Abstract: A method of determining an inlet flow rate (Finlet) of a flowable material including passing an inlet stream of flowable material through a chamber (20) having an outlet aperture (100); measuring a first rate of change of quantity of material in the chamber (20) when the material is entering at said inlet flow rate; measuring a second rate of change of quantity if material in the chamber (20) when no material is entering the chamber (20); and calculating the inlet flow rate (Finlet) from said first and second rates, wherein both rate measurements are made while the whole of the outlet aperture (100) of the chamber (100) of the chamber (20) is occupied by the flowable material.

Abstract: A process is provided for the treatment of an alumina process feedstock prior to transferring the treated feedstock to an alumina process for extracting refined alumina from the treated feedstock. The treatment process includes: (a) heating the alumina process feedstock to a temperature of 400° C. to 650° C. by direct contact with combustion gas, and (b) cooling the heated feedstock to a temperature at which it can be handled and fed to the alumina process. The treatment process also includes controlling the contact time of the alumina process feedstock at temperatures in step (a) to ensure decomposition of alumina trihydrate and alumina monohydrate. The process also includes: (i) limiting the maximum temperature of incoming gas to a stage of the process in which the alumina process feedstock reaches the above temperature range of 400° C. to 650° C.

Abstract: A process for the removal of reactive silica from a feedstock to the digestion step of the Bayer process for the manufacture of alumina, in which (a) the feedstock is contacted with a caustic liquor under process conditions which result in dissolving and stabilizing at least 50% of the silica into solution at a level of at least 3 gpL and without significant precipitation from solution of dissolved silica, (b) the silica bearing liquor is separated from solid residue of step (a) under conditions which do not promote significant precipitation of the silica; and (c) aluminosilicates are precipitated from the separated silica bearing liquor from step (b), to form a solid aluminosilicate product which is free of a majority of all other components of the feedstock.

Abstract: A casting apparatus for direct chill casting of molten metal includes a mold having an inlet to receive molten metal, a side wall and an outlet for withdrawal of a casting from the mold, a water spraying device positioned to direct water sprays which impinge directly on an outer surface of the casting emerging from the outlet and an infra-red detector positioned adjacent a region in which the water sprays impinge directly upon the outer surface of the casting being withdrawn from the outlet of the mold. The detector is thus exposed to radiation from this region as the casting is cooled by the water sprays, and any molten metal bleeding out from the casting in this region immediately exposes the infra-red detector to high temperature radiation.

Abstract: An aluminium smelting cell comprising side walls (5) and a floor (2) defining an active cathode, an anode (3) overlying the cathode floor (2), some said side walls (5) being covered by a wetted cathode material (6), such as one contained TiB.sub.2, so that the covered side walls become active cathode surfaces on which a film of aluminium metal forms to protect the side wall parts against bath attack, thereby enabling the cell to operate at the desired temperatures without the usual protective side ledge of the frozen electrolyte material.

Abstract: A process is disclosed for the production of alumina by the Bayer process, including a precipitation process having an agglomeration stage and a growth stage in which the precipitation slurry is passed through a multiplicity of growth tanks. In the agglomeration stage, the precipitation slurry is maintained at a temperature of about 75.degree. C. to 85.degree. C. In the growth stage, the agglomeration slurry is cooled by about 1.degree. C. to 3.degree. C. in each growth tank of the multiplicity of growth tanks as compared to an adjacent previous growth tank. The temperature of the precipitation slurry leaving the final precipitator is preferably about 55.degree. C.

Abstract: A cast hypereutectic Al-Si alloy having 12% to 15% Si, and a method of producing such alloy. The alloy and a melt used in the method has at least one element of a first group of elements and at least one element of a second group of elements and further comprises Cu 1.5 to 5.5%; Ni 1.0 to 3.0%; Mg 0.1 to 1.0%; Fe 0.1 to 1.0%; Mn 0.1 to 0.8%; Zr 0.01 to 0.1; Zn 0 to 3.0%; Sn 0 to 0.2%; Pb 0 to 0.2%; Cr 0 to 0.1; Si modifier (Na, Sr) 0.001 to 0.1%; B (elemental) 0.05% maximum; Ca 0.03% maximum; P 0.05% maximum; and others 0.05% maximum each, the balance, apart from incidental impurities being Al. The element of the first group provides stable nucleant particles in the melt. The element of the second groups forms an intermetallic phase such that crystals of the phase form in advance of and nucleate primary Si to provide complex particles which promote nucleation of Al-Si eutectic on cooling of the melt below the eutectic solidification temperature.

Abstract: A mould assembly comprising mould segments of generally non-thermally conductive material which define a mould cavity is upwardly filled with liquid metal through at least one in-gate. A thermal extraction member of a high thermally conductive material contacts a portion of the mould cavity through which heat is extracted rapidly to establish positive thermal gradients in the casting and thereby promote directional solidification. The mould assembly is also provided with a seal to selectively isolate the mould assembly from the liquid metal source to allow the mould assembly to be removed from the casting station and transferred to the cooling station, providing a more efficient use of the casting station. In addition, once a shell has solidified then the mould segments and metal contained therein can be transferred to the cooling station.

Abstract: Al base - Si hypereutetic alloys can exhibit problems of variable and unwanted microstructure throughout the section of the article being cast. This problem is overcome by controlled cooling of the mold in critical areas, to remove or prevent excessive accumulation of heat energy and avoid the formation of intense convection currents in still molten alloy. Consequently, the necessary coupled growth of the Al-Si eutectic is promoted and the resultant microstructure is substantially free of primary Si. The 3HA and modified 3HA alloys of the applicant are considered on the basis of their wear resistance and improved machineability for automotive applications, such as engine blocks and cylinder heads. A first feature of the controlled cooling procedure is supply of coolant to regions in the mold, above and extending from the gate, such that solidification progresses uniformly from the remote regions of the mold spaces towards the gate to give a substantially uniform microstructure throughout the casting.

