ZA200203520B

ZA200203520B - An electrolytic cell.

Info

Publication number: ZA200203520B
Application number: ZA200203520A
Authority: ZA
Inventors: Peter-John Garbutt
Original assignee: Garbutt Peter John
Priority date: 1999-11-05
Filing date: 2002-05-03
Publication date: 2002-12-09

Description

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AN ELECTROLYTIC CELL

BACKGROUND TO THE INVENTION

This invention relates to an electrolytic cell as well as to an array of electrolytic cells for use in an electrowinning process for extracting metals from an electrolyte.

The electrolytic recovery of certain metals, such as cobalt, nickel, : manganese and copper, typically occurs within an electrolytic cell containing a plurality of anode and cathode electrode pairs which are . immersed in a suitable electrolyte. The electrolyte may be a chloride or suiphate base. The metal is deposited on the cathode electrode when an electric current is passed between the anode and cathode electrodes. A manifold having a plurality of outlets is mounted on the outside of the container and is used to feed the electrolyte into the cell as well as to extract electrolyte from the cell. Since the manifolds are mounted on the outside of the container, the containers have to be placed in pairs, with there being sufficient walkway clearance between adjacent pairs of containers for accommodating and maintaining the manifolds.

A disadvantage of this spaced-apart arrangement is that the intercell bus- bars required to electrically connect adjacent pairs of cells to one another have relatively long underfloor bridging portions, and this has significant cost implications, both from a material and space utilization viewpoints.

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SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided an electrolytic cell comprising: a container having a base and a plurality of side walls defining a footprint representative of the total surface area occupied by the container, the container being arranged to accommodate an electrolyte and an array of anode and cathode electrodes which are electrically connectable to negative and positive bus-bars respectively; and manifold accommodating means for accommodating a manifold for feeding electrolyte into and/or extracting ) electrolyte from the container, the manifold accommodating means being arranged to accommodate the manifold . inwardly of the footprint, so as to allow adjacent containers to be positioned in a contiguous side-by-side relationship.

In one version, the manifold is non-integral with the container and includes a manifold pipe which is detachably mountable relative to the container with the manifold accommodating means defining a support surface for accommodating the manifold pipe.

Typically, at least one side wall of the container includes a recess formed near an operatively upper edge of the at least one side wall which defines the support surface for accommodating the manifold pipe.

The recess may be an elongate recess that terminates short of the adjacent side walls, with at least one end of the manifold pipe being arranged to overhang an adjacent side wall. Alternatively, the recess may

.- extend the length of the at least one side wall and through at least one of the adjacent side walls, with the manifold pipe being arranged to extend in a substantially straight line through the at least one adjacent side wall.

In another version, the manifold is integral with the container and includes a manifold pipe with the manifold accommodating means being arranged to mount the manifold pipe to the inside of a side wall.

Preferably, the electrolytic cell includes a shield mounted to a side wall, the shield being arranged to extend inwardly into the container so as to overhang and protect the manifold pipe.

Conveniently, the shield defines the support surface for receiving and supporting the manifold pipe.

Typically, the electrolytic cell includes bus-bar receiving means for receiving the bus-bars, the bus-bar receiving means being integral with the - shield.

According to a second aspect of the invention there is provided an array of electrolytic cells, each electrolytic cell comprising: a container having a base and a plurality of side walls defining a footprint representative of the total surface area occupied by the container, the container being arranged to accommodate an electrolyte and an array of anode and cathode electrodes which are electrically connectable to negative and positive bus-bars respectively, wherein the array includes manifold accommodating means for accommodating a manifold for feeding electrolyte into and/or extracting electrolyte from the container, the manifold accommodating means being arranged to accommodate the manifold inwardly of the footprint, so as to allow a plurality of containers to be positioned in a contiguous side-by-side relationship so that the intercell spacing is negligible and substantially uniform.

Preferably, at least one side wall of the container includes a recess formed near an operatively upper edge of the at least one side wall which defines the support surface for accommodating the manifold pipe.

Alternatively, the manifold is integral with the container and includes a : manifold pipe with the manifold accommodating means being arranged to mount the manifold pipe to the inside of a side wall.

