permanent cathode and device for electrowinning metals including said permanent cathode

1. A permanent cathode (1) to be used as an electrode in electrowinning of metals, including a permanent cathode plate (4) at least partially made of steel and providing the possibility of electrochemically depositing metal from an electrolytic solution on its surface (6, 6a, 6b), characterized in that the plate permanent cathode (4) comprises a surface area (6a) with properties of strong adhesion which is in contact with the electrolyte and is etched, because plate permanent cathode ( 4) comprises a surface area (6b) with properties weak bond is in contact with the electrolyte and is not etched, because the dimensions in the surface (6) of the plate permanent cathode (4) on the surface (6a ) with strong adhesion properties and which is in contact with the electrolyte and is recorded are: (i) the grain size (1) of the grains (8) measured by the formula 1 = 1 / NL where NL is the number of grain boundaries (7) divided by the measurement distance is 1 to 40 micrometers (ii) the average width (W) of the grain boundary of the plate permanent cathode according measured with an atomic force microscope is from 1 to 3 microns, and (iii) the average depth of grain boundary (d) of the plate permanent cathode according measured with an atomic force microscope is less than 1 micron, and because the surface area (6b) with weak adhesion properties and which is in contact with the electrolyte and which is not recorded is located at a point where the separation of the metal deposit (11) intended to start.