WO2021130765A1 - Appareil d'amélioration de rendement de cellule de réduction d'aluminium dans un procédé de fusion - Google Patents

Appareil d'amélioration de rendement de cellule de réduction d'aluminium dans un procédé de fusion Download PDF

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Publication number
WO2021130765A1
WO2021130765A1 PCT/IN2020/050460 IN2020050460W WO2021130765A1 WO 2021130765 A1 WO2021130765 A1 WO 2021130765A1 IN 2020050460 W IN2020050460 W IN 2020050460W WO 2021130765 A1 WO2021130765 A1 WO 2021130765A1
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WO
WIPO (PCT)
Prior art keywords
collector bar
insert
inserts
cell
current
Prior art date
Application number
PCT/IN2020/050460
Other languages
English (en)
Inventor
Amit Gupta
Amit Jha
Original Assignee
Aditya Birla Science and Technology Company Private Limited
Hindalco Industries Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Aditya Birla Science and Technology Company Private Limited, Hindalco Industries Limited filed Critical Aditya Birla Science and Technology Company Private Limited
Priority to CN202080092006.XA priority Critical patent/CN115103931A/zh
Publication of WO2021130765A1 publication Critical patent/WO2021130765A1/fr

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Classifications

    • 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
    • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
    • C25C3/085—Cell construction, e.g. bottoms, walls, cathodes characterised by its non electrically conducting heat insulating parts
    • 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
    • C25C3/16—Electric current supply devices, e.g. bus bars

