Desulfurization Capacity And Removing Alkali Capacity Of CaO-SiO₂-MgO-Al₂O₃-BaO Blast Furnace Slag System

The special iron concentrate used as ironmaking raw materials for a long time by a domestic steel company contains a great deal of barite.When they are introduced into the blast furnace,the produced BaO due to decomposition of barite will get into the blast furnace slag directly,which makes the properties of blast furnace slag change.However,there are less research in the effect of BaO on the properties of slag,it has application potential to guide the industrial production by studying the properties of barium-bearing blast furnace slag,especially the desulfurization capacity and removing alkali capacity.In the paper,the experimental slags are prepared by analytically pure reagents on the basis of field blast furnace slag.When the temperature is in the range of 1400¹550℃,basicity in 1.0¹.2,Al₂O₃ content in 6%¹4%,MgO content in 4%¹2%and BaO content in 0%⁵%,the change rule of the viscosity,desulfurization capacity and removing alkali capacity in CaO-SiO₂-MgO-Al₂O₃-BaO blast furnace slag were investigated systematically by combining with the viscosity and high temperature experiments.The results ars as follows:The viscosity of slag was measured by using the rotating cylinder method.It was found that from the viscosity experiments that there was a trend of gradually decreasing with the temperature increasing from 1400℃to 1550℃,basicity increasing from 1.0to 1.2,and MgO content increasing from 4%to 12%in slag.The slag viscosity decreased slightly due to the increase of a small amount of BaO content at low temperature.When the temperature was high,increasing BaO content was not conducive to decrease the slag viscosity.The gas-slag equilibrium method was employed to study the influence of different factors on desulfurization capacity.The results showed the sulphide capacity increased obviously with the basicity increasing,but decreased with an increase of Al₂O₃ content.A small increasing trend was found when MgO content increased.The sulphide capacity firstly increased and then decreased gradually with BaO content increasing from 0 to 5%.It showed a good linear increasing relationship between sulphide capacity and optical basicity.The Sosinsky and Sommerville’s model could be employed to predict the sulphide capacity of present slag systems containing barium.The graphite crucibles were taken as reaction vessel to investigated the removing alkalis capacity of target slag systems.The experimental results showed that the increase of temperature from 1450℃to 1550℃,basicity and MgO content made the fluidity increase,improving the reduction of potassium ions,which was unfavourable to improve the capacity of removing alkalis.The actual basicity would be enhanced with the increasing of Al₂O₃ content in slag,leading to a strong ability to fix alkalis.When BaO content was less than 3.5%,the removing alkalis capacity reduced slightly.However,further increase in BaO content had little effect on alkali removing rate when BaO content was beyond 3.5%.