Study on expanding flotation performance differentiation of quartz and magnesite by amino-trimethylphosphonic acid in dodecylamine system

Abstract

In this paper, amino trimethylene phosphonic acid (ATMP) was introduced into the separation process of magnesite and quartz, in order to reduce the content of associated minerals in magnesite and improve the industrial utilization value of magnesite. Micro-flotation tests showed that under the system of dodecylamine as collector, ATMP can selectively depress magnesite within the alkaline pulp environment. When the dosage of ATMP was 100 mg/L and the pulp pH was 11, the flotation recovery of magnesite was 12.65 % and that of quartz was 91.00 %. Additionally, the findings of the artificial mixed mineral flotation showed that a concentrate with a grade of 43.53 % MgO and a recovery of 91.03 % was achieved. Zeta potential, FTIR and XPS analyses demonstrated that ATMP chelated with the active site Mg2+ on the surface of magnesite through –PO3 group. In addition, DFT calculation indicated that the adsorbed ATMP increased the distance of N atom in dodecylamine (DDA) to the surface of magnesite from 2.671 Å to 5.106 Å. The interaction energy between DDA and magnesite increased from −201.28 kJ/mol to −136.75 kJ/mol, resulting in it difficult for DDA to adsorb on the magnesite surface. However, ATMP was difficult to adsorb on the quartz surface and had no effect on the interaction between DDA and quartz. Therefore, the selective depression effect of ATMP on magnesite was realized.