Development of Novel Ligands used in Sludge Washing for Produced Water Value Extraction

C53-21b-271141Unconventional REE sources, such as mine tailings, produced water, geothermal brines, and coal byproducts are abundant in the US, and each offers a potential means to diversify the critical materials supply chain. Unlike the concentrations of REEs in natural water sources, reported to be between 15 – 710 ng/L, the concentrations of REEs in the aforementioned unconventional sources is reported to be between 50 – 380 µg/L. Furthermore, generation of sludges from fracking operations have appreciable amounts of rare earths present as well, our data shows some sludges may contain 1 – 5 ppm, and literature values show concentrations of up to 380 ppm in produced water sludges. Therefore, sludges offer a significant increase in REE concentration relative to cation concentrations in produced water. Therefore, these waste streams are of particular interest as a source of these valuable REEs. GlycoSurf, Inc. will continue to build on its Phase I successes for recovering rare earths from fracking sludge. GlycoSurf’s Phase I results showed that our surfactant-based ligands are capable of binding with rare earths to extract and recover them from fracking waste materials. During our Phase I project, we have validated our ion flotation approach, as well as a novel approach for surfactant-enhanced sludge washing (SESW). Multiple glycolipid surfactants were shown to have excellent ability to bind with rare earths both in solution or loosely bound to sludge. We have preliminary data that establishes the capability to achieve REEs recovery using these techniques, which will be a major focus of our proposed Phase II project. The metals recovery utilized ligands developed from two classes: (1) rhamnolipids and (2) xylolipids. Both of these classes of ligands were synthetized by GlycoSurf, Inc. At the end of Phase I, the technology is currently at a TRL 3. During the first year of Phase II, GlycoSurf will develop a robust process for SESW as a stand-alone process at the bench-scale to understand the boundary conditions associated with maximum metals recovery to advance the technology through TRL 4. In parallel, GlycoSurf will implement certain aspects of continuous flow chemistry to increase the production of the necessary glycolipids used in this project. During the second year of the Phase II, our team will work to develop a pilot-scale processing system for SESW, and build, test, and begin operation of a fully operational prototype capable of producing small quantities of REOs.