The selective flotation separation of celestite from fluorite and calcite using a novel depressant EDTA

The dissolved components of calcium-bearing gangue minerals will adsorb onto the celestite surface, which increases the difficulty of the flotation separation of celestite from fluorite and calcite. Single mineral and artificial mineral flotation experiments show that EDTA exhibits an excellent selective inhibition effect towards celestite and calcium-bearing minerals. Surface dissolution experiments reveal that EDTA can strongly inhibit the dissolution of calcium ions on the fluorite surface, thus reducing the influence of dissolved calcium ions on celestite flotation. Zeta potential experiments and adsorption experiments demonstrate that the amount of depressant EDTA adsorbed on the fluorite surface is greater than that on the celestite surface, which is contrary to the adsorption amount of collector sodium dodecyl sulfate (SDS) on the fluorite and celestite surfaces. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses further reveal that, through chelating with calcium ions, EDTA can change the chemical surroundings of elements on the fluorite surface, while the chelation is not evident on the celestite surface. Based on the experimental and analytical results above, a possible model for the flotation separation process is created. (C) 2019 Elsevier B.V. All rights reserved.