Strategic Partner Showcase: University of Kentucky Faculty Blazing Trails in Recovery of Critical Minerals

[Image: UK College of Engineering]

When discussing the future of metals recycling, it is important to consider that very few metals exist in native form. And within many metals are some of society’s most in demand elements.As a result, researchers at the University of Kentucky College of Engineering are working to become leaders in the methods and processes for the identification of critical minerals for future reuse.

Critical minerals by today’s definition are driven by demand due to advances in technology for personal and commercial use. Some of the most sought-after are the critical minerals that house the rare earth elements (REEs) that are central to the development of things like batteries, wind turbines, and solar and electronic devices.

The challenge we are faced with is there are only two ways to obtain these – through mining or recovery. The former faces economic and political difficulties, which makes the latter crucial in sustaining our high-tech world. A world, UK Mining Engineering Professor Rick Honaker says, where the critical mineral supply chain issue is impeding the renewable energy movement.

“One of the most significant obstacles to society’s transition to renewable energy is the supply chain involving critical materials,” Honanker said. “According to the International Energy Agency, worldwide supply of lithium will need to increase by 42 times current production levels, graphite over 25 times and cobalt 21 times over the next two decades. Copper, nickel and rare earths are other critical materials that have been identified as being in a production deficit. The initial supply of these critical materials will need to be met by primary sources involving mines and processing facilities. However, long-term sustainability will require society’s ability to recover the required materials from the recycling and processing of end-of-life products. The University of Kentucky is well positioned to be a leader in primary resource processing and recycling of the critical elements.”

In recent years, UK researchers have done extensive work in the area of recycling and mineral recovery in batteries. Researchers from departments across the College of Engineering Xin Gao, Qing Shao, Jian Shi, Ahamed Ullah, Yuxuan Zhang, Neng Huang and Kunlei Liu have made remarkable progress in the process of recovering valuable materials from end-of-life lithium-ion batteries.

The team is developing a new method of battery recycling to recover materials from used lithium-ion batteries, including nickel, lithium, and cobalt. Lithium and cobalt mining are labor and environmentally intensive processes, making their recovery at the end of the battery's useful life crucial for sustainability. Currently, when batteries reach the end of their useful life, they end up in landfills or recycled using strong acids.

The methods developed by the team are more environmentally friendly as they do not use strong acids, rather, hydrogen, water and heat to achieve separation. In addition, the extracted nickel, lithium and cobalt can be used to manufacture new lithium-ion batteries. This research is focused on increasing the metal recovery rate and developing the process for large-scale implementation. The goal? To make batteries more economical and renewable.

Mining engineering faculty Josh Werner and Jack Groppo have spearheaded an electronics recycling program at UK that educates, trains and conducts research in a field that they believe holds great promise for the next generation of scientists, engineers and technicians. Through this program, they are developing processes to mine batteries and other metal-rich components on-site.

Werner and Groppo have also established methods for recycling end-of-life solar panels. As the incorporation of solar photovoltaic (PV) technology into the national energy grid is rising, end-of-life panels or panels destroyed due to natural disasters are becoming an urgent waste issue. Due to the concentration of lead in end-of-life PV panels, they are required to be disposed of as a hazardous waste. With estimates that end-of-life solar panels will be worth a combined total of $15 billion in 2050, the urgency is not just ecological, its economical as well.

Werner and Groppo’s research and developments in solar panel recycling begun by defining the elemental composition of end-of life panels and where the elements of interest were concentrated. Further, their work seeks to establish and evaluate recycling methodologies to separate the glass, plastic and solar cell fractions. The goal? A sustainable future. Through the selective recovery of these elements, it allows the would-be hazardous waste to be reintegrated into the green energy sector.

In Kentucky especially, the potential for sourcing critical elements from acid mine leachate (AML) is of great interest. Honaker is among the most interested in this area, establishing a selective precipitation process involving the recovery of REEs and critical metals from acid mine drainage material. Unlike the others researching in the area of critical mineral recovery, Honaker’s focus has been on the processing of the primary source, which in this case is material from ore bodies.

“For the primary sources, we have developed a process to recover critical materials using a staged precipitation approach,” Honaker said. “This process is especially attractive when the concentrations of the critical materials in the primary source are low and cannot be physically concentrated (by density separations, magnetic separations, or any separation relying on differences in physical properties). These materials are introduced to an acid solution to remove the critical element from the solid and introduce the element into a solution. Next, we simply raise the pH in a controlled manner to initially recover an iron rich product, aluminum product, rare earth product, cobalt, nickel, zinc and manganese. Subsequently, these elements are purified in another series of processes to produce product qualities exceeding 90% purity.”

Honaker and his team were the first ever reported to have achieved rare earth concentrates from a coal source at that level of purity. His recovery process, like those mentioned from his colleagues, is more low-cost and environmentally friendly than alternative technologies. Together, these researchers are helping to establish UK as one of the nation’s foremost critical minerals research and development operations.