Typically, the containers are arranged side-by-side with the side walls of adjacent containers substantially abutting against each other. Alternatively, the containers are contiguous, with the side walls of adjacent containers being integral so that adjacent containers share a common side wall.

Conveniently, the side walls cf adjacent containers are straddied by a shield, the shield including at least one overhanging portion which overhangs the manifold pipe so as to protect it.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a partly schematic perspective view of an electrolytic cell according to the invention;

Figure 2 is a cross-sectional front view of the cell along the line 2-2 of Figure 1 showing an electrode assembly focated in position within the cell;

Figure 3 is a cross-sectional side view along the line 3-3 of

Figure 1 of a part of the container showing a plurality of the electrode assemblies of Figure 2;

Figure 4 is a partly cross-sectional front view of an array of electrolytic cells connected in direct side-by-side ’ relationship;

Figure 5 shows a top plan view of the electrolytic ceils of Figure 4,

Figure 6 shows a top plan view of a corner of an electrolytic cell according to a second embodiment of the invention;

Figures 6A to 6C show cross-sectional side views taken along lines A, B and C respectively of Figure 6;

Figure 7A shows a cross-sectional side view of a capping plate according to a third embodiment of the invention;

Figure 7B shows a cross-sectional side view of a capping plate according to a fourth embodiment of the invention;

; + WO 01/32962 PCT/1B00/01594 and

Figure 7C shows a cross-sectional side view of a capping plate according to a fifth embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring first to Figure 1, an electrolytic cell 10 comprises a container 12 having a base 14, a pair of side walls 16 and 18 and a pair of end walls 20 and 22. The upper inner portion of the side wall 16 is formed with a recess 24 which is specifically designed to accommodate a manifold pipe 26. The side wall 18 may also be formed with a recess, as is shown at 24A. The container 12 is moulded from a polymer concrete, from concrete lined with ) glass fibre or entirely from a glass fibre or polymeric material. : The manifold 26 is fitted with a plurality of inlet pipes 28 for removing an electrolyte from the electrolytic cell 10. An integral overflow box 30 is formed in the end wall 22 of the container, and includes an outflow pipe 32.

A feed pipe 33 feeds electrolyte into the container, which is then removed via the inlet pipes 28. Excess electrolyte flows through the outflow pipe 32 via the overflow box 30. In an alternative mode of operation, the manifold distributes electrolyte into the container via the pipes 28, which become outlet pipes in place of the feed pipe 33, with electrolyte being removed via the overflow box 30 and outflow pipe 32.

Figures 2 and 3 show a mcre detailed view of part of the assembled electrolytic cell. The manifold 26 rests on a support surface or shelf 34, extends over the top edge of the end wall 20 of the container 12, and terminates in a connecting flange 36 for allowing it to be removably coupled to a main inlet or outlet pipe. In one version of the invention, shown in

Figures 6 and 6A to 6C, the recess 24 extends through the entire length of the side wall 28. This arrangement therefore allows the manifold 26 to extend in a straight line through the end wall 20, without it having to extend over the top edge of the end wall 20. A paddle flange 37 seals the manifold 26 in position within the recess 24. A significant advantage of this feature is that the manifold pipe can be slid into and out of the container 12, which greatly simplifies the replacement of the manifold pipe.

An elongate capping plate 38 has an overhanging portion 40 which overhangs the manifold 26 to protect it. An opposite flanged portion 42 extends over the side wall 44 of an adjacent container. Mounted on top of the capping plate 38 are intercell bus-bars 46A and 46B, which are in turn surmounted by respective spacer insulator block strips 48A and 48B. The opposite side wall 18 is formed with a similar arrangement of capping plate 38, intercell bus-bar 46 and spacer block strip 48. An anode electrode ; plate assembly 50 is housed snugly within a permeable anode bag 52, and spacer grids, one of which is shown at 54, are used to space opposed . faces of an anode plate 56 from the permeable bag 52. A hanger bar 58 is mounted at an uppermost end of the anode plate 56, with the ends 58A and 58B of the bar resting within recesses 60 and 62 defined within the spacer block strips 48A and 48B. A pair of lifting apertures or lugs 64 are formed just beneath the bar 58, and are used for removing the anode plate assemblies 50 from the anode bags 52 via an overhead crane or gantry for maintenance and replacement purposes.

