GB2111900A

GB2111900A - Method of, and apparatus for, breaking up carbon blocks

Info

Publication number: GB2111900A
Application number: GB08235865A
Authority: GB
Inventors: Josef Holtrup; Richard Redemann
Original assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Current assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Priority date: 1981-12-24
Filing date: 1982-12-16
Publication date: 1983-07-13
Also published as: FR2519285B1; DE3151398A1; DE3151398C2; CH660693A5; CA1190846A; GB2111900B; AU9167082A; AU551299B2; BR8207319A; FR2519285A1

Abstract

Apparatus for breaking up carbon blocks comprises a breaker 10 and a conveyor 12 for feeding carbon blocks 34 to the breaker. The breaker has a vertically-movable splitter blade 19 for breaking pieces of carbon off the carbon blocks 34. Sensing means 13 are provided for determining the height of the carbon blocks 34, and means are provided for pushing each of the carbon blocks incrementally into the breaker 10. The arrangement is such that each of the carbon blocks 34 is pushed into the breaker 10 in incremental steps the length of each of which is at least 0.3 times the height of that carbon block. <IMAGE>

Description

SPECIFICATION Method of, and apparatus for, breaking up carbon blocks This invention relates to a method of, and apparatus for breaking up carbon blocks, particularly the carbon blocks which are used as the electrodes in electrolytic smelting apparatus.

As is well known, carbon blocks are used for the electrodes of electrolytic aluminium smelting baths, and these carbon blocks have greatly differing dimensions and forms. For example, where the carbon blocks are parallelepipedoil, they can have a rectangular cross-section of, for example, 600 by 800 millimetres and a length of about 3000 millimetres.

Similarly, where the carbon blocks are cylindrical, they can have differing diameters, for example, of 1500 millimetres or more, and a length of about 3000 millimetres.

After a period of time, the carbon electrodes used in aluminium smelting baths must be replaced by new electrodes. The used carbon electrodes can, however, be cleaned and then comminuted priorto being re-constituted into new carbon electrodes. It is known to comminute carbon blocks (which are difficult to break on account of their toughness and their tendency to flake) using special crushers such as jaw crushers. Unfortunately, the carbon blocks used to make the electrodes of aluminium smelting baths are too large to feed into the jaws of known types of jaw crusher. Accordingly, carbon blocks of this size need a preliminary breaking-up step prior to being fed to jaw crushers of this type.

The aim of the invention is to provide a method of, and apparatus for, this preliminary breaking up of carbon blocks.

The present invention provides a method of breaking up a carbon block, the method comprising the step of breaking pieces of carbon off from the carbon block using a splitting device, wherein said pieces of carbon have a length which is at least 0.3 times the dimension of the carbon block measured in the direction of splitting.

Advantageously, said pieces of carbon have a length which is at least 0.4 times said dimension.

Experiments have shown that splitting off pieces of carbon from carbon blocks can be achieved successfully only when the length of each of the pieces to be broken off is at least 0.3 times (and preferably at least 0.4 times) the thickness of the carbon block being split. If smaller pieces of carbon are split off, a smooth break is not guaranteed, so that it is by no means certain that the broken-off pieces are sufficiently small to enter between the jaws of a jaw crusher.

Where a jaw crusher is used to crush the pieces of carbon which are broken off by this method, the size of the carbon pieces should be between 500 and 550 millimetres at the most. This means that carbon blocks having a thickness which is greater than about 900 millimetres must be broken up in two stages. Accordingly, the method of the invention further comprises the step of breaking said pieces of carbon into smaller pieces of carbon, each of said pieces of carbon being broken, in a direction perpendicular to the direction in which it was broken in the first breaking stage, by a second splitter device, wherein each of the smaller pieces of carbon has a length which is at least 0.3 times the thickness of the piece of carbon from which it is broken as measured in the direction of splitting.

Advantageously, each of the smaller pieces of carbon has a length which is at least 0.4 times the thickness of the piece of carbon from which it is broken.

As with the first breaking stage, said pieces of carbon can be broken into said smaller pieces of carbon by smooth splitting operations.

