Hongliang Zhang

Against the global drive for energy conservation and emission reduction, lithium-ion batteries (LIBs) have witnessed increasingly widespread adoption across diverse sectors, thereby generating an urgent imperative for the efficient recycling of electrodes from spent LIBs. This paper presents a comprehensive review of recent research progress in this domain. It begins by elucidating the fundamental architecture of LIBs and the key physicochemical characteristics of their electrode materials, followed by a critical analysis of the major technical bottlenecks inherent in current recycling processes. While conventional separation techniques are briefly discussed, the primary emphasis is placed on reviewing deep learning-based visual inspection systems, with particular attention to YOLOv8-based approaches reported in the literature. Finally, future development trajectories are delineated, and pivotal research directions including the optimization of multi-technology integration and the expansion of training dataset scale and diversity are proposed to facilitate the large-scale, standardized industrial implementation of electrode recycling technologies.

Surface defects play a pivotal role in modulating the physicochemical properties of minerals and their interfacial interactions with flotation reagents. In this study, we systematically investigated the electronic structure and reactivity of defective hematite (001) surfaces using density functional theory (DFT) calculations. Both Fe- and O-terminated surfaces containing iron and oxygen vacancies (marked with VO and VFe) have been calculated to elucidate their influence on the competitive adsorption of oleate collectors (OL and OL-), hydroxide anion (OH-), and water molecule (H2O). The results demonstrate that atomic vacancies induce localized in-gap electronic states and narrow the band gap, creating accessible reactive sites that facilitate electron transfer. Defect formation energy analysis reveals a termination-dependent stability, Fe-terminated surfaces favor positively charged vacancies (V+O and V2+Fe), whereas O-terminated surfaces stabilize electrically neutral defects (V0O and V0Fe). Crucially, adsorption energy calculations and Reduced Density Gradient (RDG) analyses indicate that while Fe-terminated surfaces exhibit strong overall adsorption affinities, they are dominated by competitive OH- adsorption, which forms a hydration layer that hinders collector attachment. In contrast, the introduction of V0Fe on the O-terminated surface selectively enhances OL- adsorption (Ea = -1.08 eV) through synergistic electrostatic and coordination interactions, surpassing the affinity for H2O and OH-. Conversely, V0O defect on the O-terminated surface is detrimental to flotation, as it preferentially combines with H2O and OH-. These quantitatively findings provide fundamental atomic-level insights into surface activation mechanisms and suggest that pretreatment strategies promoting specific vacancy types, such as V0Fe on O-terminated surfaces, can significantly optimize hematite flotation performance.

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.

Sodium diethyldithiocarbamate (DDTC), a common collector used to enhance the hydrophobicity of minerals in froth flotation, nevertheless weakens the hydrophobicity of the talc surface. To rationalize this anomaly, the interactions of a hydrophobic alkyl group and hydrophilic mineralophilic group (-NCS₂^-) of heteropolar surfactant DDTC, and a water molecule with the talc (001) surface, were investigated. Herein, DFT simulations found that the talc (001) surface features natural hydrophobicity determined by the competition between adhesion (surface water) and cohesion (water-water interactions). The interaction of the hydrophobic alkyl group of DDTC with the talc surface is more favorable compared to that of the -NCS₂^- group and H₂O, favoring the hydrophilic modification of the talc surface. Additionally, adsorption isotherms, time-of-flight secondary ion mass spectrometry (ToF-SIMS), microflotation tests, and contact angle measurements also indicate that the differences in adsorption orientation of the heteropolar surfactant DDTC on the talc surface enhance the hydrophilicity of the talc surface, leading to a decreased recovery of the talc. This study provides crucial surface chemistry evidence for the selective adsorption of heteropolar surfactants and contributes to the understanding of the mechanism for the efficient flotation separation of molybdenite from talc.