Molecular Design and Mechanism Study of Non-Activated Collectors for Sphalerite (ZnS) Based on Coordination Chemistry Theory and Quantum Chemical Simulation

Sphalerite flotation is generally achieved by copper activation followed by xanthate collection. This study aims to propose a design idea to find novel collectors from the perspective of molecular design and prove the theoretical feasibility that the collector can effectively recover sphalerite without copper activation. To address this, 30 compounds containing different structures of sulfur atoms and different neighboring atoms were designed based on coordination chemistry. Twelve potential collectors were screened, and their properties and interactions with a hydrated sphalerite (110) surface were evaluated. Compound 27 (C₂H₄S₂^2-) showed the greatest reactivity, suggesting that the double-coordination structure of two sulfhydryl groups is an effective molecular structure for direct sphalerite flotation. The DFTB+ and MD results demonstrate that 1,2-butanedithiol (C₄H₁₀S₂), having a similar coordination structure to compound 27, has the potential to replace the traditional reagent scheme of sphalerite flotation. The strong reagent-surface interaction is attributed to the overlap of Zn 3d with S 3p orbitals, the most negative electrostatic potential, the relatively high E_HOMO and low average local ionization energy, and the eliminated steric hindrance effect. It is expected that this study can provide a design idea for the targeted design and development of novel reagents for complex sulfide ore flotation.