Research On The Removal Mechanism Of Phosphorus (P) From Oolitic Hematite Based On The Microwave-enhanced Reduction

High-phosphorus oolitic hematite is an iron ore resource with huge reserves and good mining conditions,the proven reserves of high-phosphorus oolitic hematite ore are about 3.72 billion tons,and the amount of new resources that can be explored is over 10 billion tons,but the iron-containing minerals embedded in these ores are extremely fine-grained,and the associated harmful impurities such as phosphorus-containing minerals are symbiotic with the hematite granules,this makes it difficult to achieve iron-phosphorus separation efficiently in most conventional beneficiation processes,therefore,such ore has not been effectively utilized so far.Microwave heating is a special heating method,it has the advantages of selective heating,increasing the reduction rate and promoting the dissociation of inclusions,It is very suitable for the treatment of complex refractory iron ore like oolitic hematite.In this study,the effect of particle size,carbon content,reducing agent and dephosphorization agent on the dielectric properties of the mixture was tested using the cavity perturbation method,and designed microwave carbothermal reduction and magnetic separation experiment.In this study,the effects of the reduction temperature,the basicity of the iron ore,the amount of dephosphorization agent and the particle size of the material on iron extraction and dephosphorization were investigated.The experimental results show that when the reduction temperature is too high and the ore size is too fine,the phosphorus content in the reduced iron powder will rise sharply,by adding dephosphorization agent and selecting an appropriate alkalinity,the iron grade of the reduced iron powder can be effectively increased,and the phosphorus content in the reduced iron powder can be lowered,after adjusting the experimental conditions,under the optimal experimental conditions,the pellets were reduced and magnetically selected to obtain reduced iron powder with a total iron content of 91.53%,a recovery rate of 89.72%,and a dephosphorization rate of 83.95%,and no phosphorus-containing substances were detected in reduced iron powder by XRD detection.The distribution of iron and phosphorus in reduced materials under different experimental parameters was detected by means of SEM and energy spectrum analysis,and the composition of reduced iron and reduced slag was analyzed.Thus,the starting temperature of migration of phosphorous minerals into reduced iron by microwave heating reduction is determined,and the mechanism of alkalinity and addition of dephosphorization agent to promote separation of iron and phosphorus is expounded.The experimental results show that the separation of iron and phosphorus would be realized under the following conditions: the reduction temperature is 950℃,the alkalinity is 0.8,the reductant coefficient is 1.0,the dosage of sodium salt additive is 15wt%,the ore granularity is 0.8 mm,respectively.Under this condition,the reduced iron accumulates well and has fewer impurities,phosphorus-containing substances are mainly present in the reducing slag in the form of sodium phosphate salts and calcium phosphate salts.