Ramp Safety Risk Analysis in Open-Pit Mines to Identify Accident-Prone Zones

The first step for carrying out mining operations in surface mines is to build a network of communication routes to access different parts of the mine, and also transport ore and waste. For the successful design of ramps in open pit mines, it is necessary to evaluate and analyze the related safety risk based on the geological conditions, geomechanical characteristics, type of machinery, and the mine design. In this research, the ramp safety risk was investigated to determine the accident-prone zones.  In this regard, the information obtained from the exploration boreholes of the Chadormalu iron ore mine was used for modeling. At first, the economic block model of the mine and the ramp were modeled in different scenarios. After selecting the optimal ramp, the total length of the ramp was zoned at 100-meter distances to assess the safety risk in 42 zones, and to identify accident-prone zones by calculating the total risk index. Thus, by drawing a bow-tie diagram, the five initial events including wall instability, car crash, stone throwing, slippery, and accident were identified as the main events leading to incidents; then the probability and consequences severity of each initial event were determined. According to the results, the car crash and wall instability events have the most negative impact on the ramp safety. Also, the highest and the lowest values of the total risk index were 110 (in zones 37 and 42) and 5 (in zones 4, 5, and 9), respectively.