Abstract: A cast hypereutectic Al-Si alloy with from 12-15% Si, having excellent wear resistance and machinability, improved fatigue strength and good levels of ambient and elevated temperature properties is provided, as well as a method of producing such alloy. The alloy and a melt used in the method contains Sr in excess of 0.10% and Ti in excess of 0.005%, the alloy further comprising: Cu 1.5 to 5.5%, Ni 1.0 to 3.00%, Mg 0.1 to 1.0%, Fe 0.1 to 1.0%, Mn 0.1 to 0.8%, Zr 0.01 to 0.1%, Zn 0 to 3.0%, Sn 0 to 0.2%, Pb 0 to 0.2%, Cr 0 to 0.1%, Na 0 to 0.01%, B (elemental) 0.05% maximum, Ca 0.003% maximum, P 0.003% maximum. Others 0.05 maximum each, the balance, apart from incidental impurities, being Al. The level of Sr in excess of 0.10% and Ti in excess of 0.

Abstract: A low cement castable refractory comprising 85 to 96% by weight of a calcined ultrafine bauxite aggregate characterized by a particle size of less than 10 um, 2 to 10% by weight of a suitable cement material, 0 to 8% of weight of a thixotropic agent and 0 to 2% by weight of suitable deflocculants and plasticizers, the cement material comprising calcium aluminate cement having an alumina content of 40 to 85% and the thixotropic agents being selected from those containing microfine silica, and/or reactive alumina, the inorganic deflocculants and plasticizers being selected from alkali phosphates, lignosulphonates or naphthalene sulphonates. A method of making a low cement castable refractory and installing a low cement castable refractory are also described.

Abstract: The toughness of Al-Li, Al-Mg and Mg-Li alloys is increased by a melting and refining process designed to reduce the concentration of alkali metal impurities below about 1 ppm and preferably below about 0.1 ppm. The hydrogen and chlorine gas constituents are also significantly reduced.

Abstract: An aluminum smelting cell comprising a cathode having an active upper surface, a plurality of anodes each having a lower surface spaced from the upper surface of the cathode, said cathode upper surface being sloped at an acute angle in a primary or longitudinal direction of each anode, and being formed with pairs of oppositely sloped surfaces extending in a transverse or secondary direction under each anode to cause complementary shaping of the lower anode surfaces to reduce the migration of bubbles between the anode and cathode along the anode surfaces in said primary or longitudinal direction to thereby reduce the path length of said bubbles whereby the turbulence caused by coalesced bubble disengagement from the bath electrolyte is significantly reduced while maintaining adequate bath circulation between the anode and cathode.

Abstract: High purity coke particularly suited to the production of anodes for aluminium smelting is produced by an integrated process that includes flash pryolysis and delayed coking. In the integrated process, flash pyrolysis of carbonaceous materials such as coal, oil shale or tar sand is operated under conditions that maximize the production of tar suitable for coking, and the delayed coking is operated under conditions that maximize the coke yield, and intermediate products may be recycled to enhance overall efficiency.

Abstract: A process for the treatment of waste materials such as spent cathode liners involving combustion of the contained carbonaceous material, decomposition of the contained cyanides, sulphides and nitrides, and recovery of fluoride values by a sulpholysis reaction, is characterized in that the sulpholysis reaction is carried out in a separate stage. The process enables a recovgery of fluoride values from smelter wastes which is especially favourable environmentally. A further advantage of the invention is that recovery of the contained fluoride values, initially in the form of gaseous fluoride species, may subsequently be treated with alumina to produce aluminium trifluoride, which is of significant economic importance.

Abstract: Aluminium alloys particularly useful as sacrificial anodes and processes for the preparation thereof are disclosed. The alloys of the invention exhibit a range of superior properties enabling high performance and reliability under a wide range of environmental conditions.

Abstract: A filter medium suitable for hot liquid and gaseous materials, more particularly molten metals, for example aluminium and its alloys, is characterized by the use of sintered ultrafine bauxite granules. Filter media according to the invention exhibit superior thermal shock resistance, may be used repeatedly and are much cheaper than filter media of the prior art.

Abstract: A process for production of useful materials including a product of similar composition to nepheline involves contacting a slurry of red mud with sulphur dioxide to dissolve components of the red mud that are soluble in sulphurous acid, removing residual undissolved solids by filtration, and recovering a filtrate containing soda, alumina and silica values, removing free water from the filtrate to produce a crystallized residue, and calcining the crystallized residue.

Abstract: A process for recovery of valuable products from Bayer process red mud comprises the steps: (a) digesting red mud with sulphur dioxide in the presence of water to dissolve soda, alumina and silica therein; (b) heating the product of step (a), with or without prior removal of insolubles, to selectively precipitate silica, and removing solids including the precipitated silica, to produce a liquor containing soda and alumina; (c) causticizing the liquor to precipitate calcium sulphite; and (d) separating the precipitated calcium sulphite from the liquor to produce calcium sulphite and sodium aluminate solution as products. In a preferred embodiment calcium sulphite produced in step (c) is calcined to regenerate lime and sulphur dioxide for recycle to the liquor causticization and red mud digestion stages respectively, and sodium aluminate produced in step (d) is returned to the Bayer process.

Abstract: A leaching process employing acidic chloride solutions, whereby the iron content of aluminous materials such as lower grade iron-containing bauxite ores is reduced, enabling the obtention of valuable products such as metallurgical grade alumina and refractory grade bauxite, previously obtainable only from higher grade low-iron aluminous materials.