US20070095672A1 - Method of controlling aluminum reduction cell with prebaked anodes - Google Patents

Method of controlling aluminum reduction cell with prebaked anodes Download PDF

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Publication number
US20070095672A1
US20070095672A1 US11/592,557 US59255706A US2007095672A1 US 20070095672 A1 US20070095672 A1 US 20070095672A1 US 59255706 A US59255706 A US 59255706A US 2007095672 A1 US2007095672 A1 US 2007095672A1
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Prior art keywords
cell
alumina
anode
anodes
concentration
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Abandoned
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US11/592,557
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English (en)
Inventor
Eugeniy Shaidulin
Alexander Gusev
Peter Vabischevich
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RUSAL ENGINEERING AND TECHNOLOGICAL CENTER
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RUSAL ENGINEERING AND TECHNOLOGICAL CENTER
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Assigned to RUSAL, ENGINEERING AND TECHNOLOGICAL CENTER reassignment RUSAL, ENGINEERING AND TECHNOLOGICAL CENTER ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: GUSEV, ALEXANDER O., SHAIDULIN, EUGENIY E., VABISCHEVICH, PETER N.
Publication of US20070095672A1 publication Critical patent/US20070095672A1/en
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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

  • This invention relates to aluminum production by electrolysis of alumina. More particularly, the invention relates to control processes for electrolytic cells utilizing prebaked anodes and improving the respective control of alumina feeding systems.
  • sludge undissolved alumina and bath deposits
  • An alumina deficiency causes the occurrence of the ‘anodic effect’ or ‘racing’ phenomenon, which causes an abrupt increase in the voltage at the terminals of the cell, which can go from 4 to 30 or 40 volts, and which has repercussions on the entire production process. This occurs because of the increased anode over potential and therefore, the metal production in all of the cells in the potline is lowered.
  • the control of aluminum feeding systems needs a rate of feed which is neither too rich nor too lean.
  • Control of alumina concentration is a critical task in electrolysis control technology and rate of control of existing alumina feeding systems are necessary to maintain feed within preset limits. Such control systems must allow no deviation because both repetitive occurrences of anode effects and excessive sludge interfering with the cathode operation are technologically unacceptable.
  • USSR Inventor's Certificate No. 1724713 discloses a prior art method for automatically controlling an aluminum reduction cell. According to this method cell voltage and potline current are measured. Then, calculations determine the “normalized” cell voltage, the rate of change thereof, and the alumina concentration in the bath. The control “normalized” voltage within the preset limits of the anode movement and with respect to the variation of the feed rate of alumina into the cell. Simultaneously the frequent overfeed and rare underfeed modes are alternated. The feeding modes are changed depending upon variations of the normalized voltage. During this process, either alumina feeding into the cell is completely terminated or one or the other feeding mode is turned on for a certain time.
  • the above-discussed prior art control method is based on the known relationship between the cell voltage U cell and the alumina concentration within the bath C Al .
  • every change in the voltage is subject only to change in the alumina concentration of the bath.
  • the method of the invention can be utilized to control processes in the aluminum reduction cells with prebaked anodes, so as to improve the quality of controlling the alumina feeding systems.
  • the method consists of the steps of measuring present electric current, comparing the value of the present electrical current with the predetermined values thereof, and maintaining such present values within preset limits by regulating the amount of alumina charged into the cell.
  • an area of reduced alumina concentration is identified in the cell by measuring the existing, present electrical current values.
  • the area of reduced alumina concentration can be also identified by reviewing the rate of increase of the back EMF value at each anode independently of other anodes in the cell.
  • a control a signal is generated by the control system to a specific feeder of the alumina feeding system to raise alumina concentration in the area of reduced alumina concentration to predetermined levels.
  • One object of the invention is to automatically control the level of alumina concentration C al within the cell and to stabilize the same at a preset level within the cell volume.
  • FIG. 1 is front elevational view showing partially in a cross-section an aluminum reduction cell with a measuring system of the invention
  • FIG. 2 is a diagram of anode current load prior to and during the occurrence of the anode effect.
  • FIG. 3 is a diagram of algorithm illustrating operation of the control system of the reduction cell, wherein Block 1 is the diagram reflecting operation of the control system according to prior art, and Block 2 is the diagram illustrating operation of the control system of the invention.
  • FIG. 1 showing a partial cross-sectional view of an aluminum reduction cell with a measuring system of the invention.
  • a plurality of prebaked anodes 1 are disposed within the cell and are combined with a system for measuring electric current.
  • Each anode 1 is provided with electric load measuring transducer 2 for detecting and directing signals to a control and data acquisition unit 3 .
  • the current at each individual anode is measured and evaluated independently of other anodes in the system.
  • information about the electrical current load at each individual anode is collected, accumulated and analyzed. These data form the basis for the dynamic analysis of the electrical current load change at each anode.
  • Each anode of the cell is assigned to a predetermined area.
  • the concentration of alumina in this area is maintained by a predetermined feeder of the alumina feeding system.
  • Reduction of the electrical current load in a single anode or in the group of the anodes is considered as the local reduction of alumina concentration.
