Investigating the performance of oxalic acid for separating bastnaesite from calcium-bearing gangue minerals based on experiment and theoretical calculation

Bastnaesite is a major light rare earth resource in the earth, which is difficult to separate from calcium-bearing gangue minerals in flotation because of their similar flotation characteristics as the semisoluble salt minerals. To address this problem, in 3-hydroxy-2-naphthyl hydroxamic acid (H205) system, the selective inhibition mechanism of oxalic acid on common calcium-bearing gangue minerals (calcite and fluorite) in bastnaesite flotation was studied by flotation tests, solution chemistry analysis, zeta potential measurements, and X-ray photoelectron spectroscopy (XPS) measurements, combined with thermodynamics and density functional theory (DFT) calculation. After the analysis of those tests and calculation results, it can be known that the hydrophilic oxalic acid can selectively compete with H205 for the active site (Ca2+) on the surface of the calcium-bearing gangue minerals, thus reducing its surface hydrophobicity and inhibiting its floating, while bastnaesite is not susceptible. In this process, fluorite is more inhibited than calcite.

Automated summary

The selective inhibition mechanism of oxalic acid on common calcium-bearing gangue minerals in bastnaesite flotation was studied, showing that oxalic acid competes with H205 for the active site on the surface of the gangue minerals, reducing their surface hydrophobicity and inhibiting their floating. In this process, fluorite is more inhibited than calcite.