US3847761A - Bath control - Google Patents

Bath control Download PDF

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Publication number
US3847761A
US3847761A US00241607A US24160772A US3847761A US 3847761 A US3847761 A US 3847761A US 00241607 A US00241607 A US 00241607A US 24160772 A US24160772 A US 24160772A US 3847761 A US3847761 A US 3847761A
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United States
Prior art keywords
cell
aluminum chloride
resistance
bath
current
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Expired - Lifetime
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US00241607A
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English (en)
Inventor
W Haupin
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Howmet Aerospace Inc
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Aluminum Company of America
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Publication date
Application filed by Aluminum Company of America filed Critical Aluminum Company of America
Priority to US00241607A priority Critical patent/US3847761A/en
Priority to CA165,341A priority patent/CA992027A/en
Priority to GB1449173A priority patent/GB1386386A/en
Priority to ZA732114A priority patent/ZA732114B/xx
Priority to FR7312116A priority patent/FR2179099B1/fr
Priority to YU00899/73A priority patent/YU89973A/xx
Priority to DD169963A priority patent/DD103270A5/xx
Priority to SU731901968A priority patent/SU841597A3/ru
Priority to DE2317672A priority patent/DE2317672C3/de
Priority to CS732443A priority patent/CS203056B2/cs
Priority to HUAU298A priority patent/HU170661B/hu
Priority to AT298073A priority patent/AT336907B/de
Priority to CH486373A priority patent/CH577035A5/xx
Priority to IT49271/73A priority patent/IT980111B/it
Priority to PH14494A priority patent/PH12408A/en
Priority to PL1973161743A priority patent/PL93978B1/pl
Priority to NL7304873A priority patent/NL7304873A/xx
Priority to RO7374398A priority patent/RO78426A/ro
Priority to JP48038812A priority patent/JPS5215361B2/ja
Priority to BR732510A priority patent/BR7302510D0/pt
Application granted granted Critical
Publication of US3847761A publication Critical patent/US3847761A/en
Anticipated expiration legal-status Critical
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/20—Automatic control or regulation of cells

