Coal Dressing And Vanadium Extraction Using Acid Leaching Of Stone Coal From Hunan Province

Coal dressing and vanadium extraction of a stone coal ore from Hunan province, which containing sulfur, vanadium and low carbon, was studied. The raw ore was crushed and ground, and sulfur concentrate was achieved by gravitation separation. Flotation of the tailing obtained by gravitation separation was conducted to get coal concentrate containing vanadium, and flotation of the flotation tailing was further conducted to obtained vanadium concentrate. Coal concentrate and vanadium concentrate were mixed and roasted in atmosphere, then extracting the vanadium of the roasting residues by sulfuric acid leching process.Gravity separation for desulfuration can not only recover some sulfur from the raw ore, but also reduce the sulfur content of coal concentrate. Flotation for coal dressing upgrades the content of vanadium and reduces reagent consumption and process cost. The mixed concentrates can be used as fuel of circulating fluidized bed boiler for power generation, which not only makes full use of the carbon resources, realizes the enrichment of vanadium, and increases the valence of vanadium that promotes leaching of vanadium while removing carbonous minerals in combustion process, which provides technical support for acid leaching of vanadium.With a grinding fineness of-0.074mm range as around90.0%of the stone coal, a sulphur concentrate with the S grade of30.57%and the recovery ratio of15.39%was prepared by the method of the Knelson-shaking table jointing gravity concentration. For gravitation separation tailing, coal concentrate with19.07%fixed carbon and0.57%vanadium was obtained using a flotation flowsheet consisting of two-roughing, two-scavenging and five-cleaning, and the recovery rate of carbon and calorific value of coal concentrate reached75.01%and6.46MJ/kg, respectively. Through a flotation process consisting of one-roughing, two-scavenging and two-cleaning, vanadium concentrate with grade of0.68%V and recovery of18.63%was obtained from coal dressing tailing. In the mixed concentrate, the gross recovery is51.32%, and the grade of coal and vanadium, the calorific value reached69.49%,80.15%and5.23MJ/kg, respectively. The removal rate of sulfur achieved46.94%in the separation process. The ash containing vanadium was obtained through sintering mixed concentrates at800℃under air atmosphere in muffle furnace with the sintering time of1.5h. After acid leaching under conditions of the dosage of sulphuric acid of15%, solid to liquid ratio of1.1:1(g/mL), stirring speed of250r/min, retention temperature of90℃and retention time of8h,89.60%vanadium was leached, and the ultimate recovery of vanadium in the acid lixivium is62.26%.