Optimization Of Phosphorus Removal Process Of High Phosphorus Iron

Due to the large fluctuations in the price of international iron ore,Chinese steel industries have shifted from capital restrictions to resource restrictions.Utilizing existing domestic resources is an inevitable choice for Chinese industries.Our country's identified highphosphorus iron ore has achieved to 7.45 billion tons,and the development of this part of resource is significant.At present,although there is a breakthrough in the dephosphorization technology of iron ore,it has not completely ruled out technical obstacles.With the development and utilization of high-phosphorus iron ore,there will be substantial problems:First is the trend of increasing phosphorus content in pig iron;Second is the increasingly strict requirements on the quality of steel products;Third is country has stricter requirements on the smelting environment.Therefore,dephosphorization is always an important research topic that has attracted much attention.This paper is based on the raw materials and the condition of high-phosphorus with low-silicon molten iron,combined with the theoretical analysis of oxidative dephosphorization and the thermodynamic simulation calculation of Factsage,and then design the experimental scheme.Develop fluorine-free calcium oxide slag's dephosphorization agent.Study of the influence suitable dephosphorization reaction temperature,composition of dephosphorization agent and its melting temperature and viscosity characteristics,addition of dephosphorizing agent,and various elements in molten iron on dephosphorization,select the optimal dephosphorization agent scheme,determine a reasonable high-phosphorus molten iron dephosphorization process and provide opinion for industrial production.The following are conclusions:?1?Through the theoretical analysis of oxidative dephosphorization,the formation of a stable phosphate is essential for the dephosphorization reaction,and the dephosphorization reaction takes place at the steel-slag interface.The thermodynamic and kinetic conditions for the dephosphorization reaction is: "Three highs and one low",which is high alkalinity,high Fe O,high slag amount,and low temperature,and it is necessary to enhance fluid movement in the reaction bath and increase the reaction interface.?2?The melting temperature and viscosity of Ca O-Si O2-Fe O-B₂O₃-Mn O premelting dephosphorization slag of type of fluorine-free were calculated and investigated the effect of alkalinity and composition ratio on it by using Fact Sage simulation software and the modified Einstein-Roscoe formula.In this paper,the optimum ratio was optimized by orthogonal analysis,variance analysis and main effect analysis.The results show that the viscosity of the slag decreases with the increase of alkalinity,Fe O content and flux content.T=1400?,The optimum ratio is basicity R=4.0,w?B₂O₃?=9%,w?Mn O?=10%,w?Fe O?=45%.?3?The effect of single factor?Fe O,Na2CO3 and Mn O content and alkalinity?on the effect of dephosphorization on molten iron was investigated by Fact Sage simulation software,the proportion of pre-molten dephosphorization slag was optimized by using the response surface method,and establish a multiple regression model to predict the dephosphorization rate of molten iron,The interaction of each factor was studied and optimized by variance analysis and response surface analysis,and predict the optimal ratio of dephosphorization slag.The best combination of prediction for?Fe O?= 37.79%,?Na2CO3?= 6.24%,?Mn O?= 9.89%,R = 4.50,T = 1387 ?.The experimental results show that the dephosphorization rate is 97.30% and the error is 2.70%,it shows that the predicted results of response surface method are in agreement with the experimental results.?4?First melt high-phosphorous smelting ore into iron and dephosphorized,then obtain a feasible dephosphorization program.However,due to the high phosphorus content of the pig iron,it is difficult to achieve one-step phosphorus reduction.Therefore,the large amount of slag,multi-slag method,dual-linked method to dephosphorization successively,and increase the alkalinity,keep low temperature isbenefical to dephosphorization.The dephosphorization rate of molten iron is affected by factors such as temperature,silicon and phosphorus content in molten iron,and the addition amount of dephosphorizing agent.Temperature is appropriate at 1380¹400°C,the content of silicon in hot metal is lower than 0.1%,the low content of phosphorus in hot metal is necessary,the ratio of slag and iron is to be determined according to the actual situation,it keeps moderate.