AU2007332181B2

AU2007332181B2 - Method for the heating of anode blocks, and an arrangement for the heating of anode blocks.

Info

Publication number: AU2007332181B2
Application number: AU2007332181A
Authority: AU
Inventors: Orjan Danielsson; Stefan Springmann
Original assignee: Sandvik Intellectual Property AB
Current assignee: Sandvik Intellectual Property AB
Priority date: 2006-12-15
Filing date: 2007-11-27
Publication date: 2010-05-20
Anticipated expiration: 2027-11-27
Also published as: EP2102387A4; WO2008073031A1; SE531376C2; CA2672507A1; AU2007332181A1; CA2672507C; EP2102387A1; CN101573475A; SE0602707L; CN101573475B; EP2102387B1

Description

WO 2008/073031 PCT/SE2007/050904 1 Method for the heating of anode blocks, and an arrangement for the heating of anode blocks. The present invention relates to a method for the heating of 5 anode blocks, and to an arrangement for the heating of anode blocks. During the production process for primary aluminium, objects known as "anode blocks" are used. The blocks consist of 10 granulated graphite. Holes are present in these blocks in order to attach electrical contacts of iron, known as "yokes", by moulding. The sizes of the blocks may vary, and the number of contact holes into which contacts are to be attached may also vary. There is normally between three and 15 six holes. The blocks may have different dimensions: the dimensions may, for example, be 1300 x 500 x 500 millimetre. The anode blocks are exchanged at regular intervals. The anode blocks are then renovated and stored until they are to 20 be reused. Water can collect in the holes in the blocks as a result of precipitation, since the blocks are often stored outdoors, to a certain extent. The blocks, furthermore, are also exposed 25 to moist air. Water is sucked into the blocks, or is absorbed into the blocks, since the material of the blocks is porous. Water must be removed and the blocks must be dried before a secure attachment of contacts by moulding can be carried out. 30 This is currently carried out through first the removal of liquid water by blowing with pressurised air, and then the heating of the block with the aid of gas burners in order to dry it. The problem with this procedure is that the gas in 2 the burners contains a certain amount of water vapour that initially condenses onto the block before the temperature of the block has been sufficiently raised. A result of this is that it takes far too long to dry the blocks. 5 It would be an advantage if the drying time be considerably reduced. The present invention thus relates to a method for heating anode blocks, which anode blocks are used in the production of aluminium and comprise contact holes into 10 which it is arranged that electrical contacts are to be attached, characterised in that the holes are caused to be heated by means of radiative heat from electrical resistive elements arranged to be used at high temperatures, in that the wire of the elements is in the 15 form of shanks with two or more legs, in that each one of the elements is caused to be arranged in a cup with an open end surface, in that one cup for each hole in the anode block is caused to lie in front of the hole in question and in that the said cup is caused to be of a 20 fibre insulating material comprising A1 2 0 3 and/or SiO 2 .. Furthermore, in another embodiment of the invention there is provided an arrangement for the heating of anode blocks, which anode blocks are used in the production of aluminium and comprise contact holes into which it is 25 arranged that electrical contacts are to be attached, characterised in that the arrangement comprises electrical resistive elements arranged to be used at high temperatures, in that the wire of the elements is in the form of shanks with two or more legs, in that each one of 30 the elements is arranged in a cup with an open end surface, in that the cups with the resistive elements are 22422431 (GHMatters) 20104/10 2a equal in number to the number of holes in the anode block, and in that the cups are placed into a holder that is common for all the cups such that one cup for each hole in the anode block is caused to lie in front of the hole in 5 question and in that the said cup is manufactured from a fibre insulating material comprising A1 2 0 3 and/or SiO 2 . The invention will be described in more detail below, partially with reference to an embodiment of the invention shown in the attached drawings, where: 10 Figure 1 shows an arrangement according to the invention seen from the side with an anode block that lies beneath it, 22422431 (GHMatters) 20/04/10 WO 2008/073031 PCT/SE2007/050904 3 - Figures 2 and 3 show different perspective sketches of the arrangement according to the invention and an anode block. 5 Figure 1 shows an arrangement 1 for the heating of anode blocks 2, which anode blocks are used during the production of aluminium and which comprise contact holes 3 into which it is arranged that electrical contacts are to be attached. 10 According to the invention, the arrangement 1 comprises elec trical resistive elements 4, 5, 6, shown in Figure 3, ar ranged to be used at high temperatures. It is preferred to use resistive elements that are manufactured by KANTHAL AB, Sweden, and that are marketed under the name "Kanthal Super". 15 This element can be heated in operation up to 1900 'C. The wires of the elements 4-6 are formed as shanks with two or more legs. Each one of the elements 4-6 is arranged in a cylindrical cup 7, 8, 9 with an open end surface. It is pref erable that the cup is cylindrical. The cups 7-9 with the 20 resistive elements 4-6 are equal in number to the number of holes 3 in the anode block 2. The cups 7-9 are placed into a holder 10 that is common for all cups such that one cup 7-9 for each hole 3 in the anode block 2 is caused to lie in front of the hole 3 in question. 25 The use by this arrangement of radiative heat from high temperature elements entails a method of heating of much greater efficiency than the previous art technology that has been described, since no water is added at the beginning of 30 the heating process. A much higher power can be achieved over a limited surface through the use of high-temperature ele ments, and this also contributes to a more rapid heating and drying of the anode blocks.

