The acid digestion of flotation tailings from Zn-Pb ore enrichment in the Boleslaw Mine and Metallurgical Plant was aimed at their initial chemical reusing by neutralization of alkaline components of gangue and potential recovery of magnesium compounds from filtrates after acid digestion. The nature of the research was explanatory and the obtained leaching residues will constitute a raw material in flotation tailings bioleaching in the presence of acidophilic microorganisms. The article presents the results of the research regarding the influence of physicochemical factors (H₂SO₄ concentration, time, temperature, the ratio of solid phase to liquid phase) on the leaching rate of magnesium, zinc, cadmium, iron and lead by acid digestion of flotation tailings as well as the characteristics of solid leaching residues and magnesium compounds obtained by the concentration and crystallization of the filtrate.