In this paper the results of the investigation of magnesium removal, from zinc concentrate derived from zinc-lead ore enrichment plant, have been presented. The characteristics of the initial concentrate and the occurrence forms of dolomite in this material are estimated. It was found that magnesium is collected in the finest fraction of the initial material. The influence of chemical treatment and flotation on the quality improvement of zinc concentrate is determined. This method permits to obtain zinc concentrate containing below 0,3% Mg and about 0,7% Ca.