Definitions

  • PATENIE Luv 1 2mm 3.847.761 SHEEI 0F 4 POWER SOURCE f v /2 I j I /4 FIG. 6.
  • This invention relates to addition of aluminum chloride to the bath of one or more electrolytic cells for productionof aluminum therefrom by electrolysis of aluminum chloride. More particularly, it relates to making the addition of aluminum chloride to the bath responsive to the concentration of aluminum chloride in the bath, preferably as indicated by total effective cell resistance.
  • the desirable optimum operating level for concentration of aluminum chloride in the bath is above a point at which the alkali metal ions deposit and the voltage begins to rise rather suddenly.
  • the aluminum chloride concentration is greater than the optimum value, current efficiency is lowered. Accordingly, when I find the aluminum chloride concentration in the bath to be below a desired optimum operating level, I add more aluminum chloride to the bath, and, if above the optimum level, I add less or no aluminum chloride.
  • the aluminum chloride concentration may be measured by quantitative analysis of a bath sample, this is rather time consuming and the concentration may often become too low, or undesirably below the optimum operating level, before detection. Accordingly, it is desirable to use quicker methods of analyzing for the aluminum chloride concentration of the bath so that a quick response in adding aluminum chloride to the bath can be made to return the concentration to the desired optimum operating level when it departs there-- from to a greater extent than desired.
  • the total effective resistance (R of the cell is defined by formula R, [E-(NE)]/I, in which Eis the total cell voltage, N the number of electrolytic cell compartments and E the CEMF of each compartment cell and I is the current in amperes.
  • E is generally between 1.9 and 2.0 volts.
  • An exact measurement may be made of this fig ure, if desired, for example by current interruption.
  • I mean that the value NE can be read while the current is interrupted momentarily.
  • bipolar cells a plurality of compartments are employed, the compartments being formed usually by a plurality of bipolar electrode plates stacked between a terminal anode and a terminal cathode. For a monopolar cell N l.
  • the total effective cell resistance (R,,,) is made up of at least four factors, viz., (1) resistance of electrical leads and joints thereof, carrying current to the electrodes in the cell, a resistance which is readily measurable, (2) bath resistance, which decreases as concentration of aluminum chloride decreases, (3) resistance of chlorine 'bubbles in the bath and a bubble layer of chlorine which form at the anode and which first decreases as aluminum chloride concentration decreases, probably because the bubbles become larger as the concentration decreases and therefore rise more rapidly and get out of the way more rapidly and then increases as large bubbles start to cling to the anode, blocking current flow, and (4) an apparent resistance resulting from the CEMF rising as cathode overvoltage increases at low aluminum chloride concentrations, whilethe calculation of the apparent cell resistance (R assumes the value of E, the CEMF, to be constant.
  • One of the surprising things about the accuracy of the measurement of total effective resistance of the cell is its reliability in measuring aluminum chloride concentration of the bath when so many factors are to be taken into consideration in computing the total effective resistance or total voltage of the cell. This is further surprising because of the fact that the aluminum chloride concentration in the bath generally ranges from only about 2 to percent or so of the total composition of the bath, the remaining amount of the bath being the alkali metal or alkaline earth metal halide salt in which the aluminum chloride is dispersed.
  • the effective bath resistance may be calculated by the aforementioned equation R,,. [E(NE)]/l and compared with a desired optimum operating level or set point of resistance R.
  • This desired optimum operating resistance level or set point R may be established by chemical analysis of bath samples with simultaneous measurement of current and voltage to calculate R over a broad range of operating levels of aluminum chloride concentration.
  • the total effective cell resistance or total voltage at constant current may be correlated with aluminum chloride concentration in the bath determined by chemical analysis.
  • a feeder may be turned on when the measured total effective resistance (for example, as calculated by the above-given formula R,, [E-(NE)]/l from measurement by a digital voltmeter and ammeter joined to a computer or the like) is less than a predetermined optimum operating level.
  • the feeder rate may be set to supply aluminum chloride to the bath at a rate in excess of that required to maintain the desired optimum concentration of aluminum chloride in the bath, and, when the total effective resistance becomes higher than that indicated for the desired optimum operating level for aluminum chloride concentration, the feeder may once again be turned off until the total effective resistance drops to the desired level.
  • three feed rates may be used.
  • a normal or standard feed rate a set amount of aluminum chloride may be employed as determined to be from past experience the most efficient for maintaining optimum concentration of aluminum chloride in the bath.
  • This normal or'standard feed rate in lbs/sec. represented here by F may be determined by the equation F kNlC where k is 1.015 X 10 as calculated from the faraday and weight equivalents of AlCl N equals the number of compartments in the cell, 1 equals the current in amperes, and C equals an assumed current efficiency in percent known from operating experience.
  • the second feed rate in this embodiment is a high feed rate, for example, a rate of 5 to 20 percent in excess of the normal or standard rate
  • the third rate is a low rate, specifically, a rate, for example, of 5 to 20 percent below the normal rate.
