Purpose. The solution to one of the important problems of the underground mining method is to substantiate cost-effective, technologically feasible and safe variants for mining steeply dipping low-thickness ore bodies. Methods. Mining systems are substantiated on the basis of a detailed analysis of the developed and existing experiential variants for mining steeply dipping ore bodies, identifying production and economic disadvantages, as well as their causes. Findings.As a result of the research, the pillar raise performance in the mining system with ore shrinkage has been substantiated. The main parameters of the proposed variants for mining systems with ore shrinkage, intended for expansion-type supports and borehole breaking, have been substantiated. A design has been developed of fastening the material-running raises (MRR) and ventilating raises (VR) on the working and ventilation horizons to ensure their performance in the mining system with ore shrinkage. Originality. For the first time, dependences of dilution and labour productivity on the ore body thickness and the type of ore breaking for blast-hole stoping and borehole breaking for a single and “twinned block” have been obtained. In addition, a certain dependence of the loading and delivery performance on the average fractional composition, as well as on the delivery distance, has been obtained. Practical implications. The research is characterized by scientific innovations created for the first time, which are able to ensure the efficiency and safety of mining operations, while creating the ability to manage the loss of minerals and dilution in the block, as well as reaching their calculated optimal ratio in order to achieve the most cost-effective production rate.

Purpose. Establishment of patterns of influence of the main factors on the physicomechanical characteristics of fiber concrete, which is advisable to use for the manufacture of pump housings operating in adverse conditions.Methodology. The work uses theoretical analysis of fiber concrete application in various industries, analysis of factors affecting fiber concrete strength; laboratory experiments are conducted to confirm theoretical results and identify regularities allowing rec ommending rational parameters of production of pump casings from fiber concrete.findings. The work attempts to offer technological solutions for the use of fiber concrete in a new field -mechanical engineer ing -in the manufacture of pump housings operating in the mining and metallurgical industry in unfavorable conditions such as pumping of aggressive liquids, highly abrasive pulp, high ambient temperature, dust, and others. The obtained results allow devel oping centrifugal pump housing casting technology without additional mechanical treatment and with high physical and me chanical characteristics as well as recommending rational composition of the fiber concrete mixture, meeting requirements to centrifugal pump housings according to strength conditions, manufacturability and economy.originality. The regularities of the effect on the strength of fiber concrete of the optimal content of steel fiber in the composi tion of the mixture as well as rational modes of mixing components are established experimentally. They are rotational speed of a mixer working part and mixing time of the components. The obtained regularities confirm theoretical studies and provide obtain ing of the fiber concrete mixture with uniform distribution of all components in its volume as well as isotropic characteristics of solidified fiber concrete.Practical value. The obtained results, presented in graphs and calculation formulas, make it possible to reasonably design com position of the fiber concrete mixture and to develop the technology of making centrifugal pump housings from it by a casting method without additional mechanical treatment. At the same time fiber concrete has density of 2200-2300 kg/m 3 versus 7500-7800 kg/m 3 of metal bodies, compression strength of 230-240 MPa, bending strength of 80-100 MPa. All these allow reducing thickness of a pump housing wall by 15-20 %.

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This article considers the prospects of the application of building structures made of polymer concrete composites on the basis of strength analysis. The issues of application and structure of polymer-concrete mixtures are considered. Features of the stress-strain state of normal sections of polymer concrete beams are revealed. The dependence between the stresses and relative deformations of rubber polymer concretes and beams containing reinforcement frame and fiber reinforcement has been determined. The main direction of the study was the choice of ways to increase the strength characteristics of concrete with the addition of a polymer base and to increase the reliability of structures in general. The paper presents the results of experimental and mathematical studies of the stress-strain state and strength, as well as deflections of reinforced rubber-polymer beams. The peculiarities of fracture of reinforced rubber-polymer beams along their sections have been revealed according to the results of the experiment. The peculiarities of fracture formation of reinforced rubber-polymer beams have also been revealed. The conducted work has shown that the share of longitudinal reinforcement and the height of the fibrous reinforcement zone are the main factors. These reasons determine the characteristics of the strength of the beams and their resistance to destructive influences. The importance and scientific novelty of the work are the identified features of the stress-strain state of normal sections of rubber-concrete beams, namely, it has been established that the ultimate strength in axial compression and tension, deformations corresponding to the ultimate strength for rubber concrete exceed similar parameters for cement concrete 2.5–6.5 times. In the case of the addition of fiber reinforcement, this increase becomes, respectively, 3.0–7.5 times.

The article contains research materials on the storage of man-made deposits, including phosphogypsum dumps. The consequences of long-term operation of phosphogypsum dumps and their negative impact on the environment have been established. The quantitative content of microelements to the soil within the storage of technogenic phosphogypsum deposit was determined. Graphical dependences of phosphorus, manganese, fluorine, mobile sulfur, zinc, nickel content depending on the depth of sampling and distance from phosphogypsum dumps to settlements and the Goryn River are presented. The directions of processing and utilization of the given waste are offered. The elemental composition of phosphogypsum dumps of PJSC "Rivneazot" has been established, in particular, the presence of a group of valuable rare earth elements.