Abstract: The present invention relates to a process and apparatus for electrochemical treatment in a static mode or in a feed motion mode of the surface of metal products of elongate shape.The process is characterized in that cathodic and anodic zones are produced within the same volume of electrolyte, the zones being separated from each other and being displaced parallel to the product in a cyclic manner.The process is carried out in a cell having a single compartment in which there are at least four electrodes, two of which have voltage applied thereto.The invention is applied more particularly to aluminium, magnesium, titanium and alloys thereof, in order to provide for regular treatment of the entire surface of the product.

Abstract: The invention concerns a method and apparatus for decomposing a sodium aluminate liquor supersaturated with alumina, obtained from alkaline action on bauxite by the Bayer process, decomposition being initiated by introduction of alumina trihydrate seed to trigger the decomposition, thereby forming a suspension. In this process the suspension is fed in at the top of a non-agitated reactor described as a "decomposer", and removed from the bottom of the decomposer; the speed at which the suspension moves downwardly is regulated at 1.5 to 10 meters per hour. The apparatus comprises a cylindrical-conical reactor which is fitted with an arrangement for feeding in the suspension at the top, and with an arrangement for taking out the suspension at the bottom. In one embodiment of the apparatus the suspension is taken from the base of the decomposer through an internal tube, with air injected into the bottom of it, is raised to the level of the top of the decomposer and is then sent downstream.

Abstract: The invention relates to a process for the thermal treatment of aluminum alloys containing zinc, magnesium and copper as main alloying elements, and the products manufactured by this process and having an average particle diameter of Al--Mg--Cr phase of between 800 .ANG. and 1000 .ANG.. This process involves carrying out a treatment at high temperature for a sufficiently short period to prevent coalescense into particles which are too large. This treatment is preferably carried out at the homogenization stage for thin products and at the final dissolution stage for thick products. The invention is applied, in particular, to the manufacture of thin or thick sheets for the aeronautical industry.

Abstract: Apparatus for continuously brushing and lubricating rolls of rolling mills for rolled flat products without pollution of said products by the lubricant used; it can be used in hot or cold rolling, in particular for Al or alloys thereof.An enclosure of general parallelepipedic shape which is open on one face and whose opposite sides which are adjacent to the opening are delimited by a circular arc, the radius of which is substantially equal to that of the roll, is applied thereto by way of a continuous resilient peripheral seal. The enclosure which contains the rotary brushes is lubricated by oil circulation and is under a slight depression.

Abstract: A process is disclosed for accurately maintaining a low alumina content of between 1 and 4.5% in a cell for the production of aluminum by electrolysis in the Hall-Heroult process. According to the invention, a control parameter P=-1/D(dR.sub.1 /dt), is determined, wherein D is the variation in the alumina content of the electrolytic bath in % weight per hour, R.sub.1 is the internal resistance of the cell, and t is the time. A series of operations is then carried out in a repeated cycle, starting with the cell being fed alumina at a nominal rate which is substantially equal to the quantity consumed by electrolysis. At periodic intervals, an over-supply of alumina is added in order to enrich the bath, and the over-supply is continued for a preset time during which dR.sub.1 dt is negative. The feed rate is then reduced to less than the nominal feed rate, during which time dR.sub.1 dt passes through zero to become positive and the regulation parameter P, the value of which tends to rise, is measured often.

Abstract: The invention concerns a tank for the production of aluminum using the Hall-Heroult process by the electrolysis of alumina in a molten cryolite-base bath in an assembly formed by the grouping in series of a plurality of aligned tanks, each tank being formed by a rectangular metal casing whose major axis is perpendicular to the axis of the series and whose interior comprises a heat-insulating lining, a cathode formed by the juxtaposition in sealed relationship of carbonaceous blocks in which metal cathodic bars are sealed, the two ends of the cathodic bars, which issue from the carbonaceous blocks, forming the cathodic outputs which extend to the outside of the casing on the upstream and downstream sides thereof, in relation to the direction of flow of the current in the series, and to which there are connected the conductors for making an electrical connection with the following tank in the series; wherein in accordance with the invention, and in order to make the ohmic resistance of the two groups of upstrea

Abstract: The invention concerns a process for producing products of Al-base alloys essentially containing Li, Mg and Cu as main alloy elements and having a high level of ductility and isotropy. The process comprises subjecting the homogenized product to a "tepid" transformation operation at from 100.degree. to 420.degree. C. The intermediate annealing operations, if required, are carried out in the range of from 200.degree. to 550.degree. C. The rate of cooling after the intermediate annealing operations is generally kept at from 1500.degree. C./second to 30.degree. C./hour. The isotropy and ductility of the resulting products are considerably improved in comparison with the prior art processes.