  • a third embodiment of the invention is a proportional control method in which the feed rate for aluminum chloride is made proportional to the cell current and equal to the cell requirement at an assumed current efficiency C in percent when R R.
  • the feed rate is increased, or decreased in the case of negative values, proportional to RR,,,.
  • the feed rate F in lbs/sec. may be represented as F 1.015 X 10 NlC,, ⁇ l.0 [(RR,,,)K] ⁇ , where I is the current in amperes, C, the most recent measured current efficiency in percent, and K a proportional band constant adjusted by experience to give rapid response without over correction.
  • the regulation of the amount of aluminum chloride added to the cell electrolyte may be adapted as desired to fit the needs of the particular situation encountered.
  • aluminum chloride may be added at a desired predetermined or pre-calculated optimum or most efficient operating rate until the concentration of aluminum chloride in the cell bath, for example, as determined by a measure of the total effective cell resistance or total cell voltage at constant current, departs a prescribed amount oneither side of a predetermined or preestablished optimum operating level.
  • addition of aluminum chloride may be stopped altogether or the rate of addition decreased.
  • the addition of aluminum chloride may be increased, or, if a batch system is used in which a batch of aluminum chloride is added at the start of the opera-.
  • addition of another batch may be made, or addition of aluminum chloride may then be started at a pre-planned rate and continued at least until the measured total effective cell resistance or voltage drop once again approaches the predetermined or pre-established optimum operating level.
  • control system may be made substantially automatic, for example, by use of a computer tied in with an aluminum chloride feeder.
  • the computer can directly read the total voltage across the cell or calculate, from this reading and a reading of the current at whatever intervals are desired, the total effective resistance, in accordance with the formula given hereinabove.
  • the computer can relay a signal to the feeder when the concentration of aluminum chloride indicates that more or less aluminum chloride is to be added, or addition of aluminum chloride started or stopped, according to any one of the preceding addition plans, using the aforementioned predetermined optimum operating level of aluminum chloride and optimum operating total effective cell resistance and a designated amount of departure therefrom as the criteria for making adjustments in the rate or amount of adchloride to the cell bath by' the feeder.
  • the AlCl being fed to the cell may be either solid, liquid, dissolved in bath, or gaseous and may, if desired, be transported either solid or gaseous in dry gas such as Cl CO N etc.
  • AlCl may be added above the bath or under the bath in the cell or in an absorption chamber external to the cell through which bath from the cell circulates.
  • a computer may also be employed to take care of correcting certain situations encountered during electrolysis of aluminum chloride which are not accurately predictable.
  • the same computer may be employed to monitor the effect of a-change in feed rate on the changes in total effective cell resistance. If the total effective cell resistance changes in the opposite direction from the predicted, that is, if it does not begin to approach the predetermined optimum operating level for concentration of aluminum chloride when more or less aluminum chloride is added in response to its departure from a predesignated efficient or opti .mum operating level, for example, as determined by whether the measured resistance is less than or more than a predetermined optimum value, but continues to depart either further upwardly or downwardly from said optimum level or value, both the computer and an operator know that the total effective resistance has passed the minimum for safe operation of the cell on the standard curve of total effective cell resistance or total voltage across-the cell versus concentration of aluminum chloride in percent, and is operating on the other side or reverse side of the standard operating slope for R or total effective cell resistance or voltage, that is, has reached the point where an increase in
  • cell current may be interrupted momentarily to avoid cathode attack before the aluminum chloride concentration can be replenished to solve the problem. If the total effective cell resistance or voltage continues to rise, the cell current may be interrupted automatically when a predetermined maximum value is reached and remain off until appropriate corrective measures have been taken so that the automatic system may be continued.
  • a computer-cell interface of such a system may consist, for example, of a group of capacitors which transfer voltage and current information through a conventional analogto-digital converter to a computer.
  • the system On the output side of the computer, the system may consist, for example, of contact closures to control feeders and adjust current.
  • the input capacitors provide isolation between the signal source and the computer and remove signal noise, which is typified by extreme or radical fluctuations in current and/or voltage.
  • a signal maybe averaged over any desired period and at the same time the greatest weight given to the data most recently received and used by the computer.
  • Resistors may also be used to attenuate the signal to a level best suited for the analog-to-digital converter.
  • such a computer In operation such a computer periodically scans current and voltage in sequence to each cell. To do this it sends a signal to an actuating device which causes the capacitor associated with each cell and a current measuring device to be switched'from the current measuring device and cell to the analog-to-digital converter for the period required for a reading, which is generally less than 1/200 second. Signals enter the computer from the converter wherein the above-described calculations are made. The computer then sends an electrical impulse or a series of electrical impulses to a feeder control on each cell requiring correction. These impulses increase or decrease the feed rate as required, for example, by activating a stepping switch.
