| Iron and steel industry is one of the main greenhouse gas emitting sectors. From a global statistical point of view, the steel industry of global CO2 emissions of total greenhouse gas emissions by 4% to 5%, while China’s steel industry accounts for about 12% of total CO2 emissions. Therefore, the iron and steel enterprises to take energy saving tasks duty and shouldering enormous pressure to reduce emissions.CO2 emissions of the blast furnace process Accounted for 90% of total steel production. Europe is currently implementing ultra-low carbon steel technology projects (ULCOS), which will be used for CO2 carbon capture and sequestration technology (CCS).But its economic feasibility, technical integration and enlarging scale aspect to achieve the necessary of industrial applications still need further research.CO2 which acts as a weak oxidizing gas, if it can be recycled use In the steel production process, not only greatly reduce greenhouse gas emissions, but also play a significant contribution to energy conservation. This article study dynamic law of the use of CO2 as an oxidant removal of silicon in molten iron and explore feasibility of the use of CO2 as the desilication agent in order to provide theoretical references to develop new processes of desilication.This study analyzed reaction conditions of application of CO2 of BF ironmaking and Hot metal pretreatment, studied dynamic law of reaction between CO2 and molten iron under the conditions with and without carburizing and discussed about the influences of temperature, gas injection and other factors on reaction of desilication and decarbonization and so on. Main conclusions of paper are as follows:(1)Thermodynamic analysis shows that low temperature is favorable for desiliconization but high temperature is helpful to decarburization. Theory of CO2 reacting with silicon and carbon reaction equilibrium concentration is very low. The results of thermodynamics show that the CO2 desilication is completely feasible in theory.(2) Investigation of desilication:By studying on CO2 and desalination effect of different hot metal temperatures and different gas flows, the conclusions are as follows:gas side mass transfer is the restrictive step of CO2 desiliconization reaction; hot metal temperature is higher, the smaller rate of silicon reduction when gas flow remains unchanged. And at the same temperature, gas flow rate is greater, the greater the rate of silicon reduction. Whether carburizing or not, the restrictive aspect of CO2 desilication reaction is the gas transport.(3) Investigation of decarbonization:In the condition without carburizing, the restrictive aspect of CO2 decarburization reaction is the gas transport. When the gas flow is constant, the higher temperature of the molten iron, the greater the degree of carbon reduction. At the same temperature, the bigger gas flows, the greater degree of carbon reduction. The restrictive aspect of carbon dioxide decarburization reaction is gas transport.In the carburizing conditions, when the gas flow is constant, the higher the temperature of hot metal, the faster the molten carburizing, the faster the carbon content reaches an equilibrium value. At the same temperature, the bigger the gas flows, the higher the volatility of carbon in molten iron, while eventually carbon content can reach equilibrium. The higher the temperature of molten iron, the faster carburizing; Larger injection volume, the better stirring carburization and the thinner the boundary layer, so the faster carburizing; In the larger gas flow injection conditions, when the carbon content of molten iron becomes stable the rate of carburizing and carbon dioxide decarbonization will be an exponential growth.(4)Under the experimental conditions, the desiliconizing optimal conditions is 1573K and the injection of CO2 is 0.6L/min.(5)In CO2 injection conditions, other key elements in liquid iron such as Mn, P, S, did not change basically. |
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