Abstract: Process for the low-temperature treatment according to the Bayer cycle of gibbsite-bearing bauxite of low reative silica content, involving desilication of the said bauxite before leaching, by a liquor of low caustic soda concentration and characterized in that this sodium liquor consists of one or more washing waters originating from the Bayer cycle, mixed or otherwise with leaching liquor, wherein the weighted reactive silica content is preferably lower than 5% of the alumina content of the bauxite and the concentration of the sodium liquor used for desilication ranges from 50 to 120 g/liter of Na.sub.2 O caustic.

Abstract: This invention relates to internal combustion engine liners having a base of aluminum-silicon alloys and of silicon grains and processes for obtaining them.It is characterized in that these grains are carefully graded in size and dispersed in the alloy matrix. These liners can also contain at least an intermetallic compound such as Ni.sub.3 Sn, for example.These liners are obtained by extrusion or sintering of a mixture of powders.The invention has its application particularly in the automobile industry and in any type of industry where it is desired to have liner-piston units from aluminum alloys having a good compatability.

Abstract: The invention relates to a cathode rod permitting extraction of the current from a cell for the production of aluminum by electrolysis according to the Hall-Heroult process, which is sealed in at least one groove which is open at the base of each of the carbonated blocks 1 forming the cathode of the electrolysis cell.According to the invention, the cathode rod 2 is extended by a metal sole 5 in electrical contact with the base of the carbonated blocks 1 over at least 20% of the total surface area of this base. The sole 5 is constituted by a metal sheet which is at least 4 mm thick and preferably at least 10 mm thick and is soldered to the cathode rod 2 before the carbonated block 1 is positioned in the cell.To prevent infiltration of electrolyte into the subcathode space, the lower face of the sole 5 is placed in a superimposed relationship and in electrical contact with a thick, continuous metal screen 26 arranged at the top of the thermally insulating lining.

Abstract: A process for the continuous production of alumina by means of the Bayer process by alkaline attack in reactors on bauxites which primarily consist of aluminum monohydrates and contain silica in a free state or combined in the form of aluminum silicate, the essential aim of which is to delay scaling of the reactors by deposits of sodium silico-aluminate on the reactor walls. The process comprises the following steps: (1) the bauxite is put into suspension by crushing in a sodic liquor (aqueous solution of caustic soda); (2) the suspension is raised to a temperature of from 90.degree. to 108.degree. C. and held at that temperature for a period of time sufficient to convert at least 75% of the aluminum silicate contained in the bauxite into insoluble sodium silico-aluminate; (3) The suspension is then subjected to steam heating by passing through a tube-type heat exchanger under pressure at a temperature which is at least equal to 160.degree. C. and preferably is from 160.degree. to 230.degree. C.

Abstract: The invention relates to acrylic telomers with grafts which can be cross linked by light, methods of synthesizing them and their applications. The telomers comprise a telogen of the mercaptan family, in particular dodecanethiol, and links of a taxogen of the acrylic family, some of which are grafted. The telomers are synthesized semi-continuously by radical initiation in the presence of initiators such as azobisisobutyronitrile, at a temperature below 75.degree. C., making it possible to obtain a number of links adapted to the desired applications. Grafting is carried out by means of glycidyl and aziridinyl groups.

Abstract: A process for the selective removal of arsenical material in the course of a process for the hot oxidizing attack on a uraniferous and/or molybdeniferous ore containing arsenical materials, comprising attacking said ore with an aqueous liquor of sodium or potassium carbonate and/or bicarbonate, said attack operation being carried out under conditions with respect to levels of concentration, temperatures and pressures which cause solubilization of the uranium and/or molybdenum and the arsenic present in the ore, then collecting a suspension of a solid phase in a liquid phase, and finally, separating said phases, wherein the arsenic which is solubilized in the attack operation is extracted in the form of magnesium arsenate by treating the material containing the arsenic with a magnesium compound.

