Effect of Ammonium Salt on the Stability of Surface Sulfide Layer of Smithsonite and its Flotation Performance

Abstract The sulfidization–xanthate method is an important method for recovering smithsonite. As the sulfidization time increases, the newly formed sulfidization layer on the smithsonite surface is unstable, which causes attenuation and affects the recovery efficiency. We studied the stability of the sulfidization layer of smithsonite and the effect of ammonium chloride on the sulfidization layer by microflotation experiments, sulfur adsorption test, X-ray photoelectron spectroscopy and time-of-flight secondary mass spectrometry. Microflotation experiments results showed that ammonium-chloride addition can increase the recovery efficiency of the smithsonite by ∼10%. Sulfur adsorption test results showed that after ammonium-chloride addition, more sulfur components were formed on the smithsonite surface. XPS results showed that after ammonium-chloride addition, the atomic concentration of the surface sulfur component increased from 0.09% to 2.38%. ToF-SIMS results showed that the newly formed sulfide component was more evenly distributed and the surface of the sulfide layer was smoother. The sulfur composition and sulfide layer thickness increased significantly, which increased the sulfide layer stability and improved the recovery efficiency of the smithsonite. All these details have established that the ammonium chloride has a good promoting effect on the sulfidization of smithsonite and increases the sulfidization layer stability.