Enhanced flotation of smithsonite from calcite based on the synergistic action of carboxylated chitosan and sodium carbonate

Abstract

As carbonate minerals, smithsonite and calcite have similar surface properties, and unavoidable ions will further narrow the difference in their floatability. Therefore, flotation separation of smithsonite from calcite has been a difficult problem in industrial production. In this study, carboxychitosan and sodium carbonate were combined to improve the efficiency of separating smithsonite from calcite with the use of sodium lauroylsarcosinate as a collector. The results of flotation tests showed that the recovery difference between smithsonite and calcite was higher than 83 % under optimum flotation conditions. In addition, the interaction mechanism between reagents and minerals was analyzed by Fourier Transform Infrared Spectroscopy (FTIR) analysis, zeta potential measurements and X-ray Photoelectron Spectroscopy (XPS) detection. The mechanistic analysis showed that for Zn(II) activation, sodium lauroylsarcosinate was able to adsorb onto the calcite surface by chemisorption, even in the presence of carboxylated chitosan. Upon addition of Na2CO3, the chemical state of Zn(II) adsorbed on the calcite surface changed and reacted with CO32– to form ZnCO3 precipitate. As a result, the inhibition of calcite flotation by carboxylated chitosan was reactivated and the separation of smithsonite from calcite was achieved.