Preferably, said pieces of carbon are broken off from the carbon block by a vertically-movable splitter blade, the splitter blade constituting the first-mentioned splitter device. Where the carbon block has a thickness (or diameter) which is greater than about 1000 millimetres, however, it is preferable if said pieces of carbon are broken off from the carbon block by means of a vertically-movable splitter blade, and by means of two side blades which are laterally movable in the same plane as the splitter blade. In this case, the splitter blade and the two side blades constitute the first-mentioned splitter device. This manner of operation is, in general, only necessary when breaking up cylindrical elec trodeswhose diameter is greater than about 1000 millimetres.In this case, the side blades make notches in the curved edges of the cylindrical carbon block, and the vertically-movable splitter blade does the actual splitting, the notches helping ensure that the splitting occurs smoothly.

Advantageously, said smaller pieces of carbon are broken off said pieces of carbon by a second vertically-movable splitter blade, the second splitter blade constituting the second splitter device.

The entire process of breaking up a carbon block in this manner can be carried out automatically, using suitable sensing and controlled devices.

The invention also provides apparatus for breaking up carbon blocks, the apparatus comprising a breaker device and a conveyor for feeding carbon blocks to the breaker device, the breaker device having a vertically-movable splitter blade for breaking pieces of carbon off the carbon blocks, wherein means are provided for determining the height of the carbon blocks, and means are provided for pushing each of the carbon blocks incrementally into the breaker device, the arrangement being such that each of the carbon blocks is pushed into the breaker device in incremental steps the length of each of which is at least 0.3 times the height of that carbon block.

Advantageously, the arrangement is such that each of the carbon blocks is pushed into the breaker device in incremental steps the length of each of which is at least 0.4 times the height of that carbon block.

In a preferred embodiment, the conveyor is provided with at least one abutment member which, in use, engages a carbon block and feeds that carbon block towards the breaker device. Conveniently, the conveyor is constituted by a pair of endless chains, the or each abutment member being fixed to, and extending between, the two chains.

Advantageously, a sensor constitutes the means for determining the height of the carbon blocks, the sensor being positioned adjacent to the breaker device immediately upstream thereof. Preferably, the sensor is constituted by a vertically-movable measuring beam which is provided with sensing elements. Limit switches may constitute said sensing elements, and the splitter blade and the conveyor may be controlled by the sensor.

The breaker device may comprise a chassis, a trolley which is vertically movable within the chassis by means of a hydraulic ram, and said splitter blade, said splitter blade being detachably mounted on the underneath side of the trolley. Advantageously, the breaker device further comprises a pair of said blades, the side blades being laterally movable in the same plane as said splitter blade. In this case, the side blades may be pivotally mounted on the chassis of the breaker device, and may be laterally pivotable by means of respective hydraulic rams.

Advantageously, the conveyor is provided with means for aligning each of the carbon blocks with the central longitudinal axis of the conveyor. Preferably, said alignment means is constituted by first and second axially-spaced alignment devices, each of the alignment devices being constituted by a pair of parallel rails positioned at the opposite sides of the conveyor, the rails of each alignment device being movable towards, and away from, said central longitudinal axis by means of hydraulic rams.

When the carbon blocks have a thickness greater than about 1000 millimetres, it is preferable to subject them to two breaking stages. Accordingly, the apparatus may further comprise a second breaker device positioned at the output of the firstmentioned breaker device. Advantageously, the second breaker device has a vertically-movable splitter blade for breaking smaller pieces of carbon off said pieces of carbon. In this case, a feed device may be provided for feeding said pieces of carbon from the first-mentioned breaker device to the second breaker device. Preferably, the feed device is constituted by a thrust head which is reciprocable by means of a hydraulic ram.

Advantageously, the apparatus further comprises a holder for holding said pieces of carbon against tilting when the vertically-movable splitter blade of the second breaker device is being used to break off said smaller pieces of carbon therefrom. Preferably, the holder is reciprocable in a vertical direction by means of a hydraulic ram.

A discharge conveyor may be positioned at the output end of the second breaker device.

