Just six years on from the horrific Brumadinho disaster, it is still difficult to talk about mine tailings without recalling those events. The sudden failure of the dam at the Córrego do Feijão iron ore mine in Brazil brought the issue of tailings management and its impact on communities to light.
Coupled with the fact that, just a few years earlier, the country had been the victim of another dam collapse in Mariana, it became clear that action was needed.
“The devastating Brumadinho dam collapse… was a stark wake-up call for the entire industry,” said Aidan Davy, Co-COO of the International Council on Mining and Metals (ICMM), speaking at the launch of the independent Global Tailings Management Institute (GTMI) earlier this year.
The disaster, he added: “Marked the beginning of a vital journey to make these facilities safer for people and the environment.” Following the incident, the ICMM, the United Nations Environment Programme (UNEP) and the Principles for Responsible Investment (PRI) launched a global tailings review aimed at establishing an international standard for best practices in tailings storage facilities (TSFs).
A global industry standard on tailings management
On 5 August 2020, the Global Industry Standard on Tailings Management (GISTM) was launched. “The GISTM is a global standard that is specially focused on the safety of tailings facilities through all phases of a facility’s life cycle, including closure and post-closure,” Adam Matthews, chief responsible investment officer at the Church of England Pensions Board, representing the PRI, tells MINE.
However, he is at pains to point out that the standard does not replace existing guidance such as that of the International Commission on Large Dams. “Rather, the GISTM is intended to complement these technical guidelines, encompassing – and standardising – expectations,” he says.
By now, although voluntary, many mining companies are well on their way to adopting the GISTM and its 15 principles covering affected communities, which include; an integrated knowledge base; design, construction, operation and monitoring; management and governance; emergency response and long-term recovery; and public disclosure and access to information. As of late 2024, ICMM members (mandated to do so), and a growing number of non-member mining companies have embarked on a path to compliance.
Ultimately, the aim is to conform with these standards and be audited and certified as doing so. For Elisa Tonda, chief of resources and markets at the UNEP, the benefits are obvious. She says a commitment will “ensure transparency, accountability and ultimately build trust among all actors, which will contribute to a more responsible mining sector”.
She adds that standards of this kind are a “proven mechanism for catalysing improvements”, but their success depends on how widely adopted and credible they are. “The GTMI has been established to oversee the implementation of, and conformance with, the GISTM. It will oversee an independent assessment process through which tailings facilities will be audited and certified,” overseen by a multi-stakeholder board.
However, despite the introduction of the GISTM, and the GTMI, governance of tailings management has never been so critical. “In the face of the ever-increasing demand for minerals and declining ore grades, tailings volumes continue to escalate,” says David Williams, professor of Geotechnical Engineering at the University of Queensland. “Mining operations are becoming mining and processing waste management operations, which must be better managed.”
He is positive about what the GISTM has already achieved, however. In addition to forcing greater governance and considerations for alternative tailings dewatering and storage options, it has raised technical capability across relevant disciplines, which has been “instrumental in raising tailings governance”. “Further, the GISTM has promoted awareness that has reached CEO and board levels,” he adds.
Anglo American can attest to this. Speaking with MINE, a spokesperson stresses that the company employs best practice standards and manages its tailings storage facilities “with the utmost care through rigorous governance and stewardship”. In 2022, it updated its already self-imposed group technical standard to align with the additional technical requirements of the GISTM, which, it says, it “played an active role” in developing. “We recognise a clear imperative to ensure that TSFs are managed to the highest standards of safety so that our industry can build and sustain trust with all our stakeholders,” the spokesperson adds, saying it also fully supports GTMI and its oversight.
“We are refining and updating a detailed plan, based on gap analysis and specific reviews of our sites, to undertake any work required to align fully with the GISTM.”
This includes additional analysis and modelling of different geotechnical and environmental conditions. And, with the full support of the board, “we have developed a processed mineral residue policy”, they say, in addition to its technical standard and other non-technical disciplines.
