Physical and mechanical properties of burnt-out coal mine waste heaps

Abstract Currently, the issue of finding new ways to process, utilize and reuse burnt-out waste heaps in order to reduce their technogenic impact on the environment becomes relevant. The presence of a porous structure in combination with undissolved properties opens up the possibility of using the burnt-out mine rock to make composite fertilizers to improve the quality of agricultural and technogenically degraded soils. The widespread use of burnt-out mine rock for the manufacture of composite soils requires the study of their physical and chemical properties and deformation characteristics. In laboratory conditions, the physical and mechanical properties of samples of burnt-out rock masses ranging in size from 1.25 to 10 mm with and without the addition of powdered soil under a load of up to 110 kN were studied. For the first time, a certain increase in load resistance was found when soil powder was added in the initial period of compression of the tested material. It was determined that the destruction of particles of burnt-out material occurs in two waves. These results indicate the presence of two strength limits in the burnt-out medium composed of two initial petrotypes.