Acid Leaching for Extracting Vanadium from Residue of High-Carbon Stone Coal after CFB Combustion

With a high-carbon stone coal from the northwest of China as the research object,the author would obtain heat energy to generate electricity by circulating fluidized bed( CFB) combustion and extract vanadium with sulfuric acid leaching from residue of stone coal to achieve the comprehensive utilization of carbon and vanadium resources. Based on the analysis of vanadium occurrence in stone coal,CFB roasting characteristics were studied,and experiments of vanadium extraction by ash acid leaching were performed to figure out the effect of the concentration of sulfuric acid,leaching temperature,leaching time and liquid to solid ratio on the leaching rate of vanadium. The results showed that vanadium in the stone coal mainly existed in roscoelite and iron and aluminum oxides,occupying 73. 89% and 14. 78% respectively of the total vanadium. When the roasting temperature was 850 ℃,combustion efficiency of69. 17% showed that the heat energy of stone coal could be effectively used through CFB combustion,and roasting was in favor of the enrichment of vanadium,which had a positive effect on the improvement of vanadium extraction. Recovery of vanadium would vary in difficulty for different minerals containing vanadium,vanadium extraction in free oxide was the easiest,then iron and aluminum oxides,vanadium in roscoelite was the most difficult. Leaching conditions of sulfuric acid concentration,leaching temperature,leaching time and liquid to solid ratio all affected vanadium recovery,but sulfuric acid concentration and leaching temperature played a greater impact. The appropriate parameters were as follows: sulfuric acid concentration of 6. 0 mol·L- 1,leaching temperature of 110 ℃,leaching time of 2 h,liquid to solid ratio of 2. 5∶ 1. 0. Under these conditions,the leaching rate of vanadium was up to 88. 61%.