Experimental Study On Kinetics Of Gaseous Dephosphorization From Converter Slag Under Flow Nitrogen Conditions

Multipurpose use of resource is considerd as a long-term strategy for national economy and social development. Sustained development of circulating economy developed by the centre of clean production is the inevitable choice. Circular utilization of steel slag was given an recognition, which raises a more scientific viewpoint of development for using of steel slag properly in metallurgical industry. Gaseous dephophorization is a new method of circulating use for slag on the base of remaining-slag operation in slag splashing process. During slag splashing process,reducing agent, such as coke powder, was added into molten pool. This method removes phosphorus and others harmful in slag impurities, which is possible that slag can be added continuously into next heat. Thereby, the method can realize the lower consumption of slag charge, little discharge of solid waste meterial, etc..According to the results of thermodynamic calculation, the mechanics of reaction for gaseous dephophorization is dicussed. On the base of reaction model, dynamic model of gaseous dephophorization is established.With experiments,the rate of gaseous dephophorization is obtained under different conditions, and the main kinetic factors are determined, so the possible effect of gaseous dephophorization is determined during the process of slag splashing.Analysis and calculation based on the experital results indicate that, gasifying dephophorization reaction occurs mainly at the interface between slag and flow nitrogen, but the little part of remainder reactions occurs in the gas film surrounding the carbon granule. Expereiment reveals that the controlling step of reaction is diffusion of P2O5 toward the interface of gas-liqud. Under experiment condition the reaction order of gaseous dephophorization behaves second order, and the reaction rate constant and the apparent activation energy are also obtained.It is researched that,under the condition of running nitrogen, temperature, content of FeO, viscosity of molten slag and grain size of coke are main influencing factors on the gaseous dephosphorization,but the basicity of slag has little influence on it. Proper CaF2 added into slag can accelerate rate of gaseous dephophorization obviously.