The flotation concentration plant in the RTB Bor started working at the industrial scale in 1933 and terminated in 2003. During those seventy years of copper ore processing, the flotation plant had disposed a huge amount of solid waste in the old flotation tailing dump. Chemical analysis had shown that an average concentration of targeted metals in tailings is: 0.23 % Cu, 0.4 g/t Au and 2.0 g/t Ag. The leaching degrees of analyzed elements, achieved after leaching the composite sample of flotation tailings in the pilot plant were: 54.35% Cu, 15.35% Fe, 3.75% Ag and 3.75 % Au.