| Facing the cost pressure brought by price rising of the international iron ore, it has been an important choice for domestic steel industries to explore high phosphorus iron ore in order to pursue Sustainable Development Path. The converter duplex process is a modern and new technology for dephosphorization, which provides an important way to cost the high phosphorus iron ore. Considering the low temperature and short melting cycle of dephosphorization converter and the comprehensive utilization of high phosph- orus slag, the rapid dissolution of lime to form slag with good dephosphorization ability plays a key role in the initial slag with high-P2O5, fluorine-free and low-R. At present, the research on this aspect is relatively rare. Therefore, the dissolution behavior of lime was studied based on the characteristics of converter duplex process, which has certain theoretical meaning for optimizing dephosphorization technology and promoting slag forming speed.In the paper, the effect of slag compositions, temperature, relative speed on dissol- ution behavior of lime were studied by static erosion method and dynamic rotation experiment method, and the restrictive step of lime dissolution was discussed. Meantime, the interfacial microstructure were observed and analyzed by mineralogical microscope and scanning electron microscopy (SEM+EDS) to disscuss the dissolution mechanism of lime. The main research results are as follows:①The effect of R, Fe2O3 content, P2O5 content, Al2O3 content, and Na2O content on lime dissolution behavior was studied by quadratic regression orthogonal combination design method.The regression equation between lime melting rate and slag composition was gained. It is bad for lime dissolution in high P2O5 slags.②In FetO-SiO2-CaO-P2O5-5%MnO-5%MgO slag series with high P2O5, the CaO dissolution rate is controlled by CaO diffusion mass in molten slags, and The relationship between lime dissolution rate and the relative speed was returned out, and j factor equation was gained. The CaO mass transfer coefficients is about 3.03×10-4-8.97×10-4cm/s, and the dissolved activation energy is about 160.32 kJ/mol.③In FetO-SiO2-CaO-P2O5-5%MnO-5%MgO-X slags, CaF2, Na2O and Al2O3 can promote the lime dissolution rate, and the promotion order is CaF2>Na2O>Al2O3. Therefore, Na2O and Al2O3 can be used as the substitution agent for CaF2, but the content should be controlled, considering the comprehensive utilization of high phosp- horus slag,④Based on the analysis of the dissolution mechanism of lime, the (Fe,Mn)O-CaO layer with high FeO next to the lime plays a key role in dissolution of lime, but the area of liquid-solid coexistence containing 3CaO·P2O5-2CaO·SiO2 solid solution next to (Fe,Mn)O-CaO layer reduces the lime dissolution rate.
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