One form of apparatus for breaking up carbon blocks, and constructed in accordance with the invention, will now be described in detail, by way of example, with reference to the accompanying drawings, in which Figure 1 is a part-sectional side elevation of breaking apparatus; Figure 2 is a cross-section taken on the line ll ll of Figure 1; and, Figure 3 is a plan view of the breaking apparatus.

Referring to the drawings, the breaking apparatus has first and second breakers 10 and 11 resectively, and a conveyor 12 for feeding carbon blocks to the first breaker. A sensor 13 is provided upstream of the first breaker 10, the sensor being effective to ascertain the shape and size of the carbon blocks being fed to the first breaker. A feed device 14 is provided downstream of the first breaker 10, the feed device being effective to feed pieces of carbon broken by the first breaker to the second breaker 11. A conveyor 15, which is positioned downstream of the second breaker 11, is provided for feeding broken pieces of carbon to a crusher (not shown) such as a jaw crusher.

The first breaker 10 has a chassis 16, in which a trolley 17 is vertically reciprocable on rollers 18. A replaceable splitter blade 19 is mounted on the underneath side ofthetrolley 17. The trolley 17 is reciprocable vertically within the chassis 16 by means of a hydraulic ram 20. The ram 20 is housed within the trolley 17, with its cylinder mounted on the trolley base by means of a joint 21, and with its piston rod 22 attached to the top end of the chassis 16. The first breaker 10 is also provided with a pair of side blades 23. The side blades 23 are pivotally mounted, in the lower region of the chassis 16, about pivot joints 24 having horizontal pivot axes. The sides blades 23 are arranged in such a manner that their cutting edges lie in the same vertical plane as the cutting edge of the blade 19. The side blades 23 are laterally pivotable by means of respective hydraulic rams 25.The cylinders of the rams 25 are mounted on the chassis 16, and their piston rods are pivotally attached to the lower ends of the side blades 23.

The second breaker 11 is of similar construction to the first breaker 10. In particular, the second breaker 11 has a trolley 27 reciprocably mounted for vertical movement within a chassis 26, the trolley being provided with a replaceable splitter blade 28. The trolley is reciprocable vertically by means of a pair of hydraulic rams 29. However, the second breaker 11 is not provided with side blades.

The conveyor 12 has a pair of endless parallel chains 30 which are driven and reversed by sprocket wheels 31 and 32. The two chains 30 are interconnected, at two positions, by abutment members 33.

The abutment members 33 are spaced apart by about half the length of the chains 30. In use, the abutment members 33 engage carbon blocks 34 which are to be broken up, and slide them along a horizontal floor 35 of the conveyor 12 in the direction of the arrow S (that is to say towards the first breaker 10). The floor 35 forms an abutment for the carbon blocks 34 as they are being broken up in the first breaker 10.

The sensor 13 is arranged above the conveyor 12 immediately "upstream" of the first breaker 10. The sensor 13 has a measuring beam 36, which is vertically reciprocable by means of at least one hydraulic ram 37. The measuring beam is provided with sensing elements such as limit switches.

The chassis 38 of the conveyor 12 is provided with means for aligning the carbon blocks 34 with the central longitudinal axis of the conveyor. This align ment means is constituted.by two pairs of side rails 39,40 and 41,42. Each of the rails 39,40,41 and 42 extends upwardly from the floor 35 of the conveyor 12, and is movable transversely with respect to the conveyor axis by means of a respective pair of hydraulic rams 43. The conveyor chassis 38 forms an abutment for each of the hydraulic rams 43.

The feed device 14 feeds pieces 34' of carbon broken from the blocks 34 by the first breaker 10 to.

the second breaker 11. The feed device 14 has a plate like thrust head 44 which is reciprocable by means of a hydraulic ram 45 whose axis lies parallel to the direction of the arrow S. The thrust head 44 is movable over the floor 46 of the feed device 14 on rollers (not shown). The floor 46 also forms an abutment for the carbon pieces 34' as they are being broken up in the second breaker 11. The hydraulic ram 45 is positioned beneath the discharge end of the chassis 38 of the conveyor 12, and the floor 46 is likewise downwardly offset relative to the conveyor floor 35.