  • FIG. 2 which is a diagram reflecting the anode current load prior to and during the occurrence of the anode effect.
  • the diagram illustrates considerable reduction of the electrical load in individual anodes relative to other anodes of the cell (see for example, anode No. 4 and anode No. 12 ). This load reduction is indicative of isolation of the anode working surface by a gas film.
  • the alumina concentration decreases in this bath area in the vicinity of the respective anodes.
  • the alumina concentration in the bath decreases the wetting of the anode by the bath declines, and as a result, gas bubbles on the anode surface enlarge causing at least partial isolation of the anode surface from the bath.
  • the isolation increases, so does the current density on the free surface of the anode.
  • the data reflecting this condition is predicative of the anode effect, as further deterioration of this process generally results in just such an occurrence. In the diagram of FIG. 2 this undesirable development takes place at the time spot 12:52.
  • a responsive signal is generated by the control system of the invention for the control of the feeder associated with the area of the cell adapted to accommodate the monitored anodes.
  • Operational mode of the respective feeder is chosen on the basis of the existing, present mode of the cell operation.
  • this feeder functions with increased operational frequency compare to other feeders of the system.
  • the increased rate of alumina feeding is carried out for a predetermined time interval or until the electrical load in the respective anodes starts to increase.
  • the method of controlling an aluminum reduction cell with prebaked anodes of the invention consists of the steps of measuring the present values of the current, comparing the present current values with preset values thereof and maintaining such values within preset limits by regulating the amount of alumina charged into the cell.
  • an area of reduced alumina concentration within the cell is defined by measuring the existing, present values of the current in each anode of the cell independently of other anodes.
  • a specific automatic alumina feeder is associated with the group of neighboring anodes.
  • the electric current reduction in an individual anode or a group of anodes is detected and measured. Such current reduction is being evaluated comparative to the electric current in other anodes or a group of anodes of the cell.
  • the rate of feeding of alumina is increased into the bath area in the vicinity of the reduced alumina concentration.
  • the rate of feeding of alumina is increased relative to the typical feeding rate of alumina into the bath.
  • FIG. 3 it reflects a combined diagram of algorithm illustrating operation of the control system of the reduction cell, wherein Block 1 is the diagram showing operation of the control system according to prior art, and Block 2 is the diagram illustrating operation of the control system of the invention. These diagrams will be discussed in detail with respect to the embodiment of Example 1.
  • the area of reduced alumina concentration is identified by verifying the rate of increase of back EMF value in each anode or group of anodes of the cell.
  • the value of the back EMF is determined by reviewing changes of the total electric current passing through all anodes of the cell. Utilization of the back EMF value for the purposes of the invention are discussed in detail with respect to the embodiment of Example 2.
  • the area of reduced alumina concentration within the cell is defined by measuring present electrical current values in all anodes of the cell independently of each other. Upon detection of such area, the alumina concentration in this area is increased until a predetermined level of concentration is reached. To carry out this task a signal is generated by the control system of the cell to respective feeder of the alumina feeding system. As a result the rate of alumina feeding is increased
  • the method of the invention it is possible to predict the occurrence of an anode effect and to anticipate the situation by providing earlier warning signals of the need to change the alumina concentration. Furthermore, the method of the invention is reflected in the improved alumina feeding control algorithm.
  • An example of such algorithm is illustrated in the Block 2 of the diagram illustrated in FIG. 3 .
  • the control system of the invention operates as follows. The existing current load at a specific anode of the cell is measured and compared to the previous value thereof.
  • the difference ⁇ Ii (where i is the number of the respective anode) between the existing and previous current load values is calculated.
  • a signal is generated by the control system, so as to regulate the alumina concentration in the cell.
  • This feeder is directly associated with the area of the cell having reduced alumina concentration.
  • the area with the reduced level of alumina concentration is evaluated according to the change of the reverse EMF which is calculated for each anode of the cell.
  • the reverse EMF values for each individual anode are calculated by the same method as for the entire cell.
  • the values of the reverse EMF of the anodes are compared to each other and the area with reduced alumina concentration is determined.
  • a respective signal is generated for the feed control system of the invention to regulate to the level of alumina concentration in the cell. To accomplish this task the alumina feeding rate by one of the feeders is increased.
  • Utilization of the method of the invention results in the improved distribution of alumina concentration in the cell bath volume. Evaluation of the reverse EMF values provides reliable and earlier diagnostic of the forthcoming anode effect. All of the above result on the improved quality control and stability of the cell operation and enhances the anticipatory aspects of the feeding system control functions.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
US11/592,557 2005-11-02 2006-11-02 Method of controlling aluminum reduction cell with prebaked anodes Abandoned US20070095672A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
RU2005133936/02A RU2303658C1 (ru) 2005-11-02 2005-11-02 Способ управления технологическим процессом в алюминиевом электролизере с обожженными анодами
RURU2005133936 2005-11-02

