Oxidative volatilization mechanism and kinetics of stibnite at low temperature
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Department of Chemical and Metallurgical Engineering, School of Chemical Engineering, Aalto University, Vuorimiehentie 2, P.O. Box 16200, FI-00076 Aalto, Finland)
2. Department of Chemical and Metallurgical Engineering, School of Chemical Engineering, Aalto University, Vuorimiehentie 2, P.O. Box 16200, FI-00076 Aalto, Finland)
Abstract: The substitution of traditional blast furnaces with steel-belt furnaces for antimony smelting was proposed. The influence of various parameters on the oxidative volatilization of stibnite was studied according to the production practice of steel-belt furnaces. Furthermore, the kinetics of oxidative volatilization was elucidated using differential thermal gravimetric analyses and non-isothermal analysis methods. The results indicated that the oxygen concentration and the temperature were pivotal variables in the oxidative volatilization process. Notably, the volatilization efficiency of antimony was 97.25% under optimal conditions. Moreover, the kinetic control stages were divided into chemical reaction control (440-490 °C), internal diffusion control (500-550 °C), and chemical reaction control (560-580 °C). These stages corresponded to activation energies of 16.40-18.79, 120.86-195.96, and 24.00-28.31 kJ/mol, respectively.
Key words: stibnite; oxidative roasting; volatile roasting; kinetics; Coats-Redfern equation