  • FIG. 1 shows a representative breakdown in graphical form of the voltage components on a percompartment basis of an aluminum chloride cell for production of aluminum.
  • FIG. 2 plots representative curves of cell volts per compartment and effective resistance per square inch of electrode surface per compartment against percent aluminum chloride in a bipolar cell where the current density is maintained at approximately amp/m
  • the curve plotting cell volts versus percent aluminum chloride in FIG. 2 shows an abrupt increase in voltage for average conditions at a concentration of aluminum chloride less than about 2 percent. Such an abrupt increase in cell voltage can generally be avoided by maintaining the aluminum chloride concentration above about 4 percent by weight. With good conditions (i.e., relatively pure aluminum chloride and the bath at appropriate temperature) the abrupt increase in voltage will occur at a lower aluminum chloride concentration, permitting safe operation as low as 1.5 percent .aluminum chloride.
  • FIG. 3 is a graphical representation showing, for an approximately 45 minute period of operation of an aluminum chloride cell, how, according to the present invention, the concentration of aluminum chloride in a cell bath may be maintained at near an optimum operating level by addition of aluminum chloride when the measured resistance departs more than a desired amount from said optimum .operating level.
  • FIG. 3 includes a graphical plotting of both percent aluminum chloride and resistance versus a short part of the duration of operation of a respective cell in time (minutes). As indicated on the graph, both resistance and percent AlCl were brought back up to an optimum operating level of about 5.3 in this particular instance for the percent AlCl and the resistance (ohms X 10 of 2.3.
  • FIG. 4 is a schematic representation or diagram showing a computer employed to read the total voltage drop across electrolysis cells or total effective cellv resistance and respond to such reading by sending commands to feeders for cells according to their individual needs when the readings depart beyond the desired or set deviation from that indicating a predesignated optimum operating level for concentration of aluminum chloride in the cell bath.
  • FIG. 5 is a schematic depiction of a representative batch type feed control relay system employable with the feed control arrangement of FIG. 4 and FIG. 6 depicts a continuous, variable speed feed arrangement for a relay system employable with the feed control arrangement of FIG. 4.
  • each cell may comprise several compartments in a bipolar electrode arrangement.
  • one second is used for a representative time constant of the RC circuits shown in FIG. 4, as described in detail hereinafter. This time constant value may be changed, if desired, and is subject to adjustment to prevent any deterioration in control.
  • a digital computer 1 is employed to read the total voltage drop across each of a plurality of electrolysis cells 2 to Zn and to measure the current flowing through each cell by use of a suitable current measuring device 3 serially connected in the circuit of the cells. Since the current and voltage of the cells are analog signals, an analog-to-digital converter 4 is shown to provide the computer with digital representations of cell current and voltage signals.
  • the cells 2 and the current measuring device 3 are connected to resistor-capacitor (RC) circuits which function to prevent extraneous electrical noise from reaching the computer, and to provide current and voltage representative signals that are averaged over a predetermined period of time while simultaneously presenting to the computer a weighted value signal representative of the most recent cell conditions relative to current and voltage.
  • RC resistor-capacitor
  • the RC circuit of the current measuring device 3 is comprised of two resistors R, and a capacitor C, connected across the current measuring device.
  • the RC circuit for each cell 2 comprises resistors R R and R and a capacitor C.
  • resistors R and R attenuate the voltage from each cell to a level suitable for use by the converter 4.
  • the converter 4 operates with a millivolt signal input. If the current measuring circuit provides an output signal of a voltage level comparable to that of an electrolytic cell, then a converter operative with a comparable voltage input would be used, and resistors R and R, would not be necessary.
  • switch pairs S, to S, are shown connecting the capacitors C through C to their respective resistor circuits.
  • Such switches may be sequentially operated on commands from the computer 1, as indicated diagrammatically in FIG. 4 by arrow lines SC, to complete a circuit between the capacitors and the converter 4. The switches are momentarily operated and then snapped back upon command from the computer.
  • the voltages stored therein are conducted to the converter and computer, and the computer reads these voltages and makes a calculation therefrom, and from those previously read and stored therein, to determine if the total effective resistance R of each cell is within a permissible range for operating level of aluminum chloride concentration, or ifthe a concentration is above or below the permissible range.
  • the feeders 6 may be of any type suitable for conveying the aluminum chloride to the cells. They may be, for example, motor operated screw conveyors, or they may be gravity feed conveyors in which solenoid operated, pneumatic valves permit the aluminum chloride to be admitted to the cell in batches or slugs from a tubular conveyor, or they may be valves that admit liquid or gaseous AlCl I
