Slag emulsification in the continuous casting process
In the continuous casting the mould flux on the meniscus of liquid steel can be introduced into the liquid steel producing defects on final product. Conditions leading to the instabilities near the slag/steel interface were investigated. Two main parameters promote the emulsification process: convective flow in the liquid metal and the interfacial convection caused by mass exchange between both phases. In the first part of present work, the stability of a liquid-liquid interface without mass transfer between phases was investigated in cold model study using a single - roller driven flow in oil - water systems with various oil properties. Using the similarity theory, two dimensionless number were identified, viz. capillary number Ca and the material number Λ, which are suitable to describe the force balance for the problem treated. The critical values of the dimensionless capillary number Ca for droplet break-up marking the start of their entrainment into the lower fluid are determined over a wide-range of fluid properties. Another dimensionless number Λ was defined as the ratio of kinematic viscosities of the dispersed phase vd and continuous phase vc, (viz. kinematic viscosity ratio). The material numbers of different steel - slag systems were calculated using measured thermo - physical properties. With the knowledge of thermo - physical properties of steel - slag systems, the critical capillary number Ca* for slag entrainment as a function of Λ could be derived. Assuming no reaction between the phases and no interfacial flow, slag entrainment should not occur under usual casting conditions. In the second part of the present work, the effect of the interfacial convection on the emulsification process was investigated. The interfacial convection is caused by the local change of the interfacial energy. Based on the investigation of the mass exchange in the industrial process the relationship between mass exchange and interfacial convection were derived using dimension free description. Additionally the model experiments with direct observation of the interfacial convection in the Confocal Laser Scanning Microscope were performed and the slag emulsification detected.
continuous casting slag emulsification interface stability interfacial energy mass transport
Piotr R. Scheller Rene Hagemann
Freiberg University of Mining and Technology, Institute of Iron and Steel Technology 34 Leipzigerstrasse 34, 09596 Freiberg, Germany
国际会议
Ninth International Conference on Molten Slags,Fluxes and Salts(第九届国际熔渣、溶剂与熔盐学术会议 MOLTEN12)
北京
英文
1-15
2012-05-27（万方平台首次上网日期，不代表论文的发表时间）