The flotation behavior and adsorption mechanism of a new cationic collector on the separation of spodumene from feldspar and quartz

Abstract

A new collector N-{3-[(2-propylheptyl)oxy]propyl}propane-1,3-diamine (PPPDA) was successfully synthesized in laboratory. The flotation behaviors of PPPDA on the separation of spodumene from feldspar and quartz were investigated through single mineral flotation experiments. The effects of pH, PPPDA concentration, metal ions concentration and the adding sequence of these reagents during the separation process were evaluated. At the condition of PPPDA concentration of 0.171 mmol/L, Ca(II) concentration of 0.171 mmol/L and pH 5.2, the greatest difference of recovery between spodumene and the gangues (feldspar and quartz) was achieved. The recovery of spodumene, feldspar and quartz under this condition was 5.39%, 89.31% and 91.7% respectively, which indicated that PPPDA had the potential to be used as a collector in reverse flotation of crude concentrate. The adsorption mechanism was investigated systematically by zeta potential, FT-IR, AFM, and adsorption amount measurements. The results demonstrated that PPPDA could be adsorbed on spodumene, feldspar and quartz through both electrostatic attraction and hydrogen bond. The amounts of PPPDA adsorbed on feldspar or quartz were much more than those on spodumene, which led to higher recovery for feldspar and quartz. The difference of the distance between the two nitrogen atoms in PPPDA and the distance between the two oxygen atoms on mineral surfaces, that is the “Spatial Matching Effect”, might lead todifferent adsorption models. Furthermore, in the presence of Ca(II), there was the competitive adsorption between Ca(II) and PPPDA. The spodumene preferred to adsorb Ca(II), while feldspar and quartz preferred to adsorb PPPDA. Therefore, Ca(II) could expand the floating difference of spodumene from feldspar and quartz with PPPDA as the collector.