Mass transfer characteristics between molten steel and particles in RH-PTB refining

• Published in: Ironmaking & steelmaking Vol. 28; no. 6; pp. 455 - 464
• Main Authors: WEI, J.-H, WANG, M, YU, N.-W
• Format: Journal Article
• Language: English
• Published: Leeds Maney 01.01.2001; Taylor & Francis Ltd
• Subjects: Applied sciences; Dispersion hardening metals; Exact sciences and technology; Fluid dynamics; Heat transfer; Iron and steel making; Metals. Metallurgy; Powder metallurgy; Powder metallurgy. Composite materials; Production of metals; Production techniques; Refineries; Steel alloys; Studies; Treatment before gravity die casting and continuous casting; Weight; Liquid solid interface; Steel refining; Steel; Experimental study; Molten steel; Powder; Mass transfer
• ISSN: 0301-9233; 1743-2812
• DOI: 10.1179/030192301678325

The mass transfer characteristics between powder particles and liquid steel in RH-PTB (powder top blowing) refining have been investigated on a 5 scale water model of a 90 t RH degasser. Sodium chloride powder of analytical purity has been used as the flux for blowing, and the mass transfer coefficient of solute (NaCl) in the liquid has been determined under the conditions of the RH-PTB process. The influence of the main technological and structural parameters on the mass transfer rate has been examined. The results have shown that, under the conditions of the present work, the mass transfer coefficient in the liquid increases with increasing lifting gas flowrate, with increasing inner diameter of the upsnorkel, with increasing circulation rate of the liquid, and with increasing particle size of powdered flux. On the other hand, mass transfer in the liquid decreases with an increase in the inner diameter of the downsnorkel. Its value is in the range (136-730) x 10 exp -4 m s exp -1 . The following dimensionless relationships, correspondingly, have been obtained for the mass transfer coefficient in the range: Sh = 2 + 0073Re sub s exp 0777 Sc exp 1/3 . Sh = 2 + 0.073( epsilon sub 1s d sub p exp 4 / v sub 1 exp 3 ) exp 0.259 Sc exp 1/3 . When the mass transfer is treated as that between rigid bubbles and molten steel, it may be characterised by Sh = 2 + 0026[Re sub s exp 048 Sc exp 0339 (g exp l/3 d sub p / D sub p exp 2/3 ) exp 0.072 ] exp 1455 .