Abstract: The flotation behaviors of magnesite and dolomite were studied with sodium oleate(NaOL) as collector and sodium hexametaphosphate (SHMP) as depressant and the effect of Ca²⁺ appeared in the flotation pulp of artificial mixed ore containing dolomite and magnesite on flotation behavior of magnesite was explored by means of zeta potential measurements， adsorption tests and SEM-EDS analysis. Flotation results show that SHMP is a good selective depressant in single mineral flotation of magnesite and dolomite， while in the flotation separation of mixed mineral，magnesite and dolomite were both depressed by SHMP， flotation separation of two minerals can not be achieved. Adsorption tests and SEM-EDS analysis show that Ca²⁺ dissolved from dolomite adsorbs on magnesite surface during flotation process. Zeta potential measurements show that the adsorption of Ca²⁺ on magnesite surface makes the two minerals surface property similar， which seriously affects the flotation separation of magnesite and dolomite.

Key words: magnesite, dolomite, floatation, dissolution, calcium ion