The potential of VFB (very fine bubbling)-technology in steelmaking, developed for the production of super clean steels, was investigated. Recent RD work has proven that with very fine argon bubbling through a developed special porous plug (SPP) at low flow rates, the total oxygen content of low carbon steel grades can be lowered to a level of 6 ppm under industrial vacuum conditions 1; 2 and to a level of 10 ppm under argon protective atmosphere 2. The perspective of industrial application of the VFB technology to a 56-t ladle furnace of Helliniki Halyvourgia S.A., Greece, in order to improve steel cleanliness, requires additional RD efforts. It is important to define the limits of VFB technology in respect of alloys dissolution, mixing time and homogenisation of steel and slag/metal reactions. In this work, a gas driven bubble aqueous reactor model simulating the bottom gas stirred ladle by means of gas injection through a SPP and a conventional porous plug was studied. Various operating conditions as well as different positions for the porous plug with and without a top oil layer were simulated. Tests concerning mixing time, solid-liquid mass transfer and critical gas flow rate, liquid/liquid mass transfer, using the SPP and a conventional porous plug have been performed. The evaluation of experimental results delivered important information for the design and operation of steel ladles, applying VFB-technology. Experimental results with SPP bubbles' agitated steel (1600 deg C) in laboratory and technical scale experiments in IF and VIF are presented and discussed.
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