Abstract: An aluminum production electrolytic cell comprises a bath with bath contents, at least one cathode electrode in contact with said contents, at least one anode electrode in contact with said contents, and a hood, defining interior area, covering at least a portion of said bath. The electrolytic cell is equipped for vent gases to be drawn from said interior area. The electrolytic cell also comprises at least one heat exchanger for cooling at least a portion of the vent gases drawn from interior area, prior to circulation thereof to interior area.

Abstract: A gas cleaning unit for cleaning an effluent gas of at least one aluminum production electrolytic cell comprises a contact reactor in which the effluent gas is brought into contact with alumina, and a dust removal device for removing at least a portion of the alumina. The gas cleaning unit further comprises a wet scrubber in which the effluent gas is brought into contact with an absorption liquid containing water for removing further pollutants from the effluent gas. The wet scrubber is positioned at a point vertically higher than that of the dust removal device.

Abstract: A gas cleaning unit for cleaning a main raw gas stream from a plant comprises a plurality of gas cleaning chambers (34a-c), each gas cleaning chamber (34a-c) equipped with a cleaning chamber inlet (46a-c); an inlet manifold (32), for dividing said main raw gas stream flowing therethrough into a plurality of separate fractional raw gas streams for flow to said cleaning chamber inlets (46a-c); and a plurality of heat exchangers (40a-c), each heat exchanger (40a-c) being located downstream of the inlet manifold (32) for exchanging heat with a respective fractional raw gas stream entering a respective cleaning chamber (34a-c).

Abstract: The process involves pouring a smothering powder onto a spent anode placed on a support to cover it, with the aim of limiting fluorinated gas emission by the anode. The support may include a temporary tank, pre-filled with powder and provided with an opening for discharging the powder towards the anode on the support.

Abstract: The subject of the invention is an anode block (13, 13a-13e) made of carbon for a pre-baked anode (4) for use in a metal electrolysis cell (1) comprising a higher face (24), a lower face (23), designed to be laid out opposite a higher face of a cathode (9), and four side faces (21,22,34), and including at least one first groove (31a-31e) leading onto at least one of the side faces, in which the first groove has a maximum length Lmax in a plane parallel to the lower face, and characterized in that the first groove does not lead onto said lower or higher faces, or leads onto said lower or higher faces over a length L0 less than half the maximum length Lmax.

Abstract: A raw gas collection system (15) for collecting raw gas from a plurality of aluminium smelting pots (4) is equipped with a plurality of branch ducts (16, 16a-d). Each branch duct (16, 16a-d) is arranged to channel a respective branch flow (32, 32a-b) of raw gas from an aluminium smelting pot (4) to a collecting duct (20a), which is common to and shared by branch ducts (16, 16a-d). Several of the branch ducts (16, 16a-d) are equipped with a combined heat transfer and flow resistance generating element (17) to remove heat from the respective branch flow (32, 32a-b) of raw gas and to balance the flow of raw gas in the raw gas collecting system (15). The combined heat transfer and flow resistance generating elements (17) reduce the need for adjusting the respective branch duct (16, 16a-d) flow volumes using dampers, thereby reducing the power required to transport the raw gas through the system.

Abstract: An aluminium production electrolytic cell (4) comprises a bath (8) with bath contents (8a), at least one cathode electrode (10) in contact with said contents (8a), at least one anode electrode (6) in contact with said contents (8a), and a hood (16), defining interior area (16a), covering at least a portion of said bath (8). The electrolytic cell (4) is equipped for vent gases to be drawn from said interior area (16a). The electrolytic cell (4) also comprises at least one heat exchanger (52) for cooling at least a portion of the vent gases drawn from interior area (16a), prior to circulation thereof to interior area (16a).

Abstract: Systems, methods and apparatus for reducing impurities in electrolysis cells are disclosed. In one approach, a method includes feeding a particulate fines feed stream to a tank, mixing particulate fines (PF) with liquid, the liquid having a first liquid and a second liquid, and separating at least some of the first liquid from at least some of the second liquid. The particulate fines (PF) may include inlet carbon fines (CFI) and inlet recyclable fines (RFI). The first liquid may include a recovered recyclable fines portion (RF1), and the second liquid may include a waste carbon fines portion (CF1). The mass ratio of the recovered recyclable fines portion (RF1) to the inlet recyclable fines (RFI) may be at least about 0.5. The mass ratio of the waste carbon fines portion (CF1) to the inlet carbon fines (CFI) may be at least about 0.1.

Abstract: An electrolysis cell (10) contains a number of carbon anodes (12) having top, bottom and side surfaces, operating in molten electrolyte (17) in an aluminum electrolysis cell (10), where gas bubbles (28) are generated at the anode surfaces and where alumina particles (20) are added to the top of the molten electrolyte, where the carbon anodes (12) have at least two inward slots (21) passing through the carbon anode (12) along the longitudinal axis 40 of the carbon anode and also passing through only one front surface (25) of the carbon anode, where the height (32) of the slots (21) is from about 45% to 80% of the anodes thickness and the slotted front surfaces (25) are disposed toward the center of the electrolysis cell so that generated gas bubbles (28) are directed to the alumina particles.

