Vanadium recovery from Na2SO4-added V-Ti magnetite concentrate via grate-kiln process
(School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
Abstract: Pilot experiments on Na2SO4-roasting of V-Ti magnetite (VTM) concentrate pellets were performed to activate vanadium with simulated grate-kiln machines. Combined with thermodynamic calculation, X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and inductively coupled plasma-atomic emission spectrometry (ICP-AES) analyses, process parameters of pellet making were optimized, and the enhancement of vanadium oxidation and conversion was realized. The results show that, in balling stage, adding Na2SO4 can promote the thermal decrepitation resistance of green pellets; in the drying stage, higher wind temperature can improve the dispersion of sodium salt in pellets; in preheating stage, using O2-rich hot gas can promote more thorough oxidation of vanadium; in roasting stage, the effect of vanadium conversion to sodium vanadate is better when the liquid amount is 15.5%-22.5%. Based on the above measures, the vanadium conversion rate achieved in the roasted pellets is 85.6%, proving the feasibility of vanadium recovery using an existing pellet production line.
Key words: vanadium; V-Ti magnetite pellet; Na2SO4 roasting; grate-kiln process; thermodynamics