High Phosphorus Iron Ore Mix Of Ilmenite Rich Oxygen Top-blown Smelting Reduction Experiment Research

There are an abundant reserves of High phosphorus iron ore in Huimin, Yunnan province. However, these reserves which are in a condition of low grade, fine precision, complex composition and difficult enrichment can not be exploited and utilized until now. The reserves of ilmenite in China are also relatively rich. The total reserves which spread over20provinces are about30million tons. When the ilmenite is smelted separately by blast furnace, foaming slag is easily generated. Although the reaction surface and rate can be enlarged among gas, slag and metal liquid, there is a bad quality of heat conduction. And heat transfer between slag and metal can be deteriorated. Besides, a series of problems can be caused, such as lock of furnace charge, overflowing foam, deteriorated condition of blast furnace, increasing loss of iron and decrease in desulfuration rate. In order to reasonably utilize High phosphorus iron ore and ilmenite, the mixed ore of High phosphorus iron ore and ilmenite are smelted by top-blown melting technology in rich oxygen, Phosphorus load of furnace charge is reduced, the content of TiO2in the slag is diluted and formation of foaming slag is reduced in this subject. In this technics, there is a strong oxidizing atmosphere on the top of reduction container. The slag composition passes a higher oxygen potential, which impels phosphorus, titanium and silicon getting into the furnace and ensures that there is a low content of impurities in pig iron. So the molten iron which was obtained by melting can be used to make steel.The influence which is affected by basicity, temperature, the mole ration on coal and oxygen, the time of ventilated oxygen, the time of heat preservation, flow rate of oxygen, CaF2cosolvent on recovery percent of iron, dephosphorization rate and the content of iron, phosphorus, sulfur and titanium is investigated in this essay. Following conclusions can be reached:(1) There is an increasing trend in the rate of iron recovery, the content of phosphorus in pig iron is going up which caused a decreasing in dephosphorization rate and the content of sulfur as well.(2) When basicity is increased, the rate of iron recovery firstly goes up and then comes down. The content of phosphorus goes down, so it causes a decreasing in dephosphorization rate. And there is a decreasing in the content of sulfur.(3) With the increasing of mole ration between coal and oxygen, the rate of iron reduction which reaches a maximum when the ration of coal and oxygen is at1.0is coming down firstly and then going up. One of the advantages in top-blown melting technology in rich oxygen is that there is better result in dephosphorization. The content of phosphorus in pig iron increases from0.067% to0.43% when the ration between coal and oxygen is at0.8to1.3. Accordingly, the rate of dephosphorization drops from92.2% to46.5%. With the increasing of ration between coal and oxygen, the content of sulfur in pig iron goes down.(4) With the extending in the time of ventilated oxygen, the recovery rate of iron goes up in advance and then decreases sharply. The content of phosphorus in pig iron comes down while the rate of dephosphorization goes up. And the content of sulfur in pig iron goes up.(5) With the extending in the time of heat preservation, the rate of iron recovery which reaches maximum in30minutes that is94.24%. The content of phosphorus in pig iron goes up firstly and then comes down. The change in the rate of dephosphorization is opposite. The content of sulfur in pig iron comes down in advance and then goes up.(6) When the flow of oxygen increase, the rate of iron recovery firstly goes up and then comes down. Then content of phosphorus in pig iron decreases firstly and increases latterly, and then it decreases again. What happens in dephosphorization rate is opposite. The content of sulfur in pig iron increases firstly and comes down latterly, and then goes up again.(7) Added CaF2in most experiments proves that it improves the iron recovery. With the increasing of added CaF2, the rate of iron recovery goes up firstly and then comes down somewhat. When the ration on CaF2and CaO is1to10and1to8, the rate of iron recovery is over93%. The content of phosphorus and sulfur comes down. The slag which is obtained in the ration on ilmenite in Mengqiao and High phosphorus iron ore in Huimin is6to4, the temperature is1500℃, the basicity is1.3, the mole ration on coal and oxygen is1.0, the time of heat preservation is20minutes, the time of ventilated oxygen is10minutes and the flow of oxygen is250L/h, is tested with X-ray and analyzed on chemical elements. The result shows that the main phase in the slag is Ca2Al2SiO7. Additionally, there is a few Fe3O4, CaTiO3, Ca3(PO4)2The content of FeO in the slag is7.06%, Fe2O3is2.75%, TiO2is8.2%and P2O5is0.96%. It also shows that top-blown melting technology in rich oxygen, which is used to smelt the mixed ore of High phosphorus iron ore and ilmenite, can transform Ti and P from ore to slag.The optimum result of this experiment is that:the ration on ilmenite in Mengqiao and High phosphorus iron ore in Huimin is6to4, the temperature is1450℃, the basicity is1.3, the mole ration on coal and oxygen is1.0, the time of heat preservation is20minutes, the time of ventilated oxygen is10minutes and the flow of oxygen is250L/h. There is a good separation between slag and iron when the ration on CaF2and CaO is1to8. At that moment, the reduction rate can reach93.5%, the rate of dephosphorization is87.4%, and the rate of desulfuration is76.6%. The content of phosphorus in pig iron is0.096%, sulfur is0.075% and titanium is0.001%.