Synergic process of molybdenum recovery and ceramic preparation for clean and efficient utilization of industrial leaching residues

Ammonia-leaching residues of roasted molybdenite concentrates are intractable wastes and are mostly stockpiled in factories. Common treatments suffer from low Mo recovery and secondary pollution. This study has developed a synergistic process involving a single-step roasting with the addition of Al2O3 and MoO3 to recover Mo and simultaneously prepare porous refractories from the residues containing 5.6% Mo. The Mo separation efficiency, ceramic properties, and thermal behaviors—including chemical reactions, melting transformations, ceramic structure evolutions, and Mo species migrations—were comprehensively investigated. It was found that the addition of Al2O3 facilitated CaMoO4 decomposition to release volatile MoO3, thus promoting Mo recovery. The mullite started to form at about 900 °C, grew into whiskers, and further into interconnected clusters, under the catalytic effect of liquid MoO3 and the sintering effect of glassy melt. Liquid MoO3 was scattered on the outer surface of whisker clusters, achieving a high separation efficiency of over 98% after roasting at 1300 °C for 150 min. Meanwhile, a ceramic with a high porosity of 64.2% and a high compressive strength of 21.2 MPa was obtained, exhibiting promise for serving as a high-temperature insulation refractory. Overall, this study presents a novel approach for both the profound recovery of Mo and the value-added utilization of gangue minerals derived from CaMoO4-bearing wastes. [Display omitted] •Synergic process of Mo volatilizing and ceramic making from wastes was explored.•98.2% of Mo was separated, and additionally an insulating refractory was obtained.•Al2O3 and MoO3 facilitate CaMoO4 decomposition and mullite formation, respectively.•Well-grown mullite whiskers work as the support to disperse Mo and Si-rich liquids.•Whisker cluster intertwining and glassy melt sintering enhance ceramic strength.