Calcite slimes removed from malachite particles surface in malachite-calcite system with water glass, sulfide ions adsorped on malachite surface increased and then malachite can be floated easily by xanthate because water glass selectively interacted with calcite slimes. Display omitted In order to eliminate the adverse effects of calcite slimes on the sulfidization-xanthate flotation of malachite, water glass was used as a depressant for calcite slimes. Micro-flotation results indicated that the floatability of malachite was restored in mixed malachite and calcite by adding water glass. Addition of the water glass into the suspension of malachite with calcite slimes promoted dispersion of these minerals and increased the selective adsorption of sulfide ions onto the malachite. The dispersion effect was supported by results of sedimentation and electrokinetics. The zeta potentials significantly increased in the negative direction, primarily for calcite, which caused removal of its slimes from the malachite surface. Thus, floatability of this mineral with xanthate was restored since it allowed a more efficient sulfidization. The DLVO calculations performed, predict the observed behaviour of the sulfidization of malachite.