Improving the efficiency of the transition from open to underground mining in the development of iron ore deposits

In order to improve the economic efficiency of the transition from open to underground mining in the development of iron ore deposits, a variant of a combined development system has been proposed that combines the technology of chamber mining under a ceiling and the technology of forced floor caving with multi-level area two-sided ore release from a block of increased height. This variant is intended for the extraction of thick ore bodies and allows for a reduction in the specific volume of preparatory and cutting operations, an increase in ore extraction rates and an increase in the concentration of mining operations, as well as the implementation of ventilation of all block workings due to general mine depression. A technical and economic comparison of the traditional and proposed variants of the development of the under-pit floor has been carried out based on the profit criterion taking into account the change in ore extraction rates and operating costs with an increase in the floor height. It has been found that the profit for the option using a combined development system is 221 rubles/t higher than for the traditional option, which is achieved by increasing the extractable value of ore by 102 rubles/t and reducing the cost of ore extraction by 119 rubles/t. The implementation of the proposed technical solution will increase the annual profit of the enterprise by 26 %.