Rare Metal Extraction & Processing: Processing for Rare Earth
Sponsored by: TMS Extraction and Processing Division, TMS: Hydrometallurgy and Electrometallurgy Committee, TMS: Recycling and Environmental Technologies Committee
Program Organizers: Takanari Ouchi, University of Tokyo; Kerstin Forsberg, KTH Royal Institute of Technology; Gisele Azimi, University of Toronto; Shafiq Alam, University of Saskatchewan; Neale Neelameggham, IND LLC; Hojong Kim, Pennsylvania State University; Alafara Baba, University of Ilorin; Hong (Marco) Peng, University of Queensland; Athanasios Karamalidis, Pennsylvania State University; Shijie Wang, Coeur Mining, Inc
Monday 9:35 AM
March 20, 2023
Room: 30B
Location: SDCC
Session Chair: Gisele Azimi, University of Toronto; Neale Neelameggham, IND LLC
9:35 AM Introductory Comments
9:40 AM
Rare Earth Elements Extraction from an Ionic Clay from South America: Gisele Azimi1; 1University of Toronto
Ionic clays (an important resource for rare earth elements (REEs)) are formed by natural weathering of REE-bearing minerals and adsorption of liberated REEs onto the clay surface. Most ionic clays around the world including those from southern China mainly contain light REEs. Here, a unique ionic clay from south America which is rich in heavy REEs, including dysprosium (Dy), is used as the feed. A desorption process using ammonium sulfate as the lixiviant is developed. The effect of operating parameters including lixiviant concentration, pH, liquid to solid ratio, temperature, and time is investigated and optimum conditions are determined. The characterization results show that this ionic clay comprises three modes of REEs, including ion exchanged REEs physically adsorbed on the surface, hydrolyzed REEs chemically adsorbed on the surface, and mineralized (non-desorbable) REEs within the clay. Mechanistic investigations show REE desorption/adsorption is controlled by the pH and sulfate ions in the system.
10:00 AM
Leaching of Neodymium from Recycled NdFeB Magnet Powders Using Citric Acid: Srujan Rokkam1; Quang Truong1; Jonas Baltrusaitis2; Manoj Silva2; 1Advanced Cooling Technologies, Inc.; 2Lehigh University
We report studies undertaken to recycle neodymium and dysprosium contained in NdFeB magnets from the End-of-Life electronics. The extraction process utilizes a two-stage process. The NdFeB powders go through wet ball mill grinding to pretreat with sodium hydroxide (NaOH) solution to form rare earth hydroxides. The rare earth hydroxides then go through leaching in mild acids. The leaching efficiencies of HCl and citric acid were investigated. As a result, a leaching efficiency of 69% for Nd and 100% for Dy was achieved after 60 minutes of milling with 3.5 mL of 4.0 M NaOH, and 60 minutes of leaching with 100 mL of 0.5 M citric acid into the solution phase. Subsequently, 100% of iron (Fe) content can be removed out of the solution. Finally, neodymium and dysprosium can be separated using multi-stage acid stripping. This work was funded by US DLA Phase I contract SP4701-19-P-0048, awarded to ACT, Inc.
10:20 AM Break
10:40 AM Introductory Comments
10:45 AM
Separation of Rare Earth Elements from Monazite via Sulfidation: Caspar Stinn1; Zachary Adams1; Vasu Kaker1; Antoine Allanore1; 1Massachusetts Institute of Technology
Rare earth elements are critical for sustainability applications; yet their extraction, separation, and smelting remain environmentally and economically tedious. Conventional rare earth processing consists of a sequence of physical beneficiation, hydrometallurgical, and metallothermic or electrolytic processes to produce pure metals and alloys. Environmental impacts are concentrated in impurities management and material separation. Recently, sulfide-based separation chemistries have been shown to offer higher separation effectiveness than legacy hydrometallurgical methods at a fraction of the cost and energy usage. However, previous experimental studies have only employed synthetic feedstocks of mixed rare earth oxides or FeNdB magnets. Herein, we conduct rare earth element separation from monazite mineral using sulfidation. We explore the use of iron and alkaline earth compounds as separation additives to enable single stage separation of light and heavy rare earth elements and sequestration of normally occurring radioactive materials. We then explore vacuum thermal treatments for carbon-free rare earth alloy production.
11:05 AM
Experimental Investigation of Liquid Metal Leaching for Rare Earth Magnet Recycling: Chinenye Chinwego1; Adam Powell1; 1Worcester Polytechnic Institute
The importance of rare earth metals for clean energy technology and the threat to their supply has prompted several researchers to consider alternative techniques to mining. One strategy that is gaining traction in this area is recycling. Various studies have shown that the magnet-to-metal method, in which rare earth metal is leached from the magnet, is a potential way to obtain recycled mixed rare earth metal that may be used as a precursor for the manufacturing of rare earth magnets.This study will evaluate the leaching behavior of rare earth magnets in a liquid metal leaching and distillation recycling method. These data and prior leaching studies will form the basis of a model of leaching mass transfer kinetics. Models of distillation for magnesium and one other leaching agent can be used for scale-up reactor engineering.
11:25 AM
Recycling of Rare Earth Elements (REEs) from Scrap Nd-Fe-B Magnets: Nityanand Singh1; Pankaj Kumar Choubey1; Rekha Panda1; Rajesh Kumar Jyothi2; Manis Kumar Jha1; 1CSIR-National Metallurgical Laboratory; 2Korea Institute of Geoscience & Mineral Resources (KIGAM)
Nd-Fe-B magnets find wide range of applications due to its high magnetic properties. At its end-of-life, huge quantity of scrap Nd-Fe-B magnets are generated, which are promising alternative resource for rare-earth elements (REEs). Recycling of scrap Nd-Fe-B magnets will mitigate the demand supply gap of REEs. Thus, the present paper reports development of feasible hydrometallurgical flow-sheet to recover REEs from Nd-Fe-B magnets. The process consists of roasting of magnets with 20% NaCl at 750°C for 2 h followed by water leaching of the roasted mass at 75°C for 60 min to produce REEs containing leach liquor. About 99.9% REEs was recovered and the left residue contained Fe, which was further calcined at 600°C for 2 h to get red oxide pigment.