Formation mechanism of the graphite-rich protective layer in blast furnace hearths
来源期刊：International Journal of Minerals Metallurgy and Materials2016年第1期
论文作者：Ke-xin Jiao Jian-liang Zhang Zheng-jian Liu Feng Liu Li-sheng Liang
文章页码：16 - 24
摘 要：A long campaign life of blast furnaces is heavily linked to the existence of a protective layer in their hearths. In this work, we conducted dissection studies and investigated damage in blast furnace hearths to estimate the formation mechanism of the protective layer. The results illustrate that a significant amount of graphite phase was trapped within the hearth protective layer. Furthermore, on the basis of the thermodynamic and kinetic calculations of the graphite precipitation process, a precipitation potential index related to the formation of the graphite-rich protective layer was proposed to characterize the formation ability of this layer. We determined that, under normal operating conditions, the precipitation of graphite phase from hot metal was thermodynamically possible. Among elements that exist in hot metal, C, Si, and P favor graphite precipitation, whereas Mn and Cr inhibit this process. Moreover, at the same hot-face temperature, an increase of carbon concentration in hot metal can shorten the precipitation time. Finally, the results suggest that measures such as reducing the hot-face temperature and increasing the degree of carbon saturation in hot metal are critically important to improve the precipitation potential index.
Ke-xin Jiao1,2，Jian-liang Zhang1,2，Zheng-jian Liu1,2，Feng Liu1,2，Li-sheng Liang3
1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing2. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing3. Baoshan Iron & Steel Co. Ltd.
摘 要：A long campaign life of blast furnaces is heavily linked to the existence of a protective layer in their hearths. In this work, we conducted dissection studies and investigated damage in blast furnace hearths to estimate the formation mechanism of the protective layer. The results illustrate that a significant amount of graphite phase was trapped within the hearth protective layer. Furthermore, on the basis of the thermodynamic and kinetic calculations of the graphite precipitation process, a precipitation potential index related to the formation of the graphite-rich protective layer was proposed to characterize the formation ability of this layer. We determined that, under normal operating conditions, the precipitation of graphite phase from hot metal was thermodynamically possible. Among elements that exist in hot metal, C, Si, and P favor graphite precipitation, whereas Mn and Cr inhibit this process. Moreover, at the same hot-face temperature, an increase of carbon concentration in hot metal can shorten the precipitation time. Finally, the results suggest that measures such as reducing the hot-face temperature and increasing the degree of carbon saturation in hot metal are critically important to improve the precipitation potential index.
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