Abstract: Alumina is reduced to molten aluminum in an electrolytic cell containing a molten electrolyte bath composed of halide salts and having a density less than alumina and aluminum and a melting point less than aluminum. The cell comprises a plurality of vertically disposed, spaced-apart, non-consumable, dimensionally stable anodes and cathodes. Alumina particles are dispersed in the bath to form a slurry. Current is passed between the electrodes, and oxygen bubbles form at the anodes, and molten aluminum droplets form at the cathodes. The oxygen bubbles agitate the bath and enhance dissolution of the alumina adjacent the anodes and inhibit the alumina particles from settling at the bottom of the bath. The molten aluminum droplets flow downwardly along the cathodes and accumulate at the bottom of the bath.

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: Module for mechanized replacement of the anodes of electrolytic cells for the production of primary aluminum, constituted by a cage-shaped structure which can be hooked to a usual bridge crane, with said structure a control cab (8), a hopper, fork-shaped positioning elements, a telescopic arm (17) for clamping, unscrewing and locking anode bars, a crust-breaker device (11), a device for cleaning the upper surface of the worn anode and a skimmer device (14) being associated.

Abstract: An apparatus for removing dendrites or other crystalline matter from the surface of a liquid in a matter transport process, and an electrolytic cell including such an apparatus. A notch may be provided to allow continuous exposure of the liquid surface, and a bore may be further provided to permit access to the liquid.

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 suspension arrangement for an anode bar in a cell for electrolytic production of aluminum includes two jacks disposed along the center line of the anode bar, between an anode superstructure and the anode bar. The anode bar is movable in the vertical direction by such jacks which are separately driven, or driven by one common motor. To prevent the anode bar from rotating around its longitudinal axis, there is disposed a torsion device between the anode bar and the anode superstructure. The anode bar is provided with side supporting structure. Which prevents the anode bar from moving side-ways.

Abstract: A method of estimating and controlling the concentration of alumina in the bath of a Hall cell. The method includes the use of an estimator that employs two sets of equations, namely, a time update algorithm that contains a dynamic model of the alumina mass balance of the cell and provides estimates of alumina concentration, and a measurement algorithm that uses a process feedback variable from the cell to modify the alumina estimate. In addition, the method includes the use of one or more tuning parameters, such as state noise variance and measurement noise variance. The measurement noise variance is modified by the process noise variance in a manner that increases measurement noise variance for high values of process noise and decreases measurement noise variance for low values of process noise. In addition, one or more of the parameters of the model are modified by the feed history of the cell.

Abstract: A process and apparatus for electrochemically separating alkali oxides to simultaneously generate oxygen gas and liquid alkali metals in a high temperature electrolytic cell is provided. The high temperature electrolytic cell comprises a cathode in contact with an alkali ion conducting molten salt electrolyte separated from the anode by an oxygen vacancy conducting solid electrolyte. Alkali metals separated in the alkali metal reducing half cell reaction are useful as reducing agents in the direct thermochemical refining of lunar metal oxide ores to produce metallic species and alkali oxides, and the alkali oxides may then be recycled to the high temperature electrolytic cell.

Abstract: A method and apparatus are disclosed for measuring the current distribution in an alumina reduction cell. The apparatus includes sensors attached to the anodes of the cell, a remote computer system for receiving and correlating data received from the sensors and a means for transmitting and receiving the data from the sensors to the remote computer.

Abstract: Method for controlling the alumina feed to reduction cells for the production of aluminum. There is employed an adaptive control with parameter estimation (3) and controller calculation (2) based upon the separation theorem. As a process model there is used a linear model having two inputs and one output. One input (u.sub.1) is in the form of alumina feeding minus assumed alumina consumption. Another input (u.sub.2) is in the form of movements of the reduction cell anode. The output (y) is in the form of the change in electric resistance across the reduction cell concerned. The model is of the first order in u.sub.1 and u.sub.2 whereas it is of the order zero in y. An estimated parameter (b.sub.1) represents the slope of the curve for resistance as a function of alumina concentration in the electrolytic bath, and the controller (2) controls the addition of alumina to the electrolytic bath in response to the value of b.sub.1.

Abstract: A process and an apparatus for producing a neodymium-iron alloy by electrolytic reduction of neodymium fluoride in a bath of molten electrolyte, consisting essentially of 35-76% by weight of neodymium fluoride, 20-60% by weight of lithium fluoride, up to 40% by weight of barium fluoride and up to 20% by weight of calcium fluoride, conducted between one or more iron cathode and one or more carbon anode.