Definitions

  • the present invention relates to an apparatus for enhancing the performance of an aluminium reduction cell in a smelting process. More particularly, the invention relates to an apparatus with current collector bar having metal insert and cell refractory lining to enhance the performance of the aluminium reduction cell.
  • Aluminium is produced conventionally by the Hall-Heroult process, by the electrolysis of alumina dissolved in a cryolite -based molten electrolyte. Specifically, the current enters the cell through the anode and then passes through the molten cryolite bath (electrolytic bath), molten aluminium and enters the carbon cathode before being collected by collector bars.
  • molten cryolite bath electrolytic bath
  • the electrical current is carried out of the cell by collector bars.
  • the flow of electrical current through the carbon cathode and collector bar follows the path of least resistance.
  • the resistance of the current path between the collector bar and the nearest external bus is lower because of which the flow of current through the molten aluminium, cathode and collector bar gets concentrated towards the exit of the collector bar thereby generating a horizontal current component as illustrated in Fig. 1 (Resistance: Ri ⁇ R2).
  • Such horizontal current component interacts with the vertical component of the magnetic field results in MagnetoHydroDynamics (MHD) instability and adversely affects efficient cell operation, thus limiting the reduction in inter-electrode distance.
  • MHD MagnetoHydroDynamics
  • FIG. 1 shows a cross sectional view of a conventional aluminium smelter showing the electrical resistive paths (R2 and Ri) from an anode (1) to the exit of collector bar (6), while passing through an electrolyte bath (2), molten metal (3) and cathode (4), which are housed inside a steel shell enclosure (7) along with refractory lining (5).
  • Current is usually made to exit from both sides of the electrolytic cell and carried to the next cell using external aluminium busbars. This lead to voltage drop and energy consumption.
  • the electric current in the cell helps in electrolysis as well as it generates heat required to operate the cell at high temperature.
  • electrolytic cells start freezing and all types of collector bars being highly heat conductive, increases the heat loss. It results in faster shutdown of the cells. Huge investment is needed to replace the frozen cells with the new one.
  • This is also applicable to the existing designs of collector bars with a metal insert. In the existing apparatus design, the metal insert is not able to reduce heat loss effectively. Therefore, there is also a need of a new design of collector bar and cell refractory lining, which slows down the cooling of electrolytic cells during power outages.
  • an apparatus for enhancing performance of an aluminium reduction cell in a smelting process comprising: one current collector bar (6) and at least one insert (8) located therein, the insert (8) tapering towards one end of the collector bar (6), such the tapering is in continuous mode or in steps and such that the current is collected at the tapered end, provided that the material of construction of the insert (8) is different from the material of construction of the collector bar (6).
  • an apparatus for enhancing performance of an aluminium reduction cell in a smelting process comprising: at least one current collector bar (6) and at least one insert (8) therein, the insert (8) being placed within the collector bar (6), such that the ends of each inserts (8) having the largest cross-section are placed in the middle of the aluminium reduction cell and the tapering ends of each insert (8) are near the respective ends of the collector bar(s) (6), similar ends of each insert (8) are equidistant from the corresponding lateral ends of the collector bar(s) (6), and the ends of each insert (8) in the middle of the aluminium reduction cell face each other so as to define a gap between the inserts (8), provided that the material of construction of the inserts (8) is different from the material of construction of the collector bar(s) (6) and the current is collected from both side of the cell.
  • Figure 1 depicts a cross sectional view of a conventional aluminium smelter, in accordance with the embodiments of the present invention
  • Figures 2(a), 2(b) and 2(c) illustrate an isometric view of various designs of the metal insert (8) inside a current collector bar (6), having a greater cross sectional area on one side of the collector bar, in accordance with the embodiments of the present invention
  • Figure 3 depicts cross sectional view of the aluminium smelter, having asymmetrical thermal insulation strips (9) with thickness 1.2 to 5 times higher along the current exit side as compared to the opposite side, in accordance with an embodiment of the present invention
  • Figures 4(a) and 4(b) illustrate an isometric view of two current collector bars (6) having at least one insert (8), having a greater cross sectional area in the middle of the collector bar (6), in accordance with the embodiments of the present invention
  • Figure 5 depicts cross sectional view of the present aluminium smelter, having symmetrical thermal insulation strips (9) on both current exist sides of cell, in accordance with an embodiment of the present invention
  • Figure 6 illustrates the cross-sectional view of the collector bar (6) and the position of metal insert (8) within the collector bar (6), in accordance with an embodiment of the present invention
  • Figure 7(a) and 7(b) shows a comparison of cell stability between prior art apparatus and apparatus of the present invention, in accordance with an embodiment of the present invention
  • Figure 7(c) shows a graph showing the operating electric current during power outage and a comparison of electrolyte temperature of prior art apparatus and the apparatus of the present invention, in accordance with an embodiment of the present invention.
  • the present invention eliminates or reduces the aforementioned problems of the prior art by providing a novel design of the apparatus for aluminium reduction cell comprising current collector bar (6) having at least one insert (8) located therein and having a tapering design. Moreover, the apparatus provides thermal insulation strips (9) placed along the bottom of the electrolytic cell and along the lower sides of the electrolytic cell from the bottom thereof up to the top of the cathode (4), such that heat escape is reduced from the said cathode (4) from the side from where the current is collected. Lastly, the present invention demonstrates collection of current from one side of the apparatus in order to save energy in the external aluminium busbar network without adversely affecting the cell MHD stability.
  • an apparatus for enhancing performance of an aluminium reduction cell in a smelting process comprising one current collector bar (6) and at least one insert (8) located therein. Placement of the metal insert (8) within the collector bar results in reduction in horizontal currents in metal region, thus reducing the MHD instability for energy reduction, without enhancing the heat loss from the collector bar region. Hence, sustaining the longevity of cell operation during power outages. Also, the current is collected at the tapered end.
  • the cross sectional area of the insert(s) (8) tapers towards one end of the collector bar (6), as shown in Figs. 2(a), 2(b) and 2(c), in cases where the requirement is to collect current at one end only.
  • the tapering is in continuous mode or in steps.
  • the tapering helps in ensuring similar resistance path in the whole cathode (4) and collector bar (6) assembly to provide higher MHD stability.
  • the ratio of the largest cross-section of the inserts (8) to the cross-section of the current collector bar (6) is in the range of 0.1:0.6.
  • the ratio of the cross-section of the tapered ends of the inserts (8) to the cross-section of the current collector bar (6) is in the range of 0.05:0.4.
  • the ratio of the length of the inserts (8) to the length of the current collector bar (8) is in the range of 0.5:0.8.
  • the material of construction of the inserts (8) is copper, copper alloys, gold, silver, platinum or a mixture thereof. Usage of all these alternatives of material of construction of insert
  • the electrolytic cell for aluminium reduction showing an enhanced cell performance in a smelting process comprises of thermal insulation strips (9) that are placed along the bottom of the electrolytic cell and along the lower sides of the electrolytic cell from the bottom thereof up to the top of the cathode (4), such that heat escape is reduced from the said cathode (4) from the side from where the current is collected.
  • This heat loss results in a thermal balance during blackouts thereby avoiding freezing of the electrolytic cell.
  • the thermal insulation strip (9) placed on the current exist side is thicker than the insulation strip (9) placed on the other side. Since current is made to exit from one side of cell using metallic collector bar (6), it acts as a thermal window as compared to opposite non-current exit end. Hence, a thicker insulation strip
  • an apparatus for enhancing performance of an aluminium reduction cell in a smelting process comprising at least one current collector bar (6) and at least one insert (8) therein.
  • the insert (8) is placed within the collector bar (6), such that the ends of each insert (8) having the largest cross-section is placed in the middle of the aluminium reduction cell and the tapering ends of each insert are near the respective ends of the collector bar(s) (6), such that similar ends of each insert (8) are equidistant from the corresponding lateral ends of the collector bar(s) (6), and the ends of each insert (8)in the middle of the aluminium reduction cell face each other so as to define a gap between the insert (8).
  • each insert (8) in the middle of the aluminium reduction cell face each other so as to define a gap between the inserts (8), as shown in Fig. 4(a) and Fig. 4(b).
  • the metal inserts (8) in the middle of the aluminium reduction cell attract least current and thus a small gap is not only economically feasible but aids in allowing current to pass through the ends of the inserts (8) which are placed in the middle of the cell thus reducing the horizontal component of current.
  • electrical conductivity increases at center as compared to that of at sides.
  • the collector bar (6) may also be single or multiple to compensate the stress generated due to thermal expansion of the collector bar (6) at operating temperature.
  • the ratio of the largest cross-section of the inserts (8) to the cross-section of the current collector (6) is in the range of 0.1:0.6.
  • the ratio of the cross-section of the tapered ends of the inserts (8) to the cross-section of the current collector (6) is in the range of 0.05:0.4.
  • the ratio of the length of the inserts (8) to the length of the current collector bar (6) is in the range of 0.5:0.8.
  • the electrical conductivity of the material of construction of the inserts (8) is greater than the electrical conductivity of the material of construction of the collector bar (6).
  • the material of construction of the inserts (8) is copper, copper alloys, gold, silver, platinum or a mixture thereof. Usage of all these alternatives of material of construction of insert (8) and others are considered to be within the scope of the present invention.
  • the electrolytic cell for aluminium reduction showing an enhanced cell performance in a smelting process comprises of thermal insulation strips (9) that are placed along the bottom of the electrolytic cell and along the lower sides of the electrolytic cell from the bottom thereof up to the top of the cathode (4), such that heat escape is reduced from the said cathode (4) from both sides of the cell from where the current is collected.
  • the reduced heat loss results in a thermal balance during blackouts thereby avoiding freezing of the electrolytic cell.
  • the thermal insulation strip (9) placed on both the sides are of equal thickness as current is collected from both the sides, as collector bars (6) with inserts (8) act as thermal window during power outages.
  • the insulation can extend from corner of the cell refractory lining up to l/3 rd of the cathode length and twice the cathode width.
  • the height of the insulation strip (9) can go up to the cathode top most end starting from the bottom.
  • the thickness of the insulation (9) can vary from one twentieth up to one third of the gap between side of cathode blocks and inner wall of steel shell (7).
  • the insert (8) is positioned within the collector bar (6), closer to the top of the collector bar (6), as shown in Fig. 6, such that the cross sectional area of the collector bar (6) above the insert (8) is smaller than the cross sectional area of the collector bar (6) below the insert (8).
  • there are various ways of the placement of metal insert (8) inside the collector bar (6) there are various ways of the placement of metal insert (8) inside the collector bar (6).
  • the insert(s) (8) may be circular, square, rectangular, trapezoidal, parallelogram, U-shape, V-shape or a combination thereof.
  • Fig. 7(a) and Fig. 7(b) shows that reduced horizontal current results in an increase in level of stability of the cell. It can be observed from the graph that, while performing pot stability test in the aluminium reduction cell with the apparatus of prior art was able to lower the anode-to- cathode distance before reaching the MHD instability at 4.13 volts, whereas the apparatus of the present invention, was able to lower the anode-to-cathode distance before reaching the MHD instability at 3.93 volts. It shows the present invention lower the MHD instability significantly.
  • Table 3 shows the cathode voltage drop and steel shell wall temperature of prior art apparatus and the apparatus of the present invention, in accordance with an embodiment of the present invention.

