Peripheral coating process of the copper conductive bar for the manufacture of anodes, used in the processes of electro-obtaining or electro-refining of metals

A method for assembling lead anodes used in the electrolytic processes, which increases corrosion resistance and improves bonding between the copper bar, dip weld into a melted bath and a final peripheral coating of such copper bar comprising the following stages:

• a) The copper bus bar is subject to pre-coating by dip welding in a melted bath, at the right temperature (300° C.-350° C.) with an alloy mainly including lead and silver. The silver content is between 0.1% w/w and 10% w/w, preferably 3% w/w;
• b) After this pre-coating while the hot copper bar is at a temperature between 250° C. to 280° C., and inserted into a proper mold, the peripheral coating of the copper bar is performed by means of injection or any other similar method with a lead-antimony alloy, between 0.01 and 11% of Sb w/w, preferably 6% w/w, with a thickness between 0.01 and 10 mm, preferably 1.5 mm;
• c) Right after injection or pre-heating the copper bar is set onto the assembly workbench to fill the groove with a lead-bismuth alloy, between 1 to 55% w/w of bismuth, preferably 50% w/w, at such temperature to allow insertion of the lead plate, while the lead-bismuth weld remains liquid;
• d) Preferably with an identical alloy to that of peripheral coating to weld reinforce the joint spot, between the peripheral coating of the copper bar and the plate, on both sides when the lead-bismuth alloy poured in the groove has solidified. FEATURED, because the copper bar is previously subject to a mechanical/chemical/electrochemical process aimed to increase its roughness, before the pre-coating process of such copper bar.