Abstract: A closed apparatus of potential fluidization type, for conveying powder materials in a dense bed from a storage region (31) to at least one region to be fed therewith, comprising a storage tank (48) for storing the powder material, referred to as a reserve container, which comprises between the two regions at least one horizontal conveyor (33) formed by a lower duct (35) for a flow of gas, an upper duct (36) for a flow of the powder material and the gas, between which ducts is disposed a porous wall (34), and at least one conduit (38) for feeding gas to the lower duct, which makes it possible to establish a pressure Pf that creates a dense potential-fluidization bed of the powder material that fills the conveyor, by virtue of the presence of at least one balancing column (39), the filling height (56) of which balances the pressure Pf of the potential-fluidization gas, the improvement wherein the closed storage tank or reserve container (48) of the region to be supplied with material, being provided with an in

Abstract: Electrolyzer for the extraction of a substance from an electrolytic bath.The electrolyzer comprises an anode and a cathode immersed in the bath. The cathode, in which the substance is formed, surrounds the anode. The electrolyzer also comprises means for confining the substance in the vicinity of the cathode and for guiding said substance along and towards the upper end of the cathode, together with means for collecting the substance at said end. These confinement and guidance means comprises at least one grid layer located in the vicinity of the cathode and passing along the same.Application to the production of alkaline metals or alkaline earth metals.

Abstract: This invention relates to a process of producing lithium metal by the electrolysis of fused mixed salts comprising electrolyzing fused mixed salts consisting of lithium chloride and potassium chloride in a diaphragmless electrolytic cell, withdrawing molten lithium metal from the cell to a receiver and cooling the lithium metal which has been withdrawn.

Abstract: In an aluminium reduction cell, the height of the anodes within the cell are controlled automatically, usually by computer. Means (S1 . . . SN, C1 . . . CN) are provided for making small anode movements in order to effect this automatic control but, for safety reasons, these control movements are limited to a maximum preset duration by timers (T1,T2). These are occasions, however, when longer anode movements need to be undertaken and the present apparatus provides means (6) for overriding these timers during such longer anode movements. Various safety measures are incorporated in this overriding function to ensure that safety requirements are maintained.

Abstract: A control system controlling the movements of a pneumatic percussion tool for breaking crust away from anode butts in an electrolysis cell. The system comprises a control arm extending through first and second plates connected to respective first and second valve stems. In a preferred embodiment, the first valve stem operates a hydraulic scissors jack for extending and retracting the tool, and the second valve stem operates a hydraulic rotator motor for radially rotating a mast supporting the tool. A preferred system also comprises a pneumatic control valve connected to the control arm for positioning and energizing the percussion tool.

Abstract: A mobile anode-block cleaning machine has a steerable workshop floor vehicle provided with its own propulsion system and with a cleaning cabin in which anode remnants are freed from melt incrustations with the aid of a separator. The cleaning operation is completed in a chamber, closed to the exterior, provided in the cleaning cabin, the chamber air expediently being cleaned with the aid of a filter. The machine also has a collecting chamber for the storage of the incrustations separated from the anode remnants.

Abstract: This invention relates to a cell for producing a metal by electrolyzing halides in a molten salt bath. It consists of using one cathode in the form of a basket, simultaneously passing a current I.sub.1 between this cathode and an anode in such a manner as to carry out a first deposit of crude metal in the basket and a current I.sub.2 between the said basket and complimentary cathodes for depositing the final metal thereon. The cell consists of a central anodic system, a tubular cathodic basket surrounding the anode and a series of cathodes surrounding this basket, a positioning which cathodes can be reversed in relation to the basket.

Abstract: A method of producing aluminum by electrolysis of alumina dissolved in molten cryolite at temperature between 680.degree.-690.degree. C. is disclosed. The method comprises the employment of permanent anodes the total surface of which is increased up to 5 times compared to the total surface of anodes in a classical Hall-Heroult cell of comparable production rate. By this means the anodic current density is lowered to a degree which permits the discharge of oxide ions preferentially to fluoride ions at an acceptable rate. Additionally, the electrolyte is circulated by suitable means whereby it passes from an enrichment zone where it is saturated with alumina to an electrolysis zone and back.

