Kinetic study of the chlorination of gallium oxide
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THE intensive use of metals in modern industry has led to the progressive exhaustion of primary metals, thus creating a need to use alternative sources such as industrial wastes, low grade minerals/ores, and polymetallic ores. Likewise, the exploitation of such sources requires the updating and development of processes that allow for maximum use of resources. The advances in the development of materials with applications on a variety of fields ranging from medicine to space navigation has made it necessary to obtain high-purity metals. Although there exist a number of methods for the production of high-purity metals, liquid-liquid extraction from metallic halides in solution and the distillation of chlorides are the two most widely used techniques. In both cases, the obtainment of metallic halides constitutes the first stage in the process. One of the most widely used techniques for this stage is previous chlorination of materials such as metals, ores, metallic oxides, or industrial wastes.[1] The use of chlorination in metal extractive procedures, by means of pyro- and hydrometallurgic methods, has attracted attention in recent decades and the use of chlorine chemistry may increase in the future. This is due to a number of factors, which include the high chlorination rates resulting from the elevated reactivity of Cl2 and other chlorinating agents; the comparatively moderate temperature involved in the chlorination process; the low cost, variety, and availability of chlorinating agents; the favorable physical and J.A. GONZÁLEZ, Associate Researcher, and M. DEL C. RUIZ, Associate Professor and Senior Researcher; are with the Institute of Investigations in Chemical Technology (INTEQUI), Universidad Nacional de San Luis and Consejo Nacional de Investigaciones Científicas y Técnicas, 5700 San Luis, Argentina. Contact e-mail: [email protected] O.D. QUIROGA, Professor and Senior Researcher, is with the Institute of Investigations for Chemical Industry (INIQUI), Universidad Nacional de Salta and Consejo Nacional de Investigaciones Científicas y Técnicas, 4400 Salta, Argentina. Manuscript submitted July 15, 2003. METALLURGICAL AND MATERIALS TRANSACTIONS B
chemical characteristics of certain metals; the properties of many chlorides (high solubility, wide variety of oxidation states, and ease of separation by liquid-liquid extraction or distillation); the selectivity of the treatment and separation processes; and the development of certain corrosion-resistant materials used for the manufacture of reactors.[2] On the other hand, the wastes from chlorination processes can be conveniently treated for the recovery of toxic materials, prior to their final disposal. The Cl2 and chlorides in effluents can be easily dissolved in water or precipitated and subsequently recycled in the same unit, or they can be used for other purposes. Gallium is present in nature in small amounts, usually associated with the ores of other common elements. It was discovered in the zinc ore blende in 1875. In 1896, it was found in bauxite, and
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