Abstract: The invention relates to a process for regulating the acidity of the electrolytic bath by recycling fluorinated effluents emitted by the Hall-Heroult electrolytic cells for the production of aluminum, in which said fluorinated effluents are collected, by the dry route, on the alumina. It comprises the following stages:a reference value for the fluorine/alumina weight ratio is fixed in connection with the alumina leaving the collecting apparatus,a continuous measurement takes place of the fluorine and alumina quantities entering the collecting apparatus,the alumina flow rate is regulated so as to maintain the F/Al.sub.2 O.sub.3 ratio at its reference value, generally fixed between 0.

Abstract: A process and an apparatus for the continuous decoposition of a supersaturated sodium aluminate liquor forming a suspension in the presence of aluminium trihydroxide seed characterised by:(a) bringing into contact in a non-agitated grading decomposer a feed flow formed by the suspension and a recycling flow which is taken off in the underflow zone of the decomposer,(b) simultaneously drawing off a production flow in the same underflow zone,(c) extraction of an overflow flow at the overflow of the grading decomposer, and(d) suitable regulation in dependence on the flow rate of the feed flow, the flow rate of the recycling flow, the speed of discharge flow of the suspension in the underflow zone and the speed of rise of the suspension in the overflow zone.

Abstract: The invention concerns a process and an apparatus for optimizing combustion in a furnace which has open chambers, referred to as a ring furnace, for the baking of carbonaceous blocks, the furnace comprising a plurality of preheating, baking and cooling chambers which are aligned in series, each chamber being formed by the alternating juxtaposition of hollow heating partitions in which the combustion gases circulate and compartments in which the carbonaceous blocks to be baked are stacked, the combustion gases being extracted by a suction pipe connected by delivery tubes to each of the heating partitions of the first natural preheating chamber.

Abstract: Process and apparatus for controlling solid electrolyte additions to electrolytic cells for aluminum production.The invention relates to a process for controlling solid electrolyte additions to a cell for producing aluminum by the electrolysis of alumina dissolved in a molten cryolitic bath according to the Hall-Heroult process.According to this process a nominal value HBC is fixed for the bath height, the level of the bath in the cell is periodically determined on the basis of a fixed dimension point PF known relative to the carbon-containing cathode substrate, from it is deduced the total height HT of the electrolytic bath layer HB and the liquid aluminum layer HM, the thickness HM of the liquid aluminum layer on the cathode substrate is determined, from it is deduced the bath layer height HB, HB=HT-HM and Hb is compared with the nominal value HBC.

Abstract: The invention relates to an aluminum alloy for thin metal sheets suitable for the production of can lids and bodies, and to a process for manufacturing such metal sheets. The alloy contains, in percent by weight:from 0.8 to 1.8 manganesefrom 1 to 2 siliconfrom 0.7 to 3 magnesiumless than 0.7 ironless than 0.5 copperless than 0.5 chromium; andremainder aluminium.

Abstract: The invention relates to a method for adjusting the level of the line of contact between the mold and the free surface of the metal in the vertical continuous casting of products of any cross-section in an ingot-mold, which includes the step of applying to the solidifying metal, by means of an electric circuit surrounding the mold, a periodic magnetic field of variable intensity having a direction substantially parallel to the axis of the mold. According to the invention, the magnetic field applied to the mold is varied over a portion of the periphery of the metal. This can be done by modifying the distance between electric circuit creating the magnetic field and the mold, by changing the vertical positioning of the circuit, or by varying the shape of the profile of the circuit.

Abstract: The invention relates to aluminum based alloys essentially containing Cu, Li and Mg, which have very high specific mechanical strength and can be used particularly to obtain heat treated articles of complex shapes. The analyses are as follows (as % by weight): Cu 2.4 to 3.5%, Li 1.9 to 2.7%; Mg from 0 to 0.8%; and up to: 0.20% Fe; 0.10% Si; 1% Mn; 0.30% Cr; 0.2% Zr; 0.1% Ti 0.02% Be preferably with the following limitation: 4.8.ltoreq.% Cu+% Li+% (Mg/2).ltoreq.6.0. In the treated state the alloys have very high specific mechanical strength (Vickers hardness/density>70), even in the absence of any plastic deformation between quench and temper, thus justifying their use inter alia for components of complex shapes such as cast or stamped parts.

