The technology of extracting vanadium from stone coal in China: History, current status and future prospects

Vanadium, as one of the important rare elements, is used mainly to produce certain alloys. Stone coal is an important vanadium-bearing resource in China and the gross reserves of vanadium in stone coal accounts for more than 87% of the domestic reserves of vanadium. Hence, much attention has been paid to research on extracting vanadium from stone coal. The traditional high salt roasting-water leaching (HSRWL) technique is the earliest technique applied in vanadium extraction from stone coal. This technique was widely adopted by small-scale factories for extracting vanadium from stone coal, but much caustic gasses and ultra-high salinity wastewater are generated and the total vanadium recovery is low in production, which makes this technique obsolete. Although the blank roasting-acid leaching (BRAL) technique, the blank roasting-alkali leaching (BRALL) technique, the calcified roasting-carbonate leaching (CRCL) technique and the direct acid leaching (DAL) technique are all more environmentally friendly in the roasting step compared to high salt roasting, each technique has its limitations and has not been applied in large scale production until now. The lately developed technique, the low salt roasting-cyclic oxidation (LSRCO) technique, is characterized by high vanadium recovery, low pollution and strong adaptability to raw ore and has good prospect of applications. Overall, the industry of vanadium extraction from stone coal is still underdeveloped in China now and much intensive research work is needed for the economic exploitation of stone coal at large scale.