Thisstudy indicatedthatthedepression effectofCMC ontalc can be facilitated in the presence of Ca2+ and − CO . 3 2 , while pyrite cannot be depressed at pH values of 6–10. This could be a novel method to eliminate the detrimental effect of Ca2+. The surface analysis confirmed that the adsorption of calcium onto talc basal planes at pH 8.5 is negligible, and in the presence − CO . 3 2 ions, the adsorption of calcium onto the talc surface is greater than that on a blank reference sample.