The move toward making energy generation as clean as possible remains a slow shift in some industries. In mining, several contributors are making inroads toward a brighter, cleaner future for mineral extraction. How do they mitigate the environmental and even social impacts of extracting the minerals needed to get there? In this feature, we take a look at some of the aspects surrounding the issue.
Solar and wind power are two alternative energy sources earmarked to take the mining industry on a more environmentally conscious and less toxic growth trajectory with greatly reduced greenhouse gas emissions and more energy efficiency. These energy sources also make operations cheaper in the long run through a combination of price hedging and not being tied to volatile global crude oil prices. Solar energy can also power far-flung mines in inhospitable places like the Atacama Desert, where heavy fuel oil generators would otherwise make exploration too expensive.
In the race to go off-grid, microgrids are fast becoming all the rage with some operators adding hydroelectric power and backup gas-powered systems. South African-owned Gold Fields mines in Australia use predictive weather technology to program energy supply software that allows easy switches between energy sources depending to cloud cover and prevailing wind speeds.
Great as all these innovations are, the reality is that, to achieve cleaner mining, rare earth elements (REEs) like the indium and cadmium used in producing solar energy, the neodymium and boron used in wind turbine magnets, as well as other minerals like aluminum, iron, and copper for wiring, must still be extracted from the earth and processed by using copious amounts of resources like water and electricity.
Another consideration when it comes to REE commodity value is availability. In light of these points, researchers are advising caution lest a single country hold power over entire supply chains. Clean energy cannot be separated, at this stage and in our present model of production, from the environmental and diplomatic challenges presented in obtaining and extracting the minerals essential for mining’s electricity infrastructure. While the lion’s share of these materials comes from faraway places like South America, Kazakhstan, the Democratic Republic of Congo, China, and even Ireland, their impact on the environment and economic value is of global and national relevance.
With some luck for North American supply chains, not all of these locations are abroad. Closer to home, California’s Mountain Pass Mine is but one mine classed by the Minerals Education Coalition as having some of the world’s biggest REE deposits outside of Asia. According to an investingnews.com article of this past June, the United States and Greenland rank seventh in the world with an estimated 1.5 metric tons of rare earth elements; however, demand is increasing, and supply is, ultimately, finite.
But dark clouds often have silver linings—mainly thanks to the sun, and this brings us to the earth-friendly promise of solar power. There are currently two forms of solar capturing technologies. The first, reserved for large power plants, is concentrated solar power (CSP) that employs reflective materials to concentrate sunlight. Then there is photovoltaic power (PV), which converts solar energy into electricity, as seen in solar panels.
Many mines are beginning to use this technology. Anglo American reported the world’s first floating solar farm at one of its mining facilities in Chile in March 2019. The almost 260 photovoltaic panels at the Los Bronces copper mine handle 330 watts per unit and are suspended as a single island-style array on the surface of the Las Tórtolas tailing pond.
Here, water from the copper mining process is stored to allow sediments to separate and settle until the water is clear enough to be repurposed and the desirable mineral particles are extracted from the slurry. The solar plant is estimated to potentially lower the mine’s carbon dioxide production by close to sixty tons annually while providing it with 150,000 kWh of electricity over the same period. It also stops any significant water losses as it covers a large part of the pond surface, preventing evaporation and allowing nearly all of the water to return to the mine’s extraction cycle. The impact of such tailing ponds is regulated by government bodies and management and mitigation protocols set out by the United Nations in 2020.
In March, the Rio Tinto mine in Utah announced its plans to start setting up a tellurium extraction facility toward the end of 2021. This by-product of copper smelting is derived from cadmium telluride. Its semi-conductor properties allow sunshine to be transformed into electricity in thin-film photovoltaic (PV) solar panels.
“The minerals and metals we produce are essential to accelerate the transition to renewable energy,” Gaby Poirier, managing director of Rio Tinto Kennecott, said in a recent statement. “Adding tellurium to our product portfolio provides customers in North America with a secure and reliable source of tellurium produced at the highest environmental and labour standards with renewable energy. Rio Tinto is committed to using innovation to reduce waste in our production process and extract as much value as possible from the material that we mine and process.”
