Simulated Experimental Study On The Application Of CO₂ In Vanadium Extraction By Composite Blowing

Carbon dioxide?CO₂?has been widely used in metallurgical industry as reaction gas,shielding gas and stirring gas.In the process of vanadium extraction,the application of CO₂ can effectively slow down the speed of temperature increase of the molten pool,owing to its weak oxidation and low exothermicity.This is benefitial to the effectiveness of vanadium extraction and carbon retention.Previously,our research group has successfully explored the process of vanadium extraction by blowing CO₂-O₂ mixed gas.In this research,we take CO₂ as the bottom blowing gas in the process of vanadium extraction by top-bottom combined blowing.CO₂ is used as not only the reaction gas but also the stirring gas,so as to get a better effectiveness of vanadium extraction and carbon retention.It is of great significance to provide theoretical basis for the application of CO₂in vanadium extraction by top-bottom combined blowing.Combined with theoretical calculation and laboratory experiment of simulated top-bottom combined blowing,different vanadium extraction processes were investigated.This research is financially supported by the National Natural Science Foundation of China?51334001?.Under this experimental conditions,the following conclusions were obtained.?1?Compared with mixed blowing,composited blowing increased the proportion of CO₂ in the reaction by about 5%and shortened the time of vanadium extraction by about1 minute;additionally,the temperature of molten pool was lowered by about 3-7°C.In the process of composited blowing,the optimum blowing ratio of CO₂ is 20%,and the critical temperature is 1347-1363°C.?2?Proper increase of bottom blowing flow rate is beneficial to vanadium extraction and carbon retention.The molten pool temperature decreased by about 5-7°C with the increase of bottom blowing CO₂ flow rate by 10%,and the heat release of molten pool was reduced by about 1.3857-2.0214 kJ due to the participation of CO₂ in the reaction.?3?The stepped blowing is beneficial to the vanadium extraction and carbon retention.To obtain a good effectiveness of vanadium extraction and carbon retention,for stepped blowing,the initial temperature of the reaction should not be higher than 1340°C,the optimum initial temperature of the experiment is 1300°C,and the optimal initial ratio is 15%.?4?The results of enlarged experiments shows that the composited blowing reduced the TFe concentration in the slag and greatly increased the distribution of vanadium between the slag and steel,which increased the grade of vanadium slag.For composited blowing,the main phases of vanadium slag at the end of the composited blowing are Fe₂VO₄ and Fe₃O₄.