Preparation of high pure graphite by alkali digestion method

Rao, R. Bhima; Patnaik, Nivedita

doi:10.1111/j.1600-0692.2004.00697.x

Cited by 27 publications

(8 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In China, SG is mainly purified by hydrofluoric acid process, acid-alkali (acid-base) process, [25] high temperature process, of which around more than 93% of SG products are produced by hydrofluoric acid process (77%) and acid-alkali (16%) processes (Table 1). But most of the superior SG products (C > 99.95%), [18] which mainly used in high-quality lithium-ion batteries are produced by the hydrofluoric acid process and high temperature processes. High temperature method is the most efficiency treatment in top-rank products for the advantage of ultrapurity, [26] accounting for around 5% of Chinese SG output in 2019.…”

Section: Overview Description Of China's Sg Production and Raw Materialsmentioning

confidence: 99%

“…[17] This method is the most popular purification treatment in Chinese SG production currently due to high purity production and simple technology process, but it also causes serious EP issues especially fluoride emission. [10,14,18] Alkali-acid (acid-base) method [19] is an alkali fusion or sodium hydroxide (NaOH) method, researchers always call it acid-alkali process in China. In this method, impurities react with NaOH under high temperature (500-750 °C) roasting, producing water-insoluble hydroxides, [14] then separate from purified SG products easily through low concentration HCl solution leaching for soluble chlorides formation, and these chloride impurities are scrubbed with water finally.…”

Section: Overview Technical Introductionmentioning

confidence: 99%

“…However, the drawbacks are as follows: largescale infrastructure investment, high electricity consumption, and low demand market for ultrapurify SG currently. [18] The chlorination roasting is, roast at a specific temperature and atmosphere, to add chlorine gas for chlorinating the impurities in the graphite, [22] and to generate gas phase or condensed complexes with chloride to eliminate impurities with low melting and boiling point. [23] The purification efficiency of this method is higher than hydrofluoric acid and acid-alkali methods, reaching more than 95%.…”

Section: Overview Technical Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Assessment of Spherical Graphite for Lithium‐Ion Batteries: Techniques, China's Status, Production Market, and Recommended Policies for Sustainable Development

Huang

Wang

Cui

et al. 2022

Advanced Sustainable Systems

View full text Add to dashboard Cite

batteries for transportation applications. [1] Researchers are actively developing lithium-ion battery materials with high specific capacity, [2] high safety, and high economic efficiency as well as studying their recycling. [3] In the past, synthetic materials were adopted as negative electrode material of Li-ion batteries (around 55% artificial graphite and 45% natural graphite) after a series of deep processing. In the past decades, improving the purification technique was never given up by researchers, and the application of natural SG was attracting more and more attention from inventors. Graphite is a sp2 hybrid orbital with three neighboring carbon atoms forming three covalent single bonds and arranged in a planar hexagonal mesh. [4] Natural graphite can be divided into lump graphite, flake graphite, and amorphous graphite according to its crystallinity. Lump graphite has a carbon content of 98% or more, but the resources are rare and expensive; flake graphite has a carbon content of 80-95%, with the advantages of impurities, crystallinity, porosity, and low cost, and it is widely used as electrode material for lithium-ion batteries; amorphous graphite generally has a carbon content of <85%, and is generally used as casting materials and refractory materials. [4,5] Artificial graphite is formed by additives and carbon-based materials under high temperature treatment. Graphite has good thermal conductivity, electrical conductivity, and lubricity, but varies from graphite to graphite. For the same purity and grain size, natural flake graphite has the best thermal and electrical conductivity, natural amorphous graphite is the second best and artificial graphite is the worst. At the same time, a lot of other negative electrode materials are researched. So far, research has focused on embedded negative electrodes such as graphite and lithium titanate, [6] silicon-based [7] and tin-based [8] alloy negative electrodes and transition metal oxides or sulphides. However, the conductivity of lithium titanate electrodes [6] and the cycling performance [7,8] of alloy-based negative electrode materials with metal oxides and sulphides need to be addressed. In recent years, researchers have succeeded in improving the conductivity of electrodes by means of nanosizing or incorporating highly conductive materials, and improving the cycling With the increasing application of natural spherical graphite in lithium-ion battery negative electrode materials widely used, the sustainable production process for spherical graphite (SG) has become one of the critical factors to achieve the double carbon goals. The purification process of SG employs hydrofluoric acid process, acid-alkali process, high-temperature process, and chlorination roasting process in the latter process. Currently, the most widely used processes in China are the hydrofluoric acid process and the acid-alkali process, but the implementation of China's new environmental protection policy has claimed higher demands on SG production. Aimed at China's environmental pol...

