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
  • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
  • C25C7/005—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells for the electrolysis of melts
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/25—Process efficiency

Definitions

• This invention relates to the lining of an electrolytic reduction cell for the production of aluminium and in particular to interlocking refractory slabs which prevent the passage of liquid components from the electrolytic process to the metal shell.
• Cells used for the production of aluminium by electrolytic reduction conventionally comprise a metal shell lined with thermal insulation and an inner lining of carbonaceous blocks forming the cathode of the cells.
• the refractory insulation placed between the metal shell and the cathode blocks is designed to maintain thermal stability within the cell and provide a barrier between the steel shell and the corrosive contents of the electrolytic bath.
• Conventional practice for the lining of an aluminium smelting cell involves placing a layer of refractory bricks on the base of the cell.
• the laying of the refractory bricks is a time consuming job requiring refractory packing or refractory mortar between each brick in order to reduce the possibility of the corrosive bath infiltrating through the refractory layer and attacking the steel shell.
• the invention disclosed in co-assigned Australian Provisional Patent Application No. P 2223 uses a vacuum lifter which enables the slab to be lowered into position without the need for sideways movement of the slab to close the gap thus minimising packing between the slabs.
• the invention provides a refractory slab for use in a electrolytic production cell, said slab having a top surface and bottom surface and at least one engagement surface for interlocking engagement with a corresponding engagement surface of at least one adjacent slab, said engagement surface comprising a top and bottom region extending from said respective top and bottom surfaces substantially perpendicularly, said top and bottom regions being connected by a sloping region such that the angle between the sloping region and the top and bottom regions is greater than 90°.
• the above refractory slab has longitudinal and lateral engagement surfaces for engagement with corresponding engagement faces on laterally and longitudinally adjacent slabs.
• the present invention is able to provide a much longer path length for any liquid between the slabs thus providing longer protection for the steel shell and less likelihood of failure of the join.
• the invention provides a method for lining an electrolytic production cell with a refractory lining including a plurality of refractory slabs forming a refractory layer, each of said plurality of refractory slabs having a top surface and a bottom surface and at least one engagement surface for interlocking engagement with a corresponding engagement surface of at least one adjacent slab, said engagement surface comprising a top region and a bottom region extending from respective top and bottom surfaces substantially - A - perpendicularly, said top and bottom regions being connected by a sloping region such that the angle between the sloping region and the top and bottom regions is greater than 90°, said method including the steps of placing a first refractory slab in the cell, placing a second refractory slab in the cell an engaging surface of the second refractory slab engages with a corresponding engaging surface of the first refractory slab, and sequentially placing further refractory slabs in the cell one or more engaging surfaces of each further refractory lining
• a slab is placed in the cell in an orientation whereby any free engaging surface or surfaces of the slab includes a sloping portion that slopes downwardly and outwardly.
• This enables further slabs to be placed in the cell with the use of vertical movement only and can avoid the requirement to laterally move a slab into engagement with other slabs once the slab has been placed in the cell.
• a layer of packing or mortar may be applied to the joints between adjacent slabs to further seal the joint.
• the layer of packing or mortar may be applied to the free engaging surfaces of a slab in the cell prior to an adjacent slab being placed in the cell.
• Figure 1 is a perspective view of six slabs joined in accordance with the present invention
• Figure 2 is a perspective view from beneath the slab of Figure 1 with the inter-engaging faces of one slab shown in hidden detail;
• Figure 3 is an orthographic plan view of the slabs of Figure 1;
• Figure 4 is an orthographic plan view as viewed from position 4 in Figure 3;
• Figure 5 is an orthographic plan view as viewed from position 5 in Figure 3;
• Figure 6 is an exploded view of the six blocks shown in Figure 1 ;
• Figure 7 is a perspective view of nine slabs joined in accordance with the present invention.
• Figure 8 is a plan view of the arrangement shown in Figure 7.
• Figure 9 is a side elevation of the arrangement of slabs in a cell having a 5 x 2 arrangement of slabs in the refractory layer.
• Figure 10 is an end elevation of the arrangement of slabs shown in Figure 9.
• each slab is shown as inter-engaging with an adjacent slab in the longitudinal and lateral directions.
• each slab has a top surface 7, a bottom surface 8 and at least one inter- engagement surface 9 (refer to Figure 4).
