Rudolf Krzyżak, Piotr Długosz, Paweł Darłak, Sylwia Pawlak

Industrial mineralogy of the Polish fly ashes and their unique utilization


This study was undertaken to recognize sintering-, softening-, melting-, flow temperature, mineralogy, chemistry and prospects for utilization of the Polish fly ashes (FA, FAs). The study is metallurgy-foundry oriented, i.e. it regards the ashes as the (potential) charge material for production the chemical compounds, ceramics, metal-matrix composites (MMC) and ceramic-matrix composites (CMC) and as an item in new technologies. Moreover, definite ashes-derived compounds, e.g. cordierite have been shown to strengthen the metals. A comparison between the ashes and the rocks is drawn, and, comparison between the Polish ashes (type) and those from over-the-world ones is undertaken. The radioactivity of the ashes is addressed as well. 24 (25) samples can be classified into ‘hybrid alumina’ (close to F-class of the ashes), ‘intermediate’ (an Al-analogue to bottom ashes) and calcium-rich ones. Several unique samples, e.g. arcanite-calcite-ettringite- and a bottom ash are outside even this classification. The ‘hybrid alumina’ is knowable by Ca-silicates and Ca-aluminosilicates, the ‘intermediate’ is knowable by anorthite and amphiboles, whereas the calcium-rich ones is devoid of Ca-silicates. Enrichments in toxic elements is addressed and discussed. One of novelties of this paper is that we have encountered the amphiboles, leucite and Fe-Mn phosphates in the ashes - which cannot be regarded as accessory ones. Apart from the ash-Al-alloy pistons, metal-(cenosphere)-ash composites and intimately-intergrown-phase (IPC) composites, a FA-glass-armoured metal is also mentioned. Of the many technologies of the Institute the production of almost pure cordierite (indialite) from fly ash containing moderate amounts of CaO and SO3 is worthy of note. Likewise, MMC- and CMC composites and ceramics thereof are also noteworthy.

Keywords: composite, waste management, fly ash, ettringite, amphibole, cordierite,
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