(503a) Selective Recovery of Fe and Rare Earth Element Concentrates from Tailings and Low-Grade Deposits

As critical components for energy and defense technologies, the U.S. rare earth element ore reserves are estimated at ~13 million tons, but domestic production is currently limited to one operational mine residing on high-grade ore deposits in Mountain Pass, CA. While low-grade REE deposits are abundant, high-grade American REE deposits are sparse. Meanwhile, hazardous REE-containing tailings pile up at the economic and environmental cost, and it is estimated that REE value locked within e.g., red mud, is $796 per ton. However, such low-grade deposits or mining tailings are challenging to access because REEs are usually locked within a mineral matrix, typically iron oxide, that renders the ore intractable to mechanical or chemical separation. Here, we propose a process for recovering REEs from low-grade deposits and tailings by electro-metallurgically removing iron oxide, hydro-metallurgically removing aluminum salt, and separating insoluble rare earth oxides. Our strategy produces not only refinable REE concentrates but also emissions-free iron metal and supplementary cementitious materials as co-products for the steel and cement industries, respectively. Our technology simultaneously addresses the challenges facing the long-term demand of REEs as well as mitigates the challenges surrounding the management of industrial and mining waste. Compared to existing methods, our technology offers a zero-waste closed-loop process to maximize the extracted product value and minimize resultant waste. The developed process eventually realizes net positive returns, mitigates the growing environmental tolls of industrial waste, and improves the sustainability of domestic supply chains.