A Tailing Storage Facility – often referred to as a tailings dam – is a structure used to contain mine waste (tailings) or mining-related run-off that cannot be treated in surface water systems. Since mine waste can contain toxic and radioactive substances, tailing dam leakages can result in catastrophic damage to the environment, infrastructure, pollution, and loss of life in the surrounding communities. The failure of a Tailings Storage Facility is often caused by intense precipitation, inadequate water management, and poorly constructed tailing facilities. By continuously monitoring tailings dams, early warning systems can be put in place to prevent such failures and improve the sustainability of mining activities. There is an increasing requirement for mining houses to monitor their tailings dams to prevent failures and align with the Global Industry Standard of Tailings Management released in 2020.
As monitoring of tailings dams has evolved, the concept of a ‘monitored system’ has emerged. Monitoring systems must be tailored to the specific characteristics of each tailings dam, and this requires an understanding of the available technologies and methods.
Two commonly implemented methods to monitor tailings dams are:
- Wireless Monitoring Systems: The use of piezometers to measure the pore pressure in the tailings facility. This may also include other sensors such as total earth pressure cells, temperature-, weather- and strain monitors.
- Distributed Fibre Optic Sensing (DFOS): to monitor the ground movement of a slope along its entire length.
1. Wireless monitoring systems – A fully automated, cloud-based solution
The relationship between the pore pressure and the stability of the surrounding tailings is well understood. When monitored, the combination of these could provide an early indication of any change and help to prevent the failure of the facility. With the advancements in technology, it is now possible to monitor such facilities with standard out-the-box solutions at a relatively low cost. Move Solutions uses LoRa WAN technology to provide a wireless monitoring solution with a range of up to 15km between sensors and the monitoring station and has a battery life of several years. All parameters of a tailings facility can be measured with ease, with a single distributed system monitoring piezometers, total earth pressure cells, temperature, weather conditions, and strain. Move Solutions sends all the data to an online cloud platform for easy access, remote setup and monitoring, and automated alarms.
2. Distributed Fibre Optic Slope Monitoring (DFOS)
Slope movement can be monitored over large areas by inserting fibre optic cables into the face of the slope. Strains and temperatures can be monitored with an accuracy of 2 ꙡm/m and < 1⁰C respectively over a length of 50 km with a resolution of fewer than 1 m between measurement points. DFOS has been successfully installed to monitor ground movements, creep, and long-term erosion of slopes as well as performing leak detection underneath the liners of tailings facilities.
Tailings dams should be monitored carefully and persistently to minimize the risk of costly failures. The abovementioned monitoring solutions make it possible to have early warning of changes and possibly prevent failures. This is indeed not just a legal requirement, but a life or death responsibility.
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