Electronic structure and flotation behavior of Ag-bearing galena

Abstract

The Ag-bearing galena is a typical resource of base metal sulfide accompanied by noble metal, and has always been the world's major mineral resource for silver output. In this paper, the flotation behavior of Ag-bearing galena has been investigated by using ammonium dibutyl dithiophosphate (ADD), ethyl xanthate (EX) and diethyldithiocarbamate (DDC) as collector, respectively, and unlike that galena could still remain its floatability in high alkaline pulp by DDC, the Ag-bearing galena is much favorable of flotation in low alkaline pulp at pH value of 9.5 by ADD. The electronic structures study indicates that the Ag atom in galena crystal has not changed the type of semi-conductivity, but narrows the band gap to benefit the transfer of electrons, which could enhance the electrochemical reaction activity of Ag-bearing galena. Analysis of frontier orbital also illustrates that the existence of silver could reduce the occupied molecular orbital of Ag-bearing galena, which is advantageous to the collector ion adsorption, and the interaction strength of the three collector ions suggests that ADD shows better selectivity to Ag-bearing galena. Moreover, the molecular dynamics models of the three collectors ions interacting with Ag-bearing galena {100} surface are constructed and simulated, and the results proved that ADD has the best adsorption performance to Ag-bearing galena of the three collectors, during which the S1-Pb distance and the S2-Ag distance are both below 3 Å, indicating that S1 and S2 both have strong bonding with Ag and Pb on the Ag-bearing galena surface. Thus, ADD is suggested to be an excellent collector to recover the Ag-bearing galena, especially in the low alkaline pulp at pH value of 9.5, which provide theoretical guidance and practical evidence to promote the Ag-bearing galena flotation performance in Ag-bearing lead-zinc deposits.