Flotation characteristics of magnesite and huntite

Because of similar chemical structures and compositions, huntite and magnesite have similar flotation behaviors and, therefore, cannot be easily separated by flotation in fine sizes. This study describes the optimum flotation conditions for the separation of huntite from magnesite by using microflotation and bench flotation tests. Zeta potential measurements and adsorption tests were performed to explain the mechanism of separation. Common ions such as Ca²⁺ and Mg²⁺ specifically adsorb on the surface of huntite and magnesite and make the mineral surface positively charged. Experimental findings on run-of-mine ore indicate that magnesite is the floated product and huntite is the rejected product. Carboxymethyl cellulose (CMC) was found to be a strong depressing agent for huntite in the alkaline region, presenting only a slight action on magnesite flotation. In the flotation tests a huntite concentrate containing 97.71% huntite was produced with an 86.2% recovery and a magnesite concentrate containing 81.28% magnesite was obtained with a 16.9% recovery.