Towards the resilient storage of tailings
A key concern, however, is the legacies that mining activities leave for future generations. While some of these legacies will have had positive changes to their communities, some are increasingly associated with the more challenging, long-term consequences of mining activity. One such example is the growing storage of tailings—literally the “tail end” of the process (pun intended)—the washed residue of processed rock.
Mining is and always has been a colossal and permanent engineering of parts of the earth. With the exception of local artisanal mining, most mining is undertaken by companies that have a growing awareness and commitment to improving how their work is completed. Large institutional investors have decided to influence and work with mining companies and are an essential part of this drive for change, as exemplified in their recent involvement with the United Nations and the ICMM. At the same time, the emergence of a generation of newly educated workers is entering the workforce, innovation is at its prime, and never-before-seen transparency of what can be revealed, invented, or reported on to a global audience is growing by the minute.
Understanding the legacy of tailings helps to understand the scale of the challenge. Since the extraction of copper produces nearly half the world's tailings (46%), put yourself in the position of a modern mining company with a copper deposit, considered economically viable at 0.70% of copper per ton of ore mined. At this kind of concentration, we’d have to successfully process nearly a ton of rock (999.3 kg.) in order to produce less than 1 kg. of copper. Imagine how much crushed rock and tailings must be produced to make the copper needed for one electric car motor, let alone the millions on order worldwide.
These tailings, all different based on where they’re mined from, are stored in giant enclosures, bound by natural features and constructed dams known as tailings storage facilities. Such storage of tailings has been central not just to copper production but also for many different valuable metals. Vulnerable to economic boom and bust in the past, mining companies have struggled to appropriately invest in tailings storage management and the vestige it leaves, with many going bankrupt before the facility’s considered safe and relinquished. Since this could happen decades later, the local municipal authorities and community are left with the liability.
The significance of the last point, the legacy of a mine lasting decades after it ceases to provide mineral wealth and profit, is a focus for improvement, with new guidelines produced in collaboration between public and private organizations and published by the ICMM. At the same time, recognizing the potential consequences doesn’t magically address the multiple untenable storage facilities that are currently awaiting treatment or tragedy.
Picture working for a mining company with at least one tailings storage facility. Let’s assume it was engineered, designed, and built to operate for fifty years after the operations close, at which point it could be safely and sustainably relinquished. Now imagine writing protocols to enable this long-term goal. Understanding what it’ll take to do this and what’s necessary to secure the chain of custody needed for the knowledge and resources required is becoming a central aspect towards establishing the legacy resilience society will expect.
All measures indicate demand for metals like copper will increase, although open pit supply is becoming harder to secure and operations go increasingly underground. The outcome? More tailings are now monitored by investor groups and made more transparent to a more socially aware generation of stakeholders. There are some adjustments necessary to begin establishing the funding needed when trees have grown, and mining towns have risen and fallen. There are agreements to make and commitments to honor, which can survive transitions in ownership.
Within the confines of this missive, it would be remiss to ignore the significant work being undertaken to reduce tailings and their consequences. Such areas of improvement include:
- better mining techniques
- re-mining existing tailings
- repurposing tailings for paste materials
- dry stacking tailings
- a myriad of other significant initiatives
However, to anchor this optimism to the floor of reality, at present, all of these efforts are still only treating a tiny fraction of the global tailings problem.
Best technologies and approaches need to be continually monitored for the breakthrough that might reduce your relinquishment time and liabilities. At the same time, the behavior and characteristics of your facility could provide you with enough data to learn and adapt your strategies. Indeed, these are some of the services being developed now by engineering companies in order to see the long-term requirements.
The challenges involved have many moving parts, with certain solutions often creating other problems to solve. These types of challenges require a coordinated strategy. It requires working with partners who understand the challenges of maintaining a knowledge base of expertise. Partners with a broad and diverse skill set who are working to make the legacies of the past resilient for the future. Partners like Hatch.