Abstract: The invention relates to a process for separating the inclusions contained in a bath of molten metal, by filtration. This process involves applying an electromagnetic force field to the filtering medium. It allows the total number and the size of the inclusions to be reduced greatly so that the products obtained by solidification of such a bath are highly suitable for transformation.

Abstract: The invention concerns a process for the electrolytic preparation of a mother alloy of iron and neodymium by the reduction of a mixture comprising at least one reactive oxygen-bearing compound of neodymium in a bath of molten halides with at least one metallic cathode, preferably of iron, and a carbon anode. In accordance with the invention, the bath is primarily formed by a mixture of molten fluorides whose decomposition potential is close to that of NdF.sub.3 or more negative, such as for example NdF.sub.3, MgF.sub.2, ScF.sub.3, CeF.sub.3, LaF.sub.3, BaF.sub.2, CaF.sub.2 and SrF.sub.2, and permitting solubilization of the oxides by a complexing effect, the solute to be reduced is formed by a mixture of salts primarily containing a reactive oxygen-bearing compound of neodymium which is very rapidly soluble in the molten electrolyte. The working temperature is in a range of from 640.degree. to 1030.degree. C., the anodic current density is from 0.1 to 1.5 A/cm.sup.

Abstract: A connection between a circular cylindrical tube and a plate or sleeve includes a housing extending along an axis from an inlet opening in a surface of the plate or sleeve and a circular cylindrical tube having an end fittable in the housing. The housing includes a first cylindrical truncated cone extending to the inlet opening and having a vertex angle .beta. with respect to the axis of between 5.degree. and 20.degree., and a second oval truncated cone coaxial with the first cone and connected thereto. The second cone has generatrices forming an angle .alpha. of between 0.5.degree. and 5.degree. with respect to the axis.

Abstract: A grading decomposer apparatus for continuously decomposing a liquor of sodium aluminate supersaturated in alumina comprises a cylindrical-conical tank for containing the liquor, having an upper cylindrical portion and an overflow generally peripherally disposed in the upper portion. A centrally disposed tubular element passes from above into the upper portion of the tank; the tubular member terminates in the cylindrical portion of the tank below the overflow. The apparatus also includes an off-take from the lower portion of the tank to an outlet; liquor is recycled from the lower portion of the tank to the upper portion within the tubular element and below the overflow, and liquor is introduced into the upper portion of the tank within the tubular element and below the overflow. A static disperser is disposed within the tubular element, the liquor feed and the recycled liquor inlet in order to create a feed and tranquilization zone within the tubular element.

Abstract: A method is disclosed for checking and obtaining in a moving mode the continuity of a metal covering on a metal wire of different nature belonging to the group of a wire being treated by a current strength and issuing from a covering bath and wire, the treatment of which is achieved and coming from a storage wheel. The method comprises continuously bringing the coated wire in contact with a volume of electrolyte solution chemically and physically inert with respect to the wire, and in which the sensitive part of a reference electrode is immersed, sliding the wire issuing from the volume against an electrical contact, measuring the electrical potential variations between the electrode and the contact, and when the potential current oscillates, noting the poorly covered wire and increasing the current strength on the wire being treated.

Abstract: In a continuous vertical casting operation carried out in a mould 3, a coil 7 applies a periodic magnetic field of variable strength whose direction is substantially parallel to the axis of the mould 3 to the liquid 5 as it solidifies, in order to regulate the level of the line of contact of the free surface of the metal 5 with the mould 3. The height of the contact of the metal with the mould can be reduced from h.sub.1 to h.sub.2 by applying the magnetic field, and the strength of the field is adjusted in dependence on the desired level. The procedure is used in casting semifinished metallurgical products, in particular in aluminium and its alloys, in which there is a wish to obtain a cortical region of zero thickness, a fine grain without the preliminary addition of refining agents, and an absence of pitting.

