Crystallization Behavior of Liquid CaO-SiO2-FeO-MnO Slag in Relation to Its Reaction with Moisture
Crystallization Behavior of Liquid CaO-SiO2-FeO-MnO Slag in Relation to Its Reaction with Moisture
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DOI：
10.1007/s11663-019-01595-z
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发表时间：
2019-05
期刊：
影响因子：
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通讯作者：
Juncheng Li;D. Bhattacharjee;Xiaojun Hu;Dianwei Zhang;S. Sridhar;Zushu Li
中科院分区：
文献类型：
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作者：
Juncheng Li;D. Bhattacharjee;Xiaojun Hu;Dianwei Zhang;S. Sridhar;Zushu Li
为了帮助维持钢铁行业的可持续发展，我们正在开发一种新的工艺，通过使熔渣与水分反应，回收热能（以氢气的形式）和炼钢炉渣中含有的有价值的金属元素。该工艺取决于炉渣的结构和性能，其中结晶趋势是关键，因为表面相影响炉渣与气体的反应性，并能够选择性地形成含有过渡金属的固相。本文采用FactSage 7.0热力学软件包计算了CaO-SiO2-FeO-MnO合成熔渣与水反应后的析出相。通过实验室实验，研究了渣中目标金属氧化物的结晶行为，旨在控制渣中目标金属氧化物的结晶。利用共聚焦激光扫描显微镜（CLSM）对液态渣与水分反应后表面的晶体析出进行了原位观察。时间温度转变（TTT）和连续冷却转变（CCT）图是根据在1873 K至1173 K（1600 °C至900 °C）温度范围内冷却期间晶体的沉淀行为创建的。用扫描电子显微镜（SEM）和能谱仪（EDS）分析了反应渣的微观结构，并用X射线衍射（XRD）表征了渣中存在的物相。反应后炉渣（含水分）的TTT曲线表明，碱度为1.00的炉渣的鼻端温度和成核临界时间分别为1473 K（1200 °C）和89 s。进一步将炉渣碱度增加到1.25和1.50将鼻部温度分别增加到1523 K和1698 K（1250 °C和1425 °C）。反应渣的CCT曲线表明，在800 ~ 10 K/min范围内，随着冷却速度的降低，析出相的结晶温度升高，而初生相的结晶温度随着炉渣碱度的增加而升高。通过SEM-EDS和XRD在反应后的炉渣（含水分）中检测到磁铁矿（Fe 3 O 4）和一氧化物（（FeO）x（MnO）1−x）相。随着炉渣碱度从1.00增加到1.25再增加到1.50，反应渣中磁铁矿含量从25%增加到32%，一氧化物含量从5%减少到2%。
To help maintain the sustainability of the steel industry, we are developing a novel process to recover thermal energy (in the form of hydrogen) and valuable metal elements contained in steelmaking slags by reacting molten slags with moisture. The process is dependent on the structure and properties of the slag, of which the crystallization tendency is key, since surface phases affect the slag reactivity with the gas and enable selective formation of solid phases containing transition metals. In this paper, the precipitated phases of the molten synthetic CaO-SiO2-FeO-MnO slags after reacting with moisture were calculated by using thermodynamic package FactSage 7.0. Laboratory experiments were conducted to reveal the crystallization behavior of the targeted metal oxides in the slags with the aim of crystallization control. A hot stage-equipped confocal laser scanning microscope (CLSM) was used toin-situobserve the crystal precipitation on the surface of the liquid slag after reacting with moisture. Time temperature transformation (TTT) and continuous cooling transformation (CCT) diagrams were created from the precipitation behavior of crystals during cooling in the temperature range of 1873 K to 1173 K (1600 °C to 900 °C). The microstructures of the reacted slags were analyzed with a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS) and the phases present in the slag were characterized by X-ray diffraction (XRD). TTT curves of the reacted slags (with moisture) indicated that the nose temperature and critical time for nucleation located at 1473 K (1200 °C) and 89 seconds for the slag with basicity of 1.00. Further increasing the slag basicity to 1.25 and 1.50 increased the nose temperature to 1523 K and 1698 K (1250 °C and 1425 °C), respectively. CCT curves of the reacted slags (with moisture) indicated that the crystallization temperatures of precipitated phases increased with decreasing the cooling rate from 800 to 10 K/min, and the crystallization temperatures of primary phases increased with increasing slag basicity. Both magnetite (Fe3O4) and monoxide ((FeO)x(MnO)1−x) phases were detected by SEM-EDS and XRD in the reacted slags (with moisture). The amount of magnetite in the reacted slags increased from 25 to 32 pct to 36 pct and that of monoxide decreased from 5 to 2 pct to 1 pct with the slag basicity increasing from 1.00 to 1.25 to 1.50.