Rare Earth Elements Are Difficult To Recycle. Science Is Attempting To Simplify Things

Rare earth elements are essential to contemporary life, yet there may soon be a shortage due to rising demand.

These 17 metallic elements are essential components of computer screens, cell phones, other electronics, compact fluorescent lamps, medical imaging devices, lasers, fibre optics, pigments, polishing powders, industrial catalysts, and a long list of other products. This is because of their unique properties. The high-powered magnets and rechargeable batteries used in electric cars and the renewable energy technologies required to move the world toward a low- or zero-carbon future, in particular, depend on rare earth.

280,000 metric tonnes of rare piles of earth were mined globally in 2021, which is around 32 times more than was done so in the middle of the 1950s. And the demand will only rise. According to researchers, by 2040, we’ll need up to seven times as many rare earths as we do right now.

That hunger won’t be simple to satiate. Concentrated deposits of rare earths elements are not known to exist. Massive volumes of ore must be extracted, concentrated by physical and chemical means, and then separated by miners. The process consumes a lot of energy, uses hazardous chemicals, and often produces a tiny quantity of radioactive waste that has to be disposed of properly. Access is also a problem since China essentially controls mining and processing, whereas the United States only has one operating mine.

Rare earths perform the majority of their tasks without adequate alternatives. Researchers are thus searching for alternatives to traditional mining in order to assist satisfy future demand, diversify who controls the supply, and maybe even make rare earth recovery “greener.”

Everything from mining the moon to very far-fetched concepts like recovering metals from coal ash is proposed. However, recycling is the strategy most likely to have an immediate impact. Ikenna Nlebedim, a materials scientist at the Critical Materials Institute of the Department of Energy and the Ames National Laboratory in Iowa, predicts that recycling will play a significant and fundamental role in the future. That is not to argue that we will be able to recycle our way out of the dilemma of crucial materials.

However, according to some estimates, recycling may be able to provide up to 25% of the demand for rare earths in the market for rare earth magnets in around 10 years. That’s a big deal, he says.

But there are scientific, financial, and logistical challenges to be solved before the rare earths in an old laptop can be recycled as often as the aluminium in an empty Coke can.

Why Is It So Hard To Extract Rare Earths?

It would seem logical to recycle in order to get additional rare earths. Recycling other metals including iron, copper, aluminium, nickel, and tin at rates ranging from 15 to 70 percent is common in the United States and Europe. According to Simon Jowitt, an economic geologist at the University of Nevada, Las Vegas, just 1% of the rare earth elements found in outdated items are recycled nowadays.

More copper wire may be made from recycled copper wiring. Steel can simply be recycled to make more steel, according to him. However, many items made using rare earths are “inherently not highly recyclable.”

In touch screens and other comparable goods, rare earths are often mixed with other metals, making removal challenging. Recycling rare earths from waste materials is similar to the difficult process of removing them from ore and isolating them from one another. In addition to using dangerous chemicals like hydrochloric acid and a lot of heat, conventional techniques for recycling rare earths also use a lot of energy. The expense of recovery may not be worth the effort considering the low yield of rare earths in addition to the environmental impact. For instance, a hard drive may only have a few grammes, whereas other items only have milligrammes.

However, chemists and materials scientists are working to create more intelligent recycling strategies. Their processes use bacteria, do away with the acids used in conventional procedures, or make an effort to avoid extraction and separation.

Microorganisms May Aid In The Recycling Of Rare Earths

One strategy relies on tiny allies. Natural organic acids produced by gluconobacter bacteria are capable of removing rare earth elements like lanthanum and cerium from depleted catalysts used in the refining of crude oil or from luminous phosphors used in lighting. According to Yoshiko Fujita, a biogeochemist at Idaho National Laboratory in Idaho Falls, bacterial acids are less damaging to the environment than hydrochloric acid or other conventional metal-leaching acids. The Critical Materials Institute’s reuse and recycling research is overseen by Fujita. They may also naturally deteriorate, she adds.

In tests, the bacterial acids can only salvage between 25 and 50 percent of the rare earths from used catalysts and phosphors. In other circumstances, hydrogen chloride may remove as much as 99 percent, which is far better. However, Fujita and colleagues stated in 2019 in ACS Sustainable Chemistry & Engineering that bio-based leaching may still be viable.

The team calculated yearly earnings to be around $1.75 million in a hypothetical factory recycling 19,000 metric tonnes of old catalyst annually. However, it costs a lot of money to feed the microorganisms that make the acid locally. If the bacteria are fed refined sugar, the annual production expenses for rare earths are about $1.6 million, leaving just around $150,000 in earnings. However, switching from sugar to corn stalks, husks, and other harvest remnants would reduce expenses by around $500,000 and increase earnings by roughly $650,000.

Other bacteria may assist in the extraction of rare earths and increase their use. Researchers found a protein produced by certain bacteria that metabolise rare earths that preferentially binds to these metals a few years ago. The rare earth elements neodymium and dysprosium, both parts of rare earth magnets, may be distinguished from one another by the protein lanmodulin. The several chemical solvents that are generally required for such separation may not be necessary in a system based on lanmodulin. Additionally, the protein waste product would degrade naturally. But it’s unclear if the method will work on a commercial level.