The manifold 26 is formed with a plurality of spigots 66 at spaced apart intervals to which the pipes 28 are connected, with the opposite ends of the pipes being connected to spigots 68 extending from the fixed bags 52. It can clearly be seen how the recess 62 is dimensioned so that the end 58A of the hanger bar forms an electrical contact at 69 with the bus-bar 46A, which is negative with respect to the bus-bar 46B. The recess 60

, . WO001/32962 PCT/IB00/01594 effectively spaces the opposite end 58B of the hanger bar from the positive bus-bar 46B. As is apparent from Figure 3, the anode plate assemblies 50 alternate with cathode plate assemblies 70, which are similarly formed with hanger bars electrically connected to the positive bus-bar 468.

The cathode plate assemblies 70 are shown in more detail in Figure 4, which shows part of an array 71 of electrolytic cells, and include a cathode plate 72 housed within a porous bag 73 and surrounded by a frame 74 for assisting in electro-deposition. The cathode plate assemblies are similarly fitted with lifting apertures 64 or lugs, and are electrically connected at 76A to the positive bus-bars 46B. The cathode plate 72 is fitted with an upper hanger bar 77A which makes the electrical connection at 76A. The surrounding frame 74 is in turn carried on a lower hanger bar 77B which rests on the support surfaces provided by the recesses 24 and 24A. The ‘ lower hanger bar and frame, in conjunction with the cathode bag 73, remain behind when the cathode plates 72 are removed for stripping.

Figures 4 and 5 show clearly how adjacent electrolytic cells 10A, 108, 10C and 10D can be positioned directly alongside one another with alternating positive and negative intercell bus-bars 46A and 46B straddling the : adjacent walls of the electrolytic cells. it is apparent from Figure 5 how the anode plate assemblies 50 alternate with the cathode plate assemblies 70, with the anode plate assemblies being electrically connected to the negative bus-bars 46A and the cathode plate assemblies being connected to the positive bus-bars 46B.

In use, the array of electrolytic cells operate as follows. The anode and cathode plates are immersed in electrolyte 78 carrying the metal ions up to a level 80 in the containers. In the embodiment illustrated in Figures 1 to 3, electrolyte is fed through the feedpipe 33 and is sucked out via the pipes 28 into the manifold 26. Gas generated at the anode plates is similarly sucked out via the pipes 28. The cathode plate assemblies 70 are regularly removed at 5 to 7 day intervals for recovery of the metal which is electro-deposited on the plate surfaces. The anode plates 50 are removed less frequently (at least at six monthly intervals) for maintenance and replacement purposes.

According to another embodiment of the invention, as shown in Figures 7A and 7B, the capping plate 82 is arranged to not only overhang and protect the manifold pipes 26 in adjacent electrolytic cells 10, but is also formed with an overhanging re-entrant portion 83 defining an upper support surface 84 for accommodating and supporting the manifold pipes 26. The overhanging portion 83 is formed with a plurality of apertures 83A through which the spigots 66 extend. In Figure 7A, the capping plate 82 is integral with the insulator blocks 86, whereas in Figure 7B, the capping plate 82 and insulator block 86 are two separate, distinct components. Intercell : bus-bars 46A and 46B having a triangular profile are accommodated and supported by a central channel 87 defined within the insulator blocks 86. In .

Figure 7C, the manifold pipes 26 are supported off the side walis 16 or 18 of the container 12 by means of a bracket arrangement 88. In this embodiment, therefore, the capping plate 82 is arranged only to protect the manifold pipes 26.

Figures 7A to 7C also clearly show adjacent containers making use of a single, common side wall, typically made of concrete, as opposed to two adjacent side walls which abut against each other as shown in Figures 2 to 5.

The primary advantage of the present invention is that by placing the manifold within the confines of each electrolytic cell, there is no need to group cells in spaced apart pairs, as has traditionally been done. This serves to eliminate the underfloor copper conductors required to bridge the pairs of spaced apart cells and allows for more cells to be installed into a given area, thereby reducing the footprint of the tankhouse.

