CN107208288B

CN107208288B - Anode for use in an electrolytic process for producing aluminium in an electrolytic cell of the Hall-Heroult type and method for manufacturing such an anode

Info

Publication number: CN107208288B
Application number: CN201680009846.9A
Authority: CN
Inventors: J·霍普; I·A·维; G·斯特凡斯基; A·利勒拜; H·屈佩尔斯; P·J·泰根; V·耶勒
Original assignee: Knowleshead
Current assignee: Knowleshead
Priority date: 2015-02-13
Filing date: 2016-02-09
Publication date: 2020-11-27
Anticipated expiration: 2036-02-09
Also published as: CN107208288A; WO2016130014A1; EP3256622A4; US20180023206A1; CA2975081A1; ZA201705026B; BR112017017062A2; NZ733895A; CA2975081C; AU2016218531A1; EP3256622A1; EA035309B1; EP3256622B1; EA201791832A1; AU2016218531B2

Abstract

An anode for use in an electrolysis process for producing aluminium in an electrolysis cell of the Hall-Heroult type, comprising a body or block (120; 20) of calcined carbonaceous material connected to a current lead, wherein the current lead is connected to an anode rod (103; 3) and is also part of an anode suspension (101; 1). The current lead comprises at least one metal suspension plate (104; 4, 4 ') with vertically oriented plug plates (105, 105', 5 ') which are at least partially embedded by their lower portions in corresponding recesses (113, 113'; 13, 13 '; 100, 100') in the top of a block (120; 20) of carbonaceous material and further connected by mechanical fixing means (108; 8; 14, 16). The recess is wider than the patch panel and is filled only with conductive particulate material. The invention also describes a method for machining an undercut recess (10) in the anode top to mechanically secure the anode block (20) to a protrusion (8) on the current lead.

Description

Anode for use in an electrolytic process for producing aluminium in an electrolytic cell of the Hall-Heroult type and method for manufacturing such an anode

Technical Field

The present invention relates to an anode and a method of manufacturing the anode. In particular, the invention relates to a prebaked anode for the electrolytic production of aluminium in an electrolytic cell of the Hall-heroult type.

Background

Typically, the prebaked anode is fixed to a pin forming part of the anode suspension. The carbon-based anode block has a preformed hole that allows the pin to enter into the hole. The fixation between the pins and the anode is performed by pouring molten cast iron into the annular space between each individual pin and the corresponding hole in the anode. The anode suspension further comprises an anode yoke claw with a pin, which is further suspended by an anode rod attached at its upper part to the anode beam. A bimetallic connection is often present between the anode rod and the yoke claw.

The use of molten cast iron has some impact on the melting mold (e.g., an oven capable of melting the cast iron) and the corresponding distribution and pouring systems. For the anode, the pin is preheated in some techniques.

Due to the consumption of the carbon material comprising the prebaked anode, the prebaked anode typically wears out after about 30 days in the cell. The prebaked anode must then be replaced. The worn anode (end) is transferred to the equipment where the pins of the anode hanger are cleaned by removing the remaining material of the anode together with cast iron residues. Typically, this is performed by using a mechanical refreshing tool.

The operations of fitting a new anode and removing the end of the worn anode are time consuming and expensive.

US4574019 relates to a process of attaching two anode blocks to an anode suspension comprising two shovels or two pins by using an adhesive. The adhesive should have strong mechanical properties and good electrical conductivity at least between 900 ℃ and 1000 ℃. The adherent may be a solid mixture, an adhesive, and a hardener. The solid may be embodied by a metal powder such as iron, copper or aluminum. The particle size of the metal should be at most 5 mm. A contact body of this type is further described in EP 0027534.

Disclosure of Invention

According to EP2242976a1 owned by the applicant, the applied electrically conductive particles are present only as a filler material between the current lead and the calcined carbonaceous material in the anode. The reuse of the conductive particles is facilitated by using only the conductive particles without using the hardened matrix. Said patent document also already states that the resistance is reduced for the plugged (rodded) anode according to this solution.

By the invention, the anode drop is further reduced due to the novel design of the yoke claws.

