Study On Phosphorus Transmission Speed In Heterogeneous Dephosphorization Slag

The phosphorus content is high in China iron ore, and the phosphorus content is highin molten iron. For example, the phosphorus content sometimes higher than0.2%inBTSteel. These caused converter a large quantity of slag, easily spraying and large ironloss. When the slag appear solid particle, the dephosphorization slag viscosity rise quickly.The mass transfer velocity and the interface of slag and steel would reduce. There were alarge number of iron particles in dephosphorization. These wouldn’t be good fordephosphorization. The heterogeneous dephosphorization slags were applied in the actualproduction and experimental study, but the study on heterogeneous dephosphorizationslags weren’t deep enough.In order to improve the efficiency of dephosphorization slag, in this paper, from theview of dynamics, the phosphorus transfer rule of2CaO·SiO2, CaO·SiO2, and CaO solidparticle was researched. The phosphorus distribution in the slag and2CaO·SiO2, CaO·SiO2,and CaO solid particles were measured with SEM-EDS, and the phosphorus diffusioncoefficient was calculated with Fick’s second law. According to the proportionalrelationship of the phosphorus diffusion depth in the2CaO·SiO2, CaO·SiO2, and CaO solidparticles and time, the formula of the relationship between the diffusion time and thediffusion distance of the particles was obtained by the least square method at thetemperature of1385℃,1400℃and1450℃. Because the equilibrium time of molten irondephosphorization about15-20min, it is concluded that the maximum diameter range of2CaO·SiO2, CaO·SiO2, CaO particles during dephosphorization and finally get thefollowing conclusions:(1) The phosphorus diffusion coefficient in the2CaO·SiO2,CaO·SiO2, and CaO solid particles are DC2S=6.417×10-12m2/s, DCaO=1.951×10-11m2/s, andD-11CS=2.783×10m2/s at1400℃; theequilibrium time of molten ironl dephosphorizationabout15min-20min, it is concluded that the maximum diameter of2CaO·SiO2, CaO·SiO2,and CaO solid particles during dephosphorization is653.26μm、603.26μm、942.96μm;(2)When the temperature is1400℃, the diffusion of phosphorus in2CaO·SiO2particles is periodic fluctuation diffusion at, the diffusion of phosphorus in CaO particles is thetendency of first increase and then decrease, the diffusion of phosphorus in CaO·SiO2particles is linear diffusion;(3) At the temperature of1385℃,1400℃, and1450℃,temperature has largest effect on the diffusion diameter of phosphorus transfer in CaO·SiO2particles, and has least effect on the diffusion diameter of phosphorus transfer in2CaO·SiO2particles;(4) At the temperature of1385℃,1400℃, and1450℃, the diffusionactivation energy of phosphorus in2CaO·SiO2、 CaO·SiO2、 CaO particles is4.414×104J/mol、3.303×104J/mol、2.416×104J/mol.