Abstract: A method of mounting an annular element on a tube which involves surrounding said tube by a tubular sleeve of aluminum or an alloy thereof, which is sufficiently thin to be plastically deformable and has a similar cross-section, with suitable clearance, with one of the sleeve ends having an outside bevel; surrounding said tube, on the side of the sleeve bevel, with an annular element to be fastened, wherein the annular element has at least one opening whose crosswise dimensions are greater than those of the tube, but whose radial clearance with said tube is less than the thickness of the sleeve, and which has, on the sleeve side, an inside bevel whose maximum crosswise dimensions are greater than the crosswise dimensions of the end of the element and the sleeve toward one another, by a suitable means, and introducing the sleeve, by force, between the annular element and the tube by plastically deforming the sleeve and tube, thereby mounting the annular element.

Abstract: The invention concerns a process for the precipitation of aluminium hydroxide by seeding in two phases, which is intended to produce at a high level of productivity alumina with large grains, referred to as `sandy coarse`, by precipitation in a succession of tanks in cascade relationship of a supersaturated solution of sodium aluminate coming from alkaline attack on bauxite in accordance with the BAYER process. The process comprises three stages:in the first agglomeration stage, the supersaturated aluminate liquor is introduce into the tank, with an equivalent amount of terms of Na.sub.2 O of between 110 and 175 g/liter, at a temperature of between 65.degree. and 80.degree. C.

Abstract: The invention relates to a carbonaceous anode intended for cells for the production of aluminium by igneous electrolysis according to the Hall-Heroult process, which is connected to the positive current input by at least one steel conductor comprising a lower portion which penetrates into the carbonaceous anode and an upper portion which is connected to the positive current input. The upper portion of the steel conductor has, over at least 30% of the length of the upper portion, a cross sectional area which is at most equal to 60% of the cross sectional area of the lower portion.The upper portion may be constituted by a solid profile of reduced cross section or a tubular profile.The invention can be applied to prebaked anodes and to Soderberg anodes. It allows a substantial gain over the voltage drop in the anodic system.

Abstract: The invention concerns a method for minimizing deformation during rapid cooling of flat metallurigcal products such as sheets, strips, flattened portions, wide sections and the like.The method comprises rapidly cooling the product by means of a fluid (or mixtures of fluids) at temperature T.sub.F, comprising at least one vaporizable liquid, with modulation in a direction perpendicular to the direction of advance of the product, so as to impart different cooling speeds to the edges and the axis (case I) or to one edge and the other (case II).The technique may be completed by careful masking of the cooling in the zone for the rapid cooling action, or by controlled precooling prior to said rapid cooling.The method makes it possible to obtain the rapid cooling which is necessary e.g. in quenching operations, while at the same time minimizing the deformations or the internal stress level of flat products.

Abstract: The invention relates to a carbonaceous cathodic block having a low voltage drop, which is intended for tanks for the production of aluminium by electrolysis using the Hall-Heroult process, said tanks comprising a parallelepipedic metal casing supporting a cathode on which the layer of liquid aluminium is formed, said cathode being formed by the juxtaposition of parallelepipedic carbonaceous blocks of elongate shape wherein the ratio of the length of the major axis to the width is at least equal to two and in which there is cut at least one groove into which is sealed a steel bar which is disposed in parallel relationship to the short side of the casing and which connects to at least one cathodic collector, characterized in that the sealing grooves are cut in the direction perpendicular to the major axis of the block which is itself disposed in parallel relationship to the long side of the casing.

Abstract: Metal sheets of aluminum are provided with raised reinforcing portions of substantial height by rolling. The rolls have recesses or channels (6) whose side faces are in a counter-taper configuration with respect to a plane perpendicular to the axis of the cylinder, with an angle of inclination (.alpha.) of up to 5.degree.. The resulting product may advantageously be used for producing perforated metal sheets with high modulus of inertia.

Abstract: A process for purifying at least a fraction of a solution in the Bayer cycle, which is preferably taken off after decomposition of the sodium aluminate, before or after concentration thereof, by causing the precipitation of the sodium oxalate in solution by the introduction of an agent for destabilization of the state of supersaturation of the sodium oxalate, which is characterized in that the supersaturation destabilization agent introduced into the Bayer solution to cause precipitation of the sodium oxalate is selected from the group comprising calcium oxalate and barium oxalate and that, in the case of solutions charged with degraded organic materials which generally result from high-temperature attack on bauxites with high proportions of humic materials, an anionic synthetic polyelectrolyte of high molecular mass is previously introduced into said solutions in order to increase the efficiency of the purification effect.