Abstract
Recovery of rare earth elements (REEs) from various industrial and natural streams currently draws significant attention in efforts to meet the demands of the manufacturing industry. Among many industrial byproducts and waste streams, phosphoric acid sludge could be one of the most economically feasible resources for the recovery of REEs because solid particles in the sludge contain relatively concentrated REEs, up to 3,000 ppm, while the liquid component of the sludge is valuable phosphoric acid (P2O5) that can be recovered and returned to the main product. Due to high viscosity and large solids content (e.g., 30–40 %), however, this byproduct stream requires multistep separation and purification processes. In this study, a single-step process involving a continuous-flow decanter centrifuge (CFDC) was employed to investigate its feasibility for continuous solid/liquid separation from real phosphoric acid sludge. High centrifugal forces generated from up to 1500 G gravity acceleration separate solid particles from the sludge, generating a liquid-rich stream and a solids-rich stream at the exit of the CFDC. A single pass of phosphoric-acid sludge through the CFDC yielded 95 % liquid recovery and 90 % recovery of REEs-containing solids from 20 to 34 wt% solids-containing sludge. A reduced order model developed for the CFDC operation showed good agreement with experimental data, and preliminary technoeconomic analysis revealed potential process feasibility.
| Original language | English |
|---|---|
| Article number | 141418 |
| Journal | Chemical Engineering Journal |
| Volume | 458 |
| DOIs | |
| State | Published - Feb 15 2023 |
Funding
This work was supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office under grant AL-12-350-001. The research was conducted at Oak Ridge National Laboratory (ORNL), which is managed by UT Battelle, LLC, for the U.S. DOE under contract DE-AC05-00OR22725. Materials characterization (SEM and X-Ray diffraction) was conducted at the Center for Nanophase Materials Sciences, which is sponsored at ORNL by the Scientific User Facilities Division, U.S. DOE. This work was supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office under grant AL-12-350-001. The research was conducted at Oak Ridge National Laboratory (ORNL), which is managed by UT Battelle, LLC, for the U.S. DOE under contract DE-AC05-00OR22725. Materials characterization (SEM and X-Ray diffraction) was conducted at the Center for Nanophase Materials Sciences, which is sponsored at ORNL by the Scientific User Facilities Division, U.S. DOE.
| Funders | Funder number |
|---|---|
| Critical Materials Institute | |
| Scientific User Facilities Division | |
| U.S. Department of Energy | |
| Advanced Manufacturing Office | AL-12-350-001 |
| Office of Energy Efficiency and Renewable Energy | |
| Oak Ridge National Laboratory | DE-AC05-00OR22725 |
Keywords
- Decanter centrifuge
- Phosphoric-acid sludge
- Process intensification
- Rare earths
- Solid–liquid separation