ITB Expert: Modern Underground Mining More Environmentally Friendly

An expert from the Institute for Research and Industrial Affiliation (LAPI) at the Bandung Institute of Technology (ITB), Dr Irwan Iskandar, has assessed that the modern underground mining concept offers advantages because it requires significantly less surface space compared to open-pit mining, making it more environmentally friendly. “The positive aspect of underground mining is that the footprint of damage or surface disturbance is small. Where we need surface space for housing, agriculture, and other activities, the disturbance becomes much smaller. This is a positive step that can be called modern underground mining,” Irwan said during a discussion on underground mining held by the Energy Editor Society (E2S) in Jakarta on Monday. According to Irwan, another aspect distinguishing modern mining practices is the management of tailings. Previously, tailings were generally placed in tailings dumps, but now underground mining companies are returning them to the mined-out voids as backfill. “The modern and tactical approach is that the processing residue is placed back, not into a tailings dump. Tailings dumps carry risks because after mining is complete, the material remains there indefinitely. We have learned from various mining disasters worldwide, including the one that occurred in Brazil in 2019,” he said. Irwan stressed that every mining activity inevitably has an environmental impact. However, he noted that the most important thing is how these impacts can be managed through the application of appropriate technology and supervision. “Mining also has impacts. The impacts must be understood, but they must be manageable. One of the most critical issues is water, both surface water and groundwater,” he stated. He explained that in underground mining, the primary concern is no longer the existence of tailings dumps or surface openings, but rather groundwater management. One of the most significant changes in environmental documentation, Irwan continued, is the decision to convert the tailings disposal system into a backfill system. According to him, this step provides substantial benefits in reducing the potential for acid mine drainage formation. “The significant change is converting the system from a tailings dump to backfill. Additionally, it successfully recovers about 32 per cent of the sulphur. If that sulphur is not removed, it actually becomes a potential source of acid mine drainage,” Irwan explained. Nevertheless, approximately seven per cent of the sulphur content remains. To prevent oxidation that could trigger acid mine drainage, the material is mixed with cement and lime before being placed back into the mine tunnels. Irwan noted that the global mining industry trend is also moving away from conventional tailings dumps following several tailings dam failures in various countries. Many companies are now switching to dry stack tailings technology and backfill systems as they are considered safer and have a smaller land footprint. While there are additional costs and technology involved, the area footprint is much smaller. This technological change represents a shift from the old system to a more efficient one. Another speaker, Technical Manager of PT Dairi Prima Mineral (DPM) Widianto, said his mining company has implemented the backfilling mining concept in underground mining, prioritising work safety and environmental protection. The main advantage of this mining concept is the minimal land clearing on the surface, so forests and ecosystems are preserved. He emphasised that the backfill tailings system in the mine located in Dairi Regency, North Sumatra, not only serves to maintain the stability of the mining area but also supports environmental protection and regulatory compliance. Through this system, backfill material is used to fill the voids of former mining areas to strengthen the rock mass, reduce the risk of collapse, protect worker safety, and safeguard groundwater quality through regular monitoring and documented reporting.