Beneficiation of Extremely Low-Grade Zinc Oxide Ore: Flotation-Magnetic Synergy Separation Study

In western China, numerous low-grade zinc oxide ores are widely distributed. These ores are characterized by extremely low metal grades and complex mineralogical compositions, posing significant challenges for effective beneficiation. For a prolonged period, such resources have remained underutilized due to technical limitations. To address this challenge, this study conducted systematic experimental and theoretical investigations using the Uragan lead-zinc ore as a case study, with the objective of achieving efficient enrichment of zinc oxides. A flotation-magnetic synergy separation process was developed to enable comprehensive recovery of zinc resources. The proposed beneficiation flowsheet integrates coarse-grained sulfide flotation, high-intensity magnetic separation, regrinding of the rough concentrate, and sulfidization-flotation of oxidized zinc minerals. Under processing conditions involving the feed grade of 0.98% Zn and an oxidation degree of 85.71%, yielding zinc sulfide concentrate assaying 49.15% with Zn recovery of 15.17%, along with zinc oxide concentrate grading 26.62% with Zn recovery of 65.34%. Further mechanistic investigation into smithsonite flotation reveals that sulfidation enhances the surface reactivity of smithsonite, thereby promoting the selective flotation of extremely low-grade oxidized zinc phases. This work provides a technically viable and scientifically sound reference for the efficient development and utilization of complex, refractory low-grade lead-zinc resources.