A Kinetic Model Of Hot Metal Dephosphorization By Powder Injection

A lot of research work has been done on hot metal dephosphorization in the literature, including kinetic model for prediction of the process. However, hardly any of them has studied the possibility of the chemical reaction being the controlling step, and the decrease of the particle size in the process of reaction, and the influence of temperature on the kinetic process, especially the mutual influence between temperature and chemical reactions has not been considered in the kinetic model. In the present work, the kinetic model for hot metal dephosphorization is further developed with consideration of these two points.Material balance provides the dephosphurization reagent calculation, and it is also the base for the development of temperature prediction model and kinetic model. Temperature and reaction kinetics are influenced each other:the change of temperature affects mass transfer and chemical reaction, and the reaction heat affects the temperature in turn. Therefore, the main contents of the present work, as well as the results obtained, are as follows.(1) Calculation of material balanceBased on mass conservation, the required quantities of oxidant and stablizer are calculated by considering all the chemical reactions. The prescription and consumption of dephosphurization agent are thus determined.(2) A coupling model of kinetic and temperature for dephosphorization pretreatment of hot metalBased on heat conservation and the above material balance result, a temperature prediction model is developed by analyzing all the heat incomes and heat outputs during the processes.Based on the analyses of the macrokinetics and transport phenomena of various sub-processes involved in hot metal dephosphurization, especially considering the effect of temperature variation, a coupled kinetic model for the process is developed.Using this model, the variations of phosphorus, silicon and carbon contents and temperature of hot metal with time under different treatment conditions are calculated and discussed.