K_(2)O和Na_(2)O对高Al_(2)O_(3)炉渣组元活度和MgO含量的影响

Effect of K_(2)O and Na_(2)O on activity of components and MgO content of high Al_(2)O_(3) slag

随着高品位铁矿石消耗的加快,资源逐渐趋于贫化,钢铁企业可利用的铁矿石原料逐渐向中低品位原料转变,尤其是高铝铁矿,这类原料的使用无疑会增加高炉渣中Al_(2)O_(3)质量分数,影响高炉现有的操作制度。Al_(2)O_(3)质量分数为15%~17%的高炉渣,由于Al_(2)O_(3)含量高而使高炉渣的冶金性能变差,为了保证高炉渣的冶金性能,必须在其中添加8%左右的MgO。然而,Al_(2)O_(3)含量相似的浦项钢铁的高炉渣,其MgO质量分数仅为4%左右,高炉实现了高效、稳定、顺行。因此,从高炉CaO-SiO_(2)-Al_(2)O_(3)-MgO四元渣系的物理化学机理出发,研究了K_(2)O、Na_(2)O对高炉渣四元渣系CaO-SiO_(2)-Al_(2)O_(3)-MgO中各组元活度的影响;研究了"渣-气"平衡条件下渣中碱金属氧化物和气体中碱金属的关系;计算了K_(2)O、Na_(2)O和MgO对黏度的影响。结果显示,在考虑高炉渣CaO-SiO_(2)-Al_(2)O_(3)-MgO中各组元活度、碱金属在渣-气间的分布和炉渣黏度的情况下,当碱金属氧化物K_(2)O和Na_(2)O存在时,可以适当减小MgO含量,并可以保证高炉渣各组元活度及炉渣黏度基本不变。这不仅有助于减少高炉原料中添加含镁熔剂、提高原料品位、高效排碱、降低碱危害、减少碳排放、延长高炉寿命及降低成本,还能促进钢铁企业实现节能减排的目标。

With the acceleration of consumption of high-grade iron ore and the gradual dilution of resources,the available iron ore raw materials for iron and steel enterprises are gradually transformed into medium and low grade raw materials.Especially high alumina iron ore,the use of such raw materials will undoubtedly increase the Al_(2)O_(3)mass percent of blast furnace slag and affect the existing operation system of blast furnace.In order to ensure the metallurgical properties of slag,about 8%MgO must be added to the blast furnace slag,which contains 15%-17%high Al_(2)O_(3).Because of high Al_(2)O_(3)content,the metallurgical properties of blast furnace slag become worse.However,the MgO content of POSCO′s blast furnace slag with similar mass percent of Al_(2)O_(3)is only about 4%,but the blast furnace has achieved high efficiency,stability and smooth running.Therefore,the effects of K_(2)O and Na_(2)O on the activity of each component in the quaternary slag system CaO-SiO_(2)-Al_(2)O_(3)-MgO of blast furnace slag were studied based on the physical chemistry mechanism of the blast furnace CaO-SiO_(2)-Al_(2)O_(3)-MgO quaternary slag system.The relationship between alkali metal oxides in slag and gas under the condition of slag-gas equilibrium was studied.The effects of K_(2)O,Na_(2)O and MgO on viscosity were calculated.The results show that considering the component activity of blast furnace slag CaO-SiO_(2)-Al_(2)O_(3)-MgO,the distribution of alkali metals between slag and gas and the slag viscosity,the content of MgO can be reduced appropriately when the alkali metal oxides K_(2)O and Na_(2)O exist,and the component activity of blast furnace slag CaO-SiO_(2)-Al_(2)O_(3)-MgO and slag viscosity can be kept basically unchanged.It is not only helpful to reduce the addition of magnesium-containing flux in blast furnace raw materials,improve the grade of raw materials,discharge alkali efficiently,reduce alkali harm,reduce carbon emissions,prolong the life of blast furnace and reduce costs,but also promote the iron and steel enterprises to achieve the goal of energy saving and emission reduction.