The second breaker 11 is provided with a holder 47 for holding the carbon pieces 34' as they are broken up, thereby preventing them tilting during this process. The holder 47 is vertically reciprocable using a pair of hydraulic rams 48. The smaller pieces 34" of carbon which leave the second breaker 11 are transferred to the conveyor 15 by means of a transfer device. This transfer device is constituted by a flap 49 which is pivotally mounted to the conveyor 15 about a horizontal pivot axis. The flap 49 can be pivoted by means of a hydraulic ram 50. Thus, by pivoting the flap 49 upwardly from the position shown in Figure 1, carbon pieces 34" are thrown onto the conveyor 15.

The breaking apparatus described above operates in the following manner. The carbon blocks 34 to be broken up are successively charged onto the conveyor 12 using a fork lift truck (not shown). In order to facilitate this charging process, the rail 40 is formed with apertures 51 for receiving the forks of the fork lift truck. After a carbon block 34 has been positioned on the conveyor 12, the two rails 39 and 40 are moved towards one another by their hydraulic rams 43. This aligns the carbon block 34 with the central longitudinal axis of the conveyor 12. The rails 39 and 40 are then moved apart, and the conveyor 12 is started up. The carbon block 34 is then advanced towards the first breaker 10 upon engagement by one of the abutment members 33.The carbon block 34 is advanced until its leading edge lies beneath the splitter blade 19 ofthefirst breaker 10 (this position being shown in Figure 1). In this position, the carbon block 34 is re-aligned with the central longitudinal axis of the conveyor 12 by moving in the rails 41 and 42. Next, the measuring beam 36 is driven downwardly until it contacts the uppermost portion of the carbon blocks 34. The sensing elements associated with the measuring beam 36 can then be used to determine whether the carbon block is of polygonal cross-section or, as shown in the drawings, of circular cross-section. At the same time, the sensing elements determine the thickness (height) of the carbon block 34.The sensor 13 then initiates and controls the hydraulic ram 20, which is extended rapidly into a position in which the cutting edge of the splitter blade 19 is about 50 to 100 millimetres above the uppermost portion of the carbon block 34.

At the same time, another carbon block 34 is deposited, by the fork lift truck, between the openedup rails 39 and 40 on the conveyor 12. The measuring beam 36 is then raised; and, after it reaches its uppermost position, it activates the drive of the conveyor 12, which pushes the first carbon block 34 forwards by a distance equal to that of the length of the carbon pieces 34' to be broken off. The splitter blade 19 is then driven down, by its hydraulic ram 20, so as to break off a piece 34' from the carbon block 34.

The length L of the piece 34' should be at least 0.3 times the thickness (or diameter) D of the carbon block 34, and L is preferably at least 0.4D. This ensures smooth breaking of the carbon block 34.

Where the maximum width of the entrance to the jaws of the downstream jaw crusher is 500 millimetres, for example, a carbon block 34 whose dimension D is greater than 900 millimetres must be broken up in two stages. If the carbon block 34 has its dimension D less than 900 millimetres, (say 750 millimetres), it is expedient for Lto be 450 millimetres. Where D is greater than 900 millimetres, the setting of the two breakers 10 and 11 must be determined in advance. Thus, if D is less than 1100 millimetres, the pieces 34' are broken off in the breaker 10 using only the splitter blade 19. In this case, the splitter blade 19 is driven down by its ram 20 until a photo-electric cell (not shown) signals that a piece 34' has been separated and has fallen down from the conveyor 12. The splitter blade 19 is then raised ready for the next working stroke.

Where the carbon block 34 has a circular crosssection with D greater than 1100 millimetres, the side blades 23 are used in conjunction with the splitter blade 19. In this case, the side blades 23 are brought rapidly into contact with the curved edges of the carbon block 34, by extending their rams 25.

When the rams 25 have been subjected to a predetermined pressure, they are retracted. This predetermined pressure is such that the side blades 23 make notches in the curved edge portions of the carbon blocks 34. The splitter blade 19 is then driven down to break off a piece 34' of carbon, the notches facilitating a smooth splitting operation.

