Working Principle

Anode plates are hung by their “handles” in electrolytic copper refining tank. Pure copper cathode sheets suspended on solid copper bars are inserted into the same tank, one sheet between each anode. When an electric current is passed from the anodes through the electrolyte to the cathodes, copper from the anodes moves into the solution and is plated onto the starter sheet. Impurities from the anodes settle to the bottom of the tank.

Ag, Au, tin and Pt are more noble than copper, insoluble in this electrolyte and so do not deposit on the cathode. They will be found as metals in the anode slime;
Soluble impurities of iron and nickel dissolve in the electrolyte, which has to be continually purified to prevent excessive deposition onto the cathodes, which would reduce the purity of the copper;
Sn, Bi and Sb dissolve anodically but will precipitate in the electrolyte as oxide or hydroxide compounds which will be found in the anode slime.