Through technological innovation, we are transforming tailings from a risk that needs to be managed, to safer, water recycling assets.
Anglo American is a leading producer of many of the metals and minerals the world needs to enable the sustainable energy transition, and to help sustain a prosperous post-carbon future.
While there is growing recognition that our evolving energy system depends on these materials, it is important that they are produced with a footprint that is environmentally and socially responsible.
FutureSmart Mining™ was designed as an enabler of this; Anglo American’s innovation-led approach to sustainable mining, it brings together technology, digitalisation and sustainability to transform our physical and societal footprint, and how we source, mine, process, move and market our products.
A visible impact of this can be seen at our El Soldado copper mine in Chile, where we are deploying a combination of innovative processing technologies to improve metal recovery, and to reduce our energy and freshwater usage.
As outlined in our Sustainable Mining Plan, we have ambitious targets for both. The need to reduce freshwater usage in water constrained areas – where 70% of Anglo American operations are located – by 50%, by 2030; and our aim to realise a 30% improvement in energy efficiency by 2030.
One of the biggest inefficiencies in mining is the crushing and grinding of rocks during processing, to separate out the valuable components of an ore. This creates significant quantities of residue material, with large tailings facilities required for waste storage.
To tackle this, we looked to a solution called Coarse Particle Recovery (CPR), building a CPR demonstrator at El Soldado in August 2019.
This effort is important because even the richest copper ore bodies have a 5:100 ratio of copper to ore, with the average being 1:100. The mining industry has typically processed 100% of the ore to get to this metal. CPR permits coarser grinding, by allowing us to float particles at sizes two to three times larger than normal.
This has several benefits. As well as requiring less energy to grind the ore, the larger particle sizes make it easier to capture, drain and recycle water during the processing phase; water that would otherwise be sent to tailings disposal, often representing the largest water loss at a mine.
CPR also delivers a waste stream that is easier to handle; a low-moisture sand containing limited ‘fines’ (hardly any material less than 100 microns), which readily drains in real time. A key enabler of our patented Hydraulic Dewatered Stacking (HDS) technology, this sand is repurposed and distributed among layers of conventional tailings deposition, where it absorbs moisture and accelerates dewatering.
As well as delivering a step change in water recovery, there is a significant safety benefit to HDS, with desaturated tailings extremely resistant to liquefaction, thereby improving stability. This affords new possibilities for land use post closure, by delivering a stable landform with the potential to be repurposed, for the benefit of all.
Early results are promising, with water recovery measured at more than 80%, with dewatering continuing and up to 85% water recovery a possibility.
While mineral residue management presents social, safety and environmental challenges throughout the lifecycle of a mining operation, our HDS pilot demonstrates the benefits of an innovation-led, systems-based approach to tackling the issue. Working in tandem, these technologies can help make mining safer, increase water recycling and re-use, and eliminate the need to store wet tailings.
We continue to explore applications for HDS and are working to identify industry partners, and licensing opportunities, to accelerate the development and implementation of the technology for the benefit of the wider industry.