One year ago, on 5 August 2015, US Environmental Protection Agency (EPA) contractors at the Gold King Mine near Silverton, Colorado, accidentally spilled 3 million gallons of contaminated wastewater into the Animas River. The disaster didn't just highlight the challenge of cleaning up abandoned mines — it also shed light on an opportunity. The metals in the wastewater and other mine waste, including, zinc, lead, arsenic, and cadmium, are indeed toxic at high concentrations. But they're also vital to many technologies, like cell phones and solar panels. Though companies haven't yet paid much attention to salvaging these metals, recovering them as commodities could offer a common-sense way to clean up abandoned mines and bring their value back into the economy.
Harnessing metals from mine waste seems like a no-brainer: we reduce the risk of future contamination to surrounding communities, spur economic development and offset the amount of metals being extracted from new mines. To see the glass half-empty, the spill in Colorado presents the mounting ecological and human health risks of abandoned mines and improperly managed mine waste. But to see the glass half-full, this same event illuminates that there are thousands of other sites, just like Gold King, across the country that contain the metals that are needed for a growing economy.
Recovering metals from mine waste is technologically possible. But it is not yet economically viable to do so on a large scale. To understand the challenges associated turning mine waste into a resource, it helps to first understand a bit about mining.
Mining boils down to this: a company removes large amounts of rock from the earth. It grinds the rock to a fine powder and adds water and chemicals to separate the metal from the waste. Not all metals are salvaged in this process. Some metals may have no market so they are not extracted. Other metals may be found in such low concentrations that it does not make economic sense to recover. After the metal concentrate is separated from the waste (which includes the excess water, byproduct metals, and rock powder, together called ‘tailings’), the rest is sent to tailings basins, for good. In the case of Gold King, the oxygen and water that permeated the mine shaft crevices, overtime created acid which dissolved the metals from the rock into the water. This is commonly the cause of acid mine drainage. When an earthen dam from the collapse of a mine tunnel was breached, the backed-up water cascaded into the Animas River.
Tailing basins, which house both mine waste, and acid mine drainage, contain many of the specialty resources that are needed for new technology. In fact, there is currently over fifty times more selenium and tellurium—two metals used in solar photovoltaic panels—in tailings than has ever been recycled or thrown away in consumer products. If we recover those metals from abandoned mine sites we may create a win-win situation: help decrease a giant pollution problem and supply the growing demand for these metals.
But metals in the tailings and acid mine drainage are not always easy to recover. They are often in lower concentration than when originally mined. Over time metals in tailing basins attach to different elements, which can make their separation more difficult. This means more energy and chemicals may be required to separate them from the waste. In some cases, the potential environmental and cost savings may be a wash. And engineering obstacles aside, our legal system holds companies that operate on hazardous sites strictly liable for any pollution, even if they did not create the mess to begin with.
The challenges of recovering metal from mine waste are still very real. But one way to start chipping away at the challenge is to invest more in research on how to economically recover metals from mining and mineral processing waste, not just from the waste that we throw out at home.
Recovering resources from mine waste is not a fanciful idea; it is happening around the globe on a small scale. In South Africa miners recover gold and platinum group metals from historical mine waste. More locally, in Minnesota, Magnetation recovers iron ore concentrate from abandoned waste rock and tailings. In December 2015, the United States Department of Energy has even awarded ten grants to support the recovery of rare earth elements from coalmine waste.
Some will argue that recycling metals and electronic waste is the answer, not excavating mine waste. But the number of elements used in electronic devices has increased substantially since the 1980s. Many of these metals are embedded in products that are still being used. While recycling is important, recycling 100% of all household waste will not supply enough materials for new products, especially electronics and renewable energy technologies.
What we need to do is start bringing conversations about resource criticality and abandoned mine threats together. At present, the people who oversee waste cleanup and those who ensure a fluid supply of critical metals are not the same.
Take the situation in the US. The Government is both one of the largest funders of remediation activities and is also one of the largest procurers of specialty metals. It procures and even stockpiles specialty metals, including the ones that are found in abandoned mines, for infrastructure and national defense. But Congress does not give the EPA enough funds to cleanup all abandoned mine sites and responsible parties may no longer exist.
Given the challenge of providing the funding needed for all cleanup activities, the US Government could incentivize the cleanup of abandoned mine sites by turning cleanup into a market opportunity. Essentially, when it procures metals it could provide a preferential price for metals that were sourced from the clean-up and re-mining of abandoned mine sites. Since metal ore and concentrate often pass through a number of hands before the refined metal is produced, in reality, the program would provide an offset to other products to the companies that begin the processing of mine waste.
In the US, this activity could present a unique opportunity for collaboration across the aisle. As many specialty metals are often imported, recovering critical metals from mine waste domestically will spur innovation and develop markets for commodities that are integral for national security.
As these events become more frequent, the debate will continue to focus on pointing fingers and how to prevent a spill like this from happening again. But if anything, these events need to push us to demand that more primary and byproduct metals are removed during mining and refining.
And these disasters also need to make us think of abandoned mines differently. Abandoned mines and tailing basins conjure conceptions of danger, liability, and worthlessness, and rightly so. But viewed differently, they represent an opportunity to develop local economies and harness the resources needed for a cleaner, more secure, and more prosperous future.
Danny Macri has a Masters in Environmental Management from Yale is a recipient of the Schmidt-MacArthur Fellowship of the Circular Economy.
Image Credit: Sebastian Pichler / Unsplash