Huge thanks to Antonio Caires, Henrique Alves, and Sean Hinchberger for contributing to such a dynamic and informative discussion. With over 50 years’ experience between them, we had a lot to learn from their insights related to current trends as well as developing technologies that could make TSFs safer, more secure, and more sustainable going forwards.
Here are some of the highlights from our discussion.
What are tailings?
Antonio, an Engineer working with Optimize Group, Inc. in Brazil, opened the discussion by making a very important and insightful point: mining is an essential part of how society is organized. It is hard to imagine life without mining, because we all use, and to some extent, rely on, things that the industry produces - e.g., cars. But, when you are mining for the minerals that are key components of car batteries, for example, not everything you extract from the site is of value to you.
All output from the mine is transported to a processing facility where the usable minerals are separated from the waste. The waste that comes out of the mine processing plant is called ‘tailings’, and from there, it is transported to a Tailings Storage Facility (TSF).
What are the different types of TSF?
Sean, who is the President and Founder of SDH Engineering - a geotechnical engineering consultancy based in Ontario, Canada, that concentrates on mine waste engineering - explained that there are two main types of TSFs.
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Tailings Dams
Generally, tailings can be mixed with water and pumped into an impoundment, like a dam. By using natural valleys or building on flat terrain, engineers create a ring dyke for the impoundment and then pump in the tailings with the water, which is later reclaimed.
Tailings dams make up the majority of TSFs in use today, but there is another way of storing the waste produced by mine processing plants.
Filtered Tailings
At the process plant, operatives use filter or vacuum presses to take the water out of the finely ground tailings before they leave the site. These filtered tailings can then be transported to a storage facility on conveyors, spread out, and compacted using specialized equipment.
How are TSFs monitored?
Henrique Alves is a Tailings Specialist with Lundin Mining in Brazil. He specializes in the design, construction, and closure of tailings dams. During the discussion, he highlighted the importance of not just ‘monitoring’ dams but managing them effectively, all the way through from conception to closure.
This starts during the planning process. When you are designing your dam, you need to set safety limits and incorporate all the equipment required to monitor your TSF in real-time.
"...we have all of this technology at our fingertips already. Now, it’s about that technology maturing and technology companies making it more accessible and affordable for mine/TSF owners."
Sean added that it’s important to set performance targets/KPIs for different factors during the initial phases of construction and operation. That way, managing the facility becomes about monitoring its performance and making corrections if you aren’t meeting your targets in terms of displacement, seepage, etc. A whole suite of technological instruments, including satellite-based radar and thermal imaging, help companies to monitor for failure indicators remotely at the tailings dams.
What challenges do you face when monitoring the dams?
According to Henrique, understanding the facility and its mode of failure is a big challenge. A risk assessment is needed to understand how or where an incident could happen and the team must define what ‘monitoring’ means in order to prevent failures. It’s important to set targets to make sure you are receiving the data properly. He emphasized that you need to be prepared to do something quickly if you spot a change in the trends of your data. You can also install more instruments to get better diagnostics. Ultimately, everything is related to better understanding your facility.
Sean weighed in by saying that leaning on new technologies and waiting and hoping they develop to help in the decision-making process, which currently requires lots of experience, isn’t ideal. Data isn’t always perfect.
Sean’s conclusion was that, while technology can be helpful, we need to make our instruments more resilient and more reliable, so we can trust the readings we are getting. Most importantly, though, he stressed supplementing technology with as many other observations as we can and exercising professional judgment based on years of experience.
What would our panelists like to see change in the future?
Henrique wants to use technology to add value to the closure phase of TSFs. Typically, closing down a site takes 10-15 years, and even when the structure is no longer operational, it remains a part of the landscape. Tailings dams are vast structures, sometimes more than fifty meters high, but the height of them can be used for the benefit of the local community if solar panels are installed on the top of the facility. This will create a renewable source of energy for homes/businesses nearby.
"...by improving the separation techniques, mines could potentially reduce the amount of tailings produced from mining operations."
Conversely, instead of coming up with reparative or restorative solutions, Antonio suggested going back to the root cause and seeing if companies can produce fewer tailings, less waste, in the first place. Currently, technology does not separate materials as effectively as it could, but by improving the separation techniques, mines could potentially reduce the amount of tailings produced from mining operations. Antonio advocated for the creation of ‘concentrated mines’ - active mine sites that utilize a set of technologies, including AI, new blasting techniques, and coarse particle flotation, to concentrate minerals at the mines themselves, thereby removing the need for processing plants.
Sean believes we have all of this technology at our fingertips already. Now, it’s about that technology maturing and technology companies making it more accessible and affordable for mine/TSF owners.
Thank you to all our panelists for sharing their thoughts and expertise with us. To view the entire discussion with Antonio, Henrique, Sean, and Tony, please request access to the tailings dam roundtable recording here.
This webinar is a part of the monthly series of Skycatch 2021 Mining Roundtable discussions where we talk with mining professionals and thought leaders about important topics to the industry. Sign up here to subscribe to the series. Our August 10th webinar will center around early studies on the DJI M300 RTK with the L1 Lidar sensor.