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

ABSTRACT

Purification of microcrystalline graphite concentrate with alkali-acid leaching process was studied in this paper. The influences of alkali leaching temperature, NaOH concentration, alkali leaching time, HCl consumption, liquid-solid ratio, and acid leaching times were investigated respectively. Final refined products with carbon content in the range of 90.88%–98.36% were prepared from flotation concentrate with carbon content of 84.27%. In addition, the volatile content in the end product was reduced from 2.7% to 1.17%. X-ray diffraction (XRD) and scanning electron microscope equipped with energy-dispersive X-ray spectroscopy (SEM-EDS) analysis revealed that the crystal structure and morphology of graphite had no obvious change when impurities composed of Si, Al, and O were almost completely removed. Alkali-acid leaching process could enhance the carbon content of microcrystalline graphite to a higher level than the traditional method of alkali roasting-acid leaching process.

KEYWORDS:

• Alkali-acid leaching
• high-purity graphite
• microcrystalline graphite

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Funding

This work was financially supported by the National Natural Science Foundation of China (No. 51774330), the Teacher Research Foundation of Central South University (2015), the Hunan Provincial Natural Science Foundation of China (No. 13JJ4015), and the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2016JM5089).

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China (No. 51774330), the Teacher Research Foundation of Central South University (2015), the Hunan Provincial Natural Science Foundation of China (No. 13JJ4015), and the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2016JM5089).