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China has abundant coal resources of stone, stone coal mostly with high ash, sulfur, low heat and hardness characteristics, reasonable and effective application of stone coal resources, not only can ease the southern provinces of China's energy supply tensions, but also through stone coal ash vanadium, production of vanadium pentoxide products. Vanadium pentoxide is mainly used in the steel industry, chemical industry, vanadium batteries, biomedical, etc., of which about 90% of the vanadium pentoxide used in the steel industry. Vanadium-titanium magnetite is currently the world production of vanadium primary resource. In addition, uranium vanadium ore, vanadate ore, crude oil, spent catalysts, production of vanadium from stone coal is an important resource. Of vanadium from stone coal resources total more than other countries and regions of the world's total reserves of vanadium, which makes vanadium extraction of vanadium gradually become China's use of resources is an important direction of development. At present, China's vanadium extraction from stone coal industry still low level of resource utilization, vanadium recovery rate is low, high production costs, poorly equipped, serious environmental pollution and a series of problems to be solved, China's scientific research, production units made a large number of tests research work, the development of many new technology. This paper summarizes the vanadium extraction process status, the main process are: Sodium roasting, roasting, roasting calcium, compound additives roasting, direct acid leaching, the middle direct acid leaching salt method and so on. Vanadium extraction technology research focuses primarily on: Increases stone coal utilization efficiency, coal firing technology research, in line with new technology development of circular economy. For Serenade stone coal characteristics, Zhejiang University presented Serenade circulating fluidized bed coal combustion power stone-SO: resource recovery - ash vanadium - vanadium ash used in building materials industry after polygeneration utilization programs. In order to solve the intermediate salt method stone cinders direct acid leaching of vanadium in the presence of acid consumption process larger issues, we propose a vanadium-containing ash composite additive secondary roasting - sulfuric acid leaching - ion exchange - Ammonium vanadium Shen new technology, namely stone cinders acid leaching of vanadium secondary roasting process. This process greatly reduces acid consumption, but also has high recovery of vanadium. Vanadium-containing raw materials for the stone coal ash circulating fluidized bed combustion fly ash, bottom ash and oxidized ore mine mixed at a mass ratio 67.5:22.5:10. By vanadium ash particle size, X-ray diffraction, scanning electron microscope photograph analysis, obtained through the circulating fluidized bed stone coal combustion, mica mineral phase decreased, mineral crystals larger fissures, internal porosity, permeability strong, beneficial result of leaching of vanadium, for the development of pilot programs, optimize the process provides a theoretical basis. Reasonable secondary roasting and acid leaching conditions: NaCl composite additive dosage 2% ~ 3%, CaF2 dosage 3% ~ 5%, CaCO3 added amount of 12% to 14%, the second calcination temperature 830-850 ℃, two times roasting time 1 ~ 2 h; sulfuric acid concentration 0.18 ~ 0.54 mol / L (0.36 mol / L for the best), at room temperature acid leaching, acid leaching time 15 ~ 30 min, liquid-solid ratio 2-2.5ml / g. Results also showed that, as Na2CO3 as a secondary firing NaCl replaced by one additive component is not feasible; secondary firing raw materials 0-50% water, can obtain a higher conversion rate of clinker vanadium, which the secondary firing process conditions in maneuverability, economy is more relaxed. The secondary roasting smoke, clinker, acid extract, residue chlorine, fluorine element content and proportions were determined, and its distribution is roughly: elemental chlorine in the flue gas is about 90%, the acid leaching solution of 7% -8% , the residue of about 1%; fluorine in the flue gas of about 13%, about 12% acid leaching solution, about 71% of the residue. In the secondary calcination process, the oxygen in the atmosphere is required, but continues to provide the air flow, even if the oxygen content is low, the secondary firing process can meet the needs of the conversion reaction of vanadium; while firing the raw material environmental gas flow rate should not be too fast, otherwise easily damage compound additives under high temperature oxidizing atmosphere generated by the reaction. Compared to the moving bed combustion fluidized bed combustion method is more suitable for secondary roasting process; moving bed combustion furnace roasting vanadium secondary raw materials, if the above Lin Shi coal as fuel, can still achieve high clinker vanadium conversion rate, this result is conducive to more efficient utilization Serenade stone coal resources, reduce production costs vanadium. In this paper, the secondary firing mechanism of a preliminary analysis, elaborated in the second of three additive components roasting process and the reaction mechanism of action, summed up the mica mineral phase is destroyed decompose the main reason. Stone coal ash roasting acid leaching of vanadium secondary indicators advanced process technology, process is simple, environmentally friendly and economically efficient use of resources, lower production costs. The process is technically and economically feasible initially considered.
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