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US (1) US20070095672A1 (ru)
AR (1) AR058504A1 (ru)
AU (1) AU2006235828A1 (ru)
BR (1) BRPI0605050A (ru)
CA (1) CA2566831A1 (ru)
NO (1) NO20065036L (ru)
RU (1) RU2303658C1 (ru)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102400182A (zh) * 2011-11-22 2012-04-04 中国铝业股份有限公司 一种控制铝电解槽内氧化铝浓度稳定均匀的方法
CN102758219A (zh) * 2011-04-29 2012-10-31 沈阳铝镁设计研究院有限公司 利用阳极导杆等距压降预测阳极效应的方法
WO2012146060A1 (zh) * 2011-04-29 2012-11-01 中铝国际工程股份有限公司 阳极效应抑制与熄灭的方法和设备
CN102851704A (zh) * 2011-06-30 2013-01-02 沈阳铝镁设计研究院有限公司 铝电解槽下料器单点控制下料方法
CN103014773A (zh) * 2012-11-26 2013-04-03 中国铝业股份有限公司 一种均衡铝电解槽氧化铝浓度的装置及方法
WO2013075376A1 (zh) * 2011-11-22 2013-05-30 中国铝业股份有限公司 抑制铝电解槽非阳极效应全氟化碳产生的方法及其系统
CN103952725A (zh) * 2014-05-16 2014-07-30 北方工业大学 一种工业铝电解过程中的决策方法
CN104499001A (zh) * 2015-01-20 2015-04-08 重庆科技学院 基于特征子空间优化相对矩阵的铝电解槽况诊断方法
EP3417095A4 (en) * 2016-02-15 2019-11-13 Dubai Aluminium PJSC METHOD FOR ESTIMATING DYNAMIC STATE SIZES IN AN ELECTROLYZIC CEMENT SUITABLE FOR THE HALL-HÉROULT ELECTROLYSIS PROCESS
CN113362912A (zh) * 2021-04-29 2021-09-07 中南大学 一种氧化铝浓度二次仿真方法、系统及存储介质

