Organic depressants are diverse, readily available and cost-effi- cient materials, and they have attracted a considerable amount of attention. For instance, dextrin (Liu and Laskowski, 1989; Bolin and Laskowski, 1991; Drzymalaa et al., 2003) has been used in the separation of chalcopyrite and galena, and thioglycolic acid has been used as a chalcopyrite depressant in the separation of Cu–Mo bulk concentrate (Nagaraj et al., 1986; Poling and Liu, 1987). Moreover, Ansari and Pawlik (2007a,b) studied the floatability of chalcopyrite and molybdenite in the presence of lignosulfonates