The carbon piece 34' drops onto the floor 46 of the feed device 14, from where it can be fed to the second breaker 11 by means of the thrust head 44 and the ram 45. If the carbon piece 34' has a length L (now a thickness as the piece is turned through 90 as it is transferred from the first breaker 10 to the feed device 14) which is greater than 550 millimetres, it is pushed into the second breaker. If the piece 34' has L less than 550 millimetres, it is pushed right through the second breaker 11, as pieces of this size do not need breaking down further in order to fit into the jaw crusher.

If the carbon piece 34' does require further breaking down, it is pushed forward, by the thrust head 44, by a distance of between 500 and 500 millimetres. The pieces 34' then lies beneath the splitter blade 28, whereupon the holder 47 is forced down against the carbon piece so as to prevent the piece from tilting during the subsequent breaking operation. When a predetermined pressure is attained in the rams 48, the rams 29 are actuated to force the splitter blade 28 down to break off a smaller carbon piece 34". As was the case in the first breaker 10, each smaller piece 34" broken off the piece 34' is arranged to have a lenth which is at least 0.3 times (and preferably at least 0.4 times) the thickness (L) of the piece 34'. This smaller piece 34" drops down onto the transfer flap 49, which is then lifted to deposit the smaller piece on the conveyor 15.The ram 45 is then extended further, and another smaller piece 34" is broken off the piece 34'. This process is repeated until the piece 34' is completely broken up into smaller pieces 34". At this stage, the ranm, 45 is fully extended to push the last part of the piece 34' out of the second breaker 11. The ram 45 is then retracted ready to receive the next carbon piece 34' from the first breaker 10. This retraction movement of the ram 45 triggers the next breaking operation of the first breaker 10.

The operations described above are repeated until the carbon block 34 is completely broken up. The next carbon block 34 is then broken up in the same way. Itwill be understood that the breaking process is such that none of the pieces of carbon fed to the crusher has a length L greater than about 0.3 to 0.4 times the dimension D of the carbon blocks 34, and this is the case whether the breaking is carried out in one or two stages.

The apparatus described above is intended primarly to be used for the preliminary breaking up of carbon blocks (electrodes) prior to the broken pieces of carbon being fed to a jaw crusher. The apparatus is suitable for breaking up cylindrical or polygonal carbon blocks of different dimensions.

Claims

1. A method of breaking up a carbon block, the method comprising the step of breaking pieces of carbon off from the carbon block using a splitter device, wherein said pieces of carbon have a length which is at least 0.3 times the dimensions of the carbon block measured in the direction of splitting.

2. A method as claimed in claim 1, wherein said pieces of carbon have a length which is at least 0.4 times said dimension.

3. A method as claimed in claim 1 or claim 2, further comprising the step of breaking said pieces of carbon into smaller pieces of carbon, each of said pieces of carbon being broken, in a direction perpen circular to the direction in which it was broken in the first breaking stage, by a second splitter device, wherein each of the smaller pieces of carbon has a length which is at least 0.3 times the thickness of the piece of carbon from which it is broken as measured in the direction of splitting.

4. A method as claimed in claim 3, wherein each of the smaller pieces of carbon has a length which is at least 0.4 times the thickness of the piece of carbon from which it is broken.

5. A method as claimed in any one of claims 1 to 4, wherein said pieces of carbon are broken off from the carbon block by a verticaliy-movable splitter blade, the splitter blade constituting the firstmentioned splitter device.

6. A method as claimed in any one of claims 1 to 4, wherein said pieces of carbon are broken off from the carbon block by means of a vertically-movable splitter blade, and by means of two side blades which are laterally movable in the same plane as the splitter blade, the splitter blade and the two side blades constituting the first-mentioned splitter device.

7. A method as claimed in claim 3, claim 4, or either of claims 5 and 6 when appendant to claim 3, wherein said smaller pieces of carbon are broken off said pieces of carbon by a second vertically-movable splitter blade, the second splitter blade constituting the second splitter device.

