Effect of lattice defects on the electronic structures and floatability of pyrites

Yong-jun Xian1), Shu-ming Wen1), Xiu-ming Chen2), Jiu-shuai Deng1), and Jian Liu1) 1) Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China 2) National Engineering Laboratory of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, China

摘 要：The electronic structures of three types of lattice defects in pyrites （i.e., As-substituted, Co-substituted, and intercrystalline Au py-rites） were calculated using the density functional theory （DFT）. In addition, their band structures, density of states, and difference charge density were studied. The effect of the three types of lattice defects on the pyrite floatability was explored. The calculated results showed that the band-gaps of pyrites with Co-substitution and intercrystalline Au decreased significantly, which favors the oxidation of xanthate to dix-anthogen and the adsorption of dixanthogen during pyrite flotation. The stability of the pyrites increased in the following order: As-substituted < perfect < Co-substituted < intercrystalline Au. Therefore, As-substituted pyrite is easier to be depressed by intensive oxidi-zation compared to perfect pyrite in a strongly alkaline medium. However, Co-substituted and intercrystalline Au pyrites are more difficult to be depressed compared to perfect pyrite. The analysis of the Mulliken bond population and the electron density difference indicates that the covalence characteristic of the S Fe bond is larger compared to the S S bond in perfect pyrite. In addition, the presence of the three types of lattice defects in the pyrite bulk results in an increase in the covalence level of the S Fe bond and a decrease in the covalence level of the S S bond, which affect the natural floatability of the pyrites.

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