Comply with environmental requirements and increase safety by advancing tailing dam monitoring
Tailing dams are built to store the by-products of mining operations created after separating the ore from the commercially worthless material that surrounds it. Tailings can come in the form of a 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 structure itself. Essentially, tailing dams 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 the stored tailings must be protected by a covering of water to prevent aerial pollution.
Specific dams have specific needs .
While the methods used for the design and construction of embankment dams can be applied to tailings dams, there are major differences between the two. Embankment dams are prestigious structures used to profitably store water, whereas tailing dams are required for the storage of unwanted waste, desirably at minimum cost.
Embankment dams are usually built to full height during one period of construction, having been designed and constructed by competent engineers (regulated by law in many countries). Modern tailing dams are often designed by competent consulting engineers, but because they are built slowly in stages over many years, and conditions may also change with time, supervision of their construction may become relaxed. Tailing Dams can also become very large. For example, one of the biggest tailing dams in the world is in Canada, at 18 kilometres long and 40 to 88 metres high. Worldwide, there are almost 3,500 active tailing dams, according to a report from infomine.com[1].The same report also notes research suggesting that tailing dams tend to fail ten times as often as conventional dams.
Specific safety requirements are also at play Brazil recently experienced a major disaster when an iron ore mines tailing dam, in Minas Gerais state, collapsed on 25 January 2019. Around 11.7million m3 of sludgy mining waste known as tailings collapsed and flattened the mining complex and tore through the surrounding countryside, and 142 people died and 194 people are still missing. This incident has raised many concerns around the construction and monitoring of tailing dams at mines Constant monitoring is required to help prevent problems in tailing dams.
In a dam, you can usually monitor displacement, strain, level, pressure, and flow. Most mines check these manually, sending operators out to the field to extract these values, the operators then capture the data on a spreadsheet later. This is largely an antiquated and inaccurate method, but is still used as a standard in this day and age. Endress+Hauser offers reliable instrumentation solutions needed to provide data for a tailing dam monitoring system.
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 can when checking the dam two or three times a week.
Smart data for consistent monitoring Some dams may have different needs, but most should have level and flow measurement at least. 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 great solutions to avoid high costs in structure. They also give a ton of process data, not to mention remote access to sensor status and configuration .
For the water table, one can install a hydrostatic level sensor in a PVC tube within a water well. The installer should make sure the sensor has enough cable, and that it is a fairly simple setup. The data can be collected using a wireless device, which provides good accuracy. The device can provide regular updates every 15 minutes, and still have a long battery life.
For the tailings dam level, a radar level transmitter can be used which can monitor the dam’s surface and send the data wirelessly, saving more money and time with its easy and minimal setup.
Finally, for the flow, another ultrasonic or radar will do the job in a parshall flume. As a standard solution in the instrumentation world, one should have no trouble installing it and reaping the same benefits as the other solutions mentioned above.
While companies may look for an inexpensive solution, it is advisable to consider a standardised protocol like wirelessHART, which provides great 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 ahead and plan for the possibilities. Trust Endress+Hauser to help you with this
