Extraction of vanadium from stone coal by roasting in a fluidized bed reactor

In order to improve leaching efficiency of vanadium pentoxide (V2O5) from stone coal and to reduce its connected environmental pollution, this article investigated the oxidizing roasting of stone coal in a laboratory fluidized bed reactor to optimize the roasting method and conditions. The examined parameters included reaction temperature, reaction time and amount and mixing method of additive. The removal of Cl from the generated effluent gas was implemented using CaO as the adsorbent, and comparison was made between the fluidized bed roasting and static roasting in a muffle oven. The results show that the fluidized roasting is more favorable to leach V2O5 from stone coal, which can shorten roasting time for reaching the maximal leaching rate, while the realized leaching rate is also higher. Comparing the mixing method applied to stone coal and additive, the impregnation method of additive on stone coal not only increased the leaching rate and shortened the roasting time for reaching the maximal leaching rate, but also reduced the amount of additive required. Adding CaO in stone coal roasting sharply decreased the content of Cl-containing gases in flue gas, which can greatly alleviate the possible environmental pollution. The optimal conditions for fluidized bed roasting were found to be impregnating 6 wt.% additive on coal, adding 3 wt.% CaO and performing roasting at 800 °C for 0.75 h.