Study of the effect of high-temperature activation of quartz on the adsorption of gold cyanide

Abstract

• Gold cyanide ions are chemically adsorbed onto the quartz surface after high-temperature activation. • After high-temperature activation, Au-Si is adsorbed together, and the valence state of Au is + 1. • The N-Si bonding is enhanced after high-temperature activation. • The Au-O interaction on the surface of Au(CN) 2 − and quartz is transformed into a Au-Si interaction. The leaching rates for gold in the roasting oxidation pretreatment-cyanidation gold leaching process are generally low. An adsorption experiment for quartz baking slag (roasting time of 3 h, roasting temperature of 650℃) and gold cyanide solution was carried out under different stirring time conditions. It is found that after high temperature activation of the quartz surface, gold cyanide can be adsorbed. When the stirring time reaches 50 min, the adsorption rate is 6.08%, and the unit adsorption amount is 0.05 mg·g −1 . The EDS spectrum clearly shows that the Au element is distributed among Si and O, and 0.02% Au is adsorbed on the surface of the quartz baking slag. To further prove the adsorption mechanism for the gold cyanide solution and quartz slag, infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface of quartz slags. Infrared spectroscopy analysis shows that new peaks emerge at 1429 cm −1 , 1878 cm −1 , and 1996 cm −1 after the elution experiment, and the characteristic peaks for inorganic cyanide are observed at 1878 cm −1 and 1996 cm −1 . This shows that after high-temperature activation of the quartz baking slag, chemical adsorption of gold cyanide occurs. The results obtained from X-ray photoelectron spectroscopy (XPS) show that during the adsorption process, Au-Si is adsorbed together, and Au shows a valence of + 1, which indicates that Au(CN) 2− ions are adsorbed onto the quartz activated at high temperature. Density functional theory (DFT) was used to determine the adsorption mechanism for Au(CN) 2− ions and different sites on the surface of quartz (1 0 1) before and after high-temperature activation (three Au-O, Au-Si, and N-Si adsorption sites). During the high-temperature activation process, the Au-O bonds and interactions on the surface of gold cyanide and quartz gradually transform into Au-Si bonds and interactions, and the N-Si bonds are also enhanced. This shows that the adsorption of gold cyanide onto quartz baking slag is enhanced after high-temperature activation. The simulation calculation result is consistent with the experimental results.