Differential collecting performance of a new complex of decyloxy-propyl-amine and α-bromododecanoic acid on flotation of spodumene and feldspar

A new complex DPA-BDDA was prepared by decyloxy-propyl-amine (DPA) and alpha-bromododecanoic acid (aBDDA) as a collector in the flotation of spodumene and feldspar respectively. The flotation was investigated under different conditions. In particular, molar ratio of DPA: alpha-BDDA, the optimum pH, and DPA-BDDA dosage were studied. It was found that the greatest difference of recovery (spodumene 82.14% and feldspar 32.48%) occurred by using 14.28 mg/L of DPA-BDDA (molar ratio of DPA: alpha-BDDA 1:1) at pH of 4.48. The flotation adsorption mechanism of DPA-BDDA on spodumene and feldspar surface was searched by DLS, FT-IR, XPS and zeta potential measurements. The FT-IR results indicated that there was halogen bond effect between DPA and alpha-BDDA, which demonstrated that the DPA and alpha-BDDA were formed supermolecules. Although the active sites on broken surfaces of spodumene and feldspar were Al and O sites, the type and the number of Al and O sites per unit area on spodumene and feldspar were different, which might lead to the difference of surface chemistry features of spodumene and feldspar. The XPS results indicated that the quantity of DPA-BDDA adsorbed on spodumene surface was higher than that on feldspar surface. The results also revealed that DPA-BDDA was adsorbed on spodumene surface through both electrostatic attraction and chemisorption. In addition, the electrostatic attraction between -NH3+ and spodumene negative surface reduced the electrostatic repulsion between -COO- and spodumene surface, which facilitated the adsorption of DPA-BDDA on spodumene. However, since the more negative surface of feldspar, the steric hindrance effect and less Al sites on feldspar surface, the DPA-BDDA was adsorbed on feldspar mainly by electrostatic attraction.