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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)

Abstract

La présente invention concerne un appareil permettant d'améliorer le rendement d'une cellule de réduction d'aluminium dans un procédé de fusion. L'appareil comprend une barre collectrice de courant et une garniture métallique placée à l'intérieur de la barre collectrice. Le matériau de construction des garnitures est différent du matériau de construction de la ou des barres collectrices. De plus, des bandes d'isolation thermique sont placées le long de la partie inférieure de la cellule électrolytique, de sorte que la chaleur ne puisse pas s'échapper à partir de chaque extrémité d'une cathode.
PCT/IN2020/050460 2019-12-24 2020-05-22 Appareil d'amélioration de rendement de cellule de réduction d'aluminium dans un procédé de fusion WO2021130765A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202080092006.XA CN115103931A (zh) 2019-12-24 2020-05-22 用于提高铝还原池在冶炼工艺中的性能的装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN201921053599 2019-12-24
IN201921053599 2019-12-24

Publications (1)

Publication Number Publication Date
WO2021130765A1 true WO2021130765A1 (fr) 2021-07-01

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PCT/IN2020/050460 WO2021130765A1 (fr) 2019-12-24 2020-05-22 Appareil d'amélioration de rendement de cellule de réduction d'aluminium dans un procédé de fusion

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CN (1) CN115103931A (fr)
WO (1) WO2021130765A1 (fr)
ZA (1) ZA202004199B (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050218006A1 (en) * 2004-04-02 2005-10-06 Delphine Bonnafous Cathode element for use in an electrolytic cell intended for production of aluminium
WO2012038422A1 (fr) * 2010-09-20 2012-03-29 Sgl Carbon Se Cathode pour cellules d'électrolyse

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050218006A1 (en) * 2004-04-02 2005-10-06 Delphine Bonnafous Cathode element for use in an electrolytic cell intended for production of aluminium
WO2012038422A1 (fr) * 2010-09-20 2012-03-29 Sgl Carbon Se Cathode pour cellules d'électrolyse

Also Published As

Publication number Publication date
ZA202004199B (en) 2021-07-28
CN115103931A (zh) 2022-09-23

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