Challenges and prospects for several-stage stoping in potash minining

Introduction. Most of the potash deposits in the world are mined using room-and-pillar mining method with natural support, which is accompanied by high mineral losses, as well as a high mine accidents due to the destruction of supporting elements, waterproof strata continuity and breakthroughs of oversalt water and brines into the mined-out void. Methods. Generalisation, systematisation and analysis of theoretical and experimental research on increasing the extraction ratio of potash ore to establish the methods degree for increasing extraction of potash reserves, to identify unexplored and problematic issues, to determine directions and approaches. Results. Theoretical justification of the possibility and expediency of several-stage stoping for potash mining implementing the principle of re-extraction of reserves from pillars with the provision of necessary protection measures of aquifer in the form of backfill. Conclusion. The article presents the results of an analysis of the specifics of underground mining of potash deposits. The concept of several-stage stoping for potash mining is formulated. Generalized variants of several-stage stoping are presented. The main problems of several-stage stoping implementation at potash deposits are described: the problem of gap-filling in rooms; prediction of altered physical and mechanical properties of seams and host rocks; the influence of multiple excavation on water-resistant properties of waterproof strata in several-stage stoping; the role of time in geomechanical processes; rational composition and recipe of backfill preparation; organization of stowing and clean-up operations at the site; technical and economic expediency of several-stage stoping. Possible lines of approach are suggested. Resume. The use of several-stage stoping for potash mining will increase the extraction ratio, improve the reliability of the waterproof strata during mining by replacing potash seams with a continuous fill mass, utilize waste from potash ore processing, and extend the service life of potash mines. A competent scientific and methodological foundation on the implementation of such technology at potash deposits needs to be built for a deep evaluation of the mining and geomechanical processes in the operation areas and the technical and economic performance of several-stage stoping. Suggestions for practical applications and future research line. The variants of several-stage stoping presented in the article can be used to develop methods of potash mining considering specific mining and geological conditions. Application of the described and similar variants of several-stage stoping in practice will significantly increase the extraction ratio while maintaining a minimal impact on the seam. Future research line will focus on the underground deposit development plan and the geomechanical justification of the parameters of the several-stage stoping.