Process for preparing solidified material containing coal ash

Abstract

A process for preparing a solid material containing coal ash includes a first step of mixing coal ash with a calcium compound to obtain a mixture, a second step of molding the mixture to obtain a molded article, and a third step of subjecting the molded article obtained in the second step to a hydrothermal treatment at a temperature of at least 120.degree. C. under high pressure. In the first step, 40 to 95 parts by weight of the coal ash is mixed with 60 to 5 parts by weight of the calcium compound, and the coal ash to be used has a bulk density of at least 0.8 g/cm.sup.3, an average particle diameter of 5 to 40 .mu.m and an aluminum content of 35% by weight or less in terms of Al.sub.2 O.sub.3. By the use of a blowing agent or the like, it is also possible to obtain a porous lightweight solid. As a consequence, there can be obtained a solid containing coal ash and having a high mixing ratio of coal ash, excellent dimensional stability to water, high strength and a decreased unevenness of the strength, and this kind of solid can be used in applications such as building materials, construction materials, artificial aggregates and the like. Furthermore, a laminated solid having not only the above-mentioned characteristics but also weight reduction properties can also be obtained, and this solid can be used to form building materials such as panels, blocks, bricks and boards for accoustic use, artificial lightweight aggregates and the like.