The object of the study is a rock massif represented by complex-structured ore bodies mined by underground systems with open stoping or systems with bulk caving. Deposits of Kryvyi Rih iron ore basin are represented by different types of ferruginous quartzite, which enables application of a great number of mining systems to mining blocks. There are also barren rock inclusions within the block which are extracted from the block along with ore, and this reduces the iron content of the mined ore mass. Findings of the comprehensive study enable concluding that application of the selective method when mining a deposit can enhance recovery rates. Analysis of methods for determining rock stability results in ascertaining that in case of a 4–7 m thick inclusion of barren rocks it is advisable to use a system with bulk caving at a single stage, and in case of a 7–12 m thick inclusion – in two stages. The first stage involves mining the hanging wall reserves, the footwall reserves are mined at the second stage. This method is distinguished by leaving a barren rock inclusion in the block. The developed options of the mining system allow increasing the iron content in the mined ore mass by 2–4% and obtaining the expected economic effect from 3.0 M to 30.2 M USD depending on mining and geological conditions.

Deterioration of mining conditions at mining deposits by open pit methods (increased mining depths, reduced ore deposit thickness) leads to an increase in mining costs. In Ukraine, to reduce open pit mining costs, overburden is disposed in temporary internal dumps located directly in the open pit over the ore reserves. Reactivation of pit areas with the temporary internal overburden dump located on them results in a surge of mining operations and deterioration of technical and economic indicators. Increased energy consumption, a decrease in working site parameters, an increase in angles of open pit slopes and stripping lags lead to unprofitability of open pit mining. One of the solutions to the mentioned scientific and engineering problem involves combined mining of deposits by integrated open pit and underground mining operations. The combined open pit-underground mining method enables reducing mining costs and enhancing technical and economic indicators. The suggested schemes for opening reserves located under the internal overburden dump enhance technical and economic indicators of deposit mining through making the internal dump a permanent one. This allows further disposal of overburden into internal dumps. Implementation of scientific recommendations and technological solutions resulted from the research performed (exemplified by the deposit Hannivske, Ukraine) reduces the cost of ore by 1.33 USD/t. At the same time, the total cost of building an underground mine makes 16.4 M USD, which is 30% less than when applying traditional opening vertical shaft schemes.

Erdenet copper-molybdenum deposit is the biggest one in the world and has a significant impact on Mongolian society and economy. Today LIEBHERR-994B hydraulic shovels from Germany, electric shovels including EKG-10 and EKG-15 from Russia operate for the mining works, and dump truck BelAZ - 75130 used for transportation. The causes of shovel downtime are classified as technical, technological, and organizational. During the study period, 41% of the total downtime of the excavator’s park was technical, 45% was technological, and 11% was organizational downtime. For shovels, 7% of technological downtime is due to blasting, and for dump trucks 8.7%. In open-pit mining, blasting is performed on a weekly basis, so the duration of this technological downtime can be considered almost constant. If the time between blasts or period of blasting can be arranged optimally, it will be possible to reduce mining equipment’s downtime due to blasting.

When mining ore bodies in Kryvyi Rih iron ore basin, underground mines apply open stoping or bulk caving systems in proportion of 55% to 45%. Most of underground mines prefer stoping with pillar caving. Yet, rock pressure contributes to growth of costs for workings maintenance and deterioration of extraction indices. Rock mass extraction indices can be enhanced by application of a protectve structure in the upper part of the block that will enable additional decrease in load on the draw level. There are a great many of methods for determining parameters of constructive elements of the protective structure that help keep its integrity for the whole period of block mining. The article suggests methods for determining parameters of the protective structure when mining steep ore bodies. The research conducted demonstrates that with the inclined protective structure, increase of unit load on it from 200 to 1200t/m2 leads to decrease of its thickness from 6.3-20.9m to 5.5-18.4m and increase of the crown length from 40m to 60m. The developed block caving system with application of the protective structure when mining steep ore bodies enables overall decrease of ore dilution in the block by 3%, increase of iron content in the mined ore by 1.3% without significant mining costs growth and decrease of loads on the workings of the receiving level.