Mössbauer Spectroscopy Study of the Iron Oxides, Phase Composition, and Porosity Structure in Ceramic Brick Based on Intershale Clay and Lignite Slag

Resumo

Ceramic brick based of intershale clay and lignite slag was obtained without the use of native conventional raw material. Investigations showed that the iron compounds present on the surface of the experimental samples (oxidizing medium) are mainly represented by hematite and the iron compounds at the center (reducing medium) by magnetite. In addition Fe³⁺ is reduced to Fe²⁺ and early formation of a liquid phase occurs, favoring reactions leading to the formation of mullite, which determines the basic physical and mechanical properties of the ceramic. The experimental samples contain mainly large (to 40 μm) oval and ‘channel’ type pores.