First, in one embodiment the yoke claw comprises at least two triangular suspension plates, wherein the upper, middle parts of said suspension plates are attached at the lower part of the anode rod. The lower part of the suspension plate and the peg plate are attached in a recess formed in the upper part of the carbonaceous anode block, and the lower part of the suspension plate and the peg plate can in one embodiment be peg-jointed according to the same principle as shown in EP2242976a 1. It can be said that the current lead and the body of calcined carbonaceous material are connected by various mechanical fixing means by a combination in which the electrically conductive plugging material comprises only electrically conductive particles.

The plates of the yoke jaws may be a clad material or composite material, preferably similar to that of the sandwich structure, which also reduces pressure drop and also maintains different thermal properties. An important advantage is that this may result in less heat loss and lower pressure drop. It is possible to design the yoke jaws in such a way that the yoke jaws are "neutral" with respect to the thermal equilibrium in the electrolysis cell when replacing the commonly used yoke jaws.

In another embodiment, the yoke claw comprises a horizontally oriented suspension plate between the anode rod and the bayonet plate. Similarly, the suspension plate can be at least partially a cladding material or composite material, preferably similar to that of the sandwich structure, which can also reduce pressure drop and also maintain different thermal properties. The suspension plate also allows easier covering with Anode Covering Material (ACM) due to fewer protruding elements.

An important advantage associated with the above design is that the design may result in less heat loss and lower pressure drop. It is possible to design the yoke jaws in such a way that the yoke jaws are "neutral" with respect to the thermal equilibrium in the electrolysis cell when replacing the commonly used yoke jaws.

Still further, the yoke claws according to the invention will have good mechanical properties and maintain excellent stability.

Drawings

These and further advantages will be obtained by the present invention as defined in the appended claims.

The invention will be further described by means of the attached figures and examples, in which;

figure 1 discloses a perspective view of a first embodiment of an anode suspension with a yoke claw and an anode rod,

figure 2 discloses the anode suspension of figure 1 from one side,

figure 3 discloses the anode suspension of figure 1 viewed in front elevation,

figure 4 discloses an anode suspension as in figure 3 assembled into a carbon anode block,

figure 5 discloses an anode suspension as in figure 4 assembled into a carbon anode block seen from one side in cross-sectional view,

fig. 6 discloses a top view from above of the anode suspension assembled into the carbon anode block as shown in fig. 5,

figure 7 corresponds in part to an enlarged view of the circled area as indicated by a in figure 6,

figure 8 discloses in part an enlarged view of the circled area as indicated by B in figure 4,

figure 9 discloses the complete anode assembly seen in perspective view,

figure 10 discloses an alternative design of the mechanical fixing means seen from one end in a cross-sectional view,

figure 11 is the same alternative design as figure 10 viewed from above,

figure 12 is the same alternative design as in figures 10 and 11 viewed from one side in cross-sectional view,

figure 13 discloses a comparative pressure drop test of an anode according to the invention and of an anode of the prior art,

fig. 14 discloses in a perspective view a second embodiment of the anode suspension with yoke claws, said yoke claws comprising a horizontal suspension plate and a vertical plug plate,

figure 15 discloses a machined and prepared anode block for plugging with a yoke jaw,

fig. 16 discloses a perspective view of an anode suspension with yoke claws, which comprise one horizontal suspension plate plugged to the anode block,

fig. 17 discloses a pressure drop test of one anode with horizontal suspension plate according to the invention.

Detailed Description

As shown in fig. 1, a perspective view of an anode suspension 1 with a yoke claw (yoke)2 and an anode rod 3 is disclosed. The anode rod is typically made of aluminum or an aluminum alloy, preferably having a rectangular cross section.

The yoke claws may in principle comprise four parts, two triangular suspension plates 4, 4 'and two socket plates 5, 5', which are each connected to one another. The suspension plates 4, 4 'and the peg plates 5, 5' may be made of steel plates of suitable quality, which are connected to each other by welding or by any other suitable means.

However, in one embodiment, the peg plate 5 and the suspension plate 4 can be made from one piece of sheet metal (e.g. steel) by suitable machining, such as cutting and possibly bending (not shown).

It will be appreciated that the terms peg board and suspension board as used herein may equally relate to components of the complete board, either manufactured from one board as described above, or from two boards, i.e. the suspension board 4 and the peg board 5 are joined together. The complete yoke jaw plate made by either method is denoted by 54, 54'.

