炉渣成分对冶炼白云鄂博矿高炉渣脱硫和排碱能力的影响

Effect of slag composition on desulfurization and alkali removal ability of blast furnace slag for Bayan Obo iron ore

为了探明炉渣成分对冶炼白云鄂博矿高炉渣脱硫和排碱能力的影响,在实际高炉渣成分的基础上,通过正交试验和Factsage 7.1热力学模拟软件绘制不同组分高炉渣渣系五元伪三元相图,探究了自由碱度(R_(o))、w(MgO)和w(Al_(2)O_(3))对高炉渣脱硫、排碱能力的影响规律,并结合生产实际给出了适宜的炉渣自由碱度(R_(o))、w(MgO)和w(Al_(2)O_(3))的控制范围.研究表明:R_(o)是影响炉渣脱硫、排碱能力的最显著因素,R_(o)增加,渣中O_(2)−浓度升高,促使硅氧复合阴离子Si−O解体,炉渣黏度减小,炉渣与金属液体之间的传质过程得到促进,使得S^(2−)更容易向渣中迁移,炉渣脱硫的热力学和动力学条件改善,脱硫能力提高,适宜的R_(o)应控制在1.05~1.15;w(MgO)是影响炉渣脱硫能力的次要因素,w(MgO)增加,炉渣的流动性和稳定性提高,有利于改善炉渣脱硫的动力学条件,且可降低炉渣中(K_(2)O+Na_(2)O)的活度,提高排碱能力,适宜w(MgO)应控制在15%左右;w(Al_(2)O_(3))是影响炉渣排碱能力的次要因素,w(Al_(2)O_(3))增加,易生成镁铝尖晶石(MgAl_(2)O_(4))等高熔点物质,使炉渣中的自由氧离子消耗量增多,不利于脱硫反应动力学条件的改善,虽然增加w(Al_(2)O_(3))有益于排碱,但高w(Al_(2)O_(3))不利于脱硫,且会导致炉渣黏度上升,适宜w(Al_(2)O_(3))应控制在12%左右.

To investigate the effect of slag composition on desulfurization and alkali removal ability of blast furnace slag for smelting Bayan Obo ore,based on the actual composition of blast furnace slag,the effect of free basicity(R_(o)),w(MgO),and w(Al_(2)O_(3))on the desulfurization and alkali removal ability of blast furnace slag was investigated by performing orthogonal experiments and on the basis of five-element pseudoternary phase diagrams of various components of a blast furnace slag system calculated and drawn using Factsage 7.1 thermodynamic simulation software,and the appropriate control range of R_(o),w(MgO)and w(Al_(2)O_(3))in the slag were given in combination with the production practice.The results show that:R_(o) is the most significant factor affecting slag desulfurization and alkali removal ability.With the increase in R_(o),the O_(2)−concentration in slag increases,resulting in Si−O disintegration,and slag viscosity decreases.In addition,the mass transfer between slag and metal liquid is accelerated,which makes S^(2−) easier to migrate into slag,the thermodynamic and kinetic conditions of slag desulfurization are improved,thus improving the desulfurization ability.The appropriate R_(o) should be controlled within the range of 1.05-1.15.w(MgO)is a secondary factor affecting the slag desulfurization ability.With the increase in w(MgO),the fluidity and stability of the slag are improved,which are beneficial for improving the kinetic conditions of slag desulfurization and reducing the activity of(K_(2)O+Na_(2)O)in the slag,thus improving the alkali removal ability.Appropriate w(MgO)should be controlled at approximately 15%.w(Al_(2)O_(3))is a secondary factor affecting the alkali removal ability of blast furnace slag.With the increase in w(Al_(2)O_(3)),high melting point materials such as MgAl_(2)O_(4) are easily formed,thereby increasing the consumption of free oxygen ions in the slag.This increase is not conducive to the improvement of desulfurization reaction kinetic conditions.Although increasing w(Al_(2)O_(3))is beneficial for removing alkali,high w(Al_(2)O_(3))is not conducive to desulfurization and leads to an increase in slag viscosity.Appropriate w(Al_(2)O_(3))should be controlled at approximately 12%.