Mining Precious Metals for Green Tech
Emerging and current green technologies such as solar panels and electric cars require stores of precious metals like cobalt, nickel, manganese, lithium, and more for continued production. Here, three primary mining methods are investigated and compared to look at future sustainable possibilities for mining these metals. We overview three mining practices: traditional (open-pit and underground) mining, deep-sea mining, and landfill mining. All three will be presented briefly and looked at from a critical perspective.
First, traditional mining methods (open-pit and underground) have been the most common, and therefore the best understood regarding efficiency and impacts on the environment. There have been hundreds of years since the development of extraction processes, and highly cost-efficient mining methods evolved in the industry. Looking specifically at cobalt—an essential metal in battery production—the mining processes are usually open-pit at a large scale. More than half of the world’s cobalt comes from the Democratic Republic of the Congo. From a human rights perspective, there is a significant child labor issue and many unsafe working conditions for all (1). From an environmental perspective, many industrial mining operations are pretty destructive to the ecosystem. They often produce a large volume of greenhouse gases during their operations, not to mention the toxic waste byproducts. The rapid development of greener technologies drives the need for these precious metals. While this is a noble effort, we must also address the challenges associated with the mining industry.
Second, deep-sea mining is under development, and the impacts on the environment along with the costs of mining are little understood. The basis for deep-sea mining is that scientists have discovered polymetallic nodules on the sea surface that form by adsorbing metal compounds in seawater to form the nodules to be mined. One estimate has a stretch of seabed between Mexico and Hawaii, having more than six times the cobalt and three times the nickel than the entire amount available on land (2). However, this method comes with many challenges both on the mining and environmental impact side. The costs for developing technologies to effectively mine the deep-sea beds are high since robotic systems are involved. Extreme underwater pressure also presents additional challenges. Although the amount of wildlife at these depths is low, extensive biodiversity is present, and mining would effectively eliminate the life remaining on the deep seafloor. In addition to directly killing wildlife, the sediment plumes from scraping the ocean bed could potentially spread the dissolved metals across the water column leading to bio-uptake of these metals—this could not possibly be good for the wildlife.
Third, landfill mining appears to be the least impactful on the environment but is quite messy and requires a significant effort to extract the metals that have been mined through traditional methods and then discarded. The basis behind landfill mining is that recycling initiatives and processes worldwide are inefficient, and there are significant quantities of metals stored in landfills. Because of rapidly advancing technologies, there are increasing amounts of waste in landfills because humans get newer and better technologies as soon as they are released. One new technology uses a porous porphyrin polymer (3) to recover precious metals from electronic wastes that can selectively bind to precious metals from e-waste processing. However, the current state of e-waste processing is little developed. A lot needs to be improved for this technology to be beneficial, and the materials required to extract metals from the e-waste can be costly and harmful to the environment.
Mining for precious metals is vital for the transition towards net-zero emissions of greenhouse gases. From comparing the above three methods, a few common themes are apparent:
high costs,
multiple negative environmental impacts, and
technological limitations.
Traditional mining operations are the cheapest and most efficient because they have been in practice for an extended period. Reducing environmental impact and addressing the efficiency of these methods will significantly benefit our society. Deep-sea mining can have a more significant environmental impact than traditional methods but looks to extract a very pure product. Landfill mining likely has the most negligible ecological impact since it works with already-produced e-waste but ends up working with a very messy matrix that requires advancement in technology and understanding how to extract precious metals from e-waste efficiently.
The overarching theme that will best address the need for precious metals in technological advancements for new green technologies is improved recycling of our current products. Strengthening our current mining technologies to reduce environmental impacts and lower costs should be pursued. The best way to address moving towards net-zero greenhouse gas emissions is to reduce the demand for metals by recycling outdated technologies simply.
For more information on how to dispose of that old laptop sitting around in your drawer or an outdated iPod, look at the EPA site (4) to find out where to donate your e-waste or recycle it.
References
1) https://ensia.com/features/cobalt-sustainability-batteries/
3) https://www.pnas.org/content/117/28/16174
4) https://www.epa.gov/recycle/electronics-donation-and-recycling