Furthermore, a manifold, if damaged by regular removal and replacement of electrode plates, can easily be removed and replaced, and thus maintenance on the cell is relatively quick and simple.

Claims

1. An electrolytic cell comprising: a container having a base and a plurality of side walls - : defining a footprint representative of the total surface area occupied by the container, the container being arranged to accommodate an electrolyte and an array of anode and cathode electrodes which are electrically connectable to : = negative and positive bus-bars respectively; and - manifold accommodating means for accommodating a manifold for feeding electrolyte into and/or extracting electrolyte from the container, the manifold accommodating means being arranged to accommodate the manifold ’ inwardly of the footprint, so as to allow adjacent containers to be positioned! in a contiguous side-by-side relationship. .

2. An electrolytic cell according to claim 1 wherein the manifold is non- integral with the container and includes a manifold pipe which is detachably mountable relative to the container with the manifold accommodating means defining a support surface for accommodating the manifold pipe.

3. An electrolytic cell according to claim 2 wherein at least one side wall of the container includes a recess formed near an operatively upper edge of the at ieast one side wall which defines the support surface for accommodating the manifold pipe.

4. An electrolytic cell according to claim 3 wherein the recess is an elongate recess that terminates short of the adjacent side walls,

, «. +» WO 01/32962 PCT/IB00/01594 with at least one end of the manifold pipe being arranged to overhang an adjacent side wall.

5. An electrolytic cell according to claim 3 wherein the recess extends the length of the at least one side wall and through at least one of the adjacent side walls, with the manifold pipe being arranged to extend in a substantially straight line through the at least one adjacent side wall.

6. An electrolytic cell according to claim 1 wherein the manifold is integral with the container and includes a manifold pipe with the manifold accommodating means being arranged to mount the manifold pipe to the inside of a side wall.

’ 7. An electrolytic cell according to any one of claims 2 to 6 which includes a shield mounted to a side wall, the shield being arranged to : extend inwardly into the container so as to overhang and protect the manifold pipe.

8. An electrolytic cell according to claim 7 wherein the shield defines the support surface for receiving and supporting the manifold pipe.

9. An electrolytic cell according to either claim 7 or claim 8 which includes bus-bar receiving means for receiving the bus-bars, the bus-bar receiving mean: being integral with the shield.

10. An array of electrolytic cells, each electrolytic cell comprising: a container having a base and a plurality of side walls defining a footprint representative of the total surface area occupied by the container, the container being arranged to accommodate an electrolyte and an array of anode and cathode electrodes which are electrically connectable to negative and positive bus-bars respectively, wherein the array includes manifold accommodating means for accommodating a manifold for feeding electrolyte into and/or extracting electrolyte from the container, the manifold accommodating means being arranged to accommodate the manifold inwardly of the footprint, so as to allow a plurality of containers to be positioned in a contiguous side-by-side relationship so that the intercell spacing is negligible and substantially uniform.

11. An electrolytic cell according to claim 10 wherein the manifold is non-integral with the container and includes a manifold pipe which is detachably mountable relative to the container with the manifold ’ accommodating means defining a support surface for accommodating the manifold pipe.

12. An electrolytic cell according to claim 11 wherein at least one side wall of the container includes a recess formed near an operatively upper edge of the at least one side wall which defines the support surface for accommodating the manifold pipe.

13. An electrolytic cell according to claim 10 wherein the manifold is integral with the container and includes a manifold pipe with the manifold accommodating means being arranged to mount the manifold pipe to the inside of a side wall.

14. An array of electrolytic cells according to any one of claims 10 to 13 wherein the containers are arranged side-by-side with the side walls of adjacent containers substantially abutting against each other.

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15. An array of electrolytic cells according to any one of claims 10 to 13 wherein the containers are contiguous with the side walls of adjacent containers being integral so that adjacent containers share a common side wall.

16. An array of electrolytic cells according to any one of claims 11 to 15 wherein the side walls of adjacent containers are straddled by a shield, the shield including at least one overhanging portion which overhangs the manifold pipe so as to protect it.

17. An electrolytic cell according to claim 16 which includes bus-bar receiving means for receiving the bus-bars, the bus-bar receiving means being integral with the shield.