  • the computer shown in FIG. 4 has been described as a digital computer, and is preferred in the present invention, an analog computer will function to control aluminum chloride level. In such a case, of course, an analog-to-digital converter would not be necessary, and some of the corrective logic provided by a digital computer would be available.
  • FIG. 5 a batch or slug type of feed arrangement is diagrammatically illustrated in which an output interface 10 of the computer 1 (of FIG. 4) is employed to control a relay. device 12 of a feeder actuating means 14.
  • the computer calculates the total effective resistance of the cell by use of the formula given hereinabove. If this calculated resistance is within a permissible variation on either side of a predetermined or pre-established optimum operating level, no corrective action is taken by the computer.
  • a signal is sent from the interface 10, via contacts 15 within the interface, and lines 16, to the relay device 12 which supplies power to the feeder actuating means 14, which means, as explained above in connection with the feeders 6, may be solenoid operated pneumatic valves which supply aluminum chloride in slugs or batches.
  • the addition of aluminum chloride is stopped via the same circuitry when the computer 1 receives a signal from the RC network (FIG. 4) associated with the cell indicating a total effective resistance value which exceeds the preplanned permissible variation on the upper side.
  • an output interface of the computer 1 provides a variable speed, continuous control arrangement for feeding the cells 2. This is accomplished with a bidirection contact closure device 22 in they output interface.
  • v When the system is operating with aluminum chloride being added at a predetermined optimum operating rate, if the total effective resistance as calculated from the-voltage relayed to the computer 1 from a cell 2 is greater than a predetermined optimum operating resistance, the rate of addition of aluminum chloride to the cell 2 is decreased by transmission of a signal from the interface to a bi-directional stepping motor 23 If, however, the total effective resistance of a cell 2 calculated by the computer 1 is within the aforementioned predetermined permissible variation, the contacts 22 in the interface 20 remain open so that no signal is transmitted to the stepping motor 23, thereby causing aluminum chloride to continue to be added at the predetermined optimum operating rate.
  • the contacts 22 in the interface are operated to direct a signal to the stepping motor 23, via line pair 26 and 27, which causes the feeder motor 32 to increase the rate at which a feeder 6 supplies a cell 2 with aluminum chloride to a preset rate higher than the aforementioned optimum operating rate.
  • EXAMPLE I Measurements were made every three seconds over approximately a 69-second period of operation of an aluminum chloride cell of current, voltage and resistance, with sufficient aluminum chloride being added in response to deviation below an optimum 0.00251 ohm until the optimum was restored and addition then cutoff. A substantially constant concentration of about 5.3 to 5.7 percent aluminum chloride was thus maintained in the cellbath.
  • the following Table I records the values for current I (amperes), voltage E (volts), resistance R, percent AlCl, in the bath determined by independent measurement, using an electrical conductivity meter precalibrated to read percent AlCl and approximate times at which a computer command went to the AlCl feeder to turn on or turn off in a fourcompartment cell. In this example, the feed automatically went on when the resistance became equalto or less than 0.00250 ohm and off when it became greater than 0.00250 ohm.
  • EXAMPLE 11 While the invention has been described in terms of Aluminum was produced by electrolysis of aluminum chloride using a computer to control various levels of concentrations of aluminum chloride in the cell, for example, as described hereinabove, at a bath (solvent) composition of about 50 percent NaCl and about 50 percent LiCl.
  • Aluminum chloride (AlCl was added and controlled at the following levels: 3.5 percent, 5 percent, 6 percent, 7 percent and 8 percent.
  • Bath. temperature ranged from about 700 to 710 C, the period of operation being days.
  • the current ranged from 1,000 to 3,000 amperes and the voltage from 9.8 to about 14.8. 3,000 pounds of aluminum were produced and 15,000 pounds of aluminum chloride consumed in a four-compartment cell.
  • EXAMPLE Ill The following Tablell shows data accumulated during minutes of a 2-month period of operation of a four-compartment bipolar cell for electrolytic production of aluminum from aluminum chloride added in response to concentration of AlCl in the cell as indicated by total effective cell resistance calculations made from measured voltage and current.
  • the aluminum chloride concentration in the cell bath was controlled by measurement of bath resistivity during a portion of the 2- month period and by a computer control arrangement whereby the total effective cell resistance was measured the balance of the time.
  • the computer turned the aluminum chloride feeder on and off at a predetermined total effective resistance for the cell.
  • the feeder status of on or off at the indicated times is shown in the table.
  • the total effective resistance for the cell was determined by the computer using the equation R (E4E)/l.
  • the resistance and current for any given cell depends upon the size of the cell, typical cell resistance being shown in Tables 1 and 11.
  • the feeder was turned on when R,, s 0.00209 and off when R 0.00209 ohm.
  • a method for operating a cell for the electrolytic production of aluminum from aluminum chloride which comprises:
  • a method for operating an electrolytic cell for the production of aluminum wherein aluminum chloride dissolved in a molten salt bath is converted to aluminum metal by passing electric current through said bath comprising:

