Water-assisted-mechanical activation of copper pyrometallurgical tailings for molybdenum leaching and selective removal of environmentally-hazardous elements

Abstract

Fayalite-rich and elemental crystalline blockade of copper pyrometallurgical slag flotation tailings (CSFT) make it difficult to dispose of safely and limits high-value reutilization. Water-assisted milling, a waste-free method, is exploratively employed for activation of CSFT and to improve elemental leachability. In comparison to traditional milling, water-assisted milling reduces the time required for amorphous transition and amorphous nano-mesoporous materials were obtained in 4 h-activated CSFT (SBET increased to 12.25 m2·g−1 from 0.99 m2·g−1; pore size: 2–50 nm). Formation and re-removal of strongly-bound water promoted the hydration expansion of mineral particles and generation of tetrahedral or octahedral silicon defects and vacancies, which provided a large number of active sites and effectively promoted the rapid diffusion and transfer of ions. Water-assisted milling improves the leachability of high-value-added Mo (from 53.09 to > 95 %). During the water-assisted milling process, the dissociation and REDOX reaction of Mo were accelerated by the co-effect of reactive metals (Ca and Al) and the electron migration in the friction environment. This procedure exposed and morphologically changed Mo, facilitated the separation of the iron phase from Mo, and enhanced its solubility in diluted H2SO4 agents. The separation and leaching recovery of high-toxicity arsenic (As) and cadmium (Cd) was enhanced and a preliminary process was proposed for selective leaching of As (>96.99 %) and Cd (96.15 %) by NaOH solution.