Interface wetting behavior between iron and coke during the carbon dissolution process in a blast furnace
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摘要: 高爐內鐵水滲碳過程是影響冶煉效率及未飽和鐵水對爐缸爐襯侵蝕的重要因素。本文通過高溫真空潤濕性測試裝置模擬了高爐爐缸區的鐵水滲碳反應，分析了不同碳質量分數（3.8%、4.3%、4.8%）的Fe?C熔體與質量分數為99.9%的石墨基體在高溫下界面間的潤濕反應，同時利用掃描電鏡（SEM）和能譜儀（EDS）研究了滲碳界面的微觀形貌及滲碳距離。結果表明：界面接觸角隨著Fe?C熔體中碳含量的增加而變大；熔化過程中，接觸角隨著反應時間延長而減小，并最終趨于穩定；4.8%碳質量分數的Fe?C熔體中由于含碳量已至飽和，處于不潤濕狀態。掃描電鏡分析顯示，Fe?C熔體與石墨基體的接觸界面形成了“球帽狀”凹陷，凹陷半徑與體積隨碳含量的增加而減小。能譜線掃描分析顯示，隨著Fe?C熔體中初始碳含量的增加，石墨基體中的碳素溶解量減少，滲碳效果變差，良好的潤濕性有利于碳的傳質。通過計算表面能發現，石墨基體中碳素溶解進入Fe?C熔體后，有效減小了兩者之間的表面能，使得表面張力減小，接觸角在熔化期間遞減。Abstract: Good gas permeability is an essential factor for the smooth operation and high performance in the lower part of the blast furnace. Under the present low carbon blast furnace smelting conditions, the coke layer is thinner, and the proportion of the molten metal in the coke layer is significantly higher, resulting in a major reduction in gas permeability, which seriously affects blast furnace operations. Also, the lower thickness of the coke layer weakens the process of solid-liquid carbon dissolution when the molten iron passes through the coke layer, which reduces the carbon content of the molten iron and further deepens the erosion of the refractory by the unsaturated molten iron. The carbon dissolution in the molten iron in a blast furnace core was measured by a high-temperature vacuum wettability test tool that analyzed the interface wetting activity between Fe?C melts with specific carbon mass fraction (3.8%, 4.3%, 4.8%) and 99.9% of high temperatures graphite plates. Besides, the scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) were used to analyze the graphite substrate’s carburizing morphology and carburizing distances. The results show that, with the increase of carbon content, the interface contact angle becomes bigger. The contact angle decreases with time, and eventually reaches a steady-state during the melting process, and the Fe?C melt with saturated carbon cannot be wet. The scanning electron microscopy analysis shows that a spherical cap-like depression is created by a cross-section of the Fe?C melt and the graphite substrate, and the radius and volume of the depression decrease with increasing carbon content. The study of the EDS scanning analysis shows that the amount of dissolved carbon atoms in the graphite substrate penetrates the Fe?C melt and decreases with increasing initial carbon concentration. The smaller the carburizing effect, the better the wetting is conducive to carbon mass transfer. It is found that by measuring carburizing of the carbon atoms in the graphite substrate into the Fe?C melt by calculating the surface energy reduces the surface energy between the two. Thus, the surface tension decreases and the melt spreads slowly with contact angle gradually decreasing during melting.
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Key words:
- coke /
- wetting behavior /
- contact angle /
- carbon dissolution /
- surface energy
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圖 2 Fe?3.8%C熔體的滲碳過程。（a）1100 ℃；（b）1200 ℃；（c）1300 ℃；（d）1400 ℃
Figure 2. Carburization process of Fe?C sample with 3.8% carbon content: (a) 1100 ℃; (b) 1200 ℃; (c) 1300 ℃; (d) 1400 ℃
圖 3 Fe?4.3%C熔體的滲碳過程。（a）1100 ℃；（b）1200 ℃；（c）1300 ℃；（d）1400 ℃
Figure 3. Carburization process of Fe?C sample with 4.3% carbon content: (a) 1100 ℃; (b) 1200 ℃; (c) 1300 ℃; (d) 1400 ℃
圖 4 Fe?4.8%C熔體的滲碳過程。（a）1100 ℃；（b）1200 ℃；（c）1300 ℃；（d）1400 ℃
Figure 4. Carburization process of Fe?C sample with 4.8% carbon content: (a) 1100 ℃; (b) 1200 ℃; (c) 1300 ℃; (d) 1400 ℃
圖 5 Fe?C熔體接觸角在升溫過程中的變化規律
Figure 5. Variation of contact angle of Fe?C sample with temperature rising
圖 6 切割前后的Fe?C熔體形狀。（a） 切割前；（b） 切割后
Figure 6. Fe?C sample shape before and after cutting: (a) before cutting; (b) after cutting
圖 7 掃描電鏡下不同Fe?C熔體的微觀形貌。（a） Fe?3.8%C 熔體；（b） Fe?4.3%C 熔體；（c） Fe?4.8%C熔體
Figure 7. Morphology of different Fe?C samples using SEM: (a) Fe?3.8%C melt; (b) Fe?4.3%C melt (c) Fe?4.8%C melt
圖 9 能譜線掃描的元素分析結果。（a） Fe?3.8%C 熔體；（b） Fe?4.3%C熔體；（c） Fe?4.8%C 熔體
Figure 9. Element analysis results by EDS line scan: (a) Fe?3.8%C melt; (b) Fe?4.3%C melt; (c) Fe?4.8%C melt
表 1 球帽尺寸計算結果
Table 1. Calculation results of spherical cap size
Mass fraction of initial carbon/% R/mm H/μm V/mm3 3.8 2.270 338.7 2.76 4.3 2.193 311.1 2.36 4.8 2.040 223.3 1.46 
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中文字幕在线观看表 2 Fe?C熔體與石墨基體的初始接觸角及表面能
Table 2. Initial contact angle and surface energy of Fe?C melts and graphite substrate
Mass fraction of initial carbon/% Initial contact angle/
(°)Surface energy/
(J·m?2)3.8 118.3 1.336 4.3 122.7 1.386 4.8 129.9 1.463
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