New insights on depressive mechanism of citric acid in the selective flotation of dolomite from apatite

Abstract

The effective separation of apatite and dolomite is always the focus of phosphate ore flotation research. The effect of citric acid (CA) on the flotation reaction of apatite and dolomite was studied. The flotation behavior of these two minerals was evaluated through micro-flotation experiment. The results of micro-flotation experiment indicate that CA has selective depression for apatite, but has no obvious depression for dolomite The depression mechanism of CA on apatite and dolomite was analyzed by infrared spectroscopy (FTIR), Zeta potential measurement and XPS analysis. CA adsorbed on apatite and dolomite to varying degrees via FTIR test and Zeta potential measurement. The results from XPS test showed that CA formed chemisorption on apatite surface to form organic complex, but not on dolomite surface. In addition, the results of adsorption amounts and mineral dissolution experiments further support the selective depression mechanism of apatite. Through adsorption amounts test and surface dissolution test, it is found that the surface of dolomite dissolves strongly, and a large amount of calcium ions are generated in the solution. Calcium ions can chelate with citric acid and consume citric acid. At the same time, the calcium density on the surface of dolomite is higher than that of apatite, and a large amount of dissolution occurs on the surface of dolomite. However, the density of remaining active sites on the surface of dolomite is still high, and sodium oleate can still be adsorbed on the surface of dolomite. The degree of surface dissolution of apatite is less. CA occupies the active sites on the surface of apatite, making it difficult for sodium oleate to adsorb on the surface of apatite, resulting in poor apatite floatability.