Por: J. Posch, S. Palma, J. Masihy, C. Morales, SRK Consulting, Santiago, Chile.AbstractRemining old tailings deposits presents significant geotechnical challenges, mainly due to the heterogeneity of tailings and the lack of comprehensive construction records. Thorough geotechnical characterization is essential and should include integrated field and laboratory campaigns—such as CPTU tests, electrical resistivity, and triaxial testing—to inform extraction strategies and enable zoning based on the physical, chemical, and hydraulic behavior of the tailings. Old tailings typically exhibit high degrees of saturation and contractive undrained response, rendering them highly susceptible to static and seismic liquefaction, particularly in seismically active countries like Chile and Peru. Therefore, excavation geometries should be conservatively designed and adapted according to tailings type and evolving phreatic conditions. Current hydraulic mining operations incorporate remotely operated monitors to minimize exposure and enhance safety, yet strict control of cutting geometries is required to prevent undercutting and flow failures. Surface water management remains critical, particularly during heavy rain events. Safety setbacks along dams must be defined and adjusted based on ongoing geotechnical monitoring. Comprehensive geotechnical monitoring is vital to anticipate and mitigate potential failures. Proactive identification and management of possible failure modes, such as over-steep cut failures, flow slides, and seismic liquefaction, are essential to safeguard operations and personnel. The article underscores the need for differentiated extraction and real-time monitoring methodologies, supported by contemporary geotechnical engineering and risk management principles, to safely and efficiently address the complexities of old tailings remining.
