Permanent cathode

1. A permanent cathode to be used as electrode in the electro-refining and/or recovery of metals, such as copper, zinc, cobalt or nickel,

wherein the permanent cathode comprises a planar mother plate that is made of metal and comprises two sides;

wherein the mother plate comprises an edge, which at least partly surrounds the metal plate; and

wherein the edge comprises a groove portion provided with a groove,

wherein:

the groove portion comprises at least one bridging section for joining together, over the groove portion of the edge of the metal plate at the said at least one bridging section, the cathode metal halves, which are formed on the sides of the mother plate in the electro-refining of the metals,

the groove portion is dimensioned and/or designed such that the cathode metal halves that are formed in electrorefining or electrowinning of metal on the sides of the mother plate are configured to at least partly be connected over the groove portion of the edge of the mother plate, and

said at least one bridging section of the groove portion is dimensioned and/or designed such that the connection between the cathode metal halves at a bridging section of the groove portion is a stronger connection between the cathode metal halves over the edge of the mother plate than exists between the cathode metal halves over the edge of the mother plate at other parts of the groove portion.

2. A permanent cathode according to claim 1 ,

further comprising a suspension means of the mother plate for suspending the mother plate in an electrolytic tank.

3. A permanent cathode according to claim 2 , wherein at least one essentially parallel side edge is provided with an edge strip.

4. A permanent cathode according to claim 1 , wherein

the edge of the mother plate comprises two essentially parallel side edges and a bottom edge; and

the groove portion is formed on the bottom edge of the mother plate.

5. A permanent cathode according to claim 4 , wherein

there is a straight and/or curved angular edge portion between each essentially parallel side edge and the bottom edge; and

the groove portion extends to at least one angular edge portion.

6. A permanent cathode according to claim 1 , wherein

the groove portion comprises several grooves; and

the bridging section is situated between two grooves.

7. A permanent cathode according to claim 1 , wherein the bridging section is formed in the groove so that a section lower than the rest of the groove is formed in the groove, constituting the bridging section over the groove.

8. A permanent cathode according to claim 7 , wherein

the depth of the groove outside the bridging section is about 1-about 1.5 mm; and

the depth of the groove at the bridging point is about 0.25-about 1 mm.

9. A permanent cathode according to claim 8 , wherein the depth of the groove at the bridging point is about 0.25-about 0.75 mm.

10. A permanent cathode according to claim 9 , wherein the depth of the groove at the bridging point is about 0.25-about 0.5 mm.

11. A permanent cathode according to claim 7 , the edge of the mother plate comprises both a groove and an essentially flat portion at the bridging section.

12. A permanent cathode according to claim 1 , wherein the edge of the mother plate is essentially flat at the bridging section.

13. A permanent cathode according to claim 1 , wherein the groove is a V groove.

14. A permanent cathode according to claim 13 , wherein the bridging section is formed by at least partly removing from the V groove the second half of the structure that constitutes the shape of the V groove at the bridging section.

15. A permanent cathode according to claim 1 , wherein the width of the bridging section is about 5-about 50 cm.

16. A permanent cathode according to claim 15 , wherein the width of the bridging section is about 10-about 40 cm.

17. A permanent cathode according to claim 16 , wherein the width of the bridging section is about 20-about 30 cm.

18. A permanent cathode according to claim 1 , wherein the bridging section forms an essentially flat portion at the groove section.

19. A permanent cathode according to claim 1 , wherein the cathode metal halves comprise cathode copper halves, cathode zinc halves, cathode cobalt halves, or cathode nickel halves.