Abstract: A method for electrolytic production of aluminium metal from an electrolytic (3) including aluminium oxide, by performing electrolysis, with at least one inert anode (1) and at least one cathode (2) thus forming part of an electorwinning cell. The anode evolves oxygen gas and the cathode has aluminium discharged onto it in the electrolysis process, where the oxygen gas enforces an electrolyte flow pattern. The oxygen gas is directed to flow into anode grooves and is drained away from the interpolar room, thereby establishing an electrolyte flow pattern between the electrodes (1) and (2) and between over the anodes (1). The invention also concerns and anode assembly and an electrowinning cell.

Abstract: A method for operating one or more electrolysis cells (43, 154, 243) for production of aluminium, the cell comprising inert or substantially inert anodes, where an oxygen containing gas (21, 126, 221) evolved by the electrolysis process in the cell is gathered and removed therefrom. The oxygen containing gas is introduced into a combustion chamber (38, 149, 238) where it is reacted with a carbon containing gas (7, 116, 209) in a combustion process. Emisions of CO2 and NOx can be reduced.

Abstract: An apparatus for collection and removal of gases emitted by an aluminum reduction cell is formed within an anode superstructure having two sidewalls spaced from each other. At least one gas transmitting channel having varying cross-section extends along the superstructure toward an end thereof associated with a gas treatment system. A plurality of gas input sections are provided within the superstructure and formed by a pair of spaced from each other members extending transversely to said sidewalls. At least one nozzle is formed at an interface between the gas transmitting channel and the respected gas input section. The ratio of cross-section area of the nozzle at an outlet thereof to a cross-section area of the gas transmitting channel and the output of the nozzle decreases in the direction of the end of the gas transmitting channel associated with the gas treatment system.

Abstract: Operations in an electrolytic cell for producing aluminum are controlled by sensing infrared radiation on an outer surface of a cell chamber to determine an actual temperature. When the actual temperature is greater than a target temperature, a crust hole is repaired or the actual rate of addition of aluminum fluoride to the cell is increased. When the actual temperature is less than a target temperature, the actual rate of addition of aluminum fluoride to the cell is reduced.

Abstract: Operations in a cell for electrolytic production of aluminum are controlled by establishing a standard rate of addition of aluminum fluoride to a molten electrolyte covered by a crust; establishing a target temperature for a duct carrying offgas from a chamber containing the molten electrolyte; measuring an actual temperature in the duct; and, in response to the actual temperature measurement in the duct, performing at least one of (1) when the actual temperature is greater than the target temperature, inspecting the crust for a crust hole and then repairing any observed crust hole, and (2) varying an actual rate of addition of aluminum fluoride to the electrolyte by increasing the actual rate above the standard rate when the actual temperature is greater than the target temperature and by reducing the actual rate below the standard rate when the actual temperature is less than the target temperature. Controlling operations in accordance with the invention improves cell energy efficiency.

Abstract: A method of maintaining molten salt concentration in a low temperature electrolytic cell used for production of aluminum from alumina dissolved in a molten salt electrolyte contained in a cell free of frozen crust wherein volatile material is vented from the cell and contacted and captured on alumina being added to the cell. The captured volatile material is returned with alumina to cell to maintain the concentration of the molten salt.

Abstract: The present invention concerns a method and device for reducing emissions of process gases from Hall-Héroult cells to the ambient air. The cells comprise an anode superstructure (1) with covers which can be opened for access to the cell's anodes, among other things. The anode superstructure comprises an extraction system for the removal of process gases, which extraction system is adjusted to remove a standised quantity of process gases during normal operation of the cell. The extraction system is designed so that an increased quantity of process gases is removed when the covers of the anode superstructure are opened. One embodiment of the present invention includes a vertical partition wall (10′) which is located inside the anode superstructure and contributes to an improved flow pattern in the anode superstructure.

Abstract: A cell for the electrowinning of aluminium comprises a plurality of metal-based anodes facing and spaced part from an aluminium-wettable drained cathode surface on which aluminium is produced. The drained cathode surface is formed along the cell by upper surfaces of juxtaposed carbon cathode blocks, the cathode blocks extending across the cell. The drained cathode surface is divided into quadrants by a longitudinal aluminium collection groove along the cell and by a central aluminium collection reservoir across the cell. Pairs of quadrants across the cell are inclined in a V-shape relationship, the collection groove being located along the bottom of the V-shape and arranged to collect molten aluminium draining from the drained cathode surface and evacuate it into the aluminium collection reservoir during cell operation.

Abstract: A cell of advanced design for the production of aluminium by the electrolysis of an aluminium compound dissolved in a molten electrolyte, has a cathode (30) of drained configuration, and at least one non-carbon anode (10) facing the cathode both covered by the electrolyte (54). The upper part of the cell contains a removable thermic insulating cover (60) placed just above the level of the electrolyte (54). Preferably, the cathode (30) comprises a cathode mass (32) supported by a cathode carrier (31) made of electrically conductive material which serves also for the uniform distribution of electric current to the cathode mass (32) from current feeders (42) which connect the cathode carrier (31) to the negative busbars.

