For fabrication of mortars was used the powder, obtained when crushing waste products of the KN (carbonitride) make. The technology of mortar preparation from carbide-silicon powders was developed. The mortar properties were investigated from the point of view of its application as a material for the laying of a heating furnace lining. In the process of investigations were obtained the optimal compositions of mortars with maximum high-temperature strength. The specifications for these mortars were formulated.