Alternative tailing disposal—is it the ‘silver bullet’ for mine waste?
February 16, 2016
February 16, 2016
New technology promises to reduce water, create a smaller environmental footprint and reduce long-term risks for mines
Likely, you’re reading this on your computer, smartphone, or tablet. The creation of these modern marvels requires resources extracted from the earth. Mining touches all our lives daily in small and large ways, and the industry works hard to make sure the net impact is positive, even though some of the potentially negative impacts are very long-lasting.
Despite technological advances in mineral processing, mining companies still face a major challenge: What is the best way to manage tailing materials? In recent years, alternative tailing disposal (ATD) has been viewed as the “silver bullet” that will address all tailing management issues.
Finding alternative methods of tailings disposal is a topic I’ve been passionate about for years. It’s become a major focus of my work and I’ve written and presented on the topic multiple times. I’m looking forward to a further discussion at the upcoming SME Annual Conference & Expo in Denver on Tuesday, February 21.
When considering tailings—what’s left behind after the ore is extracted—there are four major types of tailing disposal. Each has advantages and disadvantages.
Mining lower grades of ore has resulted in increased water use per unit of production. In some cases, the availability of water is one of the greatest constraints on mine development. By optimizing water recovery, ATD technologies promise to reduce water use at mines. This is of great advantage in some settings, and in others ATD technologies promise a smaller environmental footprint and reduced long-term risks.
It sounds like a win-win opportunity, but it is not always easy. There are three major considerations that limit ATD’s “silver bullet” status.
Each mine is unique. The mine’s physical setting, the ore body, and the area’s climate all greatly impact how the tailings can be handled. Considering that the social setting is ever more important, it’s a huge mistake to simply apply the same formula on different sites. While recent failures have sparked a cry for filtering everywhere, it remains important that mine owners consider the issues at each mine site and establish what would be best there.
Some considerations impacting the use of ATD:
Every mine needs water. When it comes to tailings and water, here is the philosophical question: Do we want to remove some water from the solids, or do we want to remove the solids from the water? In some settings we want to improve the performance of the tailings after disposal, while in other settings we really want to recover all the water because it is so scarce. In some cases, the residual water might pose a risk and removing it results in a more attractive post-mining outcome for the owner. Knowing what the question is leads one to the right answer for that situation. Of course, the answer isn’t always the same.
Considerations impacting the use of ATD:
Nobody wants the tailings material. It’s simply the residue of mining. But it hangs out a lot longer than the products we consume. How we handle tailings now may have a significant impact on the environment and health of the mining company in the very long term. We need to know how this new landform will behave in the future.
Mine closure, post-closure liability management and the mitigation of risk need to be considered when selecting the tailings disposal method. Often this is not given as much attention as the extraction and beneficiation process, although the risks and liabilities endure far longer. Mining companies are taking a much longer-term view and exploring ATD options to improve their performance.
This is an exciting time to work in the mining industry. Technology is changing the way we work.
And now, as MWH merges with Stantec, our teams bring the whole toolbox with us when we come to a mine and we’re in an even better position to contribute to better tailings management.