WO 2008/073031 PCT/SE2007/050904 4 According to one preferred embodiment of the invention, the said elements are caused to be a high-temperature element. 5 According to another preferred embodiment, the said cup is caused to be of a fibre insulation material comprising A1 2 0 3 and/or SiO 2 . According to a further preferred embodiment, each resistive 10 element is caused to develop a power of approximately 10-20 kW. According to another further preferred embodiment, the dis tance between the said open end surface and the anode block 15 is caused to exceed a couple of millimetres and to lie below a couple of centimetres. This method has been shown to be able to reduce significantly the drying time for anode blocks from that required by the 20 prior art technology. The drying time is as short as approxi mately 4 minutes with the dimensions of the anode block given above as examples. The present invention thus solves the problem described in 25 the introduction. It has, in addition, proved to be the case when testing the arrangement that the drying time can be further reduced by blowing air, in association with the heating process, through 30 the cups down into the holes of the anode block using a suit able and previously known blowing arrangement.

5 The present invention is not by any means limited to a method or an arrangement to be used with anode blocks having three holes. The invention can be used for all designs of anode block with holes. 5 Several embodiments have been described above. However, the invention can be varied in ways that will be obvious for one skilled in the art, and thus the invention is not to be seen as limited to the embodiments described above, since it can be varied within the scope of the attached 10 patent claims. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as 15 "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. N:\Melbourne\Ca.es\Patent\81000-81999\P81226.AU\Speci.\PB1226.AU GH peci first.doc 24/06/09

Claims

1. A method for heating anode blocks, which anode blocks are used in the production of aluminium and comprise contact holes into which it is arranged that 5 electrical contacts are to be attached, characterised in that the holes are caused to be heated by means of radiative heat from electrical resistive elements arranged to be used at high temperatures, in that the wire of the elements is in the form of shanks with two or more legs, 10 in that each one of the elements is caused to be arranged in a cup with an open end surface, in that one cup for each hole in the anode block is caused to lie in front of the hole in question and in that the said cup is caused to be of a fibre insulating material comprising A1 2 0 3 and/or 15 Si0 2 .

2. A method according to claim 1, characterised in that the said elements are caused to be a high-temperature element.

3. A method according to claim 1 or 2, characterised 20 in that each resistive element is caused to develop a power of approximately 10-20 kW.

4. A method according to any one of the preceding claims, characterised in that the distance between the said open end surface and the anode block is caused to 25 exceed a couple of millimetres and to lie below a couple of centimetres.

5. An arrangement for the heating of anode blocks, which anode blocks are used in the production of aluminium and comprise contact holes into which it is arranged that N:\Melbourne\Cases\Patent\81000-81999\P81226.AU\Specis\P81226.AU GH epeci f irst.doc 24/06/09 7 electrical contacts are to be attached, characterised in that the arrangement comprises electrical resistive elements arranged to be used at high temperatures, in that the wire of the elements is in the form of shanks with two 5 or more legs, in that each one of the elements is arranged in a cup with an open end surface, in that the cups with the resistive elements are equal in number to the number of holes in the anode block, and in that the cups are placed into a holder that is common for all the cups such 10 that one cup for each hole in the anode block is caused to lie in front of the hole in question and in that the said cup is manufactured from a fibre insulating material comprising A1 2 0 3 and/or SiO 2 .

6. An arrangement according to claim 5, characterised 15 in that the said element is a high-temperature element.

7. An arrangement according to claim 5 or 6, characterised in that each resistive element is arranged to develop a power of approximately 10-20 kW.

8. An arrangement according to any one of claims 20 5 - 7, characterised in that the distance between the said open end surface and the anode block is caused to exceed a couple of millimetres and to lie below a couple of centimetres.

9. A method for heating anode blocks or an arrangement 25 for the heating of anode blocks, substantially as herein described with reference to the accompanying drawings. NI\Melbourn\Cases\Paenc\81000-81999\PB1226.AU\Specis\P81226.AU GH opeci firetdoc 24/06/09