Abstract: A method of determining the depth of the molten electrolyte layer in an aluminium electrolytic reduction cell, and using the measurement to control the operation of the cell, is based on the fact that when an anode is raised, the current passing through it drops to zero when the anode carbon face loses physical contact with the molten electrolyte. The method involves raising the anode and noting the distance travelled before the current falls to a predetermined fraction of its initial value. The method is well adapted to automatic control of electrolyte depth.

Abstract: The plant for the electrolytic production of a metal in a molten salt bath by deposition at the cathode in the solid state includes an outer casing, means for maintaining an atmosphere inert to the metal to be produced in the casing, a container within the casing and arranged to contain the molten salt bath and having a movable cover, a plurality of electrodes suspended in the molten salt bath each bearing on means for supporting it and connecting it electrically, the means comprising for each of the electrodes a pair of electrically conductive elements facing each other and supported respectively by two opposite walls of the container and handling means associated with the outer casing for removing any one of the electrodes from the container after raising of the movable cover.

Abstract: Disclosed are electrolytic cell and method in which first and second electrodes are adapted to pass a current through an inter-electrode zone of specified dimension for containing electrolyte, wherein the first electrode is held free from support by internal cell surfaces, and one electrode is provided with electrical connection to a liquid pad, e.g., of molten metal product, having a higher electrical conductivity than cell electrolyte.A preferred embodiment includes channeling gas from the anode, facilitating run-off of product liquid from the cathode, and incorporating bipolar electrode assemblies. The cell and method of the present invention are suitable for the production of a metal, for example, aluminum, from a compound of the metal, e.g., alumina, dissolved in an electrolyte, e.g., cryolite.

Abstract: An improved closed apparatus for conveying powder materials from a storage region to at least one region to be supplied. The apparatus includes at least one horizontal conveyor formed by a lower gas flow duct, an upper duct for flow of the powder and gas, and a porous wall separating the ducts. At least one conduit supplies gas to the lower duct, permitting the establishment of a pressure Pf. The conveyor is provided with at least one balancing column the height of filling of which balances the pressure Pf of the potential fluidization gas for the purpose of potentially fluidizing the material filling the conveyor.

Abstract: A process for measuring the potential of an indicator electrode of a transition metal, which dips into a bath of molten chlorides disposed in an electrolytic cell relative to a reference electrode. It is characterized by introducing into the bath an amount of alkali metal and/or alkaline earth fluorides such that the molar ratio of the fluorine contained in the bath to the amount of dissolved transitions metal is between 4 and 8.

Abstract: Disclosed is an electrolytic cell including first and second inclined or nonhorizontal electrodes, means for holding the first electrode in position relative to the second electrode to form an inter-electrode zone of specified dimension, wherein the first electrode is held essentially free from support by the internal surfaces of the cell, and conductive means for electrically connecting one electrode to a separate liquid pad of higher conductivity than the electrolyte.Also disclosed is an electrolytic method including establishing first and second inclined or nonhorizontal electrodes in relative position in an electrolytic cell to form an inter-electrode zone of specified dimension for containing an electrolyte, supporting the first electrode essentially free from support by an internal cell surface, and connecting one electrode electrically with a separate liquid pad of higher conductivity than the electrolyte.

Abstract: Lithium metal is continuously prepared by, in a specially adapted electrolytic cell, (i) continuously electrolyzing the lithium chloride which comprises a mixture of molten salts, which mixture comprises the medium of electrolysis and such medium of electrolysis naturally circulating within an interspace defined between the electrodes of the cell, said interspace being devoid of physical barrier between said electrodes, (ii) continuously withdrawing therefrom product lithium metal in admixture with the mixture of molten salts, and (iii) continuously discharging undiluted chlorine gas therefrom.

Abstract: A non-conductive plugger foot is disclosed for breaking through a solidified crust of electrolyte on an electrolytic reduction cell. The plugger foot includes a cylindrical sleeve having at least one downwardly depending leg attached thereto. The opposite end of the sleeve is connected to a vertically movable rod attached to a fluid or air actuated apparatus. A hollow cylindrical shell, which is closed at one end, is designed to receive the sleeve in its opposite end. The sleeve is inserted into the shell such that the leg is completely enclosed therein. The shell is then filled with a heat resistant, non-conductive refractory material which forms a permanent bond between the sleeve, the leg and the shell.