Abstract: The invention concerns Al-base alloys with substantial proportions of Li and Si, containing, by weight:from 3.6 to 8% Lifrom 5 to 14% Sifrom 0 to 1% of each of the following optional elements: Fe, Co, Ni, Cr, Mn, Zr, V, Ti, Nb, Mo, O.sub.2, Sc, andfrom 0 to 2% of each of the optional elements Cu, Mg and/or Zn, the total amount of the optional elements being less than 5%, and the balance being Al and impurities, each impurity.ltoreq.0.05%, with total impurities.ltoreq.0.15%. The products are obtained by rapid solidification processes and contain from 15 to 60% by volume of phase T (Al, Si, Li), in the form of particles of from 0.01 to 10 .mu.m.

Abstract: The invention relates to an apparatus for dissolving alloy elements and dispersing gas in an aluminum bath comprising a vertical shaft (1) pierced along its axis by a duct (2) intended for passing the gas, connected in its upper part to a gas source and to a drive motor and comprising in its lower part which is immersed in the bath a disc (3) with the same axis as the shaft. It is characterized in that the disc is provided with blades (4) which extend along the generatrices of a right prism of parallelogrammatic section, have a rounded end, are inclined with respect to the horizontal at an angle of at most 45 degrees, have their faces between the two planes containing the upper and lower faces of the disc and are provided with axial orifices (7) connected to the duct (2) by a tubular passage (3). The apparatus permits the rapid production of alloys with a low proportion of alkaline elements therein, in particular in a transportation ladle.

Abstract: The invention relates to a process and an apparatus for casting in a pit, without risk of explosion, of aluminum and its alloys, particularly with lithium.It comprises placing an elastic shield (3) around the cast product in order to stop the cooling water and any liquid metal outpouring, the water and metal being collected by flowing over the shield, into inclined channels (5 to 14), where the water forms a film and the metal is stopped in portionwise manner by strips (19) located at appropriate distances within the channels.

Abstract: The invention relates to an apparatus of the vibrocompactor type for compacting carbonaceous blocks, and which comprises a vibrating table on which a carbonaceous paste is to be disposed, a heavy mass located below the table, and damper means located between the table and the mass for suspending the table above the mass. According to the invention, the damper means comprises inflatable pneumatic cushions. These cushions may be connected in parallel permanently to a source of fluid under a controllable pressure, or alternatively may be connected in parallel during the inflation of the cushions, and then isolated individually or in groups from the source of fluid. The apparatus may also include a means for measuring the pressure in each cushion or in a group of cushions, and a means for signalling the drop in pressure in each cushion or group.

Abstract: The invention relates to an apparatus for pressure casting of metal parts which possibly contain fibres of ceramic material. The apparatus includes a cold chamber, and comprises a lower fixed plate 1, an upper movable plate 2, and a die 3 disposed between the upper plate and the lower plate, with the lower plate being provided with an injection means for liquid metal comprising an injection sleeve 5 having a piston 6 supported on a rod 7 slidable in the sleeve. The metal is contained in a sealed vessel connected to the injection sleeve by a conduit 9 by way of an orifice 8 in the sleeve, with a gas inlet in the vessel connected to a source of gas for selectively placing the liquid metal in the vessel under a gas pressure P2 which causes the flow of liquid metal in the conduit towards the sleeve.

Abstract: The invention concerns a process and an apparatus for applying prestresses to carbonaceous cathodic blocks in the operation of sealing the cathodic bar in position with cast iron.The block (1) in the course of the sealing operation is lifted on two rollers (16A, 16B) in the vicinity of its ends (E) and stresses F1 and F3 are simultaneously applied respectively to the ends (10) of the lateral edges of the limb portions (3) of the block and to the central part (C) of the block. Such stresses must be applied during the sealing operation and maintained for 15 to 30 minutes after the end of the cast iron casting operation.That virtually totally suppresses the occurrence of cracks in the cathodic blocks.

Abstract: A method and apparatus for decomposing a sodium aluminate liquor supersaturated with alumina, obtained from alkaline action on bauxite by the Bayer process, is initiated by introduction of alumina trihydrate seed, thereby forming a suspension. 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.