The depression behavior and mechanism of carboxymethyl chitosan on calcite flotation

The separation of scheelite and calcite by froth flotation is difficulty as these two minerals have similar physicochemical characteristics. To solve this problem, the role of carboxymethyl chitosan in the flotation separation of scheelite from calcite has been studied and the depression mechanism has been discussed. Micro-flotation tests show that carboxymethyl chitosan has strong depression effect on calcite and the depression effect decreased with the increase of pH. However, its depression effect on scheelite is weak. A concentrate with WO3 grade of 65.21% and WO3 recovery of 77.48% can be achieved in the mixed minerals flotation when carboxymethyl chitosan was used. The adsorption tests show that carboxymethyl chitosan has adsorbed on the calcite surface and the adsorption amount increased with the increase of added amount. The adsorption mechanism of carboxymethyl chitosan on calcite surface was analyzed through the X-ray photoelectron spectroscopy (XPS) tests and the results revealed that carboxymethyl chitosan adsorbed on calcite surface mainly through chemical interaction. Keywords: Calcite, Scheelite, Carboxymethyl chitosan, Selective depressio