• the inter-engagement surface consists of a top region 10 and a bottom region 11 which extend from the respective top and bottom surfaces at an angle of about 90° and a sloping region 12 which intersects with the top and bottom regions 10, 11 along edges 13, 14 at an angle greater than 90° and less than 180°.
• the angle is in the range of 120° to 170° and most preferably in the range of 135° to 170° and most preferably 140° to 155°. It is preferable that the angle between the top surface and top region of the inter-engagement surface be about 90° as an increase in the angle on one inter-engagement surface will require a decrease in the angle on the corresponding inter- engagement surface of the adjacent slab. An acute angle of less than about 80° results in a structural weakness at the corner of the top surface and the top region thus increasing the likelihood of that corner being damaged while the slab is being positioned. Similarly the angle between the bottom surface and the bottom region of the inter-engagement surface should be about 90° preferably between 80° to 100° and most preferably between 85° to 95°.
• the inclined region of the inter-engaging surface extends from the top region of the surface to the bottom region.
• the inclined region intersects the top of bottom regions at an angle than greater than 90° and most preferably greater than 135° but less than 170°.
• the angle between the inclined region and the top and bottom regions is 90° or less, structural weaknesses are formed in the inter-engagement surface and corresponding surface on the adjacent slab. Also stress concentrating corners are formed at edges 13, 14 which increases the risk of a major fracture occurring in the slab.
• at least two slabs are used across the width of the cell.
• each slab has at least one laterally extending engagement surface and at least one longitudinally extending surface.
• Each slab is made from a low cement castable refractory material such as sold by Comalco Aluminium Limited under the name of COMCAST " SCB and described in Australian Patent No. 622727 the disclosure of which is incorporated by reference and weighs from about 700 kgs to 3000 kgs.
• each slab has engaging surfaces that engage with corresponding engaging surfaces of each adjacent slab.
• slab 1 is designed to fit into the corner of the electrolytic cell and accordingly includes substantially vertical sides 1A and IB that fit snugly against the vertical side walls of the cell.
• Slab 1 also includes engaging surfaces 1C and ID. Engaging surface 1C engages with corresponding engaging surface 3C of slab 3 and engaging surface ID engages with corresponding engaging surface 2D of slab 2.
• Slab 2 is also a corner slab and includes substantially vertical sides 2A and 2B to fit into the corner of the cell.
• Engaging surface 2C engages with corresponding engaging surface 4C of adjacent slab 4.
• engaging surfaces 3D and 4D of slabs 3 and 4 respectively engage each other.
• engaging surface 3C engages with surface 5C of adjacent slab 5 and surface 4C of. slab 4 engages with surface 6C of adjacent slab 6.
• Surfaces 5D and 6D of slabs 5 and 6 also engage.
• the refractory lining is formed by initially placing slab 2 into the cell. As can be seen from Figure 6, engaging surfaces 2C and 2D of slab 2 slope downwardly and outwardly. Slab 1 may then be placed into the cell in the orientation shown in Figure 6.
• the slabs may be positioned in the cell in the order of 2, 1, 4, 3, 6 then 5.
• the slabs may be positioned in the cell in the order of 2, 4, 6, 1, 3 then 5.
• the engaging surfaces of the slabs positioned in the cell include downwardly and outwardly sloping portions that enables the further slabs to be positioned in the cell with only vertical movement.
• the embodiment shown in Figure 6 shows a cell that has six refractory slabs making the refractory layer.
• the slabs are arranged in a 3 x 2 configuration (i.e. 3 slabs along the length of the cell, 2 slabs across the width of the cell). This arrangement can be varied to meet the particular dimensions of any cell.
• Figures 7 and 8 show a 3 x 3 arrangement whilst Figures 9 and 10 show a 5 x 2 arrangement.
• Using the refractory slab system to line electrolytic cells operated by the applicant has reduced the amount of mortar used from 200 kg (in linings using refractory bricks) to just a few kilograms.
• the time required to install the lining has been reduced from 60 man hours (using refractory bricks) to about 4 man hours, which represents a significant saving.
• the design of the refractory slabs of the present invention is very robust and the slabs are less likely to be damaged by handling. This leads to reductions in the scrap rates of the slabs.

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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)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)
• Fuel Cell (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=3777358

Family Applications (1)

Country Status (5)

Cited By (2)

Citations (3)

Family Cites Families (1)

• 1994
  • 1994-11-16 CA CA002173860A patent/CA2173860C/en not_active Expired - Fee Related
  • 1994-11-16 WO PCT/AU1994/000705 patent/WO1995014119A1/en active IP Right Grant
  • 1994-11-16 DE DE69417914T patent/DE69417914T2/de not_active Expired - Fee Related
  • 1994-11-16 EP EP95900567A patent/EP0729521B1/en not_active Expired - Lifetime
• 1996
  • 1996-05-14 NO NO961982A patent/NO309105B1/no unknown

Patent Citations (3)

Non-Patent Citations (2)

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