Experiment On Vanadium Extraction Process By Reburning And Sulfuric Acid Leaching From Ash Of Stone Coal

China is abundant in stone coal resources and most of the stone coal has high-ash, high-sulfur, low-heat and high-rigidity in character. To applying stone coal reasonably and effectively not only can ease the energy shortage in south China, but also can produce vanadium pentoxide from stone coal ash. Vanadium pentoxide is mainly used in steel industry, chemical industry, vanadium battery, biomedicine, etc. About 90% of the vanadium pentoxide is used in the steel industry.V-Ti magnetite is the major source of vanadium production in the world. In addition, uranium vanadium ore, vanadate ore, crude oil, spent catelyst and stone coal are important source of vanadium production. The amount of vanadium in stone coal in China is more than the amount of vanadium in all of other countries and regions, which makes vanadium extraction from stone coal become an important development direction of using vanadium resource.At present, the industry of vanadium extraction from stone coal in China still has many problems such as low utilization of stone coal, low recovery rate of vanadium, high producing cost, tatty equipment and serious environmental pollution. The main processes of vanadium extraction from stone coal include:sodium burning, oxidation burning, calcium burning, compound additive burning, directly acid leaching, acid leaching by interim salt method, etc. the main research emphases of vanadium extraction from stone coal are improving comprehensive utilization efficiency of stone coal, recearch on burning technology of stone coal and the development of new process adapting recycling economy.The vanadium extraction process by reburning and sulfuric acid leaching from ash of stone coal is raised, which route is reburning with compound additive-dilute sulfuric acid leaching-ion exchange-vanadium precipitation by ammonia. The process can significantly reduced acid consumption and has a high vanadium recovery efficiency.Experiment raw materials consists of stone coal fly ash, bottom ash and oxide ore with mass ratio 67.5:22.5:10. The particle size. X-ray diffraction, and scanning electron micrographs of mixed ash are analyzed. The stone coal burning in circulating fluidized bed boiler is conducive to the leaching of vanadium. The optimal conditions of reburning and acid leaching are as follows:NaCl added amount is 2%～3%; CaF2 added amount is 3%～5%; CaCO3 added amount is 12%～14%; reburning temperature is 830～850℃; reburning time is 1-2 h; leaching temperature is room temperature; concentration of sulfuric acid is 0.18-0.54 mol/L; ratio of liquid to solid is 2-2.5 ml/g;and the leaching time is 15～30 minutes.Chlorine is about 90% in the flue gas,7%～8% in the leaching solution, and about 1% in the residue. Fluoride is about 13% in the flue gas, about 12% in the leaching solution, and about 71% in the residue.The oxygen atmosphere is required during reburning process. Even if the low oxygen content, the continuous supply of airflow can meet oxygen conversion reaction needed in reburning. At the same time, the gas flow rate should not be too fast in reburning. Moving bed combustion is more suitable for the reburning process than fluidized bed combustion. Using stone coal as fuel, the clinker reburned in moving bed combustion still can get a high vanadium conversion efficiency.The reburning principle is preliminarily analyzed, the reaction principle of compound additive is elaborated, and the main reason of mica mineral destructed and decomposing is summarized.The vanadium extraction process by reburning and sulfuric acid leaching from ash of stone coal is advanced technological, simple processing, and environment friendly. And the process is lower producing cost and economically feasible on a preliminary view.