Management of hardening mixtures properties when stowing mining sites of ore deposits

Underground mining is characterized by the weakening of the bearing rock mass strata competence and the accumulation of mineral waste. The full use of subsurface resources is ensured by the use of technologies with filling voids by hardening mixtures, which requires high-quality raw materials to obtain the required strength. The deficit of the binding component can be filled with the use of granulated slags of blast-furnace process, mill tailings, ash-slags and other waste

Ensuring Stability of Undermining Inclined Drainage Holes During Intensive Development of Multiple Gas-Bearing Coal Layers

At high rates of production face advance, requirements towards reliable operation of undermining drainage holes get raised. The issue of maintaining high intensity of gaseous seams development under naturally increasing gas content, mining depth and capacity of production equipment poses a problem. The greatest threat comes from the loss of hole stability in the bearing pressure affected zone (in front of the face) and in the intensive shift area of overhanging rock corbels (behind the face). Intensification of air leaks due to deformation of borehole channel leads to impoverishment of removed methane-air mixture and an increasing risk to disturb safe aerogas regime in the mining area. The paper describes a mechanism of how coal-face operations affect the state of underground holes and formation of overhanging rock corbels. A typification of basic kinds of borehole deformations is presented. Authors point out critical disadvantages of the most widely-used technological schemes of gaseous seams development under high load on the production face, which hinder normal operation of a gas drainage system. As a result of research, a dependency of shot hole number, as well as the distance between shot hole axes and the borehole, on the stress state of the borehole outline has been defined more precisely. Basing on that, a formula to calculate drilling parameters of the discharge hole system has been suggested. Implementation of these measures will allow to increase the efficiency of underground gas drainage and to maintain growing intensity of gaseous coal seam development

THE USE OF TAILINGS WHILE PREPARING HARDENING FILLING MIXTURES

The relevance of the work is conditioned by the need to increase the completeness of the use of metal mineral raw materials extracted from the depths. The complexity of its use by increasing the scope of new environmental and resource-saving technologies is also important. Unfortunately, the resource-saving technologies use little-studied reserves of production. The purpose of the work is to substantiate the technological possibility and expediency of the use of waste from processing and metallurgical industries. This is done for the manufacture of hardening mixtures with an increase in their activity in the activators of the “disintegrator” type simultaneously with the extraction of residual metals. Research methodology: analysis of theory and best practices, industrial and laboratory experiment, and interpretation of research results. Results. Natural and resource-saving trends are implemented in the development of the mining industries. This happens under the conditions when many mining enterprises of Russia may switch to underground mining of ore deposits. There is a tendency of using chamber versions of technology with filling technological voids with hardening mixtures. The problem of providing mining operations with raw materials for the manufacture of hardening mixtures was formulated. The production of raw materials is open. It is environmentally incorrect in connection with the destruction of the earth’s surface. The solution to the problem of providing raw materials for preparing hardening mixtures in the form of enrichment tails and metallurgy is associated with the need to extract rare and noble metals from them. The results of an industrial experiment using mechanochemical activation of metal-containing substandard raw materials, are described. This activation allows to extract metals and increases the activity of the tailings to the state when they exhibit binding properties. The directions of activators improvement to achieve the goals of mechanochemical technology. Conclusion. The technology proposed is a real opportunity to solve the problem of providing raw materials and ease the load on the environment. Mining and geological conditions and trends in nature conservation make the preferred technology options with filling man-made voids with hardening mixtures. A promising line of utilizing metal-containing substandard raw materials. This not only allows to extract metals, but also to increase the activity of tails, is the mechanochemical activation of leaching processes in the disintegrator