| With the demand of high quanlity steel increasing, secondary refining is becoming an indispensable section. However, as the increase of refining steel grade and the high quanlity of steel, the problem that slag bonding onto refractory of refining equipment is occurred in many firms. This thorny problem has a strong impact on normal product.There is almost a blank in mechanism of slag build onto RH immersion tube and additives for reducing slag build-up, the mechanism of slag building-up was studied by experiments and theory research to the puzzle of slag bonding-up onto RH immersion tube during RH refining in Panzhihua Steel. The calculation modle has been built for analyzing the thermodynamics condition of high-melting point phases which has deeply effect to slag build-up. The addivites for reducing slag build-up has been developed on the base of it.The mechanism of slag build-up is that, firstly, the refining slag has corroded the refractory, little MgO fuse into the ladle slag, flowed by a mount of MgO·Al2O3 and 2CaO·Al2O3·SiO2 crystallize, and build up onto the RH immersion tube. With the RH furnace operating life increasing, the thickness of slag building-up layer gradually increase which have a serious influence to productivity improving.The result of thermodynamic modle calculation shows that, when slag basicity is between 4.2 and 4.9, the contents of Al2O3 is between 14.2 and 17.6, the contents of MgO is between 8.0 and 8.7, the contents of FeO is between 13.3 and 14.4, the contents of CaF2 is between 4.0 and 5.2, the activities of MgO·Al2O3 and FeO·Al2O3 do not reach saturation, hence there are no MgO·Al2O3 and FeO·Al2O3 crystallized from refining slag. Of cause, the result of experiment is coincided with it.The result of industrial experiment shows that, there is almost no slag building-up onto the RH immersion tube after experiment, it can efficiently reduce amount of slag buildup by additives, which can ensure the product continuity and productivity improve.
|
PDF Full Text Request