The Best Way To Extract Rare Earths From Used Magnets

Another strategy, which is currently being marketed, employs copper salts instead of acids to extract rare earths from abandoned magnets, a desirable target. The world’s greatest use of rare earth metals, neodymium-iron-boron magnets contain around 30% of the metals by weight. According to one estimate, by the end of the decade, recovering the neodymium in magnets from American hard disc drives alone might satisfy around 5% of the global need outside of China.

Nlebedim oversaw a group that created a method for extracting rare earths from magnet-containing shred electronic debris using copper salts. The rare earths in the magnets are dissolved by soaking the electronic debris in a copper salt solution at room temperature. The copper may be recycled to create additional salt solution, and other metals can be removed for individual recycling. The rare earths are then consolidated and converted into powdered minerals known as rare earth oxides with the aid of additional chemicals and heating. Nlebedim’s team has proved that the procedure, which has also been used to material leftover from the manufacture of magnets that ordinarily goes to waste, can recover 90 to 98 percent of the rare earths and that the material is pure enough to be utilised to create new magnets.

An economic study of the process predicts that in the best-case scenario, employing it to recycle 100 tonnes of residual magnet material might result in 32 tonnes of rare earth oxides and more than $1 million in earnings.

The research also assessed how the method might affect the environment. The copper salt approach has a carbon footprint that is less than half that of creating one kilogramme of rare earth oxide using one of the primary mining and processing techniques presently employed in China. According to Nlebedim’s team’s paper published in 2021 in ACS Sustainable Chemistry & Engineering, it generates an average of 50 vs 110 kilos of carbon dioxide equivalent per kilogramme of rare earth oxide.

But it’s not always more environmentally friendly than other types of mining. One problem with the method is that it calls for harmful ammonium hydroxide and roasting, which uses a lot of energy and still emits some carbon dioxide. Now, Nlebedim’s team is adjusting the method. We aim to reduce the process’ carbon footprint and make it safer, he adds.

The technique seems to be so promising that TdVib, an Iowa-based firm that creates magnetic materials and devices, has licenced it and established a pilot plant. The original goal, according to TdVib President and CEO Daniel Bina, is to manufacture two tonnes of rare earth oxides each month. Rare earths from outdated hard disc drives from data centres will be recycled at the factory.

Neodymium-iron-boron magnets made from recyclable materials are already produced by Noveon Magnetics, a business in San Marcos, Texas. The rare earths are mined, converted into metal alloys, ground into a fine powder, magnetised, and then turned into magnets in conventional magnet manufacture. These first two stages are eliminated by Noveon, according to CEO Scott Dunn.

Noveon immediately grinds used magnets into a powder after demagnetizing and cleaning them before reassembling them as new magnets. There is no need to remove and separate the rare earths out first, in contrast to conventional recycling techniques. More than 99 percent of the end product may be recycled magnets, according to Dunn, who calls the little amount of virgin rare earth elements the “secret sauce” that enables the business to customise the magnets’ properties.

According to a study published in Environmental Technology & Innovation in 2016 by Miha Zakotnik, chief technology officer of Noveon, and other researchers, Noveon’s process uses around 90% less energy than conventional magnet mining and manufacturing. According to a 2016 investigation, around 12 kilos of carbon dioxide equivalent are released for every kilogramme of magnet generated using Noveon’s technology. Compared to traditional magnets, they emits roughly half as much greenhouse gas.

Dunn refused to disclose the quantity of magnets Noveon now manufactures or the price of its magnets. However, the magnets are also employed in certain industrial applications, including as pumps, fans, and compressors, as well as various electronics and home power tools.

Recyclating Rare Earths Has Logistical Challenges

Even when researchers overcome technical obstacles, recycling still faces logistical challenges. According to Fujita, “We don’t have the infrastructure for collecting end-of-life items that contain rare earths, and there are costs associated with disassembling such devices.” Before rare earth recycling can start for a lot of e-waste, you must locate the pieces that contain those priceless metals.

For the purpose of removing magnets from hard drives and other devices, Noveon has developed a semiautomated procedure.

Additionally, Apple is attempting to automate the recycling procedure. Daisy, a company’s robot, is capable of destroying iPhones. And Apple revealed Taz and Dave, a pair of robots that make it easier to recycle rare earths, in 2022. Taz can collect modules that contain magnets, which are often lost when electronics are destroyed. When a user taps an iPhone screen, for example, Apple’s taptic engines, which employ magnets to provide haptic input, may be recovered by Dave.

It would still be much simpler, even with robotic assistance, if businesses just built their goods to make recycling simple, according to Fujita.

No matter how effective recycling becomes, according to Jowitt, there is still a need to increase mining to meet the demands of our rare earth-hungry civilization. But he acknowledges the value of recycling. We are working with resources that are by their very nature limited. “It would be better if we tried to extract what we could rather than simply throwing it in the trash.”