The

protrusions

8, 8 "are arranged at the peg plate 5 for interaction with a recess formed in the top of the anode. A recess is also formed that allows the insertion of the peg plate into the top of the anode. This will be explained below. A similar projection is arranged at the jack plate 5' (not shown).

It is also disclosed that the upper part of the suspension plate 4, 4' is attached to the lower part of the anode rod 3. In order to ensure a low pressure drop between the anode rod 3 and the yoke claw 2, a connection member 6, 6 'having good electrical conductivity may be arranged in electrical contact with each of the anode rod 3 and the suspension plates 4, 4'.

In fig. 2, the anode suspension 1 is shown from one side. The anode rod 3 is connected to the suspension plate 4 via

several connection members

6, 6 ', 7', 7 ", 9. The connecting

member

7, 7 ', 7 "may be a bimetal or trimetal steel plate member as it faces the suspension plate 4, 4' made of steel. The connecting members 6, 6' are preferably of aluminium in order to increase the contact area between the aluminium anode suspension 3 and the bi-or tri-metallic connecting member. The connecting member 9 is used as an aluminum member composed of bimetal or trimetal. In the case of trimetal, a bonding plate represented by a thin sheet of titanium is additionally arranged between the connecting member 9 and the connecting member 7 (similarly arranged at the bonding points of 3 and 7 ″ and at the bonding points of 6 'and 7').

The connecting member preferably has good electrical conductivity and a certain mechanical strength.

In principle the bimetal part will have two contact areas consisting of a material compatible with the material in the anode rod 3 and the material of the suspension plates 4, 4', respectively. The tri-metal connection will additionally include a third metal that enables the connection to function properly at high temperatures.

For example, the tri-metallic connection component may be constructed of components based on steel-titanium-aluminum materials.

In addition, the figures disclose in more detail the protrusions 8, 8' in the plug plate 5, which protrusions are arranged for interaction with corresponding recesses in the top of the anode. The protrusion can have a substantially rectangular or circular cross-sectional shape.

In fig. 3, the anode suspension 1 of fig. 1 is shown in a front view, wherein two suspension plates 4, 4 'with respective bayonet plates 5, 5' are attached to the anode rod 3. The connecting part 6' is shown in the contact area between these parts. In the lower part of the plug plates 5, 5 'there are shown protrusions 8, 8'. These projections have a rectangular shape in this example and can pass through the patch panels 5, 5' in such a way that they project at the outside and at the inside of the patch panels.

In fig. 4 is disclosed an anode suspension 1 as shown in fig. 3 fitted into a carbon anode block 20, wherein first of all a machined recess (groove, notch) 13, 13 'oriented in the length direction of the anode block, which recess is able to receive a plug plate 5, 5' at a certain insertion depth. In addition, the projections 8, 8 ' arranged at the plug plates 5, 5 ' match with corresponding recesses 10, 10 ' in the anode block 20. Details regarding the circled area at B will be further explained with respect to fig. 8.

The anode block may have downwardly

open slots

21, 22 for the discharge of anode gas, said anode block having cantilevered exterior surfaces 23 at its corner regions.

Fig. 5 discloses a cross-sectional view of the anode suspension 1 fitted to a carbon anode block 20 shown in fig. 4, seen from one side, wherein the anode stem 3 is attached to a suspension plate 4 with a peg plate 5, the protrusions 8, 8 'engaging in corresponding undercut recesses 10, 10' formed in the anode block 20. The plug plate 5 enters the recess 13. The anode block has cantilevered surfaces 23, 23'. Details regarding the protrusion 8 "and the recess 10" are shown in fig. 6 and 7.

Fig. 6 discloses an anode suspension as shown in fig. 5 fitted into a carbon anode, seen from above, wherein the anode 20 is provided with

recesses

10, 10 ", 10 ', 10"'. The yoke jaw parts have

protrusions

8, 8 ', 8 "' that have entered into the recesses. The recess can be made by using a circular milling tool (e.g. formed as a small "saw blade" with axial and radial polycrystalline diamond cutters (PCD)) which is further arranged on a sufficiently long shaft that allows the tool to machine a hole by a first step down motion and to machine an undercut recess in a subsequent machining step in which the tool is moved along the length axis of the anode block (20).

