TAILINGS WATER MANAGEMENT:

Tailings dams are built to store by-products of mining operations after separating the ore from the commercially worthless material that surrounds it.

Tailings can be liquid, solid or a slurry of fine particles, and are usually highly toxic and potentially radioactive. Solid tailings are often used as part of the dam structure itself. They have many features in common with embankment dams, which are built to retain reservoirs of water, particularly where there is a requirement for the storage of water over the tailings, or where the stored tailings must be protected by a covering of water to prevent aerial pollution.

On 11 September 2022, a catastrophic tailings dam failure occurred at the Jagersfontein diamond mine in South Africa, leaving the residents of the small mining town in the Free State province destitute.

Another major disaster was recorded in Brazil where an iron ore mine tailings dam collapsed – 270 people died after the dam near Brumadinho in Minas Gerais state collapsed in 2019. Around 11.7 million m3 of sludgy tailings flattened the mining complex and tore across the countryside, damaging houses, schools, road infrastructure and motels. This incident has raised many concerns around the construction and monitoring of tailings dams at mines.

Mitigating risks to avoid disaster

Constant monitoring is required to help prevent disasters occurring in tailings dams. Endress+Hauser offers reliable instrumentation solutions needed to provide data for a tailings dam monitoring system.

In a dam, you can usually monitor displacement, strain, level, pressure and flow. Most mines check these manually, sending operators to the field to extract these values; the operators then capture the data on a spreadsheet later. This antiquated and inaccurate method is still used currently.

Smart instrumentation now exists that can send data throughout the day directly to a monitoring or control system. These tools can reduce or even eliminate human error from the readings. They can also provide more data in one day than an operator checking the dam two or three times a week. Some dams may have different needs, but most should measure level and flow measurement as a minimum. Mines typically need two level measurements – one for the water table level and one for the dam level.

For tailings dam monitoring, wireless devices provide effective solutions to avoid high costs in structure. They also provide significant process data, not to mention remote access to sensor status and configuration. While companies may look for an inexpensive solution, it is advisable to consider a standardised protocol like WirelessHART, which provides great diagnostic options in the case of device failure. Security should always be taken into consideration.

A mesh network will give stable network conditions if set up correctly. It will also encrypt all the data in the network to keep the information safe. Always remember that an economical solution today may cost more in the long run. We can’t see into the future, but we can think and plan ahead.

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