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首页> 外文会议>32nd Annual Hydrometallurgy Meeting and International Conference on the Practice and Theory of Chloride/Metal Interaction, Vol.2, Oct 19-23, 2002, Montreal, Quebec, Canada >Mechanism of the Chlorination of Metallic Oxides in the Presence of Carbon
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Mechanism of the Chlorination of Metallic Oxides in the Presence of Carbon

机译：碳存在下金属氧化物氯化的机理

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摘要

The chlorination of various metallic oxides, such as TiO_2 and ZrO_2, is performed in the presence of carbon. This reducing agent gives a low oxygen potential during the chlorination, which makes formation of the respective chlorides thermodynamically favourable. This type of reaction, called carbochlorination, involves at least one solid-solid and two solid-gas reaction interfaces. Although carbochlorination is currently carried out in industry, in the production of zirconium metal and titanium metal, the mechanism in not understood. The present work presents an analysis of the mechanism of the carbochlorination of pure oxides and oxide mixtures. The study, based on thermogravimetry, scanning electron microscopy, energy dispersive X-ray spectroscopy and x-ray diffraction, reveals various phenomena occurring simultaneously during carbochlorination. These are solid-solid first order phase transitions in oxides such as titania and zirconia, cracking of particles in ZrO_2, formation of intermediate solid compounds in Ti-Fe-O systems, existence of two reaction stages in several oxides and passivation of the carbon surface in the carbochlorination of iron oxides. These processes modify both the chemical composition and physical properties of the reacting solids as a function of the reaction time. The relative importance of such phenomena, seldom used in the interpretation of kinetic data of solid-gas reactions, is discussed in this paper in order to obtain a more fundamental understanding of the elementary steps involved in carbochlorination.
机译：各种金属氧化物（如TiO_2和ZrO_2）的氯化在碳的存在下进行。该还原剂在氯化过程中提供低的氧势，这使得在热力学上有利于各个氯化物的形成。这种类型的反应称为碳氯化反应，涉及至少一个固-固反应和两个固-气反应界面。尽管碳氯化目前在工业上进行，但是在锆金属和钛金属的生产中，机理尚不清楚。本工作介绍了对纯氧化物和氧化物混合物进行碳氯化反应的机理的分析。这项基于热重分析，扫描电子显微镜，能量色散X射线光谱和X射线衍射的研究揭示了在碳氯化过程中同时发生的各种现象。这些是氧化物（例如二氧化钛和氧化锆）中的固-固一阶相变，ZrO_2中的颗粒开裂，Ti-Fe-O系统中形成中间固体化合物，几种氧化物中存在两个反应阶段以及碳表面钝化在氧化铁的碳氯化中。这些过程根据反应时间改变了反应固体的化学组成和物理性质。为了获得对碳氯化反应中涉及的基本步骤的更基本的了解，本文讨论了这种现象的相对重要性，这种现象很少用于解释固-气反应的动力学数据。

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