Urban mining and mineral recycling: State of the art

Sergio Cambronero for DSM Observer

The energetic transition to a low-carbon future is boosting the market for renewable energies, and this is increasing the demand for minerals. Consequently, with a renewed push for sustainable development and environmental protection, these minerals will have to come from sources that do not affect vulnerable ecosystems.

Society has generally overlooked the value of recovering metals from discarded products. Inefficiency in this aspect has increased our reliance on primary resources and the subsequent pollution by hazardous materials. Recycling is an essential aspect of circular economies and sustainable development, but its adoption in the mining sector has not been comprehensive. Although many experts indicate that recycled minerals alone cannot sustain global demand by 2050, they all agree on the fact that recycling could play an increased role in meeting demand to supply a low-carbon transition while reducing disturbance to natural ecosystems.

A massive “gold mine” ready to be exploited is found in society’s electronic garbage or “e-waste”. Most electrical products are composed of valuable elements such as gold, nickel, cobalt and rare earth metals. Some common devices are composed of 30-50 elements, many of them recoverable. In 2019, the world generated 53.6 millions tons of e-waste, the equivalent to almost 150 Empire State buildings. The potential value of recycled minerals on this amount of garbage was estimated by experts at more than 70 billion USD.

One of the most important challenges of mineral recycling and urban mining is the recycling of lithium-ion batteries, which have been intensively produced over the last years. Earlier this year, the “Battery and Critical Mineral Recycling Act of 2020” introduced in the US Congress called to designate $150 million over the next 5 years to support research on cutting-edge battery recycling approaches and to help establish a national collection system. Worldwide estimates indicate that just 5% of lithium-ion batteries are recycled at their end of life, mainly due to challenges with high-energy demand technologies and caustic chemicals.

Historically, most battery recycling companies use smelting processes or pyrometallurgy, resulting in high emissions and low recovery rates of about 30-40 per cent with the loss of critical minerals. Novel technologies within the field of hydrometallurgy allow it to have higher recovery rates of at least 95% while reducing greenhouse gas emissions. Researchers from the Idaho National Laboratory recently published a paper describing a new electrochemical-assisted leaching process in which they demonstrate an 80% reduction in energy and chemical costs as compared to conventional hydrometallurgical routes.

In November, Finnish company Fortum announced a breakthrough in mineral recycling, claiming a patent on a hydrometallurgical process that reduces CO2 emissions up to 90% compared to traditional methods, while obtaining high recovery rates of up to 80% of manganese, lithium, cobalt and nickel. This company signed cooperation agreements with Europe’s giants BASF and Nornickel, that add to the list of emerging projects in the region such as the recent joint ventures by Axion, Aspire, Aceleron in the UK and TES new recycling plant in France. These projects will contribute towards the rise of the urban mining movement in the EU, previously developed by Agoria, Recupel and Umicore. In this regard, a recent communication by the European Commission indicates that from January 2027, EV batteries would have to declare their recycled cobalt, lead, lithium and nickel content, while from 2030 they will have to meet a minimum recycled content threshold that would increase over time.

Unlike polymer plastics, metals can be recycled almost indefinitely. Recycling imparts environmental benefits in several areas, especially with greenhouse gas emissions and carbon footprint but it also has negative impacts that need to be assessed against its benefits, one of them being the manipulation and transportation of required materials. In December 2020, Canadian company Li-Cycle announced full operations of the North America’s largest capacity lithium-ion battery recycling facility in Rochester, New York, capable of processing 10,000 tonnes of batteries per year. This company is making significant advances not only in the hydrometallurgical process but also on the recollection and transportation of recycled materials. Li-Cycle proposes a “hub and spoke” model, where they collect batteries at local “spoke” facilities that shred materials and send to a central “hub” factory for final processing.

As the demand for electric vehicles is growing explosively, so is the amount of used batteries that once powered those cars. Industry analysts predict that by 2020, China alone will generate some 500,000 metric tons of used Li-ion batteries and that by 2030, the worldwide number will hit 2 million metric tons per year. Electric vehicle manufacturer BYD recently announced a partnership with Japanese trading house Itochu, which will generate a global market for disposed EV batteries that still can be used in large power storage units. In order to achieve a successful circular economy, urban mining must not only contemplate the recycling but also the re-usage and refurbishment of batteries and devices. Itochu has developed a system that fits about 160 BYD batteries into a specialized 20-foot container capable of powering 100 households for one day.

Batteries are just a fraction of total e-waste, which is composed of entire devices such as laptops, cellphones, tablets, wiring and cables. On this matter, promising advances have been made in North America by Tesla co-founder’s company Redwood Materials, which in 2020 made an important incursion on the market by making agreements with Tesla, Panasonic and Amazon, positioning itself as one of the most profitable cleantech startup companies. Another major leap in the implementation of recycled materials has been made by Apple, which has manufactured its newest iPhone 12 with 100% recycled rare earth metals and has developed highly specialized robots to dissemble and reuse old iPhones on an industrial scale.

Many technologies to recover minerals from secondary sources are being implemented in pilot projects set to be scaled up in the next 10 years. However, there is still a lot of room for innovation and improvement. The latest advances in metal-organic frameworks offer substantial advantages that could improve mineral recycling processes, especially wastewater treatment and pollution reduction. A team of Australian and Chinese researchers have recently developed an ultrathin water stable nanosheet capable of separating harmful ions from water such as lead and mercury. In August, lithium producer Orocobre entered into a partnership with EnergyX to develop metal organic framework nanoparticles capable of selectively separating lithium ions from the rest of ions in high salinity mixtures.

Another cutting-edge technology with high potential to change global recycling is the emerging field of biometallurgy, which consists of technologies and processes that use microbial species to extract metals from their surroundings. Some microbes have evolved the ability to dissolve metals from solid rocks and accumulate metal ions in their cell walls, in a process called bioleaching.

Although these technologies are still under ongoing research, some companies are already implementing these solutions into pilot scale. Take BRAIN AG, a German bioeconomy company that has identified the most talented metal extraction microbes and developed the BioXtractor, a mobile self-contained plant that contains all the biological machinery to generate a sustainable metal extraction in a 48-hour period, while replacing aggressive chemicals and reducing energy demand. A similar endeavor based in New Zealand called Mint Innovation aims to take this process global, by setting metal biorefineries in every major city around the world. The potential is promising enough that some microbes are being tested onboard the International Space Station.

Many challenges lie ahead for Urban Mining to achieve its full potential and contribute to the green transition. Landfill recovery, adaptation of public policies and proper commercial regulations for this industry will continue advancing as Urban Mining provides an essential contribution to our green and blue future.

Featured image: Electronic waste at Agbogbloshie, Ghana. Photo by Muntaka Chasant.