Adsorption of gold in gold-thiosulfate solution onto a quartz surface

Abstract

Experimental research and quantum chemical calculations were used to study the adsorption of gold-thiosulfate ions on a quartz surface from a solution. The adsorption rate of gold-thiosulfate ions from a quartz-containing solution was 9.52% when a stirring time of 30 min, a stirring speed of 500 r·min−1, a 30% quartz mass ratio in the slurry, and an initial gold concentration of 56.50 mg·L−1 were used. Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS) were used to study the interaction mechanism of quartz and gold-thiosulfate ions in the gold-containing solution. The results showed that quartz and gold-thiosulfate underwent both physical and chemical adsorption in solution under different conditions. The CASTEP module in Materials Studio was used to perform quantum chemical calculations. The band structure, density of states, and Mulliken population analysis of the optimized quartz crystal structure showed that the p orbital of quartz was the most active. The calculated adsorption energy of gold-thiosulfate onto the (101) surface of quartz was −386.70 kJ·mol−1. The calculated S2–O36 distance was 1.628 Å, and the S3–O44 distance was 1.622 Å. The results of the Mulliken charge population analysis and bond population analysis showed that gold-thiosulfate ions adsorbed via the formation of relatively stable bonds on the (101) surface of quartz. Some gold was adsorbed by quartz when thiosulfate was used to leach gold ore, which affected the extraction of gold. These results indicate that quartz has the ability to “rob” gold during the thiosulfate gold leaching process, thereby affecting the leaching efficiency.