Contribution of ammonium ions to sulfidation-flotation of smithsonite

Sulfidation-flotation is commonly performed to recover base metal oxide ores. Sulfidation could become the key process in recovering zinc from zinc oxide ores. We investigated the common zinc oxide mineral. An ammonium salt was used to enhance sulfidation-flotation of smithsonite. The effect of ammonium ions on sulfidation and flotation of smithsonite was investigated by microflotation, inductively coupled plasma analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. Addition of the ammonium salt facilitates flotation of smithsonite and improves the flotation recovery by similar to 25%. Solubility tests under different conditions indicate that the surface solubility of smithsonite in the presence of ammonium ions significantly decreases. Energy-dispersive X-ray spectroscopy based semi-quantitative analysis shows that the concentration of sulfur on the ammonium enhanced sulfurized smithsonite surface is 8.55%, whereas that on the sulfurized smithsonite surface is 2%. XPS analysis reveals that smithsonite is more easily sulfurized by sodium sulfide in the presence of ammonium ions. Therefore, ammonium ion addition can be used to enhance sulfidation of smithsonite and improve the flotation performance. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.