Effect Of Aluminum Ash And Rare Earth Concentrate On Refining Slag Modification

Aluminum ash is a dangerous waste,but it is also a kind of industrial solid waste with high reuse value.The metal aluminum and alumina contained in it can be used as refining slag modification agent,and can also reduce the pollution to the environment.The rare earth concentrate contains a large number of rare earth oxides,which are used for analysis of rare earth oxides and further preparation of rare earth alloys.Rare earth alloys play a role in purifying liquid steel in the process of iron and steel smelting.In this thesis,based on CaO-MgO-SiO₂-Al₂O₃-CaF₂ slag system,the effects of aluminum ash and rare earth concentrate on melting point,viscosity,desulfurization and deoxidation performance of refining slag and inclusion in steel were studied by using Factsage software calculation and experimental method.The addition of aluminum ash has obvious influence on the melting point,fusibility temperature and viscosity of the experimental slag,which makes the refined slag show better deoxidation and desulphurization effect.The melting point,fusibility temperature and viscosity of refined slag decrease first and then increase with the increase of the ratio of aluminum ash.When the amount of aluminum ash is 15%,the melting point and melting temperature of refining slag are 1310℃and 1351℃,with good fluidity.With the increase of aluminum ash ratio,the oxygen content and sulfur content in steel decrease first and then increase.When aluminum ash content is 15%,the deoxidation and desulfurization effect of refining slag is the best.After slag addition,the free oxygen content in steel decreases 77.31ppm and sulfur content decreases to0.0046%.The results show that with the increase of the ratio of rare earth concentrate,the melting temperature of refining slag increases gradually,the deoxidation effect of refining slag becomes worse,the sulfur content in steel increases gradually,and the desulfurization effect becomes worse.When the ratio of rare earth concentrate increased from 10%to 30%,the melting temperature of slag increased from 1300℃to 1380℃,the free oxygen content in steel increased from 63.93ppm to 75.12ppm,and the sulfur content in steel increased from 0.0068%to 0.0141%.After adding aluminum ash and rare earth concentrate modified refining slag,the number of inclusions in steel increases,but the size of inclusions decreases,and the average particle size of inclusions decreases from 5-10μm to 2-5μm.The inclusions in steel mainly include MnS inclusions,Al₂O₃ inclusions,composite inclusions with Al₂O₃ as the main component and accompanied by CaO,MgO and other oxides,and composite inclusions with Al₂O₃ as the core and coated by MnS inclusions.Si-Ca-Ba deoxidizer was added to the slag system with rare earth concentrate.In contrast,Ce-Fe alloy was added to the other group during smelting.The number of inclusions and the size of inclusions in the steel after smelting by the two methods have little change,and the number of inclusions remains between 400 and 600 in the area of 8.49×10⁵μm²,and the average particle size of inclusions is 2-5μm.After Si-Ca-Ba alloy is added,the main inclusions are:Ce-S-Ti-O inclusions with MnS inclusions and Ce-S-O inclusions,Ce-S-Al-Ti-O inclusions with MnS inclusions and Ce-S-Al-Ti-O inclusions.After the addition of Ce-Fe alloy,the inclusion species mainly include:Ce-S-Ti-O composite inclusion,Ce-S-Ti-O inclusion as the core,the outer layer of MnS inclusion and Ce-S inclusion.And after the addition of the two alloys,most of the inclusions are approximately spherical,indicating that if Si-Ca-Ba is used as deoxidizer during smelting,adding rare earth concentrate into the slag can have the same effect as adding rare earth metals.