Comparative dissolution of lime and limestone in molten slag for dephosphorization
The rapid dissolution of lime in molten slag to improve the slag basicity contributes to the efficient dephosphorization and energy saving during steelmaking.The comparative study on the dissolution and dephosphorization behavior of lime and limestone in slag was conducted through high-temperature dissolution experiments and slag-metal reaction dephosphorization experiments.Results show that lime dissolved rapidly in the initial stage after added into molten slag,followed by a gradual decrease in dissolution rate and almost stagnation in the later stage.In the initial stage of limestone dissolution,a large amount of CO2 generated by the decomposition of CaCO3 hinders the contact between the slag and the surface CaO layer formed by CaCO3 decomposition,thereby hindering the penetration of slag into the lime layer and the dissolution of lime.The CO2 generated by later decomposition plays an important role in accelerating the dissolution of lime.There is an important correlation between the dephosphorization reaction and the rapid increase in CaO content in the slag.Due to the slow dissolution of lime in the later stage,the dephosphorization rate is lower,and the phosphorus content in the liquid metal is relatively higher.During the dissolution of limestone for dephosphorization,the CaO content in the slag increases more slowly than lime due to slow dissolution in the early stage,which leads to a slightly slower mass transfer coefficient of dephosphorization reaction in the early stage compared with the test of lime.In the later stage,because of the accelerated dissolution of limestone,the mass transfer coefficient in the dephosphorization reaction increases by about 11.6 times compared with that in the early stage and about 6.6 times higher than that in the test of lime.
万方数据
维普