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
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US00241607A 1972-04-06 1972-04-06 Bath control Expired - Lifetime US3847761A (en)

Priority Applications (20)

Application Number Priority Date Filing Date Title
US00241607A US3847761A (en) 1972-04-06 1972-04-06 Bath control
CA165,341A CA992027A (en) 1972-04-06 1973-03-06 Bath control
GB1449173A GB1386386A (en) 1972-04-06 1973-03-26 Control of electrolytic bath for aluminium production
ZA732114A ZA732114B (en) 1972-04-06 1973-03-27 Bath control
YU00899/73A YU89973A (en) 1972-04-06 1973-04-04 Process for obtaining aluminium by electrolysis of aluminium chloride
FR7312116A FR2179099B1 (de) 1972-04-06 1973-04-04
AT298073A AT336907B (de) 1972-04-06 1973-04-05 Verfahren zur regelung der aluminiumchloridzugabe in einer schmelzflusselektrolysenzelle zur gewinnung von aluminium
DE2317672A DE2317672C3 (de) 1972-04-06 1973-04-05 Verfahren zur elektrolytischen Gewinnung von Aluminium in einer Elektrolysezelle
CS732443A CS203056B2 (en) 1972-04-06 1973-04-05 Method for the electrolytic production of aluminium
HUAU298A HU170661B (de) 1972-04-06 1973-04-05
DD169963A DD103270A5 (de) 1972-04-06 1973-04-05
CH486373A CH577035A5 (de) 1972-04-06 1973-04-05
IT49271/73A IT980111B (it) 1972-04-06 1973-04-05 Regolazione del bagno elettrolitico per produrre alluminio dal suo cloruro
SU731901968A SU841597A3 (ru) 1972-04-06 1973-04-05 Способ регулировани подачиСыРь B элЕКТРОлизЕР дл пОлучЕНи АлюМиНи
PL1973161743A PL93978B1 (de) 1972-04-06 1973-04-06
NL7304873A NL7304873A (de) 1972-04-06 1973-04-06
RO7374398A RO78426A (ro) 1972-04-06 1973-04-06 Procedeu de obtinere a aluminiului
JP48038812A JPS5215361B2 (de) 1972-04-06 1973-04-06
PH14494A PH12408A (en) 1972-04-06 1973-04-06 Bath control
BR732510A BR7302510D0 (pt) 1972-04-06 1973-04-06 Processo aperfeicoado de controle da concentracao de cloreto de aluminio na operacao de uma celula eletrolitica

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US00241607A US3847761A (en) 1972-04-06 1972-04-06 Bath control

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US00241607A Expired - Lifetime US3847761A (en) 1972-04-06 1972-04-06 Bath control

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US (1) US3847761A (de)
JP (1) JPS5215361B2 (de)
AT (1) AT336907B (de)
BR (1) BR7302510D0 (de)
CA (1) CA992027A (de)
CH (1) CH577035A5 (de)
CS (1) CS203056B2 (de)
DD (1) DD103270A5 (de)
DE (1) DE2317672C3 (de)
FR (1) FR2179099B1 (de)
GB (1) GB1386386A (de)
HU (1) HU170661B (de)
IT (1) IT980111B (de)
NL (1) NL7304873A (de)
PH (1) PH12408A (de)
PL (1) PL93978B1 (de)
RO (1) RO78426A (de)
SU (1) SU841597A3 (de)
YU (1) YU89973A (de)
ZA (1) ZA732114B (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4654130A (en) * 1986-05-15 1987-03-31 Reynolds Metals Company Method for improved alumina control in aluminum electrolytic cells employing point feeders
US20070295615A1 (en) * 2006-06-27 2007-12-27 Alcoa Inc. Systems and methods useful in controlling operations of metal electrolysis cells
US20170370017A1 (en) * 2016-06-27 2017-12-28 Tel Nexx, Inc. Wet processing system and method of operating