In fig. 7, which shows an enlarged detail of the circled area indicated by a in fig. 6, the peg board 5 with the protrusion 8 "first engages into the top open portion 11" of the recess 10 "of the anode block 20, and then it moves horizontally and further engages into the top closed portion or undercut portion of the recess 10" of the anode block 20. This enables the anode block 20 to be suspended by the yoke claw via the undercut

recess

10, 10 ', 10 "' and the

protrusion

8, 8 ', 8"'. This means that the weight of the anode block 20 is borne by these mechanical fixing means.

Fig. 8 corresponds in part to an enlarged view of the circled area indicated by B in fig. 4 and shows more details of the recess 13 and the recess 10. The drawing includes a first open top portion or hole 11 similar to that shown in figure 7, which has been machined at the appropriate location in the recess 13. In addition, the recess 10 is undercut and has two flanges 12, 12'. When, as shown in the figures, the peg plate 5 has entered the recess 13, the protrusion 8 arranged at the peg plate 5 has entered the hole 11 downwards and has moved further inside the undercut portion (top closed portion) of the recess, the peg plate will be resting in this position and be able to take up the vertical load represented by the anode block 20 via the flanges 12, 12' formed in the anode block. At the same time, the

projections

8, 8 ', 8 "' will enter their

corresponding recesses

10, 10 ', 10"', respectively, see fig. 5 and 6.

Fig. 9 discloses an anode assembly with an anode rod 3, suspension plates 4 and 4 ', bayonet plates 5 and 5 ', recesses 13 and 13 ', (partial) holes 11 and 11 "and an anode block 20.

After the first plugging step, conductive particles are filled into the gap between the plug plate and the recess in the anode block, a collar member may be applied to the metal part at the top of the anode as protection against corrosive effects (not shown).

The

projections

8, 8 ", 8 ', 8"' in the above example may be constituted by cylindrical rods which enter the holes through the plug plate. These rods can be fixed by a press fit arrangement and are arranged to be easily removed and interchanged.

Alternatively, the shape of the protrusions may be flat, i.e. the protrusions have a more extended planar surface acting against the recesses in the anode. This distributes the load of the anode block over a larger area. In one embodiment, the tabs may comprise pins welded to the exterior and/or interior of the respective patch panel.

Fig. 10 discloses an alternative design of the mechanical fixing means seen from one end in a cross-sectional view, wherein the anode block 20 has

grooves

21, 22 in its bottom part, wherein recesses 100, 100' are formed in the top part of said anode block. In the recesses, two bayonet plates 5, 5' have been inserted, respectively, and

bolts

14, 15 have been applied in order to fix the yoke claw plate to the anode block. The

bolts

14, 15 pass through holes in the socket plates 5, 5' and are secured into pre-formed recesses or holes in the anode block. The bolts may be threaded and corresponding threads may be arranged in the socket plate and/or in the holes of the anode block 20.

In addition, the suspension plates 4, 4' have in their upper part an

additional plate material

16, 17 of better electrical conductivity, such as copper or a suitable copper alloy, which will significantly reduce the pressure drop in the assembly. The additional sheet material may be a clad material or a material that is otherwise electrically integrated with the yoke jaw plates. The additional plate material may also be used to optimize the heat loss of the yoke jaws.

In addition, details of the connection between the suspension plates 4, 4' and the anode rod 3 are shown. The figures show two reinforcing

members

27, 28 that can preferably be welded to the suspension plates 4, 4'. The reinforcement member is preferably a metallic material (such as steel) and will improve the lateral stability of the yoke jaws. The reinforcement will also reduce the pressure drop between the anode rod and the yoke claw.

In addition, a

trimetal plate

18, 19, 26 is shown arranged between the suspension plate 4, 4' and the anode rod 3, similar to what is explained according to fig. 2.

Fig. 11 is the same alternative design as shown in fig. 10, seen from above, where the plug plates 5, 5 ' are fixed to the anode block 20 by means of

bolts

14, 14 ', 14 "and 15, 15 ', 15".

Fig. 12 is the same alternative design as fig. 10 and 11, seen in cross-sectional view from one side, where the anode block 20 has a slot 21 in its bottom part, into which the patch panel 5 is inserted from the top side. The patch panel is secured by

bolts

14, 14', 14 ". The cladding sheet material is shown at the hanger plate 4 as reference numeral 16 and the anode rod as reference numeral 3.