Abstract: An electrolytic cell for metal, particularly Mg, production includes a cathode or intermediate bipolar electrode having a cathodic face provided with a plurality of small cavities shaped to trap droplets of molten metal formed during electrolysis. The cavities help the metal droplets to coalesce and reduce the extent of back reaction with e.g. chlorine generated at the anode.

Abstract: In an electrolytic cell for the production of aluminum from alumina, having an anode-to-cathode gap of from 1 to 5 cm, the flow of electrolyte through the interelectrode gap is induced by positioning the cathode at an inclination of from about 2 to about 15 degrees from the horizontal, and operating at an anode current density of from about 0.5 to about 3.0 A/cm.sup.2. The cathode surface is a Refractory Hard Material which is wetted by aluminum.

Abstract: Silane, SiH.sub.

Abstract: An anode of reducing agent material particulates is introduced into an electrolytic solvent bath under compression. The carbon material is selected such that there is a minimum number of particle contacts. In such a selection, the contact surface area is important and is determined primarily by particle size. The compression of the anode is maintained greater than about 5 psi.

Abstract: A cell for the electrolytic reduction of alumina to aluminum comprises an electrolyte bath composed of halide salts having a density greater than aluminum but less than alumina. A non-consumable anode is located at the bottom of the bath, and a dimensionally stable cathode coated with titanium diboride is spaced above the anode and totally immersed in the bath. Particles of alumina are introduced into the bath where the alumina dissolves and forms ions of aluminum and oxygen. The oxygen ions are converted at the anode to gaseous oxygen which bubbles upwardly through the bath, agitating the bath. As a result, the bath is substantially saturated with dissolved alumina in the region of the anode, and the build-up of a layer of undissolved alumina on the anode is prevented. The aluminum ions are converted to metallic aluminum at the cathodes, and molten aluminum accumulates as a pool atop the bath above the cathodes.

Abstract: In a process for producing aluminum by electrolysis of alumina dissolved in a cryolite-based molten salt contained between a cathode and a plurality of previously baked carbon anodes which are consumed with evolution of oxides of carbon, the improvement including setting all anodes at the same time.

Abstract: This invention relates to an electrolysis process and cell for producing a metal by electrolyzing halides in a molten salt bath. It consists of using one cathode in the form of a basket, simultaneously passing a current I.sub.1 between this cathode and the anode in such a manner as to carry out a first deposit of crude metal in the basket and a current I.sub.2 between the said basket and the complimentary cathodes for depositing the final metal thereon. The cell consists of a central anodic system, a tubular cathodic basket surrounding the anode and a series of cathodes surrounding this basket, a positioning which can be reversed in relation to the basket. The invention finds its application in the continuous production of good quality refractory metal with a suitable material and electric yield.

Abstract: For cleaning purposes, residual anodes obtained in fused-salt electrolysis are rotated and exposed to a flow of striker bodies which knock the bath material off the residual anode. To this end it is particularly recommended to pivot the residual anode from a vertically suspended position to an inclined pivoted position, in which free-falling striker bodies strike the anode with sufficient force and clean the same.

Abstract: A device for the fused salt electrolysis of alkali metal halides by the Downs principle becomes operable on an expanded scale, by a process ensuring a favorable thermal economy of the cell, through the incorporation of a double bottom, an improved housing for receiving the anode sleeves, and a differentiatedly heat controllable base, shell, and cover construction with variable current load.

Abstract: In order to control a crust breaker featuring a chisel which can be moved up and down to break the crust on a fused salt electrolytic cell, an electric impedance measuring circuit comprising signal generator and registering instrument is connected between the chisel and the molten electrolyte. As such the generator is preferably in the form of an alternating signal generator, and DC signals, such as operating parameters of the cell and the voltage between the anodes and the cathode, are excluded from the impedance measuring circuit by means of DC neutralizing capacitors.

Abstract: In an electrolytic reduction cell in which molten metal is produced by electrolysis of a molten electrolyte, less dense than the molten metal product, the molten product metal collects at the bottom of the cell. A filter is provided at this location and is constructed from a material which is resistant to attack by both the molten metal and molten electrolyte, and which is wetted by the molten metal, but not by the electrolyte. By correcting sizing of the passage or passages in the filter molten metal product can be drawn out of the cell without simultaneous withdrawal of molten electrolyte. In the case of a cell for the production of aluminium the filter is preferably constructed from titanium diboride.

Abstract: Aluminum cells may be produced having cathode surfaces which are wetted by aluminum, said surfaces comprising Refractory Hard Materials in a non-graphitized carbon matrix. Such cells may utilize inclined or drained cathodes as well as non-consumable anodes.

