A novel technique for microcrystalline graphite beneficiation based on alkali-acid leaching process

Wang, Hao; Feng, Qiming; Liu, Kun; Zuo, Kesheng; Tang, Xuekun

doi:10.1080/01496395.2017.1405986

Cited by 25 publications

(6 citation statements)

References 45 publications

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“…18,19 Although the alkali−acid method can greatly improve the purity and has the advantages of simple equipment and versatility, it has high production costs, high graphite loss, and severe water pollution, and more importantly, it also destroys the graphite structure. 20 Chlorination roasting has the advantages of energy saving, high purification efficiency (99.9%), high recovery rate, etc., but it is difficult to deal with the tail gas, serious pollution, serious corrosion of the equipment. 21 These methods are limited to the actual production process.…”

Section: Introductionmentioning

confidence: 99%

“…Under high temperatures and the protection of the inert atmosphere, 99.99% high-purity graphite can be obtained by heating graphite to 2300–3000 °C using high-temperature purification equipment and expelling impurities from graphite . However, this method has high requirements on raw material purity, material fineness, and equipment process, and high energy consumption. , Although the alkali–acid method can greatly improve the purity and has the advantages of simple equipment and versatility, it has high production costs, high graphite loss, and severe water pollution, and more importantly, it also destroys the graphite structure . Chlorination roasting has the advantages of energy saving, high purification efficiency (99.9%), high recovery rate, etc., but it is difficult to deal with the tail gas, serious pollution, serious corrosion of the equipment .…”

Section: Introductionmentioning

confidence: 99%

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Hydroxyl Removal in Muscovite by Heating for Low-Fluoride Purification of Natural Flake Graphite

Feng,

Zou,

Zhao

et al. 2024

Energy Fuels

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To reduce the amount of hydrofluoric acid in the purification process of natural flake graphite and increase the utilization rate of spherical graphite tailing, high-purity spherical graphite tailing was prepared by hydrochloric acid leaching, heat treatment, and hydrofluoric acid leaching. After hydrochloric acid leaching, the purity of spherical graphite tailing was increased from 97.05 to 97.72%, and the remaining impurities were mainly muscovite and quartz. Compared with uncalcined graphite, 99.9% high-purity graphite was obtained by heat treatment at 900 °C, and the ratio of hydrofluoric acid to spherical graphite tailing was decreased from 1.6 to 0.6 mL g −1 . In the process of heat treatment, the chlorite structure decomposes at 800 °C to form forsterite, enstatite, and spinel. As the −OH group of muscovite was removed, the intermediate layer of muscovite was opened, making it easier to react with hydrofluoric acid and reducing the amount of hydrofluoric acid. The high-purity spherical graphite tailing obtained was used as an anode material for lithium-ion batteries, with a reversible capacity of up to 400 mAh g −1 after 400 cycles, which had a wide application prospect in energy storage.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydroxyl Removal in Muscovite by Heating for Low-Fluoride Purification of Natural Flake Graphite

Feng,

Zou,

Zhao

et al. 2024

Energy Fuels

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“…Graphite is an indispensable and crucial raw material for emerging scientific and industrial fields, such as metallurgy, electronics, defense, and aerospace [1]. Natural graphite is mainly found in three types: crystalline flake, amorphous, and crystalline vein [2].…”

Section: Introductionmentioning

confidence: 99%

Improved Flotation of Fine Flake Graphite Using a Modified Thickening Process

Peng

Fang

et al. 2023

Separations

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Natural graphite ores are usually upgraded by froth flotation. However, complex processes with multistage grinding and flotation are required to achieve decent liberation and separation of graphite and gangue minerals. This study reports a short and improved flotation process for fine flake graphite ore by employing a thickening stage. The results indicated that increasing the regrinding concentration via thickening can improve the grinding efficiency and, thus, shorten the separation process. With thickening, a high-grade intermediate concentrate of 96.01% was obtained after three steps of cleaner flotation, which is close to the final concentrate after five steps. Particle size distribution analysis and FIB-SEM-EDS studies suggested that the main contribution of thickening–regrinding was to achieve better abrasion rather than attrition of the graphite flakes, thus liberating the interlayer impurities without reducing the size of the graphite flakes. This study offers a more cost-effective pathway for the simplified flotation of natural graphite ores.

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“…At high temperatures, the alkali in the molten state can react with acidic impurities, 39 especially undissolved oxide, forming acid-soluble salts after alkali etching. 32,40 Thus, these impurities can be easily washed and removed from the graphite in the subsequent treatment. 41 However, the melting temperature of a single alkali is relatively high.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Additionally, compounds of some elements, such as Al and Fe, are hard to be removed by unitary physical or chemical processes. ,,, Thus, developing a scalable purification technology is extremely significant for treating industrial-grade SG powders containing various impurities. At high temperatures, the alkali in the molten state can react with acidic impurities, especially undissolved oxide, forming acid-soluble salts after alkali etching. , Thus, these impurities can be easily washed and removed from the graphite in the subsequent treatment . However, the melting temperature of a single alkali is relatively high.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial Regeneration of Spent Graphite Anode Material by an Eco-friendly In-Depth Purification Route

Gan

Jiang

et al. 2021

ACS Sustainable Chem. Eng.

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Recovery of spent graphite (SG) anode has been largely overlooked and undervalued due to the difficult regeneration process and the relative low price of graphite compared to valuable elements in the cathode. Moreover, lacking feasible low-cost techniques for the recovery of SG seriously restricts the development of all-component recycling of end-of-life batteries. Here, a novel in-depth purification process via KOH–NaOH composite alkali etching is proposed to eliminate impurities incorporated in SG. Residual acid-insoluble impurities, such as Al- and Fe-related compounds, can be removed effectively by alkali roasting treatment at 180–300 °C. Furthermore, in situ TEM investigation is conducted to unravel the gradual graphitization of the coating layer and the construction of Li+ transport channels between the newly formed structures and the original graphite bulk particles via an epitaxial growth manner during the regeneration process. After optimized purification and regeneration treatments, the recycled graphite can be used suitably as a regenerated anode, and a full cell containing commercial LiFePO4 and recycled graphite shows satisfactory capacity retention of 85.8% after 500 cycles at 1 C. This work demonstrates a promising recyclization route of SG anodes.

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A novel technique for microcrystalline graphite beneficiation based on alkali-acid leaching process

Cited by 25 publications

References 45 publications

Hydroxyl Removal in Muscovite by Heating for Low-Fluoride Purification of Natural Flake Graphite

Hydroxyl Removal in Muscovite by Heating for Low-Fluoride Purification of Natural Flake Graphite

Improved Flotation of Fine Flake Graphite Using a Modified Thickening Process

Epitaxial Regeneration of Spent Graphite Anode Material by an Eco-friendly In-Depth Purification Route

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