Material scientists invented a new chemical process to recycle valuable metals from battery and magnet scrap using inexpensive and environment-friendly salts. It is a possible improvement to modern recycling methods of rare earth metals, which sometimes produce hazardous wastes and are only occasionally employed.
Iowa State University and researchers at an affiliated national laboratory are seeking a patent for their method of dismantling used metal alloys for their valuable rare earth metal components. At the center of their method is mixing in ammonium or iron(III) salts and reacting them through physical grinding.
The patent application was published by the U.S. Patent and Trademark Office on Feb. 4.
Rare earth metals are crucial components of a wide range of technologies — including computers, electric vehicles and permanent magnets — because of their electrical, magnetic, catalytic and other properties. Demand for the metals is predicted to skyrocket in the next decade, but mining for new ores is often expensive and environmentally harmful. Recycling the metals, currently a rare practice, has been receiving more attention as an alternative to mining.
Viktor Balema, an inventor of the patent and a senior scientist at Ames Laboratory, explained in an interview with The Academic Times that recycling research was also motivated by trade conflict in 2010, when China restricted exports of rare earth metals by 40% while having a near-monopoly on their production. (China eased the restrictions in 2012 and ended them in 2015 after the World Trade Organization ruled that it had violated trade rules, unpersuaded that the restrictions were driven by environmental protection efforts.)
Recycling electronic waste and batteries generally involves grinding or crushing parts, chemically converting the metal compounds and separating the desired elements from the scrap. Currently available methods, however, use high temperatures, have long processing times or produce hazardous waste from strong acids being used.
“There is therefore a strong demand for cost-effective and environmentally benign approaches to recycling of spent rare earth metals- and cobalt-containing materials incorporated into permanent magnets, electronic and energy generation devices and batteries,” they wrote.
According to the application, the new recycling process converts cobalt, nickel and 16 of the 17 rare earth metals from hard-to-change compounds into more manageable molecules from which the metal can be easily extracted. Magnet or battery scrap is mixed with salts containing ammonium or iron(III) and mechanically milled or ground to drive the reactions, which are most effective in water or another solvent.
Once the recycling process is complete, the resulting metal compounds can then be reacted to spit out the metals in their elemental form.
“This patent is about how you break chemical structure of material that you want to recycle,” Balema said. “Once you broke the structure, once you dissolve it, then … you can easily separate different components, you can precipitate whatever you want.”
Balema and his colleagues said that compared with preexisting recycling methods, this process would be cheap, easily scalable and have little environmental impact in the way of producing little or no hazardous waste. The ammonium and iron(III) salts could also be easily recovered and reused.
In one of several experiments they conducted, small amounts of an iron-boron-neodymium alloy and iron(III) chloride were mixed and ground. The resulting powder was added to water and went through a series of heating and filtering before sodium sulfate was added, creating a neodymium-containing compound at an 87% yield over the course of about two days. A similar experiment that did not grind the material yielded only 49% of the neodymium compound.
Balema expects that if the pending patent is granted by the USPTO, Iowa State as its potential owner would license the recycling method to manufacturers, where it would be further developed to salvage valuable metals from waste material. The U.S. Department of Energy, which provided funding for the research, also has “certain rights in the invention,” according to the application.
The application for the patent, “Chemical Dismantling of Permanent Magnet Material And Battery Material,” was filed July 23, 2020, to the U.S. Patent and Trademark Office. It was published Feb. 4 , 2021 with the application number 2021/0036387. The earliest priority date was Aug. 2, 2019. The inventors of the pending patent are Viktor Balema, Ihor Hlova, Oleksandr Dolotko and Vitalij Pecharsky, Ames Laboratory. The assignee is Iowa State University Research Foundation.