Rio Tinto is the first recorded large mining corporation to commit to investing in ‘clean’ energy as it sold the last of its coal assets—Australian-based Hail Creek coal mine and Valeria coal project—to Glencore in 2018. It now reports powering its operations with over seventy percent renewable energy. Part of Anglo-Australian’s multinational mining portfolio, the company went on record in 2020 with its goal to achieve net-zero emissions by 2050. In a 2016 report, the mine vowed to close all three of its coal-burning units at the Kennecott mine for good. Since then, its power needs have been fulfilled by renewable energy certificates procured from Rocky Mountain Power, which has been supplying the mine with energy derived from a range of renewable local sources as well as wind turbines in Wyoming.
Considering the hefty amount of minerals needed to fabricate wind turbines, it is good to see that mines are beginning to employ the energy generated by these whispering giants to power their extraction activities. Once these minerals are extracted and transformed into workable materials like steel, most can be reused infinitely. This is exactly what the Rio Tinto mine has discovered in Utah where it derived nearly three million pounds of copper in 2018 from waste that had accumulated since the early 2000s.
Some of the mined materials needed to fabricate solar and wind-generated power include the more common ingredients like clay, shale, gypsum, limestone, silica, molybdenum, zinc, aggregates used in the cement that anchors these large structures, and even coke, a fuel product made from coal. This list is by no means exhaustive.
While lithium and cobalt are still the leading components of batteries used for power storage, researchers are looking to replace highly flammable, toxic lithium with gentler substances. One alternative power storage device, the proton battery, which powers itself by separating water into hydrogen and oxygen, was presented recently by the Royal Melbourne Institute of Technology. Others are working on batteries based on graphite, potassium, or aluminum salt liquids while China reportedly developed an earth-friendly, non-toxic battery using nickel-zinc that is fully recyclable but has a shorter life span. Trade-offs prevail.
There continue to be some major environmental impacts to consider when it comes to extracting rare earth elements. Scientists point out that the solvents used in the extraction process are often more toxic to the environment than burning fossil fuels. REEs are noted as ‘relatively abundant’ but rare due to the complexities involved in isolating these metals from the dirt in which they are found. Part of the difficulty is that these elements are not found in concentrated deposits, and so large volumes of earth must be processed to obtain comparatively small amounts of these minerals, taking much hard work and energy.
On the bright side, there are always smart people capable of solving big problems and big companies with the ability, vision, and budget to bankroll such work. Last year, in the Financial Times, U.S. Bureau of Energy Resources Assistant Secretary of State Francis Fannon referred to the mining for clean energy issue as “the green revolution’s inconvenient truth about mining.” As the market currently stands, investors are increasingly shying away from industries running on fossil fuels and coal, making it imperative for renewable energy development to become a whole lot cleaner a whole lot faster.
According to a McKinsey Sustainability report last year, titled ‘Here’s how the mining industry can respond to climate change,’ between a third and a half of the world’s deposits of minerals needed by the renewable energy market are located in areas without plentiful water needed for cooling machinery and supporting workers. These areas are also already under great pressure from climate change. Issues like water shortages in desert mining regions and flooding in coastal mining areas pose very real threats to extraction operations. Automation is playing a huge part in protecting workers from toxins, yet methane and carbon dioxide from the mining industry account for nearly one-tenth of the world’s greenhouse gas emissions.
In 2019, in the United Kingdom, Lord Sales of the UK Supreme Court, questioning whether companies can act ethically toward the environment on their own, suggested a new senior management requirement for mining corporations in the form of a director dedicated to overseeing the integrity and safety of a company’s presence in the natural world.
There are other solutions to help ‘green’ the mining industry. Apart from attempting to use cleaner REE chemical extraction methods, materials can and should be recycled and reused. While this is still a painstaking and expensive process, the technology needed will likely get cheaper over time.
Sustainalytics.com describes itself as providing “environmental, social and governance (ESG) research, ratings and data to institutional investors and companies,” and mentions in a 2019 article titled ‘Implications of the use of rare-earth elements in the wind energy market’ that only 1 percent of REEs are recycled at present, making a strong argument for strengthening supply through reuse. It also notes that Goldwind, a wind turbine fabricator already smelts used magnets and reuses the precious metal content.
As well as recycling, improvements in design could potentially eliminate the need for REEs. Enercon, a German firm, has come up with a gearless wind turbine design that does exactly that. Another wind turbine project was driven by the EU Framework Programme for Research and Innovation Horizon 2020, which footed the bill for developing superconductor technology that would render permanent magnets obsolete in generators, slashing the need for REEs in many of these machines.
Considering the red tape posed by European countries’ protective environmental legislation, the search for alternative technologies could go beyond these precious metals toward a genuinely cleaner energy future.