Abstract: The device permits controlled batch feeding from a silo with at least one outlet opening and is particularly suitable for supplying alumina from a day's storage silo to the break in the crust on a fused salt electrolytic cell for producing aluminum. Flanged on to the silo outlet is a feed pipe running at an angle steeper than 45.degree. and joining up to the upper half of a containment pipe, likewise inclined steeper than 45.degree.. This containment pipe features at the bottom a compressed air supply line, at the top a receiving or braking chamber and connecting up to that a discharge pipe. By briefly opening the control valve at regular intervals, compressed air is forced into the containment pipe and the plug of particulate material lying there ejected into the receiving or braking chamber.

Abstract: Apparatus for removing frozen electrolyte bath from surface portions of an electrode body, the apparatus having crust breakers adapted to penetrate and fracture the crust which breaks into discrete pieces and which separates from the body. The crust breakers are attached to a frame through a linkage system which is adapted to move the breakers along a line of travel substantially adjacent to the salt encrusted surfaces of the body. With application of sufficient power to the crust breakers to penetrate and fracture the crust, substantially all of the crust is removed from the electrode body with minimal generation of dust and noise.

Abstract: A compressed air-powered retractor for an inert anode in a Hall-Heroult cell is actuated after power interruption by a time delayed solenoid actuating a valve controlling the air supply to a cylinder connected to the anode support structure.

Abstract: In an electrolytic reduction cell for the production of a molten metal by electrolysis of a molten electrolyte, the product metal collects on a cathodic carbon floor having embedded steel current collector bars for leading out the cathodic current. In order to reduce the wave motion of the metal due to interaction of horizontal currents in the product metal with the magnetic fields due to currents in conductors associated with the cell, electrically non-conductive barrier members are arranged on the floor of the cell transversely of horizontal currents in the product metal. Such barrier members have at least a surface layer of material resistant to product metal and extend upwardly from the cell floor to a height approximating to the normal maximum operating level of product metal.

Abstract: The invention relates to a process for thermally insulating precalcined anodes in cells for the production of aluminum by the electrolysis of alumina dissolved in an electrolysis bath based on molten cryolite, comprising covering the upper part of the anodes with a heat-insulating layer of alumina and/or ground electrolysis bath, in which process a strip of aluminum substantially equal in height to the heat-insulating layer is applied to the upper part of the anode and over its entire periphery.To facilitate positioning of the strip, a ledge to which the strip is applied is formed around the periphery of the anode.

Abstract: An apparatus for electrolysis of MgCl.sub.

Abstract: A manufacture, including a ceramic tube, and a metal liner within the tube and closer to one end of the tube than the other. A method of using such a manufacture wherein material such as subliming material is fed through the tube in the direction from the liner-close end to the liner-distant end.

Abstract: An apparatus for the precise adjustment of the anode plane of a cell for the production of aluminum by electrolysis of alumina dissolved in the molten cryolite of which the anodic system comprises a plurality of prebaked anodes arranged in two parallel lines and provided with suspension rods connected electrically to an anode bus bar which permits the positive intake of current.

Abstract: In an electrolytic reduction cell for aluminium production, the cathode is constituted by an array of upwardly open tubular elements (5) filled with molten metal and extending upwards from the molten metal pool (8) into the molten electrolyte (9). The metal within each tube is in open communication with the molten metal in the pool. The elements are of a material such as titanium diboride which is wetted by molten aluminium but not by molten electrolyte. The vertical tubes in the elements have an internal diameter, preferably of 0.5-2.5 cms, chosen so that the molten metal level therein is maintained at or close to the top of the tube by capillary action. Preferably the tubular elements extend about 1-4 cms up into the molten electrolyte layer and are positioned at a center-to-center spacing of 1.2 to 3 times their external diameter.

Abstract: The invention relates to a method for recovery in a furnace for producing aluminium by melting electrolysis of alumina. The furnace gases are passed through a bed (23) of alumina while the bed being fluidized around a tube coil (25). Then, heat exchange takes place between the furnace gases and an external fluid passing through the tube coil, for recovering heat energy in the furnace gases.

Abstract: Device and process for automatic, process-controlled feeding of electrolytic cells for producing aluminum. Besides a low degree of wear on the feed pipes, a fast and accurate feeding of fluxing agents to a particular cell is assured.