The trimetal connections are shown as

reference numerals

18, 19, 26.

The size of the suspension plate and the receptacle plate depends on the yoke jaws to be replaced.

For example, the yoke jaw of the present invention has twice the contact area with carbon as compared to a yoke jaw having four legs with a diameter of 180 mm. A patch panel of 20mm thickness will reduce the cross section of the thermally conductive steel by 50%.

This means that the pressure drop is sacrificed for reducing heat loss, but still lower than the pressure drop of the leg yoke claws because the contact area between the yoke claws and the carbon is increased by 100% and larger bimetal cross section.

An increase in the plate cross-section will increase the heat loss and reduce the pressure drop, both of which can contribute to an increase in the amperage of the electrolyzer.

A reduction in size will reduce heat loss and increase pressure drop, and it is beneficial to reduce the space between the two poles.

In the case of no cladding material or composite material in the suspension plate member, the suspension plate may be of steel material and have a thickness of 35 mm. The patch panel may be of the same material with a thickness of 20 mm.

In one embodiment, the thickness of the clad Cu material may be 8mm, while the thickness of the suspension plate of steel is 20 mm. The thickness of the patch panel may be 20 mm.

Yoke claws of the bayonet plate having a thickness smaller than the thickness of the suspension plate have been shown to have a positive effect of reducing heat loss via the anode yoke claws.

In an embodiment not disclosed, more than two yoke jaw plates with corresponding grooves in the top of the anode may be applied. For example, a central yoke jaw plate may be applied, which is arranged between the two yoke jaw plates shown in the figures.

Fig. 13 discloses a comparative pressure drop test of one anode (lower curve) with two suspension plates/peg plates (named double) and a prior art reference anode (upper curve) with legs according to the above described embodiment, and where a hole is formed at the top of the anode and the peg plates are made of cast iron. In the drawings, the curves have been made more suitable for printing assisted by manual drawing. The voltage drop measurements are done at the anode rod and at the corresponding position at the top of the anode.

The curve shows the pressure drop (vertical axis) after start-up in the cell as a function of time.

It will be observed from the upper curve, which is the reference anode, that the voltage drop can average to about 200mV when the current flux has stabilized.

From the lower curve, which is the anode according to the invention, the pressure drop is stabilized to a level of about 120 mV.

Comparative tests between 8 anodes and 8 standard anodes according to the invention (twin) as described above have been performed, where the average resistance in the duration (from new anode to worn anode) has been measured and averaged. See table 1.

TABLE 1 comparison of resistance of the twin anode with reference anode

Another embodiment of the invention is shown in fig. 14, where an anode suspension 101 with a horizontally oriented suspension plate 104 and five

pinboard plates

105, 105 ', 105 "', 105" ", is seen in perspective view. The plug plate 105 "" has two projections 108 "and 108'". Similarly, the patch panel 105 also has two projections 108, 108' (not shown) like this. These four protrusions will match corresponding recesses in the anode block and enable hanging of the anode block.

As shown in fig. 1,

connection members

106, 106', 106 "between the anode rod and the suspension plate are disclosed. The connecting member may be of a bimetal type and/or a trimetal type.

Furthermore, a spacer 144 between the anode stem 103 and the suspension plate 104 is disclosed. The spacer is advantageous in that it separates the connecting part from the heat and corrosive gases emitted during electrolysis. The spacer 144 can be made of a metallic material (such as steel) and can be welded to the hanger plate. However, in one embodiment, the suspension plate can be connected to the anode stem via a connection member without any spacer 144 (not shown). In another embodiment (not shown), the spacers 144 can be made of several plates of electrically conductive material and further arranged in such a way that the plates define a gas-tight void, which can be filled with an insulating material. A similar construction can be applied to the suspension plates 4, 4' in the first example. One advantage of this solution is that the necessity of covering the top of the anode with an anode covering material is reduced and possibly eliminated.

Fig. 15 discloses a perspective view of an anode block 120, which is machined and prepared for plugging with the anode suspension 101. In the anode block 120, there are five

recesses

113, 113 ', 113 "', 113" ", which are machined, which can receive the corresponding plug-in boards described above. Furthermore, similar to what is shown in fig. 7, holes 111, 111 ', 111 "' and undercut

recesses

110, 110 ', 110"' are shown/indicated for receiving

corresponding protrusions

108, 108 ', 108 "' at the

outer bayonet plate

105, 105" ", for carrying the weight of the anode block 120.

