Metal recycling limited and not even possible in some cases

Reck, B. K. et al. Challenges in Metal Recycling. Science 10 August 2012 Vol 337 # 6095 pp. 690-695

Bloodworth, A. Track flows to manage technology-metal supply. Recycling cannot meet the demand for rare metals used in digital and green technologies. Nature 2 Jan 2014 Vol 505 pp 19-20

Pihl, E., et al. 2012. Material constraints for concentrating solar thermal power. Energy 44 , 944-954

Wadia, C. et al. 2009. Materials Availability Expands the Opportunity for Large-Scale Photovoltaics Deployment. Environ. Sci. Technol. 43 2072-2077

“…modern technology has produced a conundrum: The more intricate the product and the more diverse the materials set it uses, the better it is likely to perform, but the more difficult it is to recycle so as to preserve the resources that were essential to making it work in the first place.”

With infinite amounts of energy, money, and time metals could be recycled.  But in the real world it doesn’t happen due to the thermodynamics of separation, poor recycling technologies, product design, and social behavior.

The amount of materials required to replace the existing vehicles with some unknown alternative burning some unknown fuel that is better than oil, replace existing and build new electronic devices, windmills, concentrated solar plants (CSP) with thermal storage (Pihl), solar PV, utility-scale energy storage batteries, and other alternative energy resources hits the wall of physically available materials and mineral production.  Without recycling, we soon hit the wall, and even with recycling, some technologies that use rare (earth) and platinum group metals will reach limits within years to decades.

Reck writes in Science: Less than 1% of 34 metals (many of them very rare) are recycled.  These metals are essential to microchips, solar PV, consumer electronics — pretty much all high-tech products.  It’s thermodynamically impossible to recover many of them.  Also it’s very expensive and energy-intensive, since they’re used in such small amounts for extremely precise purposes, and co-mingled with other rare metals.

Bloodworth writes in Nature: “Although recycling is important for managing stocks of common industrial metals, its application to technology metals is more complex.  Some materials are impractical or impossible to retrieve after use….Recycling has technical limits.  From mobile phones to motor vehicles, technology metals are used in myriad applications.  Up to 60 different elements go into the manufacture of microprocessors and circuit boards (Gunn), usually in tiny quantities and often in combinations not found in nature. Metals such as tantalum, gallium, germanium, and rare-earth elements are oxidized and effectively lost in the smelter slag (Hageluken).”

metal recycling rates

The need to recycle is obvious — only by doing so can the life of these resources be extended to future generations (since ores continue to be of lower and lower grades that need more energy to extract at the same time as oil, coal, and natural gas are diminishing).

Recycling could save as much as a factor of 10 to 20 in energy consumption.

The most commonly recycled metals are also the cheapest and most abundant on the planet, such as steel, aluminum, copper, zinc, lead, and nickel, with rates often over 50%.  This high recovery rate is due to their presence in relatively pure form in large amounts in products.  But even these are reused 2 or 3 times before being lost to landfills.

Even the valuable precious metals only have a recycling rate of 60%, and there’s only a 50% recovery of platinum, palladium, and rhodium from auto catalytic converters because so many old cars are exported to developing countries that don’t have recovery technology.  And for the same reason, when it comes to the platinum group metals in electronics, the rate is even lower, just 5 to 10%.

Many of these metals are highly toxic to plants and animals, yet they’re recycled at very low rates.  One of the worst, cadmium, is mainly recycled from nickel-cadmium batteries, but a very low rates.  Mercury recovery is at best 10-20% from fluorescent light bulbs.  Ecotoxicity from metal-containing nanomaterials is also a problem.

Even when attempts are made to recycle, material is lost all along the way:

Initial collection: a fraction of overall electronic equipment is turned into recycling centers, the percent depends on social and government factors

Recycling centers: much of the electronic waste is sent to countries that have inadequate recycling facilities

Preprocessing & Sorting – some components are too much effort to take apart, so they’re discarded. Nor is there enough material to justify the cost of machine recycling technology.

Recycling technology: Usually just shredding, crushing, magnetic sorting is done.  It’s too expensive to recover even more with lasers, near-infrared, or x-ray sorting.

Product design: often makes it hard to separate products out, such as laminated permanent magnets in computers.

Smelter – the easier, larger, most common metals make it to the smelter, i.e. iron, aluminum, etc.  Not all material that was collected and could be smelted reaches the smelters, especially if smelters are distant.

Thermodynamics is the ultimate limitation at the final processing stage and can’t be separated out.

Gunn, A. G. In Proc. 12th Bienn. Soc. Geol. Appl. Miner. Depos. Meet (SGA, 2013)

Hageluken, C et al. Precious Materials Handbook, Ch 1. Hanua-Wolfgang, 2012.





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4 Responses to Metal recycling limited and not even possible in some cases

  1. Actually,The most commonly recycled metals are also the cheapest such as steel, aluminum, copper, zinc, lead, with rates often over 50%. This high recovery rate is due to their presence in relatively pure form in large amounts in products. But even these are reused 2 or 3 times before being lost to landfills.Please post more information…Carry on…

    • energyskeptic says:

      Yes, the science article discusses how and why common metals are recycled, but even they are lost since we’re not close to a 100% recycling rate, so in the long run, these more common metals will be lost and dissipated as well. The problem is, far sooner the rare metals will be gone. In the race to make microchips faster, those agog over Moore’s Law have forgotten that these rare metals that will be available for just a blink of time and shouldn’t be used. Once they are gone, so what if we still have iron and aluminum? You can’t make an iron microchip. After our oil-based civilization crashes, future engineers won’t be able to build microchips like the ones we have now to gain access to all the knowledge stored on any surviving computers, hard drives, laptops, tablets, e-readers, etc. It wold be great if engineers now could come up with a design for a very simple iron-and-aluminum microchip that could be made from scavenged materials. I would love to know if that’s even possible, and how much computing could be done with them. Plastic, electricity, and so many of the other pieces will be hard to come by as well, so they need to be considered. if even one essential component can’t be made with future technology, then we’re back to the dark ages, since books and microfiche have very short lifespans.

  2. Recycling metals and even technological wastes has become an extremely important factor in three pillars of sustainable development.

    • energyskeptic says:

      The January 2nd issue of Nature points out that some rare metals can not be recovered: “Metals such as tantalum, gallium, germanium, and rare-earth elements are oxidized and effectively lost in the smelter slag”. The main argument of the article is “Recycling cannot meet the demand for rare metals used in digital and green technologies”.