Ti3O5 and Al2TiO5 Crystals Flotation Characteristics from Ti-bearing Blast Furnace Slag: A Density Functional Theory and Experimental Study

Anosovite crystalline is an ideal mineral for flotation from the Ti-bearing blast furnace (TBBF) slag. Ti3O5 crystal and Al2TiO5 crystal are two kinds of anosovites, and the Al element significantly affects the electronic structure and flotation performance of anosovite. The floatability of Ti3O5 and Al2TiO5 crystals were studied by Mulliken populations, energy bands, and density of states (DOS). In addition, the flotation experiment of the two kinds of anosovite crystals (Ti3O5 and Al2TiO5) was conducted and proved that the density functional theory (DFT) calculation results were accurate. Compared with Ti3O5 crystal, the Fermi energy level of Al2TiO5 crystal shifts around 2 eV in a negative direction by DOS analysis, which is beneficial to flotation. And Al2TiO5 crystal possesses a larger value of bond population, which is 0.41, for Ti-O bonds than Ti3O5 crystal and the bond length of Ti-O in Al2TiO5 crystal is shorter, therefore Al2TiO5 crystal shows a stronger covalency. The changes of the Fermi energy level and the covalency bonds in Al2TiO5 crystal both demonstrated that doping the Al component into the Ti3O5 crystal was beneficial to improve the flotation effect. Moreover, the Al2TiO5 crystal had a higher flotation efficiency compared to the Ti3O5 crystal when the dosages of salicylhydroxamic acid (SHA) and sodium oleate were the same. Therefore, both DFT calculation and experiment show that the flotation effect of the Al2TiO5 crystal is better than that of the Ti3O5 crystal.