Iron Oxides and Their Composition in Ceramic Brick Based on Power Plant Waste: Data from Mössbauer Spectroscopy

The distribution of iron oxides on firing ceramic brick produced from interstitial shale clay and iron-bearing slag from power plants, with no traditional materials, is studied by means of Mössbauer spectroscopy. A relation between the strength, frost resistance, and iron content is established. The calculated area of the spectral doublets indicates that the reduction of iron oxides by carbon oxides converts the iron compounds at the sample surface, where oxidant predominates, mainly to hematite, whereas those at the center, where reducing agents predominate, are converted to magnetite. The increased Fe²⁺ content in the samples hastens the appearance of liquid, which facilitates mullite formation and strengthens the ceramic structure.