Vanadium emission during roasting of vanadium-bearing stone coal in chlorine

The characteristics of the vanadium-bearing stone coal during chlorination roasting at different temperature were investigated. Chlorination roasting could promote the breakage of the structure of the main vanadium-bearing minerals, such as muscovite and illite, in the stone coal and more than 90% of the vanadium was lost after the sample was roasted in chlorine at 1000 °C for 1 h. The volatile collected on the inner surface of the tube is mainly composed of chlorine, vanadium and other metals and it shows similar physical and chemical properties to vanadium oxytrichloride (VOCl3). Hence, it is reasonable to predict that the vanadium was emitted as VOCl3 in this process. The anhydrite gradually decomposed with the increasing temperature and the hematite in the samples reacted with the chlorine and disappeared above 700 °C. Some new refractory mineral phases such as cordierite and hornblende can be found during the chlorination roasting. The decrease in the fluxing minerals and the formation of the refractory minerals can elevate the ash-fusion temperature of the stone coal and make it hard to sinter.

► The change of vanadium content in stone coal roasted in chlorine was investigated.
► We probed the characteristics of mineral phases during chlorination roasting.
► The fusibility and morphology of samples roasted in air and chlorine were analyzed.
► Provided a potential way for extracting vanadium from stone coal.