The enrichment behavior of phosphorus in CaO-SiO2-FeOx-P2O5 slag was studied by making an investigation on the distribution of phosphorous content in the CaO-SiO2-FeOx-P2O5 molten slag.The research results showed that the 2CaO·SiO2 solid particles existing in molten slag were the condensation sites for the phosphorus enrichment.The enrichment process of phosphorus in the molten slag can be recognized as three substeps:mass transfer of phosphorus from bulk slag to the surface of 2CaO·SiO2 particle,superficial solid solution reaction of phosphorus around the 2CaO·SiO2 particle,and diffusion of phosphorus through the product layer of 2CaO·SiO2-3CaO·P2O5 solid solution to the inner of 2CaO·SiO2 particle.Moreover,higher temperature is favorable to the phosphorous enrichment from molten bulk slag to the 2CaO·SiO2 particles.
The effects of adjusting technological conditions on the phosphorous enrichment of adjusted converter slag were investigated. The results showed that the phosphorus could be effectively enriched to 2CaO·SiO2 and 2CaO·SiO2-3CaO·P2O5 solid solution (SS, namely phosphorus-rich phase) to be formed with the decreasing of basicity and cooling rate. Moreover, the morphology of the phosphorus-rich phase changed from granular for the original converter slag with higher basicity to the coexistence of granular shape and rod-like for the adjusted slag with lower basicity. P2O5 content in phosphorus-rich phase exceeded 30% while the basicity was 1.3 at the cooling rate of 1.0 ℃/min.
The 3D turbulence k-ε model flow of the steel melt(continuous phase)and the trajectories of individual gas bubbles(dispersed phase)in a continuous casting mold were simulated using an Eulerian-Lagrangian approach.In order to investigate the effect of bubble size distribution,the radii of bubbles are set with an initial value of 0.1-2.5mm which follows the normal distribution.The presented results indicate that,in the submerged entry nozzle(SEN),the distribution of void fraction is only near the wall.Due to the fact that the bubbles motion is only limited to the wall,the deoxidization products have no access to contacting the wall,which prevents clogging.In the mold,the bubbles with a radius of 0.25-2.5mm will move to the top surface.Larger bubbles issuing out of the ports will attack the meniscus and induce the fluid flows upwards in the top surface near the nozzle.It may induce mold powder entrapment into the mold.The bubbles with a radius of 0.1-0.25mm will move to the zone near the narrow surface and the wide surface.These small bubbles will probably be trapped by the solidification front.Most of the bubbles moving to the narrow surface will flow with the ascending flow,while others will flow with the descending flow.
Chong-lin LIUZhi-guo LUOTao ZHANGShen DENGNan WANGZong-shu ZOU