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Publication number Priority date Publication date Assignee Title
FR2487386A1 (fr) * 1980-07-23 1982-01-29 Pechiney Aluminium Procede et appareillage pour reguler de facon precise la cadence d'introduction et la teneur en alumine d'une cuve d'electrolyse ignee, et application a la production d'aluminium

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GB272246A (en) * 1926-06-07 1927-11-10 Aluminium Ind Ag Improved process for the electrolytic extraction of pure aluminium from crude aluminium, alloys and the like
GB687758A (en) * 1951-02-27 1953-02-18 Ind De L Aluminium Sa A process for producing molten aluminium by electrolysis of aluminium chloride
US2919234A (en) * 1956-10-03 1959-12-29 Timax Associates Electrolytic production of aluminum
US3400062A (en) * 1965-05-28 1968-09-03 Aluminum Co Of America Method of controlling aluminum content during aluminumg electrolysis
US3573179A (en) * 1965-12-14 1971-03-30 Ibm Method and apparatus for the control of electrolytic refining cells
US3712857A (en) * 1968-05-20 1973-01-23 Reynolds Metals Co Method for controlling a reduction cell

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FR1243741A (fr) * 1959-12-29 1960-10-14 Procédé de production de l'aluminium très pur
US3625842A (en) * 1968-05-24 1971-12-07 Kaiser Aluminium Chem Corp Alumina feed control

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Publication number Priority date Publication date Assignee Title
GB272246A (en) * 1926-06-07 1927-11-10 Aluminium Ind Ag Improved process for the electrolytic extraction of pure aluminium from crude aluminium, alloys and the like
GB687758A (en) * 1951-02-27 1953-02-18 Ind De L Aluminium Sa A process for producing molten aluminium by electrolysis of aluminium chloride
US2919234A (en) * 1956-10-03 1959-12-29 Timax Associates Electrolytic production of aluminum
US3400062A (en) * 1965-05-28 1968-09-03 Aluminum Co Of America Method of controlling aluminum content during aluminumg electrolysis
US3573179A (en) * 1965-12-14 1971-03-30 Ibm Method and apparatus for the control of electrolytic refining cells
US3712857A (en) * 1968-05-20 1973-01-23 Reynolds Metals Co Method for controlling a reduction cell

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4654130A (en) * 1986-05-15 1987-03-31 Reynolds Metals Company Method for improved alumina control in aluminum electrolytic cells employing point feeders
US20070295615A1 (en) * 2006-06-27 2007-12-27 Alcoa Inc. Systems and methods useful in controlling operations of metal electrolysis cells
US20170370017A1 (en) * 2016-06-27 2017-12-28 Tel Nexx, Inc. Wet processing system and method of operating

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CA992027A (en) 1976-06-29
BR7302510D0 (pt) 1974-07-18
PL93978B1 (de) 1977-07-30
DE2317672B2 (de) 1978-09-07
RO78426A (ro) 1982-12-06
DD103270A5 (de) 1974-01-12
DE2317672A1 (de) 1973-10-18
SU841597A3 (ru) 1981-06-23
YU89973A (en) 1982-02-28
ZA732114B (en) 1974-01-30
ATA298073A (de) 1976-09-15
PH12408A (en) 1979-02-07
IT980111B (it) 1974-09-30
CS203056B2 (en) 1981-02-27
AT336907B (de) 1977-06-10
GB1386386A (en) 1975-03-05
JPS499412A (de) 1974-01-28
NL7304873A (de) 1973-10-09
FR2179099B1 (de) 1975-04-04
DE2317672C3 (de) 1979-04-26
CH577035A5 (de) 1976-06-30
HU170661B (de) 1977-08-28
JPS5215361B2 (de) 1977-04-28
FR2179099A1 (de) 1973-11-16

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