Reconsidering waste in mining
October 25, 2021
A circular economy challenges our common economic approach of manufacturing something new, using it, and then disposing of it
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Recently, there has been an increased need to develop long-term sustainability strategies to transform the mining industry. The extractive nature of mining can create a variety of environmental issues before, during, and long after a mine’s life.
Natural resources provided on this earth are finite. As such, overuse today poses a threat to future generations. The mining industry has an obligation to operate within the concept of sustainable development—it must extract resources responsibly. This means monitoring consumption of limited raw materials before they run out.
Resource scarcity can be lessened by upcycling, reusing, and recycling waste. This is where the concept of a circular economy comes into play.
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The extractive nature of mining can create environmental disruptions before, during, and long after a mine’s life.
What is a circular economy?
A circular economy is based on three principles, all driven by design. They include eliminating waste and pollution, circulating products and materials, and regenerating nature. It all seeks to rebuild capital, whether this is financial, manufactured, human, social, or natural (according to the Ellen Macarthur Foundation).
A circular economy in mining means breaking away from the traditional take, make, and waste economic model. One place to start is decreasing waste along the whole mining value chain. We can transform a throwaway economy into one that gives us the tools to tackle climate change.
By looking for opportunities to reuse and recycle materials, we can begin mitigating climate change.
Upcycle: Mine waste becomes building materials
Unlike a mining site, which has a life span and will cease operations eventually, mine waste is here forever. Finding ways to turn liabilities like large tailings storage facilities and heap leach piles into assets—through reuse—is crucial to a circular economy. Plus, finding proactive ways to use the material limits the need to extract and process new material, which reduces upstream emissions.
Upcycling transforms waste and unwanted products into new, higher-quality products. The waste can be reused by the mine itself or sold to a third-party.
For example, waste rock can be used to refill old open-pit mines, as a material in landscaping projects, or as aggregates in road construction. Sometimes it can even be used as feedstock for cement and concrete. It can also be reprocessed a second time to extract additional minerals. This is a good way to add value to the waste, uncovering extra raw elements that the mine operators weren’t originally seeking.
Tailings is a common by-product of the minerals recovery process and there are several different ways to give tailings new life. Manganese tailings can be used in agroforestry, buildings, and construction materials like resin, glass, and glazes. Clay-rich tailings are often used for making bricks, floor tiles, and cement. Slag can be used in road construction, concrete, and cement.
Upcycling waste rock into construction materials is one way to reduce the amount of waste that needs to be safely stored and managed.
Reuse: Recognizing the value of water
In addition to waste rock and tailings, wastewater can also be reused and recycled. Recycled water used in material extraction can be reused on site for dust suppression, material processing, as a coolant, and even as a source of drinking or shower water at a mine camp. Sometimes, mining water gets sent offsite to be reused for nearby industrial and agricultural pursuits.
Operating sustainably and valuing water requires planning in the design of the mine. Recently, our teams completed the detailed engineering and design of an underground pumping station for dewatering at a large gold mine. We built the system with separate contact and non-contact sumps and pumping systems. The water could be safely and efficiently reused onsite because the non-contact water was protected from impurities through its own separate set of piping and pumps.
Water is a critical resource on many mine sites and needs to be used efficiently and treated carefully to avoid wasting it.
Recycle: Building durable mine infrastructure
When a mine closes, the infrastructure typically gets torn down and scrapped. But what if we could repurpose it somewhere else? If we build infrastructure with high performance and durability in mind, process plants and other mining buildings could be dismantled and moved to another site.
Our teams recently worked on a project involving recycled infrastructure. We completed engineering, design, procurement, and construction of an entire pilot plant, built to test gold leaching and adsorption. The setup consisted of 22 tanks and more than 2.5 tons of stainless steel. The client intended for the pilot plant to be reused at other sites once the initial trial campaign had been completed. By reusing existing infrastructure components, we reduced the need to produce new materials. This serves as an excellent example of working within a limited supply of earth’s resources.
Mining requires a lot of infrastructure for extracting, processing, and transporting materials. If it’s built at a high quality, the infrastructure could be reinstalled at other mine sites once the original mine closes.
Achieving circular economy in mining
Is a circular economy possible? In short, it must be. The circular economy concept is a key component to a more sustainable mining industry. By looking for opportunities to reuse and recycle materials, we can begin mitigating climate change. The resources on this earth won’t last forever, so we must take steps now to ensure we don’t run out. Waste is too common in our modern society, and we must break the habit.