Effect of a self-rotating oxygen lance system on mass transfer between slag and molten steel
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ORIGINAL PAPER
Effect of a self-rotating oxygen lance system on mass transfer between slag and molten steel Qi Gao1 • Wei Wu1
•
Jian-guo Zhi2,3 • Bo Zhang1 • Xiang-chen Li1
Received: 14 December 2019 / Revised: 13 June 2020 / Accepted: 14 June 2020 Ó China Iron and Steel Research Institute Group 2020
Abstract To improve the efficiency of the steelmaking process, a system of self-rotating lance was designed, and corresponding cold simulation mechanism was developed. The influence of the self-rotating lance on the mass transfer rate between slag and molten steel was investigated by comparing this novel system with the traditional oxygen lance. The results show that the self-rotating lance can stably rotate with a gas jet as the power source. The mass transfer rate increases with an increase in the top and bottom blow flow rates and with a decline in the lance position. Approximately 13.7% of the top blow flow rate is converted to stirring energy, which is approximately twice that of the traditional oxygen lance, and the mass transfer rate can increase by over 30%. Furthermore, the impact energy can be concentrated at different depths of the molten bath by adjusting the rotational speed. With the same energy density, the mass transfer rate produced by the self-rotating lance is higher; however, the influence of the energy density on the mass transfer rate is low when the rotational speed is 30–50 r/min. Keywords Self-rotating lance Reaction force Rotational speed Mass transfer rate Impact energy
1 Introduction As steel companies have become increasingly eager to reduce production costs, medium- or high-phosphorus iron ore is now used in the ironmaking process [1, 2]. However, the smelting process of the medium- or high-phosphorus hot metal has several problems, such as a long dephosphorization time, large slag volumes, and slag splashing. Lemitar Steel [3, 4] and Tata Steel [5] use high-phosphorus hot metal to produce low-phosphorus steel, which is a process that is difficult to control because excess slag is produced. In Japan, high-phosphorus low-silicon hot metal is smelted by blowing oxygen through the bottom of the
& Wei Wu [email protected] 1
Metallurgical Technology Research Department, Central Iron and Steel Research Institute, Beijing 100081, China
2
Inner Mongolia Enterprise Key Laboratory of Rare Earth Steel Products Research and Development, Baotou 014010, Inner Mongolia, China
3
Inner Mongolia Baotou Steel Union Co., Ltd., Baotou 014010, Inner Mongolia, China
converter. This approach can be used for hot metal with a phosphorus content of about 0.14%. However, this process is not suitable for hot metal with a higher phosphorus content [6]. In European countries, the top blow-spray lime powder approach is used to treat medium- and high-phosphorus hot metal [7]. Two different methods can be used for reducing the amount of slag produced during steelmaking: the top-blown basic oxygen converter method and the top lance powder-spraying oxygen conv
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