Fig. 16 discloses a perspective view of an anode with an anode suspension comprising one anode rod 103, connecting

members

106, 106', 106 ", spacers 144, suspension plates 104 plugged with anode blocks 120.

It should be understood that the anode block is fixed to the current lead by pins, bolts, etc. interconnecting the socket plates (105, 105 "") and the anode block (120).

During the plugging step, conductive particles are filled into the gap between the plug plate and the recess in the anode block, and a collar member may be applied to the metal part at the top of the anode as a protection against corrosive effects (not shown).

The

projections

108, 108 ", 108'" in the above example may comprise cylindrical rods that pass through the patch panel into the holes. These rods can be secured by a press-fit arrangement and the rods arranged for easy removal and interchange.

Alternatively, the shape of the protrusions may be flat, i.e. the protrusions have a more extended planar surface acting against the recesses in the anode. This will distribute the load of the anode block over a larger area. In one embodiment, the tabs may comprise pins welded to the exterior and/or interior of the respective patch panel.

Fig. 17 discloses the voltage drop test of one anode with horizontal suspension plate according to the invention (lower curve) compared to a normal standard anode (upper curve). It can be observed that the voltage drop can be reduced by about 12 micro-ohms (lower curve) with respect to a typical standard anode.

Furthermore, the cladding material and composite sheet material applied to the suspension plate(s) may be protected from degradation by a shroud or any other suitable means. A shield made of steel plate covering the cladding material or composite material is suitable.

It will be appreciated that the main part of the recess in the top of the anode for the peg plate may be formed when the anode is in its green state (i.e. before firing the anode). The main part of the recess can also be formed by an anode insertion device, for example as shown in the published patent EP 1781441 a1 owned by the applicant.

After this, the recess is then calibrated by a rotating machining tool having a shape complementary to the final shape of the recess or having dimensions smaller than those of the final shape. The tool can be arranged to fit a CNC machine or the like so that the machining (treatment) will be performed in an automated manner. During machining, an open-topped recess is formed, and then the same tool or any other suitable tool is moved along the recess in the top of the anode to form a closed-topped recess with load bearing flanges 12, 12'.

It should be understood that the conductive solid or conductive particles may be any suitable metal (such as steel, iron, copper, aluminum, etc.) or alloy of such metals. Furthermore, the shape of the solid may be spherical, oval or elliptical, flake-shaped or have any suitable shape. The size and distribution of the particles may vary. The maximum size will be limited mainly by the space to be filled. An uneven distribution of the particle sizes can conveniently achieve as compact a packing as possible with little space between the particles.

In addition to having good electrical conductivity properties, the applied material should have good mechanical properties (crush performance) and be able to withstand high temperatures. The magnetic properties may be advantageous for recycling reasons in the end treatment station.

Furthermore, the size of the solid body may start from 0.1 mm and be close to the smallest opening (gap) between the socket plate and the wall of the recess in the anode block. Typically, this dimension can be up to 10 mm.

The conductive particles may be stored in a container or suitable reservoir at a higher level than the recesses in the anode to be filled. A pipe fixed to the container and having a valve and an opening towards the tank can adjust the correct amount of particles entering the tank. Thus the transport and distribution can be performed by gravity feed. During filling, vibrations may be applied in order to obtain a more compact filling. The anode block and/or the yoke jaw bars may vibrate. Alternatively, a vibrating rod may be applied in the recess filled with the conductive particles so as to directly generate vibration of the filling material.

In addition, collar adhesives commonly used for anodes or other protectors may be used to form encapsulation and protective layers at the top of the conductive particles.

Worn anodes can typically be handled in a docking station where the ends are removed from the yoke jaws (after removal of any anode cover material). Preferably, the end is broken in such a way that: the end portion falls mainly in the form of a few large pieces separated in the direction in which it is fixed. Otherwise, the end may be crushed or knocked off the anode suspension. The end is conventionally placed on a conveyor belt.

In case magnetic conductive particles have been applied as filling material, the anode yoke claws are preferably magnetized by suitable means, so that the particles will be attracted to the yoke claws during end removal.

