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The Use of Transition Metal Oxides in Microwave Sintering of Coal Ash-Derived Bricks and Tiles

Published online by Cambridge University Press:  21 February 2011

Eric P. Bescher
Affiliation:
Department of Materials Science and Engineering, Univ. of California, Los Angeles, 90024, U.S.A
Yu-Hua Kao
Affiliation:
Department of Materials Science and Engineering, Univ. of California, Los Angeles, 90024, U.S.A
C. Y. Li
Affiliation:
Department of Materials Science and Engineering, Univ. of California, Los Angeles, 90024, U.S.A
John D. Mackenzie
Affiliation:
Department of Materials Science and Engineering, Univ. of California, Los Angeles, 90024, U.S.A
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Abstract

The generation of undesirable ashes from municipal and hazardous waste incineration, and from coal-fired power plants has become a serious environmental problem. Ash contains heavy metals and/or unburned organics, and the disposal of this material is drawing increased concern from the public and government agencies. Since the leaching of a toxic constituent from a powder is proportional to the surface area of the powder, any method of consolidation is welcome. The interest of such a consolidation process would be greatly increased if, in addition to making this material safe, a commercially useful material could be produced. Conventional methods of heating such as oil-fired furnaces require large flows of air. They are also time and energy consuming because it is relatively difficult to heat up a powder. Microwave processing creates rapid heating and allows for the attainment of uniformly high temperatures; therefor, it is a viable alternative. However, most ashes will not easily absorb microwaves if they do not contain a phase that couples with the microwaves. Transition metal oxides are lossy materials when submitted to microwave radiation. If they are mixed into ashes in a sufficient amount, they will generate heat, cause sintering and reduce the surface area of the powder. In the present work, coal ash-derived bricks and tiles were successfully obtained. Details of processing, mechanical properties and chemical durability of these consolidated ceramics are presented

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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