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2135975A1 (en) 2008-06-16 2009-12-23 Alcan International Limited Method of producing aluminium in an electrolysis cell
CN106460210B (zh) * 2014-06-19 2019-01-11 俄铝工程技术中心有限责任公司 用于控制向用于生产铝的电解池进料铝的方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3629079A (en) * 1968-02-23 1971-12-21 Kaiser Aluminium Chem Corp Alumina feed control
US4035251A (en) * 1968-08-21 1977-07-12 Reynolds Metals Company Method and apparatus for reduction cell control
US4069115A (en) * 1977-04-27 1978-01-17 Maskin A/S K. Lund & Co. Method and arrangement for removing a gas cushion
US4126525A (en) * 1977-06-22 1978-11-21 Mitsubishi Keikinzoku Kogyo Kabushiki Kaisha Method of controlling feed of alumina to an aluminum electrolytic cell
US4392926A (en) * 1980-05-30 1983-07-12 Showa Aluminum Industries K.K. Process and apparatus for production of aluminum
US6033550A (en) * 1996-06-17 2000-03-07 Aluminium Pechiney Process for controlling the alumina content of the bath in electrolysis cells for aluminum production

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3629079A (en) * 1968-02-23 1971-12-21 Kaiser Aluminium Chem Corp Alumina feed control
US4035251A (en) * 1968-08-21 1977-07-12 Reynolds Metals Company Method and apparatus for reduction cell control
US4069115A (en) * 1977-04-27 1978-01-17 Maskin A/S K. Lund & Co. Method and arrangement for removing a gas cushion
US4126525A (en) * 1977-06-22 1978-11-21 Mitsubishi Keikinzoku Kogyo Kabushiki Kaisha Method of controlling feed of alumina to an aluminum electrolytic cell
US4392926A (en) * 1980-05-30 1983-07-12 Showa Aluminum Industries K.K. Process and apparatus for production of aluminum
US6033550A (en) * 1996-06-17 2000-03-07 Aluminium Pechiney Process for controlling the alumina content of the bath in electrolysis cells for aluminum production

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102758219A (zh) * 2011-04-29 2012-10-31 沈阳铝镁设计研究院有限公司 利用阳极导杆等距压降预测阳极效应的方法
WO2012146059A1 (zh) * 2011-04-29 2012-11-01 中铝国际工程股份有限公司 利用阳极导杆等距压降预测阳极效应的方法
WO2012146060A1 (zh) * 2011-04-29 2012-11-01 中铝国际工程股份有限公司 阳极效应抑制与熄灭的方法和设备
CN102851704A (zh) * 2011-06-30 2013-01-02 沈阳铝镁设计研究院有限公司 铝电解槽下料器单点控制下料方法
WO2013000270A1 (zh) * 2011-06-30 2013-01-03 中铝国际工程股份有限公司 铝电解槽下料器单点控制下料方法
CN102400182A (zh) * 2011-11-22 2012-04-04 中国铝业股份有限公司 一种控制铝电解槽内氧化铝浓度稳定均匀的方法
WO2013075376A1 (zh) * 2011-11-22 2013-05-30 中国铝业股份有限公司 抑制铝电解槽非阳极效应全氟化碳产生的方法及其系统
CN103014773A (zh) * 2012-11-26 2013-04-03 中国铝业股份有限公司 一种均衡铝电解槽氧化铝浓度的装置及方法
CN103952725A (zh) * 2014-05-16 2014-07-30 北方工业大学 一种工业铝电解过程中的决策方法
CN104499001A (zh) * 2015-01-20 2015-04-08 重庆科技学院 基于特征子空间优化相对矩阵的铝电解槽况诊断方法
EP3417095A4 (en) * 2016-02-15 2019-11-13 Dubai Aluminium PJSC METHOD FOR ESTIMATING DYNAMIC STATE SIZES IN AN ELECTROLYZIC CEMENT SUITABLE FOR THE HALL-HÉROULT ELECTROLYSIS PROCESS
CN113362912A (zh) * 2021-04-29 2021-09-07 中南大学 一种氧化铝浓度二次仿真方法、系统及存储介质

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BRPI0605050A (pt) 2007-09-04
AR058504A1 (es) 2008-02-06
NO20065036L (no) 2007-05-03
RU2303658C1 (ru) 2007-07-27
AU2006235828A1 (en) 2007-05-17
CA2566831A1 (en) 2007-05-02

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