Effect of Sodium Polyphosphate on the Flotation Separation of Brucite and Dolomite Using a Sodium Dodecyl Sulfonate Collector

Sodium polyphosphate (SP) is a representative phosphate that can integrate metal ions. Herein, the inhibition effect and mechanism of SP on the flotation of dolomite in the flotation separation of brucite and dolomite were studied in a sodium dodecyl sulfonate (SDS) flotation system. In the flotation test, SP exhibited a strong inhibition effect on dolomite flotation but had little effect on brucite. In the contact angle test, SP had a stable inhibition effect on two types of minerals and strongly inhibited dolomite flotation. In the zeta potential test, the effect of SP under negative charge on dolomite potential was significantly higher than that of brucite, and the stronger adsorption capacity reflected the affinity of SP to dolomite. Infrared spectrum analysis revealed that SDS displayed strong collecting ability toward both types of minerals; however, it lost its collecting effect because of the selective adsorption of SP on the dolomite surface. In X-ray photoelectron spectroscopy analysis, the changes in the characteristic elements of the two minerals and the change characteristics of the P element belonging to SP again indicated that the strong interaction between SP and the dolomite surface was the key factor inhibiting dolomite in flotation.