I am part of Anglo American’s Projects team, with responsibility for mine waste rock disposal, mineral residue management – including, crucially, tailings – and water dam safety. My remit encompasses implementing leading practices in all aspects of dam management: from concept, design, engineering, maintenance and surveillance, to post-closure. Beyond this ‘work portfolio’ of the dams themselves, my team provides technical support and expertise to the operations and works closely with our colleagues engaged in interrelated fields such geosciences, water management, environment, mine closure, and social and government relations, to name a few.
Addressing challenges
Tailings management is becoming an ever-bigger challenge for the mining industry. Ore grades are generally declining – as the best known deposits are steadily being depleted – causing us to need more ore to yield the same amount of metals and minerals. This results in increased tailings production which need larger tailings storage facilities and taller dams to contain them.
That scale of challenge needs proper resourcing, and this can sometimes be difficult in an economic downturn.
Fortunately, Anglo American has maintained a positive, constructive and well-resourced team, and I’m privileged to work for a business that prioritises safety and environmental excellence in this area. Even for the industry at large, which has been battered in recent years by decreasing and volatile commodity prices, there’s a far greater appreciation of just how crucial mineral residue management is for the mining business, with required funding being prioritised.
Technical and operational challenges are only one side of the story. A high level of tailings storage facilities stewardship is key to maintaining one’s license to operate, with local communities and members of society at large more aware and better informed of requirements for safe management of such facilities. Implementing best available practices and best available technologies – such as mine waste co-disposal, underground backfilling, dewatered tailings deposition and dry stacking, and in-pit backfilling – will serve to instil greater confidence and help us in the business of engaging with host communities, securing permits and, more broadly, ensuring we continue to have that license to operate based on solid scientific and engineering concepts.
So, how do we achieve this, as an industry?
Raising the bar
Mineral residue facilities are assets, not liabilities, and viewing them in this way is critical to our success as an industry. As part of this, we need to have the right systems and processes in place. We will be able to build from strength-to-strength if we ensure mineral residue management is prioritised from a risk-based and governance perspective, combined with optimal ways of working: solid professional operational practice, highly qualified people on site, and use of state-of-the-art technologies.
At Anglo American, we saw the writing on the wall in this area some years ago. We upgraded our internal technical standards to align with leading global practice at the end of 2013, rolling them out across the Group the following year. I am pleased to say we have had good reviews from several external peer-group experts.
Let’s remember that the industry is making some significant technological advances. Over the past 10 to 15 years, a great deal of work has gone into tailings dewatering technologies, including improvements in filtration and deposition processes. Today, we are able to dry-stack tailings, which is much safer than having them in more liquefied form. Unfortunately, this is still a relatively high-cost option, with a current maximum implemented throughput limit of around 36,000 tonnes per day. In contrast, many world-class deposits would need to handle in excess of 100,000 tonnes per day, so there is still a way to go.
Moving up the technology curve
Another important development has been the improved monitoring and surveillance of tailings facilities. There has been a step-change in surveillance performance through the introduction of satellite-based technologies. We are now able to measure much more accurately, and in real time, movements and deformations over time in dam behaviour, with measurements being made available on a computer screen or mobile device, anywhere in the world.
The industry also continues to make progress in the instrumentation of dams by, for instance, making more use of fibre-optic cable (FOC) technologies. These allow much more precise and accurate measurements of dam movement, again in real time, and to sub-millimetre accuracies. At Anglo American, we are already using FOC technology in Chile, and are introducing it in Brazil and South Africa shortly. At our Platinum business’ Mototolo operation, a new tailings storage facility is set to be a first in our portfolio of dams fully equipped from the outset with FOC technology for both deformation and seepage monitoring, scheduled for completion in 2018. In an ideal world, every water and tailings dam should be equipped with FOC technology, and Anglo American is striving exactly towards this goal.