Study On Reaction Characteristics And Stirring Effect Of CO₂ In Vanadium Extraction From Hot Metal

CO2 is a greenhouse gas and a major component of the waste gas from the iron and steel industry.The recycling of CO2 is an important way of energy conservation and emission reduction and is a research hotspot of metallurgical industry researchers in recent years.Based on the characteristics of weak oxidation and low exothermic property of CO2,our research group studied the oxidation law of vanadium and carbon and the optimal injection ratio under the modes of CO2-O2 mixed injection and CO2-O2 composite injection.It is proved theoretically and experimentally that CO2 can be used to extract vanadium from vanadium-bearing hot metal.Effects of thermal effect,utilization rate,and stirring characteristics of CO2 on vanadium-bearing hot metal were investigated.The results provide a theoretical basis for applying CO2 in vanadium extraction from hot metal and have specific academic significance and application value.Based on thermodynamic calculation and experimental test,the thermal effect and reaction characteristics of CO2 injection into a molten iron bath containing vanadium were studied.After establishing the stirring energy equation of molten iron bath,combined with thermal experiment,the stirring effects of CO2 and O2 injection on molten iron bath are analyzed and compared.The results are as follows:①The results show that the reaction between bottom-blown CO2 and molten pool[C]in vanadium-bearing hot metal is a zero-order reaction and has a strong cooling effect.The calculation shows that the molten pool temperature can be reduced by 22℃ by injecting CO2 to oxidize 0.1%[C].②The factors affecting the stirring energy of molten iron include the composition of molten iron,injection flow rate,injection temperature,and gas type.The equation of energy density of bottom-blown CO2 and O2 is the same,shown as follows.When the stirring utilization rate of CO2 increased by 10%,the energy density increased by about 12%.When the flow rate of CO2 was 1.714 L/(kg·min),the energy density of the molten pool by CO2 stirring was twice that of Ar.When the temperature increased by 20℃,the ratio of εCO2/εAr increased by about 2%.③ The stirring utilization rate of gas injection in the molten pool is related to gas type,injection flow rate,bath composition,and other factors.When the flow rate of bottom blowing was 0.343 L/(kg·min),the injection temperature 1320℃,and the injection time 15 min,the stirring utilization rate of bottom blowing CO2 turned out to be 76.66%,while the stirring utilization rate of bottom blowing O2 was 62.89%.It indicates that under the same experimental conditions,CO2 reacts with molten pool[C]to produce more CO,beneficial to the stirring of the molten pool.④For the top-bottom combined blowing method,the bottom blowing gas is mainly used for stirring.When the bottom blowing flow rate is 0.343 L/(kg·min)and the injection temperature is 1320℃,the energy density of CO2-O2 combined blowing molten pool is 82.5%higher than that of Ar-O2 combined blowing molten pool,which indicates that CO2-O2 combined blowing mode is better for the mixing of the molten pool.