Purpose is to determine a function of the reduced expenditures connected with drilling-and-blasting operations, loading and hauling operations, and rock fragmentation depending upon the cost of machine-shift of the applied facility, its operation modes, hardness of rock being blasted, cost of the used explosive, and rock fragmentation quality based upon the developed optimization mathematical model. Methods. Method of statistical evaluation of natural blockiness structure of the rock as well as quality of its fragmentation by means of explosive energy has been applied. Statistical studies have been carried out concerning the basic indices of rock fragmentation depending upon its largeness and block hardness. Purposely-designed experimental equipment has been applied for sampling analysis of the rock fracturing in the process of its drilling by means of rotary drilling rig. The abovementioned supported representativeness of the sampling. Findings. Statistical distributions of the rock blockiness structure in terms of each bar length involving its place within the drilling assembly as well as in terms of the well depth have been compiled. Visual comparison of experimental data and theoretical data has helped determine that the statistical distributions of natural blockiness structure of the rock have the closest correlation with gamma distribution which differential function has two positive parameters. Statistical dependence has been defined between drilling-and-blasting results and the total expenditures connected with hard rock mining. Originality. A concept of oversize crushing coefficient has been introduced; its statistical dependence upon the mined rock hardness and specific consumption of the applied explosive has been derived. An alternative has been proposed concerning changes in parameters of the differential function of the assumed gamma distribution relative to the predicted granulometric composition of rock mass. Practical implications. Economic and mathematical model has been developed involving a target function of the total expenditures connected with the listed operations as well as a set of constraints avoiding incorrect decisions. The optimization method makes it possible to control drilling-and-blasting parameters at each stage of hard rock mining.

Main properties of the processes of iron ore destruction in terms of its simultaneous effect by mechanical load and electric field of ultra-high frequency have been studied. That was compared with the case when only mechanical load is applied. Theoretically, it has been proved that in the first case, quartz crystals accumulate more energy, and this effect is manifested mostly in terms of resonance. For the first time, the iron ore samples of cubic geometry were tested using a non-uniform volumetric compression unit. Application of the ultrahigh frequency field resulted in ultimate strength reduction by 1.5 – 2.0 times and significant increase in plasticity of the destruction. At the same time, density of the sample destruction energy in a volume unit is significantly lower than that in the case of mechanical load (1.05 and 2.6 MJ/m3, respectively). There is also a tendency of reducing large fraction yield and increasing fine fraction yield along with the increase up to 11% in iron content in the products after grinding. The results of theoretical and numerous experimental studies have been substantiated the necessity to continue the research and development work on adapting the proposed jaw crusher to the production conditions.