show abstract

Section: Overview Description Of China's Sg Production and Raw Materialsmentioning

confidence: 99%

Section: Overview Technical Introductionmentioning

confidence: 99%

Section: Overview Technical Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of Spherical Graphite for Lithium‐Ion Batteries: Techniques, China's Status, Production Market, and Recommended Policies for Sustainable Development

Huang

Wang

Cui

et al. 2022

Advanced Sustainable Systems

View full text Add to dashboard Cite

show abstract

“…Therefore, flake graphite can be easily purified by flotation. However, "run-of-mine" flake graphite is only available in a purity range of 80-98% using froth floatation, to achieve flake above 98%, other methods such as chemical-based and thermal-based methods must be used subsequent to floatation [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Preserving Flake Size in an African Flake Graphite Ore Beneficiation Using a Modified Grinding and Pre-Screening Process

Qiu

Zhang

2017

Minerals

View full text Add to dashboard Cite

As the high value and the scarcity of large-flake graphite ore resources, it is in the best interest to maximize the amount of large flakes and minimize any processing that will reduce flake sizes. In the study, the mineralogy of an African graphite ore was estimated using X-ray diffraction (XRD), X-ray fluorescence (XRF), and optical microscope analyses. The results indicated that it was a heavily weathered large flake graphite ore and the main gangue minerals were quartz and kaolinite. The graphite flakes were thick, bent, and fractured, and some clay minerals were embedded into the graphite interlayer, which made it difficult to prevent the large flakes from being destroyed using mechanical grinding methods. An approach of steel rod coarse grinding and pebble regrinding effectively reduced the destruction of graphite flakes and improved the grinding efficiency. In addition, comparing with the conventional process, a pre-screening process was applied and the content of large flakes in the final concentrate was significantly improved.

show abstract

“…Furthermore, the most effective method for the purification is leaching in the hydrofluoric acid or vaporization at ultra‐high temperature . Whereas, both methods can result in environmental concerns due to the residual fluorine in the discharged water or high‐energy consumption. In general, the main impurities that co‐existed in the natural graphite are silicate and carbonate minerals, metal oxides and sulfides .…”

Section: Introductionmentioning

confidence: 99%

Enhanced adsorption performance of the graphene oxide with metallic ion impurities by elution

Peng

Wang

et al. 2017

Surface & Interface Analysis

View full text Add to dashboard Cite

The graphene oxides (GOs) with various content of metallic ions impurities were prepared, and the adsorption performance of the GO before and after elution was evaluated. The prepared GOs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, inductively coupled plasma and atomic force microscopy. The results indicated that the metallic ion impurities hardly affected the interlayer distance, microstructure and thickness of the prepared GOs. The adsorption isotherm and adsorption kinetic results showed that the metallic ions adsorbed on the GO surface had a negative influence on both the adsorption capacity and rate. After eluted by HNO 3 or HCl, most of the metallic ions adsorbed on the GO-91 surface were ion-exchanged by the protons of the acid eluents, and the purified GO showed enhanced equilibrium capacities and improved adsorption rate. The elution efficiency of HCl was better than that of HNO 3 , and the adsorption capacity and rate of the GO eluted by HCl approximately reached to those of the GO prepared from the graphite with high purity. It indicated that HCl could efficiently remove the metallic ions adsorbed on the GO surface.

show abstract

Preparation of high pure graphite by alkali digestion method

Cited by 27 publications

References 2 publications

Assessment of Spherical Graphite for Lithium‐Ion Batteries: Techniques, China's Status, Production Market, and Recommended Policies for Sustainable Development

Assessment of Spherical Graphite for Lithium‐Ion Batteries: Techniques, China's Status, Production Market, and Recommended Policies for Sustainable Development

Preserving Flake Size in an African Flake Graphite Ore Beneficiation Using a Modified Grinding and Pre-Screening Process

Enhanced adsorption performance of the graphene oxide with metallic ion impurities by elution

Contact Info

Product

Resources

About