Ultrasonic pretreatment for enhancing flotation separation of elemental sulfur and silver-bearing lead minerals from an oxidative pressure leaching residue of zinc sulfide

Abstract

Ultrasonic pretreatment was introduced to enhance the flotation separation of elemental sulfur and silver-bearing lead minerals from an ultrafine residue produced by oxidative pressure leaching of zinc sulfide. The particle size analysis of residue shows that ultrasonic pretreatment increases the number of particles with high sulfur content in the −19 μm fraction. This resulted from the associated sulfur was effectively liberated from other minerals. The complete liberation proportions of elemental sulfur and plumbojarosite in residue are respectively increased by 20.91 % and 38.53 % after ultrasonic treatment, in terms of mineral liberation analysis (MLA). Time-of-flight secondary ion mass spectrometry (ToF-SIMS) investigation implies that the surface structure difference between elemental sulfur and silver-bearing lead minerals is expanded by ultrasonic pretreatment. As a result, the separation of sulfur and silver-bearing lead minerals is significantly improved by ultrasonic pretreatment. Under optimized conditions of ultrasonic power, ultrasonic treatment time and solid weight, pilot-scale flotation produced a concentrate that the sulfur grade and recovery of concentrate increased by 11.63 % and 9.10 %, respectively, and the lead and silver recoveries of tailings increased by 8.72 % and 9.50 %, respectively, compared with those obtained by using the flotation without pretreatment. This work may provide an important reference for effectively recycling complex secondary resources and reducing the difficulty of subsequent values extraction.