Sustainable mining of natural vein graphite via acid-extraction from waste attached to rock pieces of vein banks

Abstract A procedure based on acid extraction using a mixture of conc. sulfuric and nitric acids (8:1) to recover graphite attached to rock pieces of the vein contact zones of graphite mines, is developed as a sustainable mining practice. When the extracted graphite is heated at 600 °C for 15 min, i...

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Main Authors: Asiri D. T. Medagedara, Poornima Dahanayake, Herath Mudiyanselage T. G. A. Pitawala, Buddika Karunarathne, K. Kanishka H. De Silva, Masamichi Yoshimura, Kosala P. Walikannage, Thennakoon Mudiyanselage W. J. Bandara, Rajapakse Mudiyanselage G. Rajapakse, Gamaralalage R. A. Kumara
Format: Article
Language:English
Published: Nature Portfolio 2023-09-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-023-42074-5
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author Asiri D. T. Medagedara
Poornima Dahanayake
Herath Mudiyanselage T. G. A. Pitawala
Buddika Karunarathne
K. Kanishka H. De Silva
Masamichi Yoshimura
Kosala P. Walikannage
Thennakoon Mudiyanselage W. J. Bandara
Rajapakse Mudiyanselage G. Rajapakse
Gamaralalage R. A. Kumara
author_facet Asiri D. T. Medagedara
Poornima Dahanayake
Herath Mudiyanselage T. G. A. Pitawala
Buddika Karunarathne
K. Kanishka H. De Silva
Masamichi Yoshimura
Kosala P. Walikannage
Thennakoon Mudiyanselage W. J. Bandara
Rajapakse Mudiyanselage G. Rajapakse
Gamaralalage R. A. Kumara
author_sort Asiri D. T. Medagedara
collection DOAJ
description Abstract A procedure based on acid extraction using a mixture of conc. sulfuric and nitric acids (8:1) to recover graphite attached to rock pieces of the vein contact zones of graphite mines, is developed as a sustainable mining practice. When the extracted graphite is heated at 600 °C for 15 min, it is converted to a highly expanded form resembling worm-like structures. The unique properties of this graphite and expanded graphite are presented by characterizing using FT-IR, Raman, SEM–EDX and XRD. This expanded graphite has the oil absorption capacity of 120 g of oil per 1 g of expanded graphite, making it the material so far known to have the highest oil absorption capacity. For comparison purpose, properties of ball-milled graphite powder which was obtained from the middle of the vein is prepared and characterized. However, the ball-milled graphite does not expand upon heat-treatment at 600 °C for 15 min. The acid-extracted graphite (AEG) has lower purity than that of ball-milled graphite (BMG), but heat-treatment increases the purity of the AEG while BMG shows opposite results. The purity of AEG has increased considerably upon heat-treatment by lowering the O wt% (weight percentage) by 6.07% to half of its original value while increasing C wt% by 8.05%. On the contrary, the C wt% of BMG has decreased by 3.71% and O wt% increased by 3.84%. The increase of purity upon heat treatment of AEG is due to the removal of some carbon and sulfur impurities as their volatile oxides. The ball-milled graphite absorbs carbon dioxide from the atmosphere when heat-treated at 600 °C. As such, the ball-milled graphite powder can be used to extract carbon dioxide from the atmosphere. The crystallite size of AEG is 1.25 times larger than that of BMG and it has been increased by 8 and 2.9 times, respectively, upon heat-treatment at 600 °C for 15 min. This is a clear evidence to expanded nature of AEG compared to BMG.
