Abstract: A method of processing an iron-rich rare earth bearing ore which includes the steps of smelting the ore to concentrate rare earth oxide minerals in the ore into a slag phase and extracting the rare earth oxide minerals from the slag.

Abstract: Disclosed is a method of decomposing ettringite, to form amorphous aluminium trihydroxide, which includes the step of lowering a pH of a slurry containing ettringite to a value between 8 and 8.5.

Abstract: Disclosed is an acid waste water treatment and method wherein heavy metal hydroxides and gypsum are precipitated in a single operation and wherein amorphous aluminium trihydroxide and gypsum are separated in a single solid-solid separation unit.

Abstract: A method of processing an iron-rich rare earth bearing ore which includes the steps of smelting the ore to concentrate rare earth oxide minerals in the ore into a slag phase and extracting the rare earth oxide minerals from the slag.

Abstract: A method of recovering gold from carbon fines in a resin-in-leach process wherein the fines are contacted with an ion exchange resin, in the presence of a suitable lixiviant, to load gold onto the resin, eluting the gold from the resin using a suitable eluent and recovering the gold from a resulting eluate.

Abstract: A method of detecting an open arc in a DC plasma arc furnace which is based on detecting a linear decrease in the log of the magnitude of the frequency spectrum of the voltage between the anode and cathode.

Abstract: Liquid metal is continuously recovered by condensing metal vapour in a sealed system, more or less at atmospheric pressure, and collecting liquid metal in a crucible. The contents of the crucible are agitated and the temperature is controlled to prevent the liquid metal from solidifying. Liquid metal and dross are tapped from the crucible.

Abstract: Liquid metal is continuously recovered by condensing metal vapour in a sealed system, more or less at atmospheric pressure, and collecting liquid metal in a crucible. The contents of the crucible are agitated and the temperature is controlled to prevent the liquid metal from solidifying. Liquid metal and dross are tapped from the crucible.

Abstract: A process for treating a metal sulphide concentrate which includes the steps of: a) roasting the concentrate to reduce the sulphide content of the concentrate, to a negligible value and b) melting the concentrate, under reducing conditions, in an electrically stabilized open-arc furnace, in particular a DC arc furnace.

Abstract: Metal lumps or pebbles are produced by introducing a molten metal stream into a stream of water in a direction which is substantially the same as the direction of the water stream and at a velocity which is substantially the same or slightly less than the velocity of the water stream.

Abstract: This invention relates to a process for removing sulphates and calcium from a water stream which includes the steps of: combining the water stream and an amount of amorphous aluminum trihydroxide (Al(OH)3); allowing the formation of ettringite (3CaO.Al2O3.3CaSO4.31/32H2O) as a precipitate; and removing the precipitated ettringite from the water stream.

Abstract: A process is provided for the leaching of copper from chalcopyrite using ferric sulfate in which acceptable rates of leaching are achieved by controlling the surface potential of the chalcopyrite to an empirically determined “window” within the broad range of 350 to 450 mV. The most effective process conditions involve the selection of the said surface potential; the leach temperature; the pH of the leach solution; and the fineness of the grind of the chalcopyrite. The invention may be applied to both tank leaching and heap leaching processes.

Abstract: A process for controlling a variable in respect of material in a series of interconnected vessels of a plant includes monitoring a variable in respect of each vessel. The monitored value of the variable is compared with a set point value of the variable. The differences between the monitored values and set point values of the variable resulting from at least one disturbance are summed. When such a disturbance in any one vessel results in a signal representative of the summed value being generated, each of a plurality of actuators of the plant are manipulated in a predetermined direction from the one vessel to cause rapid reduction of the disturbance. The invention extends to a control system for controlling a variable in respect of material in a series of interconnected vessels of a plant.

Abstract: A method of enhancing the appearance of a polished surface of an artifact is provided in which the artifact is formed from a non-ferrous alloy, in particular, but not exclusively, a precious metal alloy, chosen to exhibit a martensitic and a parent phase structure. The surface, or relevant part thereof, is polished in one of the phases, usually the parent phase, followed by heat treatment to effect a phase transformation, generally to the martensitic phase. This phase change causes a visible surface effect to the polished surface which may be described as a spangle effect.

Abstract: High chromium stainless steels having enhanced corrosion resistance are provided in which the steels have 25% to 35% by weight chromium; 0.1 to 5% by weight molybdenum; 0.1 to 6% by weight nickel; 0.0 to 4% by weight copper; 0.0 to 1% by weight titanium and/or niobium and/or vanadium; and, 0.02 to 5% by weight of a platinum group metal. The steels are particularly resistant to sulphuric and phosphoric acids.

Abstract: A direct resistance heating electrical furnace of the type in which a bed of electrically conductive elements are located between two spaced electrodes in the furnace, and a method of controlling the operation of same, are provided. The furnace is of the type having a generally tubular heating chamber with a pair of spaced electrodes associated therewith and conveniently located one at each end of the tubular heating chamber. The furnace has feed or discharge control means and the rate of feed or discharge is controlled according to the electrical resistance or current flow between the electrodes. No temperature measurement is required to control the furnace operation.

Abstract: A method and means for measuring a characteristic, in particular one associated with particle size, of any of the feed, underflow or overflow streams of a hydrocyclone is provided. Information as to the flowrate and density of the feed stream as well as the angle of flare or other related variable associated with the shape of the underflow stream are fed to processing means which applies a formula or algorithm, which is usually empirically derived, to such information to provide a value of the required characteristic. The characteristic may be related to particle size, particle size distribution in any of the streams or the liquid content or the flowrates of solids or liquids in the underflow or overflow. Measurement apparatus comprising a dedicated hydrocyclone is also provided.

Abstract: A gold selective ion exchange resin and process for the recovery of gold from solutions thereof is described. The resin has a macroporous structure and functional groups selected from alkylamine groups wherein the alkyl chain has between 3 and 6 carbon atoms, preferably tributylamine groups. The functional group content of the resin is from 0,4 mmol/g to 1,8 mmol/g and the water retention capacity is at least 30%. The process for recovering gold involves adsorption thereof onto such resin, optionally directly from a slurry, and elution preferably using a thiourea solution.

Abstract: A method is disclosed of controlling the operation of a hydro-cyclone or a circuit embodying same. The method involves the measurement of a variable associated with the shape of the slurry underflow emanating from the hydro-cyclone outlet. The variable is generally the cone angle or, in effect, the radius or diameter of the conical shaped stream of slurry flowing from the outlet at a selected position below the outlet and this diameter can be measured using an arm or arms which operatively rides on the outer boundary of the slurry underflow stream.

Abstract: A method of carrying out a chemical reaction in a fluidized bed reactor is provided wherein the reactants include at least one finely sub-divided reactant having a particle size substantially smaller than that of the particles constituting the fluidized bed. The reactor includes a downcomer compartment and a riser compartment operated such that the fluidized bed particles circulate by moving down the downcomer compartment and up the riser compartment. The finely divided solid reactant is introduced, either as such, or in an agglomerated form, into the central or upper region of the fluidized bed in the downcomer compartment such that it becomes entrained in the downwardly moving fluidized bed in the downcomer compartment and moves countercurrent to the fluidizing gas towards the lower end of the riser compartment. The reaction products which may be, or include, fine divided solids are carried out of the top of the reactor from the riser compartment.