Project Description

REEs are the “vitamins” of many high technology products. China now controls over 90% of the world’s rare earth supplies. Since REEs are similar in chemical and physical properties, separation of mixtures of 17 REEs into individual REEs is the most challenging step in the production process. Conventional technologies for REE purification employ two-phase liquid-liquid extraction methods, which require 1,800 mixer-settler units in series or in parallel for REE purification, while generating large amounts of toxic wastes. US companies cannot compete with China using the conventional methods for REE production, because of strict environmental regulations. 
We are developing new separation methods for producing high-purity REEs from ores, coal fly ash, and other sources. Advanced chromatography methods have been developed to replace 1,800 mixer-settlers units with a few chromatography columns, which are 100 times smaller in volume and with an order of magnitude smaller foot print. The process requires 25 times less processing chemicals, and most of the chemicals are safe and can be recycled. We propose to develop a pilot scale process to demonstrate the new methods. The new technologies have potential to transform the REE production methods and to enable production of high-purity REEs in the US.

Start Date

Spring or Fall 2020

Postdoc Qualifications 

Desired but not required research experience: Chemical Engineering, Separation Methods, Chromatography, Process Simulation and Optimization, Analytical Methods (HPLC, ICP-OES), Techno-economic analysis, Life Cycle analysis

Co-advising 

Prof. N.-H. L. Wang
wangn@purdue.edu
Chemical Engineering

Prof. Robert S. Bean
bean@purdue.edu
Nuclear Engineering

References 

Ling, L. and N.-H. L. Wang, “Ligand-Assisted Chromatography for Lanthanides Separation,” International Patent Application, July 18, 2017. 

Choi, H., D. Harvey, Y. Ding, and N.-H. L. Wang, “Key Parameters Controlling the Development of Constant-Pattern Isotachic Trains of Two Rare Erath Elements in Ligand-Assisted Displacement Chromatography,” J. of Chromatography A, 1563, 47-61 (2018). 

Choi, H. Choi, H., D. Harvey, Y. Ding, and N.-H. L. Wang, “Constant-Pattern Design Method for the Separation of Ternary Mixtures of Rare Earth elements Using Ligand-Assisted Displacement Chromatography,” J. of Chromatography A, 1580, 49-62 (2018). 

“Preparation of Rare Earth Metals and Other Chemicals from Industrial Waste Coal Ash,” Patent Application, US 0153562 A1, Nov. 22, 2018. 

“Methods for Designing an Efficient Preparative Chromatographic Separation Process,” Patent Application, Oct. 29, 2018.