After the end has been removed, the yoke jaws are preferably moved to another part of the docking station for recovering the filling material. The yoke jaws can then be demagnetized to allow the particles to fall out. As the particles fall off easily, any remaining particles on the previously embedded portions of the yoke claws can be removed by a simple mechanical method such as scraping.

As a final cleaning step, the previously embedded parts of the yoke jaws can preferably be blasted (e.g. by sandblasting) with particles (such as iron, steel or any other conductive material) that are identical or compatible with the actual filling material. In addition, the blowing may be performed by sand, aluminum, or any other suitable material.

It should be understood that the non-magnetic filler material may also be recovered and reused, even though the separation and recovery techniques may differ somewhat from those described above. A screen may be applied to separate the ends from the packing material.

The recovered filler material may fall off as a group of particles. These clusters may need to be crushed into more or less single particles in order to be reused as filling material determined by the opening of the actual recess to be filled. The crushing can be accomplished by adjusting conventional equipment.

Claims

1. An anode for use in an electrolysis process for producing aluminium in an electrolysis cell of the Hall-Heroult type, said anode comprising an anode block of calcined carbonaceous material connected with a current lead, wherein said current lead is connected with an anode rod and is also part of an anode suspension, wherein said current lead is embedded in a recess in the top of said anode block of calcined carbonaceous material, said recess being wider than said current lead and only filled with electrically conductive particulate material, and said current lead and said anode block of calcined carbonaceous material are further connected by mechanical fixing means,

the anode is characterized in that it is characterized in that,

the current lead comprises at least one metal suspension plate composed of a metal material and having at least two bayonet plates at least partially embedded by their lower portions in corresponding recesses in the top of the anode block of calcined carbonaceous material, wherein the at least one metal suspension plate is electrically connected with the anode rod at the upper portion of the suspension plate, and

the patch panel has a thickness less than a thickness of the suspension panel.

2. The anode of claim 1,

the suspension plate is connected to the anode rod via one or more connection members.

3. The anode of claim 2,

at least one of the connection members is a trimetal connection member, a portion of which is connected to the vertical surface of the anode rod, and another portion of which is connected to the upper portion of the suspension plate, and is triangular in shape.

4. The anode of claim 1,

the suspension plate is made of a composite or clad material, wherein at least an upper portion of the yoke jaw plate has a relatively better electrical conductivity than a lower portion of the yoke jaw plate.

5. The anode of claim 1,

there is one horizontally oriented hanger plate with two or more vertically oriented plugboards at its lower surface.

6. The anode of claim 1,

the suspension plate is connected to the anode stem via a spacer.

7. The anode of claim 1,

there are at least two vertically oriented suspension plates, which are connected at their lower ends with the plugboard, respectively.

8. The anode of claim 1,

the conductive particulate material includes particles having a spherical shape.

9. The anode of claim 1,

the conductive particulate material includes particles having an oval or elliptical shape.

10. The anode of claim 1,

the conductive particulate material includes magnetic particles.

11. The anode of claim 1,

the conductive particulate material includes particles made of iron or an iron alloy.

12. The anode of claim 1,

the electrically conductive particulate material comprises particles made of steel or a steel alloy.

13. The anode of claim 1,

the anode block is fixed to the current guiding portion by a pin, a bolt, which interconnects the socket plate and the anode block.

14. The anode of claim 1,

the anode block is fixed to the current lead by means of an undercut recess arranged in the anode block and a protruding fixing means on the plug plate.

15. The anode of claim 1,

the material in the upper portion of the hanger plate comprises copper.

16. The anode of claim 1,

the metal material of the suspension plate is steel.

17. The anode of claim 1,

the metal material of the plugboard is steel.

18. A method for manufacturing an anode according to claim 14, the method being characterized in that,

the recess is formed by machining an elongated slot or notch in the top of the anode block, then forming a hole in the recess at a suitable location by applying a rotary machining tool, the hole being wider than the recess and thus defining an entry point for the protruding fixture, and then machining an undercut recess with a flange in the recess by moving the machining tool along the recess within the anode block.

19. The method of claim 18,

the rotary machining tool is arranged to machine the bore and the undercut recess in the anode block by first axial machining followed by radial machining.