Abstract: The present invention is directed to methods for preheating a molten salt electrolysis cell having inert anodes (24) using recuperative gas heating by combusting a first gas outside the cell chamber (20) in a combustion chamber (2) and using to heat a second gas in recuperator (8) which second gas us passed to the cell chamber (20). The inert anode can be a cermet inert anode.

Abstract: A method of maintaining molten salt concentration in a low temperature electrolytic cell used for production of aluminum from alumina dissolved in a molten salt electrolyte contained in a cell free of frozen crust wherein volatile material is vented from the cell and contacted and captured on alumina being added to the cell. The captured volatile material is returned with alumina to cell to maintain the concentration of the molten salt.

Abstract: The present invention is directed to methods for preheating a molten salt electrolysis cell having inert anodes (24) using recuperative gas heating by combusting a first gas outside the cell chamber (20) in a combustion chamber (2) and using to heat a second gas in recuperator (8) which second gas us passed to the cell chamber (20). The inert anode can be a cermet inert anode.

Abstract: An electrolytic cell and electrolytic process for producing a metal by reduction of a metal oxide dissolved in a molten salt bath containing at least one chloride and at least one fluoride. A solid conductor of oxide ions is interposed between the anode and the cathode. The solid conductor preferably comprises zirconia, stabilized in cubic form by addition of a divalent or trivalent metal oxide such as yttria.

Abstract: The present invention includes uranium-bearing ceramic phase electrodes and electrolysis apparatus and electrolysis methods featuring same, including methods of metal production and the like by the electrolytic reduction of oxides or salts of the respective metals. More particularly, the invention relates to an inert type electrode composition, and methods for fabricating electrode compositions, useful in the electrolytic production of such metals. The present invention also includes an inert-type electrode composition, and methods for fabricating electrode compositions, used in processes for generating energy from fossil fuels.

Abstract: A process is provided for removing fluorinated compounds, such as perfluorinated or partially fluorinated C1 to C4 hydrocarbons, NF.sub.3 and SF.sub.6, out of a gas by passing this gas through gamma alumina, wherein the temperature of the gamma alumina is between ambient temperature and 600.degree. C. The gas stream and the gamma alumina are anhydrous. The fluorinated compounds chemically react with the gamma alumina to result in a gas containing a diminished quantity of fluorinated compounds and an aluminum fluoride containing composition.

Abstract: A process for recovering at least one of CF.sub.4 and C.sub.2 F.sub.6 from a vent gas from an aluminum electrolysis cell. The process includes the steps of:(a) removing inorganic fluorides from a vent gas comprising inorganic fluorides and at least one of CF.sub.4 and C.sub.2 F.sub.6 to obtain a purified vent gas; and(b) contacting the purified vent gas with a membrane at conditions effective to obtain a retentate stream rich in at least one of CF.sub.4 and C.sub.2 F.sub.6, and a permeate stream depleted in at least one of CF.sub.4 and C.sub.2 F.sub.6.

Abstract: A process for changing spent anodes while recovering the majority of the gaseous compounds evolved by the spent anodes and by the bath crust removed from the electrolytic pots during the cooling phase uses an effluent-collection device for electrolytic pots. A device for collecting gaseous effluents from pots for the production of aluminum by igneous electrolysis allows the recovery of the gaseous compounds evolved by the spent anodes and by the crust which they contain during the replacement and cooling of these anodes and this crust. The device preferably includes a degassing and cooling container located at one of the ends of the hooding device of the pots. The container can be made to communicate with the suction produced by the gas collection device.

Abstract: An electrolytic cell for reduction of a metal oxide to a metal and oxygen has an inert anode and an upwardly angled roof covering the inert mode. The angled roof diverts oxygen bubbles into an upcomer channel, thereby agitating a molten salt bath in the upcomer channel and improving dissolution of a metal oxide in the molten salt bath. The molten salt bath has a lower velocity adjacent the inert anode in order to minimize corrosion by substances in the bath. A particularly preferred cell produces aluminum by electrolysis of alumina in a molten salt bath containing aluminum fluoride and sodium fluoride.

Abstract: The present invention relates to a method for closing and cooling of the top of a Soderberganode for use in connection with electrolytic production of aluminum, which anode is equipped with an anode casing and vertical contact bolts for holding and for conducting operating current to the anode and where the top of the anode casing is equipped with at least one cover having openings for the contact bolts and at least one off-gas opening. The amount of gas removed from the top of the anode through the off-gas opening is regulated in such a way that a sufficient diminished pressure is provided on the top of the anode that surrounding air will flow through air gaps arranged between the cover and each of the contact bolts in such an amount that gas from the top of the anode does not escape through the air gaps and to keep the temperature of the top of the anode casing below a preset temperature.