SEM: IHS-Cinder-Conditioning

Within the context of renaturation of mining used areas, different soil improvement concepts were prepared. One of it is the conditioning of iron hydroxide slurry (IHS) by power plant cinders within a pilot project. These conditioned IHS shall be applied as pure soil or as soil mixed with dump material.

Caused by the interaction of IHS and cinder, the soil will be enriched with essential nutrient for plants. Further it plays a part in stabilizing the pH-value of the acidification-prone dump substrate due to its buffer function.

LAOP performed qualitative electron optical and microchemical analysis of the conditioned IHS. The aim was to describe the chemical reaction of different cinder compounds with the iron hydroxide slurry.


The microscopic results fit perfectly in soil chemical and soil physical investigations and provided crucial information to characterize potential cinders for conditioning.

A particular phase, originated from conditioning, is a very rare calcium-aluminum silicate. In microscopic-scale grains the grossular variety “hibschite” could be analyzed. Telethermal temperatures und a high diffusivity at conditioning enable the formation of such phases in some cases.

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