Adapting TSFs to address a changing climate
However, with commitments to better manage tailings globally, the industry is urged not rest on its laurels. Mining practices, the communities they impact, local laws and the environment – including weather patterns – are all changing. “The world’s demand for mined products has accelerated in recent decades,” says Anglo American, “and as the grades of many orebodies have decreased… so the volumes of mineral residue has increased.”
Climate change is an important factor, Willams explains, emphasising the importance to never design for “average” conditions, both dry and wet. It is a view ICMM’s director of environment, Emma Gagen, concurs with. She says changes in climate patterns can complicate the management of water and waste in both the short and long term. “For example, heavy rainfall from increasingly frequent and extreme weather events can lead to increased water accumulation in tailings facilities, while extended dry periods can alter both the physical and chemical properties of the tailings.”
Gagen says the industry should therefore build operational resilience to climate change, but that depends on a company’s ability to anticipate, adapt and respond to changes like extreme weather events.
“The GISTM emphasises mitigation measures and adaptive management approaches that respond to evolving conditions, including addressing climate change risks as they apply to tailings storage facilities,” she adds.
Describing the climate crisis as the “defining challenge of our time”, Anglo American says it is embedding best practice risk management tools, controls and technologies – including a set of “cutting-edge monitoring technologies and data analysis processes” to monitor environmental changes – to enhance the resilience of its operations and host communities to the dangers posed.
It is likely welcome news to Gagen, who says: “Early risk assessments and data gathered from modelling and monitoring throughout the planning and operation phases are critical to inform decision-making around adaptation measures required throughout the rest of the tailings facility life cycle.”
Innovating tailings technology
As guidance and applied standards become increasingly robust, and the requirements surrounding permitting tighten, one way of addressing the growing presence of tailings might be to reduce them to begin with. Anglo American says it is working on implementing “a number of step-change technologies” that will significantly decrease the volume of waste material produced in the extraction and process, while “offering major water and energy usage reductions”.
The company says its patented Hydraulic Dewatered Stacking (HDS) technology – being piloted in Chile – utilises fines-free, rapidly draining sand to create a 3D drainage structure to deliver a predominantly desaturated tailings storage facility. “By dewatering the tailings and eliminating the surface pond, HDS improves the stability and safety of tailings storage, a key element of the GISTM,” the spokesperson says.
Dewatering tailings is gaining traction as a potential solution and as an area ICMM members are working on. Williams says methods as such compacted tailings stacks have “become the norm” in Brazil, where requirements by law have been an impetus for change.
Other options include reducing the volume of tailings and/or eliminating the need for actively managed TSFs altogether by, for example, reprocessing existing tailings.
Gagen says such methods offer co-benefits in terms of tailings management and waste reduction. “Not only does reusing minerals and metals in old tailings for new purposes and products help to reduce the volume being stored from a safety perspective, it also creates additional value while helping to improve the circularity of these companies and the value chains of their mined products,” she explains. For Williams, right now “there is no silver bullet”. But thanks to the GISTM, the consideration of alternative tailings options has become an obligation.
With permitting becoming more challenging and the regulatory environment more stringent in many countries, as Anglo American puts it, tailings management in the mining industry is being reshaped. As devastating as events like those in Brazil were, change is coming – and mining companies are embracing it.
As larger miners innovate, their learnings will help the wider industry. “Smaller and medium operators will be looking for guidance from larger companies… facilitated through the GTMI,” says Matthews. He adds that with increasing regulatory pressure and a large group of investors now recognising the importance of demonstrating good management, there is a very clear expectation among industry to implement the GISTM. “Companies need to walk this path. It is difficult, but the GTMI has been established to support them,” he concludes.
Gagen echoes this view, saying that although the GISTM is voluntary, there are consequences for ignoring it. For example, she cautions: “The Church of England Pension Board – managing about £4bn in assets – has said it will vote against the chairs of companies that have not committed to implementing it.” It is a key message worth noting, and one that will no doubt lead to more adoption.
