Environment protection and economy considerations forces changes in coal combustion and desulfurization processes. It causes production of new kinds of waste material. Volatile ash coming from power engineering in form of hydromixture are utilized in underground mining technologies for many years. In every case the main component of the mixtures was volatile ashes coming from different coal combustion installations. Application of hydromixtures made on the basis of power plant waste in mine workings contributes to natural environment protection and has positive effect on the following problems connected with exploitation of mines: limitation of surface deformations thanks of consolidating filling application (mainly in ore mines) and other filling methods of empty space making by exploitation, limitation of the fine-grained waste quantity on the surface, better utilization of deposit (the consolidating filling application allows to eliminate pillars and reduce their dimensions), improvement of climatic conditions and reduction of gases outflow from cavings, fire prevention realized by grouting of cavings and building of backfill plugs and dams.