Recycling of strategic elements is essential for maximizing the current supply. Even if the supply chain for every strategic element was functioning at full capacity, the supply would not be sustainable without recycling programs in place. Recycling is not only healthy for the landfills of the world by removing recyclable materials from them, but also healthy in that it reduces the pressure on mines to close the gap between current supply and demand. However, recycling treatment differs widely for each element, and our current ability to recycle strategic element-containing materials is heavily dependent on which elements it contains. There are two general types of recycling that can and should be applied to each element in order to slow down depletion of the earth's resources: recovery recycling and consumer product recycling.
Recovery recycling is the reuse of partially processed components. The goal of recovery recycling is to improve the percent yield of pure element during the extraction and refining process. The current refining processes for each element are not extremely efficient; most of the lanthanide and actinide series has a percent yield below 85% (see pages about refining for more detail.) Although attaining 100% yield is impossible, focusing on improving refinement at every step in the pathway will help close the gap between supply and demand.
An excellent example of recovery recycling is the extraction of neodymium and dysprosium from magnetic "slag" (Tang et al. 2009). In a study conducted by the Oko Institute for Applied Ecology (Schuler, 2011), double precipitating the scrap created while purifying neodymium and dysprosium with MgCl and Na2SO4 yields a substantial amount of their oxide forms; the highest reported yields during the study were 82.1% for neodymium and 99% for dysprosium (Tang et al. 2009). In another experiment, electrical reduction by P5O7 separated 96.1% of neodymium oxide from a similar magnetic scrap created by the refining process (Zhang et al. 2010). Though initially acquired experimentally, these percentages are now industrial standards in China.
Improving recovery recycling yields greater efficiency in the refining process. Improving the refining process will require more government-funded research that can be shared internationally.
Consumer Product Recycling
Consumer product recycling is the re-extraction of strategic elements from outdated or unusable consumer products. The type of extraction and the efficiency of each method depends on what element is being recycled. Here is an overview of existing methods for certain strategic elements:
Phosphorus can be reobtained from animal and urban waste (Vaccari, 2009). Farm waste, including animal bones and inedible plants, can be recycled into a main source of fertilizer after biological treatment or natural composting. Returning phosphorus-rich urban waste to the land instead of dumping it into landfills and waterways is also a good method of recycling. Reducing erosion by way of no-till agriculture also helps preserve the current supply of phosphorus in the soil.
Platinum and platinum group elements can be recovered with relatively high efficiency from the catalytic converters of hybrid car engines, and to a lesser extent, from chemical catalysts and glass. In the past decade, catalytic converters containing platinum can be recovered for at least 99.8% of their functionality due to the easy removal of carbonaceous deposits (Hilliard, 1998). Honda has led the way in terms of setting up a vertical model for selling used batteries and buying the recycled scraps, which contain recoverable nickel and cobalt, as well as reactivated parts, such as the platinum-based catalytic converters (Muri, 2012).
Nuclear fuel can be reprocessed to obtain uranium, plutonium, and other fission materials ("Processing of used," 2012). About 96% of nuclear fuel is uranium, of which about 0.5% is the usable U-235 and 0.8% is plutonium; the rest is nuclear waste. Both can be recycled as fresh fuel, saving up to 30% of the natural uranium otherwise required. Although most separated uranium currently remains in storage instead of being used in widespread recycling programs, there are plants in the UK and Russia committed to recycling high-level wastes.
Rare such as yttrium, neodymium, niobium, and dysprosium are required for powerful magnets. These small but extremely strong magnets are required for common appliances including refrigerators, cell phones, and engines of all types. However, because they are only present in trace amounts (less than 1%) in these products, it is extremely difficult to recycle these appliances with the intention of recovering REEs . However, materials that contain much larger amounts of REEs (around 20%), such as wind turbines and other compressors, can be dismantled and scrapped (Clenfield Shiraki, 2010), though they have a much longer lifespan than household appliances and thus cannot be recycled as often (Messenger, 2012). Battery alloys contain the remainder of the lanthanide and actinide series, most importantly lanthanum, cerium, and yttrium, and many of these metals can be recovered from slag after being treated with nickel-metal-hydride (Ni-MH) electrodes. A 95% recovery rate through sulfuric acid leaching is the current industry standard, but it creates harmful metal sulfide by-products. The Ni-MH electrodes recover a more usable type of metal oxide without the negative environmental externalities. (Goonan, 2011).
Although these methods for recycling exist, they vary widely in cost effectiveness. In order to make strategic element recycling a plausible solution, the price of recycling externalities must be taken into account for each individual element. The environmental risks posed by certain recovery and consumer recycling techniques, especially for rare earth oxides, must also be considered. Further research needs to be conducted into more efficient and less harmful methods of recycling in order to achieve true sustainability. For more details about further environmental risks, costs of externalities, research, technology, and governmental policy, see the future prospects page.
Schuler et al. (2011, January 20). Study on rare earths and their recycling. Retrieved from
http://www.resourcefever.org/publications/reports/Rare earths study_Oeko-Institut_Jan 2011.pdf
Vaccari, D. A. (2009, June). Phosphorus: A looming crisis. Retrieved from http://web.mit.edu/12.000/www/m2016/pdf/scientificamerican0609-54.pdf
Processing of used nuclear fuel. (2012, May). Retrieved from http://www.world-nuclear.org/info/inf69.html
Goonan, T. G. G. (2011). Rare earth elements—end use and recyclability. Retrieved from http://permanent.access.gpo.gov/gpo10499/sir2011-5094.pdf
Messenger, B. (2012, November 11). Recycling: Rarely so critical. Retrieved from
Hilliard, H. E. (1998). Platinum recycling in the united states in 1998. Retrieved from http://www.goldrecovery.us/goldrecovery/documents/USGS_Pt_Doc.pdf