Study On The Dephosphorization Process Of Vanadium-bearing Semi-steel Directly Smelting Vanadium-bearing Hot Metal

Vanadium,which is among the rare metals,is called modern industrial monosodium glutamate.Vanadium-containing products are widely used in various industries,85%of which are used in the field of alloy steel,and vanadium-containing steel is produced by adding vanadium-iron alloy to molten iron.The production of V2O5 and vanadium alloys is based on vanadium extraction routes,resulting in a long vanadium steel smelting process and low vanadium utilization.In 2018,the consumption proportion of vanadium in the iron and steel industry rose to 91%.The promulgation of the new national standard cancelled HRB335 and added HRB600 type steel bars to further promote vanadium consumption.In order to reduce the production process of vanadium steel,reduce market demand for ferro-vanadium alloys and other products,and ease production pressure,the research team proposed that the vanadiumcontaining molten iron in the blast furnace does not undergo the operation of vanadium extraction.purpose.Based on this background,this paper studies the mechanism of"dephosphorization and preservation of vanadium" in vanadium-containing molten iron.The paper calculates the thermodynamics of CO2 dephosphorization,establishes a multielement slag system mass effect concentration model,examines the influence of different dephosphorization slag systems on the dephosphorization end point,examines the injection of CO2-N2 gas in different proportions,and verifies the list The feasibility of CO2 dephosphorization by slag method,the following conclusions are drawn.(1)Under standard conditions,thermodynamic calculations are carried out at temperatures between 1523～1973 K.The results show that CO2 gas can oxidize with all elements in the molten pool except phosphorus.The direct oxidation of phosphorus will only occur when CaO participates in the reaction.The equilibrium oxygen potential of vanadium is greater than that of phosphorus,and the difference in oxygen potential between the two increases with the increase of[C]content,and there is a linear relationship between[C]content and phosphorus activity.The equilibrium oxygen potential difference of[V]and[P]decreases with the increase of temperature,and is always positive before 1900 K.The calculation results of the CaO-SiO2Fe2O3-FeO-Al2O3-P2O5-V2O5 multivariate slag system model show that the activity of iron oxide increases with the slag basicity.(2)The addition of BaO and Na2CO3 can greatly improve the dephosphorization capacity of the slag system,and the dephosphorization effect of Na2CO3 slag is better than that of BaO.Both sets of experiments showed the rule of first oxidation and then reduction.The addition of Na2CO3 increased the oxidation peak of vanadium in the oxidation stage.The average peak dephosphorization rate of the BaO slag system was 23.451%,and the average dephosphorization rate at the end of the experiment was 14.876%;the average peak dephosphorization rate of the Na2CO3 slag system was 30.990%,and the dephosphorization rate at the end of the experiment was 14.565%.(3)The single-factor experimental study of the partial pressure of the CO2-N2 mixed gas injection shows that the dephosphorization effect of the pure CO2 gas injection is the best,the end point phosphorus content is 0.0401%,and the end point vanadium content is 0.301%.Phosphorus continues to be oxidized under 80%CO2 partial pressure,vanadium oxide enters the reduction stage,which proves the existence of the[V]and[P]oxygen potential difference.The dephosphorization reaction reaches equilibrium when the CO2 partial pressure is 60%,and the end point is phosphorus.The content is 0.0613%.The single factor of barium oxide content change is sprayed with CO2 partial pressure of 80%gas,the average end point phosphorus content is reduced from 0.0721%to 0.0540%,and the dephosphorization effect is increased to 2.5 times.(4)At a temperature of 1550℃ and a CO2 flow rate of 1000 mL/min,a semi-steel containing vanadium can be obtained by continuous decarburization for 50 minutes,with a carbon content of 0.113%,a vanadium content of 0.276%,and a phosphorus content of 0.0426%.The study of decarburization kinetics shows that the activation energy of carbon dioxide decarburization reaction is 26.43 kJ/mol,which is fitted as a zero-order reaction by data,and the reaction rate control step is a gas phase mass transfer process at high carbon.