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Title: An acid baking approach to enhance heavy rare earth recovery from bituminous coal-based sources

Abstract

The recovery of rare earth elements (REEs) from secondary resources, particularly coal-based materials, has recently received attention due to supply and demand imbalance. Research reported to date indicates that a high REE recovery can be realized when treating bituminous coal sources using strong acid solutions of approximately100 g/L or higher. This study introduces an approach to enhance the total rare earth recovery (TREE), especially for heavy rare earth elements (HREEs), from these coal sources at significantly lower acid concentrations. Based on the presence of REE minerals like monazite and xenotime, a detailed investigation was undertaken to quantify three pre-leach treatment methods, i.e., 1) roasting, 2) direct acid baking, and 3) acid baking after roasting. Roasting tests at 600°C revealed that the recovery of light REEs (LREEs) was enhanced while the recovery of HREEs remained relatively unaffected. LREE and HREE recovery values of 38.3% and 21.3%, respectively, were achieved using a 50 g/L (0.5 M) sulfuric acid solution at 5% solid concentration and a solution temperature of 75°C for 2 h. Comparatively, direct acid baking at 250°C provided substantial increases in LREE and HREE recovery values to approximately 49.4% and 53.0%, respectively, using an equivalent acid dosage. Recoveries were maximized tomore » 77.0% and 79.6% for LREE and HREE, respectively, by roasting followed by acid baking. Similar results were obtained from the treatment of a second bituminous coal source. Due to strong correlations between REE and Al recovery values, tests were performed on kaolinite and illite, which were prominent clay minerals within the source coals. In conclusion, these experiments revealed that the REE recovery improvements were likely a result of dehydroxylation of clays and subsequent release and decomposition of REE-bearing minerals such as monazite, xenotime and zircon.« less

Authors:
 [1];  [1];  [1]
  1. Univ. of Kentucky, Lexington, KY (United States)
Publication Date:
Research Org.:
Univ. of Kentucky, Lexington, KY (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1977456
Grant/Contract Number:  
FE0031827
Resource Type:
Accepted Manuscript
Journal Name:
Minerals Engineering
Additional Journal Information:
Journal Volume: 184; Journal ID: ISSN 0892-6875
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; rare earth elements; coal; roasting; acid baking; leaching

Citation Formats

Nawab, Ahmad, Yang, Xinbo, and Honaker, Rick. An acid baking approach to enhance heavy rare earth recovery from bituminous coal-based sources. United States: N. p., 2022. Web. doi:10.1016/j.mineng.2022.107610.
Nawab, Ahmad, Yang, Xinbo, & Honaker, Rick. An acid baking approach to enhance heavy rare earth recovery from bituminous coal-based sources. United States. https://doi.org/10.1016/j.mineng.2022.107610
Nawab, Ahmad, Yang, Xinbo, and Honaker, Rick. Thu . "An acid baking approach to enhance heavy rare earth recovery from bituminous coal-based sources". United States. https://doi.org/10.1016/j.mineng.2022.107610. https://www.osti.gov/servlets/purl/1977456.
@article{osti_1977456,
title = {An acid baking approach to enhance heavy rare earth recovery from bituminous coal-based sources},
author = {Nawab, Ahmad and Yang, Xinbo and Honaker, Rick},
abstractNote = {The recovery of rare earth elements (REEs) from secondary resources, particularly coal-based materials, has recently received attention due to supply and demand imbalance. Research reported to date indicates that a high REE recovery can be realized when treating bituminous coal sources using strong acid solutions of approximately100 g/L or higher. This study introduces an approach to enhance the total rare earth recovery (TREE), especially for heavy rare earth elements (HREEs), from these coal sources at significantly lower acid concentrations. Based on the presence of REE minerals like monazite and xenotime, a detailed investigation was undertaken to quantify three pre-leach treatment methods, i.e., 1) roasting, 2) direct acid baking, and 3) acid baking after roasting. Roasting tests at 600°C revealed that the recovery of light REEs (LREEs) was enhanced while the recovery of HREEs remained relatively unaffected. LREE and HREE recovery values of 38.3% and 21.3%, respectively, were achieved using a 50 g/L (0.5 M) sulfuric acid solution at 5% solid concentration and a solution temperature of 75°C for 2 h. Comparatively, direct acid baking at 250°C provided substantial increases in LREE and HREE recovery values to approximately 49.4% and 53.0%, respectively, using an equivalent acid dosage. Recoveries were maximized to 77.0% and 79.6% for LREE and HREE, respectively, by roasting followed by acid baking. Similar results were obtained from the treatment of a second bituminous coal source. Due to strong correlations between REE and Al recovery values, tests were performed on kaolinite and illite, which were prominent clay minerals within the source coals. In conclusion, these experiments revealed that the REE recovery improvements were likely a result of dehydroxylation of clays and subsequent release and decomposition of REE-bearing minerals such as monazite, xenotime and zircon.},
doi = {10.1016/j.mineng.2022.107610},
journal = {Minerals Engineering},
number = ,
volume = 184,
place = {United States},
year = {Thu May 19 00:00:00 EDT 2022},
month = {Thu May 19 00:00:00 EDT 2022}
}

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