Oxidation consolidation of vanadium–titanium magnetite pellets strengthened by pretreatment of high-pressure grinding rolls
摘要
The production of vanadium–titanium magnetite (VTM) pellets has the problems of low consolidation strength and high energy consumption in the preheating and roasting process. High-pressure grinding roll (HPGR) pretreatment process was used to increase the fine-grained content and specific surface area of VTM concentrates, to strengthen the oxidation consolidation process of VTM pellets, and oxidation kinetic experiments were carried out. The results showed that the specific surface area of VTM concentrates was increased from 872 to 1457 cm2/g by HPGR and then pelletising and roasting. With preheating at 1000 °C for 10 min and roasting at 1260 °C for 10 min, the strengths of preheated pellets were increased from 329 to 535 N, and the strengths of roasted pellets were increased from 1010 to 2591 N. The limiting link in the early stage of VTM pellets oxidation was the control of chemical reaction, while the limiting link in the later stage of oxidation was the mixed control of chemical reaction and gas diffusion. The activation energies of VTM pellets before and after HPGR pretreatment were 53.07 and 40.03 kJ/mol in the early stage of oxidation reaction, while the activation energies in the later stage of oxidation were 29.24 and 22.75 kJ/mol, respectively.