Abstract
	Experimental results of the electrolytical refining of silver aimed to study of the influence of metallic impurities on the cathodic metal purity from secondary resources are presented in this paper. Horizontal Thum electrolyser was used for these experiments. Influence of the concentration of the metallic impurities in the electrolyte on the purity of cathodic silver was studied after redistribution of the impurities between electrolyte, anode slime and cathodic metal.
	The influence of silver concentration in electrolyte on the cathodic silver was studied in the first set of experiments. Decreasing of silver content in the nitrate electrolyte under     55 g.dm-3 caused decreasing of the cathodic silver purity. The influence of the Cu, Zn, Pd, Ni, Au, Pt, Sn, Pb, Fe, Bi and Sb content in the anodes and in the electrolyte on the resulting purity of cathodic silver was studied in the second set of experiments. The results obtained are presented in the figures and tables in this paper.
	It is possible to divide the metallic impurities into three groups. Copper and palladium is the in the first group and their concentration in the cathodic silver were more than            10-1 wt.%. Palladium is dissolved in the electrolyte and due to higher electrochemic potential than that silver has, is precipitated in the cathode preferently. Copper has much higher concentration in the electrolyte as silver and at lower potential is mechanically precipitated together with silver as a copper “cathodic sponge”.
	Zinc is in the second group only. Zn content was 10-2 wt.% in the cathode at 20 g.dm-3 of Zn concentration in the electrolyte. Mechanism of Zn precipitation in the cathodic metal was very similar as at copper. Zinc at law electrochemic potential is precipitated in the cathode mechanically at its high concentration in the electrolyte.
	The third group is created by other metallic impurities and their content were under  10-2 wt.% in the cathodic silver. Gold and platinum is not dissolved in the electrolyte and so its influence is negligitle and these metals are concentrated in the anode slime. Ni, Fe, Sn, Pb, Sb and Bi have similar dissolving and precipitating mechanism as Cu and Zn but their content in the anode were very low.