Phosphorus And Iron Enrichment Behaviors During Reduction Roasting And Magnetic Separation Of High-Phosphorus Oolitic Hematite

Abstract:China is rich in high-phosphorus content oolitic hematite ore resources. There are many studies about dephosphorization on this ore. But the ore has not been effective utilization because of its low iron grade and complex structure.Take the high phosphorus oolitic hematitie from western Hubei as research object. In this paper, based on dephosphorization effects and restricting factors of high temperature and short reduction time, the process of direct reduction with carbon-containing pellets for making high phosphorus rion were manily studied. It provided a new approach for effective utilization of the ore. The main conclusions are as follows.The study of high temperature reduction of carbon-containing pellets shows that:The optimum conditions of reduction roasting are as follows:15%Na2SO4, reduced at1350℃for10min and2.4basicity and C/Fe ratio0.48,-0.074mm coutents for95.72%after grinding and magnetic field intensity1000Gs.Metallic iron product with iron grade of94.06%and phosphorus content of0.25%was obtained under the optimal conditions, at the same time, the recovery of iron was91.37%, and the corresponding dephosphorization of magnetic separation ratio was up to91.79%. In order to form plenty of Ca2SiO4, which can consliodat part of phosphorus and improve the dephosphorization of magnetic, and to get high Fe content in concentration, the basicity must as high as2.4and15%sodium salts must be added. Becaouse of large amount of slag and high energy consumption and general dephosphorization, the process can not use the ore effectively.The study of commen direct reduction of carbon-containing pellets shows that:The optimum conditions of reduction roasting are as follows:15%dosage of Na2SO4, reduced at1050℃for60min and carbon-bearing C/Fe ratio0.12and all C/Fe ratio8.51,-0.074mm coutents for97.27%after grinding and magnetic field intensity1000Gs. Metallic iron product with iron grade of92.31%and phosphorus content of1.12%was obtained under the optimal conditions, at the same time, the recovery of iron was89.32%, and the corresponding recovery of phosphorus was up to38.97%. Without Na2SO4and carbon in the pellet, iron grain can not grow and separate with gangue sufficiently. Iron grain growth can be promoted by liquid formed in the pellet with Na2SO4. But the phosphorus content of concentrate is reduced due to the teaction of Na2SO4and SiO2and A12O3. On the other hand, due to the formation of low melting point material, the pellet appears melting and serious inflation. The reducing atmosphere internal the carbon-containing pellet can be improved and the same with part of apatite. The concentrate with high grade Fe and phosphorus can obtained with Na2SO4and carbon combination, it can also ensure the pellet complete morphology.