through a manifold (26). A weir (14) prevents back flow.

Abstract: An improved method is described for the continuous shielded arc melting of calcine in an electric arc furnace to obtain molten slag, underlain by molten metal.The furnace is so operated that the major portion of the total energy supplied thereto is released in the arc, and the minor portion in the molten bath. The improvement consists of adjusting the electrical energy released in the bath, directly to obtaining a required active bath area calculated by means of the rate of change in the volume of the slag and indirectly to the silica:magnesia ratio in the slag. The optimum range of active bath area is derived from conditions required for the safe and continuous operation of the furnace, in order to protect the furnace walls from slag erosion and to avoid excessive electrode movement.

Abstract: A lateritic ore reduction process wherein a light, low sulphur-containing naphtha is employed to produce a pre-reduced calcine and a heavy residual fuel is utilized to provide the energy to subsequently melt the calcine, and wherein both operations are carried out at a location remote from a source of the fuels required. Two different fuels are mixed at the source to form a blend, which is pumped, at ambient temperature, through a single pipeline to the ore reduction plant. The blend is fractionated into two products required for two or more operations in the ore treatment, and the two product fuels are consumed substantially in their entirety in the respective operations.

Abstract: A method for electrowinning metal from metal chloride-bearing electrolyte in an electrolytic cell wherein diffusion of chlorine from anolyte to catholyte is limited, thereby limiting concentration of chlorine gas around the cell so as to be within acceptable limits. Catholyte is withdrawn through a catholyte overflow duct in the cell to establish a catholyte level and the anode is maintained in an electrolyte-permeable diaphragm which is attached to a hood extending above the electrolyte level. Chlorine gas generated at the anode is withdrawn from the hood by applying suction via a suction duct located in the hood above the catholyte level and electrolyte is drawn through the diaphragm into the anolyte and upwardly inside the hood. Anolyte is withdrawn therefrom under the suction as an overflow via an anolyte outlet duct in the hood above the catholyte level.

Abstract: A method and apparatus for hydraulically hoisting particulate solid mined minerals from one mine level to another in which bore holes are used as conveying conduits for the mineral-water mixtures. Batches of the mineral are charged into a pressure vessel at a lower level and discharged intermittently into a borehole conduit system in which water is circulated, under pressure, between the two mine levels. The mineral is separated from the conveying water at a higher level by a conventional dewatering apparatus and the water is returned to the vessel for mixing with a new batch of mineral. The method is conducted cyclically with mineral batches being charged to and then discharged from the vessel at controlled intervals, the control being achieved by valve means which alternately isolate and integrate the vessel with the water circuit. The pressure vessel is further characterized by a discharge port in a sidewall of the vessel connected to a discharge pipe outside the vessel.

Abstract: A reusable integrated cathode unit and an associated electrolytic method are disclosed for the simultaneous production of a multiplicity of metal electrodeposits by plating from a base metal electrolyte. The rigid cathode unit has two integrated components, a slab of non-conductive material and a metal assembly which is embedded therein. The metal assembly has projections that penetrate the slab surface at spaced locations thereby forming an array of conductive metal islands flush with or raised above the surface of the cathode unit which serve as the sites for plating of the electrodeposits. The method is advantageously characterized by the production of unique, crown shaped electrodeposits with basal areas much larger than the areas of the conductive islands on which they are formed, and a significant component of growth in a direction normal to the plating surface.

Abstract: There is provided a cobalt ion exchange process for recovering cobalt from ammoniacal solutions comprising the steps of bringing the ammoniacal solution into contact with carbonaceous material, the redox potential of the solution being in the range +20 to -150 mV as measured by a platinum-calomel standard electrode pair, extracting the cobalt from the leach solution with a cationic ion exchange reagent, and recovering substantially all the cobalt from the ion exchange reagent by elution. The process of the invention enables cobalt to be removed from an ammoniacal leach solution which may also contain nickel and copper, in the form of a highly pure cobalt eluate.

Abstract: A hydrometallurgical process for separating iron and nickel contained in iron and nickel-bearing sulphide materials, comprising selective leaching of iron with respect to nickel with hydrochloric or other mineral acid to provide a leach solution and leached solids. The nickel contained in the leach solution is separated from the dissolved iron as nickel sulphide by precipitation with hydrogen sulphide in the presence of an iron-bearing substance in which the iron is present in a form selected from the group comprising oxides, hydroxides and combinations thereof.

Abstract: A method for selectively recovering metals from generally sulphidic particulate materials containing metals selected from nickel, copper and precious metals in which the particulate material is preferentially leached in an agitated chloride solution containing cuprous ions by the action of chlorine. The redox potential of the solution increases upon feeding chlorine thereto and decreases upon feeding particulate material thereto, and the rate of feeding of chlorine is controlled relative to the rate of feeding of material to control the redox potential substantially at or below a selected potential at which the metal is leached preferentially with respect to other metals in the material. Nickel is leached preferentially with respect to copper and precious metals in a matte, for example, to produce a nickel-rich solution and to concentrate the precious metals in a nickel-depleted residue.

Abstract: A switch or circuit breaker that provides a high contact pressure when closed and provides a reduced and automatically regulated contact pressure during opening and closing. In one embodiment a pair of contacts is mounted opposite one another and one of the contacts is carried at one end of a pivotably mounted lever so that it can move towards and away from the other by a movement of the other end of the lever. A fluid operated cylinder arrangement is provided to move the switch blade from a first disengaged position to a second engaged position between the blades. The cylinder is mounted on a mechanical linkage so that the linkage is deflected in accordance with the resistance of the blade to movement, and the deflection of the linkage moves the lever tending to decrease contact pressure. A balance is reached between contact pressure and the blade movement tending to maintain a constant and reduced contact pressure during opening and closing.