Effect of gas-based reduction of high-phosphorus oolitic hematite and dephosphorization agent on phosphorus removal effect
Aiming at the current situation that high-phosphorus oolitic hematite can not be effectively utilized due to its complex and diversified mineral composition,fine embedded particle size,impurity components such as SiO2 and Al2O3,and high phosphorus content,the gas-based direct reduction and dephosphorization agent-magnetic separa-tion process was used to study the influence of each process parameter on the reduction product and the magnetic separation of the iron ore concentrates with grade and phosphorus content indexes.Using hydrogen as the reducing agent and dephosphorizing agent,experimental research on high-phosphorus oolitic hematite ore with iron grade of 46.75%and mass percent of phosphorus of 0.92%in a foreign region were conducted.In the test,the dephosphoriz-ing agent not only destroys the oolitic structure and inhibits the reduction of phosphorus-containing minerals,but also promotes the growth of iron particles in the reduction process.Under the conditions of reduction temperature of 1 050℃,holding time of 90 min,alkalinity of 1.2 and H2 flow rate of 200 mL/min,the effects of the type and dos-age of dephosphorizing agent and different process parameters,such as the particle size of the reduction products and the intensity of the magnetic field,on the effect of iron and phosphorus removal in this ore were investigated by means of chemical composition analysis,particle size analysis and microstructural analysis,including polarized light microscopy and scanning electron microscopy analysis.The results show that the iron grade and iron recovery rate of iron concentrate are improved and the phosphorus content is also greatly reduced after adding dephosphorization agent.Among the four commonly used dephosphorization agents CaCO3,Na2CO3,Na2SO4 and SiC,the dephos-phorization agent Na2SO4 has a better effect on improving iron grade and phosphorus removal,and the dephosphori-zation agent Na2CO3 has a better effect on improving iron recovery.When the particle size of the reduced ore pow-der is less than 0.074 mm,the magnetic field strength is 1 000 Gs,the mass ratio of Na2SO4 to Na2CO3 is 9∶7,and the total mass percent is 16%,the phosphorus content is reduced to 0.23%,and the iron recovery rate is 82.35%.Some theoretical guidance for phosphorus removal from high phosphorus oolitic hematite are provided.
high phosphorus oolitic hematitegas-based direct reductiondephosphorizeriron phosphorus removalmagnetic separation
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