The DFT Study of Salicylohydroxamic Acid and Methylenediphosphonic Acid as Collectors in Niobium Minerals Flotation

In this paper, salicylohydroxamic acid (SA) and methylenediphosphonic acid (MDA) are investigated by the Density Functional Theory (DFT) and flotation test for studying niobium minerals flotation. The DFT computation results show that the two oxygen atoms in the dianion of SA charge more negative charges than other atoms do, and thus become their reactive center. Meanwhile, the SA dianions, MDA anions and MDA dianions show higher atomic charge value and HOMO (Highest Occupied Molecular Orbital) energy; hence they have stronger flotation ability for niobium minerals than that of other forms. The result of flotation test is consistent with DFT analysis. However, there is a conflict between the results of quantum chemistry analysis for the compare of flotation ability, and we cannot draw the explicit conclusion. Therefore, experiment is a more reliable tool for comparing the flotation capacity of compounds whose structures are very unlike one another.