Surface Features of Fluorapatite and Dolomite in the Reverse Flotation Process Using Sulfuric Acid as a Depressor

Abstract

The surface features of fluorapatite (FA, Ca5(PO4)3F) and dolomite (CaMg(CO3)2) conditioned with sulfuric acid (H2SO4) were examined through flotation experiments, contact angle tests, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and FTIR experiments. The flotation and contact angle results suggested that oleate insufficiently adsorbed onto the H2SO4-treated FA surface such that the FA surface remained hydrophilic. However, using oleate as a collector, the recovery and hydrophobicity of H2SO4-treated dolomite were satisfactory. TOF-SIMS and FTIR studies indicated that sulfate anion bound with Ca atoms on the FA surface, which hindered oleate adsorption onto the FA surface. Meanwhile, sulfate anion and oleate species appeared on the dolomite surface, thereby generating a hydrophobic dolomite and also a satisfactory recovery.