Relationship between pit slope design and coal reserve estimation in Pit X, Muara Enim, South Sumatra Province

Mine planning is an important part of mining activity. Improper mine plan will increase production costs, non-optimal extraction of mines and safety factors that do not meet the standard. One of the most important aspects before undertaking mine plan is determining the optimal slope design as a basis for making mine pits for coal extraction. This study aims to estimate the maximum reserves that can be taken from the mine pit by taking account of the safety factor of the pit slope design. The study was conducted using drill log data and rock engineering characteristics. Analysis of slope stability is done using the Rocscience Slide V.6 software while coal reserves estimation is done using Minescape V.5.2. Slope stability analysis is modeled with several scenarios of slope angles until a single optimal slope angle is obtained, with the value of the slope safety factor that meets the safety criteria. The results showed that the maximum single slope angle in a safe pit was 52° with a safety factor of 1.266, while the coal reserves obtained with the said slope angle are 29, 965, 008 tons.