Sustainable management of hard coal resources implemented by identifying risk factors in the mining process.

Dealing with risk and addressing risk consequences constitute indispensable and specific elements of every business activity. The aim of this paper has been to assess the level of risk connected with the process of exploitation of hard coal deposits used for the production of coke in Poland, that is why a methodology has been developed which takes into account the impact of significant risk factors resulting from both geological and mining conditions upon unit cost of coal mining. This methodology constitutes a comprehensive approach to sustainable management of hard coal resources. The key source of information pertaining to exploitation risk factors is the digital geological model of hard coal deposit which has been developed. It comprises a structural model as well as a quality model of the basic quality parameters of coal. Structural models and coal quality models have been developed on the basis of litho-stratigraphic profiles from geological exploratory boreholes and underground observations (boreholes drilled from underground workings and their profiling). The structural grid model also contains information on tectonic disturbances (faults) or sedimentation disturbances (intercalations, wash-outs, and the like). The digital model was used as the basis for devising time schedules of development and preparatory works, as well as coal extraction proper. Historical results of mining and economic data from 81 longwalls mined in the years 2016–2022 have been used for the purpose of analysis of the impact of risk factors on unit operating costs. The analysis comprised a total of 23 criteria which influence the costs of mining. From that group, 10 risk factors have been selected by means of statistical analysis using segmented regression, these factors have been utilized to make an assessment of the forecast concerning risk factor level for zones of the deposit meant for mining until the year 2035. The risk factors taken into account were those which are due to natural hazards, geological structure of the deposit (coal seam) and technical limitations. Risk factor (RF) indicator has been developed, for its construction the Fuzzy Analytic Hierarchy Process (FAHP) has been used. The value of RF, which expresses the aggregated form of variability concerning individual factors pertaining to geology and mining, has been used to determine the adjusted own risk assessment when estimating the economic efficiency of the coking coal deposit for 8 exploitation zones with the use of discounted cash flow method. The assessed average value of RF for the entire deposit amounted to 0.29. The lowest level of RF was noted in case of zone W (RF = 0.17), whereas the highest value of risk occurs in zone PN (RF = 0.64). The values of RF were used to calculate the rate of discount as consolidated measure of own risk, when assessing investment projects in mining. For zone W with the lowest risk of mining the discount rate amounts to 8.34%, whereas in case of zone PN which has the highest risk level, it amounts to 15.02%. Assessing the level of mining risk provides the possibility to optimize the cost of mining, and may be utilized for making decisions concerning the sequence and time of mining from particular zones of the deposit. [ABSTRACT FROM AUTHOR]