Study On Phase Evolution Of High Phosphorous Iron During Carbothermal Reduction Process

The iron ore is one of important non-renewable resources.With the rapid development of the iron and steel industry,the demand for the iron ore is rising year by year,causing the iron ore import volume to increase year by year.The iron ore severely dependent on import has become a bottleneck of the development of our country’s iron and steel industry,and development and utilization of rich high-phosphorus ooide iron deposit is one of the important ways to solve the shortage of resources in the iron and steel industry.However,due to the high phosphorus content in high-phosphorus iron ore,appropriate technical means need to be adopted to improve iron and reduce phosphorus.Therefore,this thesis studies the reduction process of high-phosphorus iron ore by carbothermic reduction,explores the migration path of phosphorus phase and iron phase in the process of carbothermic reduction,and explores the the mechanism of carbothermic reduction of high-phosphorus iron ore.Through the research,the following results are obtained:（1）In the reduction process,when the reduction temperature is 1200℃and the reduction time is 15min,The reduced phosphorous phase in the high phosphorous iron ore enters the iron to form iron-phosphorus solid solution,while the phosphorous phase and hematite are gradually reduced to elemental phosphorus and metallic iron.During the reduction process,the gangue phase combines with the gradually generated stage reduction products to form different slag phases.（2）Reduction temperature,reduction time and reducing agent type also have a certain effect on the degree of iron phase phosphorus absorption.With the increase of reduction temperature,the greater the reduction degree of fluorapatite,the easier to reduce a large amount of elemental phosphorus;The reduction effect of using graphite as reducing agent is higher than that of activated carbon.When the reduction temperature is 1200℃,the reduction time is 15min,and the reducing agent is graphite,a large amount of iron and phosphorus solid solution is generated during the reduction process.（3）The presence of SiO₂ and Al₂O₃ in gangue phase causes the reduction temperature of fluorapatite to drop by more than 140℃,and promotes the reduction of fluorapatite to produce Ca₃（PO₄）₂ and Ca F₂,which are more reducible.The promotion effect of Si O₂ is higher than that of Al₂O₃,and the compound gangue phase is more likely to promote the reduction of phosphorous phase than single gangue phase.It accelerates the production of reduction products and thus allows phosphorus phase to enter the iron more easily.