The Study On Derect Dephosphorization Of Oolitic Hematite By Microwave Heating

With the domestic iron ore resources available for blast furnace smelting increasingly scarce and the rapid rise in international iron ore trade prices,the development and utilization of the “difficult to beneficiation and metallurgy” iron ore was again concerned by domestic scientific research workers.Oolitic hematite is recognized as one of the most difficult iron ore in the world,and it has a huge amount of storage in China.Therefore,it is great significance to explore the economical and effective beneficiation process of oolitic hematite.This article uses microwave reduction-magnetic separation process explore the effect of reduction temperature and holding time,pellet alkalinity,reducing agent content,and additive type and dosage on the iron removal and dephosphorization index of high-phosphorus oolitic hematite.Research indicates: At microwave power of 1500 W,reduction temperature1250?,holding time 10 min,pellet alkalinity 0.8,carbon content 1.6,grinding fineness-0.074 mm 90%,magnetic field strength 70 m T under experimental conditions,add 5% Na2SO4,reduction metallization rate reaches 92.96%,The iron grade of metal iron powder obtained after grinding magnetic separation was 92.23%,the metallization rate was 90.84%,and the recovery rate was 89.72%.At microwave power of 1500 W,reduction temperature of 1250?,holding time of 10 min,pellet basicity of 0.6,carbon content of 1.6,grinding fineness of-0.074 mm of 90%,and magnetic field strength of 70 m T under experimental conditions,add 5% Na2SO4,after the magnetic separation,the content of phosphorus in the metal iron powder was0.22%,and the dephosphorization rate was 74.18%.The microstructure and phase analysis of the reduced sample and metallic iron powder show that: during the reduction process,the iron elements in the pellet aggregated into a large number of particles,and they were distributed in a chain shape at the edge of the carbon pore,forming a clear boundary with the components of the gangue,the content of iron in the reduced iron particles is up to 99.84%.Phosphorus in raw ore reacts with gangue and additives to form calcium sodium phosphate,after iron ore magnetic separation,iron becomes a magnetic separation product,and sodium calcium phosphate enters non-magnetic slag,thereby achieving separation from iron.Graphite as reducing agent,constant temperature kinetics of graphite reduction oolitic hematite at reduction temperature of 700~950? and reduction time 60 min.The results show that: the reduction process of oolitic hematite conforms to the secondary reaction model,interfacial chemical reaction and solid iron ion diffusion reaction is restrictive link.In the reduction temperature of 950~1100?,graphite-reduction oolitic Hematite Reaction Process Complies with Avrami-Erofeev equation model,solid iron ion diffusion reaction is restrictive link.