Tailings ponds are large reservoirs that store the waste materials generated by mineral processing operations. They are essential for reducing the environmental impact of mining, but they also pose significant risks if not properly monitored and maintained. In this article, you will learn about some of the best practices and technologies for tailings pond management.
Monitoring tailings ponds is crucial for ensuring their stability, safety, and compliance with environmental regulations. By regularly measuring and analyzing parameters such as water level, chemistry, temperature, seepage, erosion, and vegetation, you can detect and prevent potential issues such as leaks, spills, breaches, or contamination. Monitoring also helps you optimize the use of water and reagents, reduce operational costs, and plan for closure and reclamation.
Proper monitoring and maintenance of tailings ponds begins (and ends) with having a skilled workforce. You can have the latest in equipment, procedures, and design - but not having the right skills can negate all of those. That may mean you need to send people to training programs, hire consults to mentor inexperienced people, pay a premium to bring in skilled employees, and/or transfer top-performing employees into the tailings area - but one way or another having skilled people will make a difference. This goes for all levels but is particularly important for the supervisor and management levels. All too often companies see tailings as a cost instead of a profit center and do not provide the right leadership that is needed.
Monitoring tailings ponds requires knowledge of how the structure was built. For example, in dykes that are earthed above ground level, monitoring the water table is also necessary for calculating the safety factor of the slopes. Piezometers are ideally installed below the ground water level, so that the measurements are more meaningful than dry ones. One of the aspects to consider in a monitoring plan.
Monitoring tailings ponds requires different methods and tools, depending on the size, location, and characteristics of the pond. Remote sensing, such as using satellites, drones, or aerial vehicles to capture images and data of the pond surface and surroundings, can provide information on water level, area, volume, turbidity, temperature, and vegetation. Additionally, sensors and instruments can be installed on or near the pond to measure and transmit data on various parameters. Sampling and analysis also involve collecting water, soil, or tailings samples from the pond and sending them to a laboratory for chemical, physical, or biological analysis. All of these methods can provide detailed information on the composition, quality, and toxicity of the pond materials. They can also help you detect changes over time and evaluate the performance of the treatment systems in order to comply with regulations.
Maintaining tailings ponds is essential for extending their lifespan, improving their efficiency, and reducing their risks. To do this, it is important to consider the site conditions, tailings characteristics, and regulatory standards when designing and constructing the pond. This includes selecting the best location, size, shape, liner, dam, spillway, and drainage system. Additionally, a tailings management plan should be implemented and followed which outlines the objectives, procedures, and responsibilities for operating, monitoring, and closing the pond. This plan should also define the frequency, methods, and criteria for tailings deposition, water management, treatment, and disposal. Furthermore, regular inspections and audits of the pond should be performed to identify any defects or malfunctions. This includes checking the integrity of the liner, dam, spillway, drainage system, sensors, instruments, and treatment systems. Lastly, preventive or corrective measures should be taken to address any issues or incidents that may affect the pond or the environment. This could include repairing or replacing any faulty equipment or adding or removing water or reagents.
Complementing the text, another point to consider when monitoring is the efficiency of the geotechnical structure's internal drainage system. Piezometric and percolation flow readings help with this. As well as any verifications with sample collection for testing, percussion drilling, piezocones, geophysical mapping. These may need to be carried out in order to maintain and complement the more accurate analysis of the data being monitored.
Tailings pond management can provide many benefits for the mining industry and the society, such as reducing environmental impact, enhancing the social license to operate, improving economic performance, and creating opportunities for innovation. Specifically, it can minimize waste generation, water and energy consumption, greenhouse gas emissions, and pollution. It can also help meet legal and ethical requirements, engage stakeholders, demonstrate commitment to sustainability and responsibility, optimize resources and processes, lower operational and maintenance costs, increase profitability and competitiveness, and adopt and apply new technologies.
Tailings pond management also faces some challenges that must be addressed and overcome, such as dealing with the variability and complexity of tailings materials which can change over time and affect the pond's behavior and performance. Additionally, adapting to changing climate and weather conditions can influence the water balance, evaporation, precipitation, and runoff of the pond. Furthermore, managing risks and uncertainties associated with the pond operation, monitoring, and closure can have serious consequences for safety and security. Lastly, balancing technical, economic, environmental, and social aspects of the pond management can involve trade-offs, conflicts, and compromises among different stakeholders and interests.
Other challenges are related to long-term geotechnical safety and how the structure will be returned to the environment. The design linked to the processing plant's master plan over time also needs to include procedures such as: - lowering of slopes to significantly increase the safety factor; - installation of structures with surface drainage, preferably protected with transition and rockfill, which is more deformable and more durable without maintenance after closure, requiring less maintenance over time than reinforced concrete.