C.V. Subban, P.J. Valdez, Q. Wang, J. Liu, J.N. Jocz, S. Ramakrishnan, S. Suffield
Pacific Northwest National Lab,
United States
Keywords: critical minerals, precipitation, flow
Summary:
The U.S. is largely import-reliant for critical minerals (CM) essential for sustainable development. To avoid supply chain disruption, there is an urgent need to domestically source CMs through processing of primary and secondary sources. Precipitation-based mineral extraction is one of the most energy-efficient approaches to CM recovery. The rate, purity, and properties of the precipitation product can impact the overall process costs and environmental footprint. We developed a laminar co-flow method (LCM) to induce the nucleation and precipitation at the mixing interface. We demonstrated that LCM could yield high-purity precipitates of Mg2+ from seawater and Dy3+ from mixed chlorides of rare-earth elements (REEs), simulating a magnet recycling stream. Unlike turbulent stirred mixing, LCM enables chemical separations in a single step without the need for specialty chemicals, ion-selective membranes, or electrodes. To evaluate scalability, we assessed relative costs associated with numbering-up microreactors versus scaling-out the dimensions of the flow channel and identified Reynolds number (1⁄Re2) as a critical parameter in LCM scale-up economics. Computational fluid dynamics models of mm-, cm-, and m-scale LCM channels identified ≤1 meter flow channel diameter and <5% difference in fluid densities as limits for maintaining a well-defined reactive interface for critical mineral precipitation. We will present results from our lab-scale demonstrations and process simulations to showcase the technical and economic feasibility of our innovative LCM technology.