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spelling doaj.art-f07fba8a8f464aaebeada1d93d695a562023-11-20T09:12:49ZengNature PortfolioScientific Reports2045-23222023-09-0113111010.1038/s41598-023-42074-5Sustainable mining of natural vein graphite via acid-extraction from waste attached to rock pieces of vein banksAsiri D. T. Medagedara0Poornima Dahanayake1Herath Mudiyanselage T. G. A. Pitawala2Buddika Karunarathne3K. Kanishka H. De Silva4Masamichi Yoshimura5Kosala P. Walikannage6Thennakoon Mudiyanselage W. J. Bandara7Rajapakse Mudiyanselage G. Rajapakse8Gamaralalage R. A. Kumara9National Institute of Fundamental StudiesDepartment of Physics, University of Sri JayewardenepuraPostgraduate Institute of Science, University of PeradeniyaNational Institute of Fundamental StudiesGraduate School of Engineering, Toyota Technological InstituteGraduate School of Engineering, Toyota Technological InstituteCentral Environmental AuthorityPostgraduate Institute of Science, University of PeradeniyaPostgraduate Institute of Science, University of PeradeniyaNational Institute of Fundamental StudiesAbstract A procedure based on acid extraction using a mixture of conc. sulfuric and nitric acids (8:1) to recover graphite attached to rock pieces of the vein contact zones of graphite mines, is developed as a sustainable mining practice. When the extracted graphite is heated at 600 °C for 15 min, it is converted to a highly expanded form resembling worm-like structures. The unique properties of this graphite and expanded graphite are presented by characterizing using FT-IR, Raman, SEM–EDX and XRD. This expanded graphite has the oil absorption capacity of 120 g of oil per 1 g of expanded graphite, making it the material so far known to have the highest oil absorption capacity. For comparison purpose, properties of ball-milled graphite powder which was obtained from the middle of the vein is prepared and characterized. However, the ball-milled graphite does not expand upon heat-treatment at 600 °C for 15 min. The acid-extracted graphite (AEG) has lower purity than that of ball-milled graphite (BMG), but heat-treatment increases the purity of the AEG while BMG shows opposite results. The purity of AEG has increased considerably upon heat-treatment by lowering the O wt% (weight percentage) by 6.07% to half of its original value while increasing C wt% by 8.05%. On the contrary, the C wt% of BMG has decreased by 3.71% and O wt% increased by 3.84%. The increase of purity upon heat treatment of AEG is due to the removal of some carbon and sulfur impurities as their volatile oxides. The ball-milled graphite absorbs carbon dioxide from the atmosphere when heat-treated at 600 °C. As such, the ball-milled graphite powder can be used to extract carbon dioxide from the atmosphere. The crystallite size of AEG is 1.25 times larger than that of BMG and it has been increased by 8 and 2.9 times, respectively, upon heat-treatment at 600 °C for 15 min. This is a clear evidence to expanded nature of AEG compared to BMG.https://doi.org/10.1038/s41598-023-42074-5
spellingShingle Asiri D. T. Medagedara
Poornima Dahanayake
Herath Mudiyanselage T. G. A. Pitawala
Buddika Karunarathne
K. Kanishka H. De Silva
Masamichi Yoshimura
Kosala P. Walikannage
Thennakoon Mudiyanselage W. J. Bandara
Rajapakse Mudiyanselage G. Rajapakse
Gamaralalage R. A. Kumara
Sustainable mining of natural vein graphite via acid-extraction from waste attached to rock pieces of vein banks
Scientific Reports
title Sustainable mining of natural vein graphite via acid-extraction from waste attached to rock pieces of vein banks
title_full Sustainable mining of natural vein graphite via acid-extraction from waste attached to rock pieces of vein banks
title_fullStr Sustainable mining of natural vein graphite via acid-extraction from waste attached to rock pieces of vein banks
title_full_unstemmed Sustainable mining of natural vein graphite via acid-extraction from waste attached to rock pieces of vein banks
title_short Sustainable mining of natural vein graphite via acid-extraction from waste attached to rock pieces of vein banks
title_sort sustainable mining of natural vein graphite via acid extraction from waste attached to rock pieces of vein banks
url https://doi.org/10.1038/s41598-023-42074-5
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