8. A method of breaking up carbon blocks into smaller pieces of carbon, the method being substantially as hereinbefore described with reference to the accompanying drawings.

9. Apparatus for breaking up carbon blocks, the apparatus comprising a breaker device and a conveyor for feeding carbon blocks to the breaker device, the breaker device having a verticallymovable splitter blade for breaking pieces of carbon off the carbon blocks, wherein means are provided for determining the height of the carbon blocks, and means are provided for pushing each of the carbon blocks incrementally into the breaker device, the arrangement being such that each of the carbon blocks is pushed into the breaker device in incremental steps the length of each of which is at least 0.3 times the height of that carbon block.

10. Apparatus as claimed in claim 9, wherein the arrangement is such that each of the carbon blocks is pushed into the breaker device in incremental steps the length of each of which is at least 0.4 times the height of that carbon block.

11. Apparatus as claimed in claim 9 or claim 10, wherein the conveyor is provided with at least one abutment member which, in use, engages a carbon block and feeds that carbon block towards the breaker device.

12. Apparatus as claimed in claim 11, wherein the conveyor is constituted by a pair of endless chains, the or each abutment member being fixed to, and extending between, the two chains.

13. Apparatus as claimed in any one of claims 9 to 12, wherein a sensor constitutes the means for determining the height of the carbon blocks, the sensor being positioned adjacent to the breaker device immediately upstream thereof.

14. Apparatus as claimed in claim 13, wherein the sensor is constituted by a vertically-movable measuring beam which is provided with sensing elements.

15. Apparatus as claimed in claim 14, wheren limit switches constitute said sensing elements.

16. Apparatus as claimed in any one of claims 13 to 15, wherein the splitter blade and the conveyor are controlled by the sensor.

17. Apparatus as claimed in any one of claims 9 to 16, wherein the breaker device comprises a chassis, a trolley which is vertically movable within the chassis by means of ofahydraulic ram, and said splitter blade, said splitter blade being detachably mounted on the underneath side of the trolley.

18. Apparatus as claimed in any one of claims 9 to 17, wherein the breaker device further comprises a pair of side blades, the side blades being laterally movable in the same plane as said splitter blade.

19. Apparatus as claimed in claim 18 when appendantto claim 17, wherein the side blades are pivotally mounted on the chassis of the breaker device, and are laterally pivotable by means of respective hydraulic rams.

20. Apparatus as claimed in any one of claims 9 to 19, wherein the conveyor is provided with means for aligning each of the carbon blocks with the central longitudinal axis of the conveyor.

21. Apparatus as claimed in claim 20, wherein said alignment means is constituted by first and second axially-spaced alignment devices.

22. Apparatus as claimed in claim 21, wherein each of the alignment devices is constituted by a pair of parallel rails positioned at the opposite sides of the conveyor, the rails of each alignment device being movable towards, and away from, said central longitudinal axis by means of hydraulic rams.

23. Apparatus as claimed in any one of claims 9 to 22, further comprising a second breaker device positioned at the output of the first-mentioned breaker device.

24. Apparatus as claimed in claim 23, wherein the second breaker device has a vertically-movable splitter blade for breaking smaller pieces of carbon off said pieces of carbon.

25. Apparatus as claimed in claim 23 or claim 24, further comprising a feed device for feeding said pieces of carbon from the first-mentioned breaker device to the second breaker device.

26. Apparatus as claimed in claim 25, wherein the feed device is constituted by a thrust head which is reciprocable by means of a hydraulic ram.

27. Apparatus as claimed in claim 23, or in any one of claims 24 to 26 when appendantto claim 23, further comprising a holder for holding said pieces of carbon against tilting when the vertically-movable splitter blade of the second breaker device is being used to break off said smaller pieces of carbon therefrom.

28. Apparatus as claimed in claim 27, wherein the holder is reciprocable in a vertical direction by means of a hydraulic ram.

29. Apparatus as claimed in any one of claims 22 to 28, further comprising a discharge conveyor positined at the output end of the second breaker device.

30. Apparatus for breaking up carbon blocks substantially as herein before described with reference to, and as illustrated by, the accompanying drawings.