The
main aim of this project was to come up with an efficient method for the purification
of graphite to at least 99%. There has been an increasing demand for high-grade
graphite products with up to 99.99% carbon that has resulted in the development
of various approaches to remove impurities even to parts per million range.
Removal of impurities from 94% graphite is important to achieve a high-purity
graphite product. Microwave irradiation was used to prepare high-purity
graphite from 94% graphite concentrate. The results showed that microwave
irradiation could enhance the fixed carbon of flake graphite to a higher level.
Under the optimum conditions selected of 4 minutes’ reaction time and 100%
microwave output (800W), a graphite product with a fixed carbon content of 98.845% was
obtained from flake graphite concentrate. According to XRD, FTIR and Handheld
XRF analysis, impurities mainly composed of Fe, Co, Sr and Zr were present
before treatment. After treatment under optimum conditions Fe, which was the
major impurity in the sample was reduced from 3.566% to 1.031%. The ash content
of graphite under optimum conditions was 1.55%. The crystal structure of flake
graphite showed no change. It can be concluded from this study that graphite
purification using microwave irradiation increases the carbon content of
graphite.
References
[1]
Reddy, M.V., Mauger, A., Julien, C.M., Paolella, A. and Zaghib, K. (2020) Brief History of Early Lithium-Battery Development. Materials, 13, Article 1884. https://doi.org/10.3390/ma13081884
[2]
Ma, J.M., et al. (2021) The 2021 Battery Technology Roadmap. Journal of Physics D: Applied Physics, 54, Article 183001. https://doi.org/10.1088/1361-6463/abd353
[3]
Mudono, S., Tshuma, J., Manhongo, T., Madzokere, T., Tsorai, P. and Witika, L. (2018) The Use of Nano-Synthesis Methodology on Electrochemical Performance of LiMn2O4 Cathode at Elevated Temperature. MRS Advances, 3, 2589-2602. https://doi.org/10.1557/adv.2018.297
[4]
Chehreh Chelgani, S., Rudolph, M., Kratzsch, R., Sandmann, D. and Gutzmer, J. (2016) A Review of Graphite Beneficiation Techniques. Mineral Processing and Extractive Metallurgy Review, 37, 58-68. https://doi.org/10.1080/08827508.2015.1115992
[5]
Robinson, G.R., Hammarstrom, J.M. and Olson, D.W. (2017) Critical Mineral Resources of the United States—Economic and Environmental Geology and Prospects for Future Supply. 797. https://doi.org/10.3133/pp1802
[6]
Hong, H., et al. (2012) In Vivo Targeting and Imaging of Tumor Vasculature with Radio Labeled, Antibody-Conjugated Nanographene. 2012 American Chemical Society (ACS Nano), 3, 2364-2370. https://doi.org/10.1021/nn204625e
[7]
Li, Y.-F., Zhua, S.-F. and Wang, L. (2012) Purification of Natural Graphite by Microwave Assisted Acid Leaching. New Carbon Materials, 27, 476-480.
[8]
Chandrasekaran, S., Basak, T. and Srinivasan, R. (2013). Microwave Heating Characteristics of Graphite Based Powder Mixtures. International Communications in Heat and Mass Transfer, 48, 22-27. https://doi.org/10.1016/j.icheatmasstransfer.2013.09.008
[9]
Mesroghli, S., Yperman, J., Jorjani, E., Carleer, R. and Noaparast, M. (2015) Evaluation of Microwave Treatment on Coal Structure and Sulfur Species by Reductive Pyrolysis-Mass Spectrometry Method. Fuel Process Technology, 131, 193-202. https://doi.org/10.1016/j.fuproc.2014.11.005
[10]
Oliver Kappe, C., Pieber, B. and Dallinger, D. (2009) Microwave Effects in Organic Synthesis: Myth or Reality?† Angewandte Chemie, 52, 1088-1094. https://doi.org/10.1002/anie.201204103
[11]
Kalakkodu, S. (2011) ICDD, PDF-2 2011 (Database). Newtown Square: Int. Centre Diffraction Data, 2011.
[12]
Fialkov, A. (1979) Uglegrafitovye Materialy (Carbon Graphite Materials). Energiya, Moscow.
[13]
Trucano, P. and Chen, R. (1975) Structure of Graphite by Neutron Diffraction. Nature, 258, 136-137. https://doi.org/10.1038/258136a0
[14]
Walkiewicz, J., Kazonich, G. and McGill, S. (1988) Microwave Heating Characteristics of Selected Minerals & Compounds. Minerals & Metallurgical Processing, 51, 39-42.
[15]
Weng, S. (1993) Mössbauer Analysis of the Microwave Desulfurization Process of Raw Coal. Journal of Applied Physics, 73, 4680. https://doi.org/10.1063/1.352763
