Document Type : Original Research Paper

Authors

• Jiaye Li ^{1, 2}
• Jing Zhao ^{1, 2}
• Zebin Wang ^{1, 2}
• Huan Liu ^{1, 2}
• Qing Wen ^{1, 2}
• Jinling Yin ^{1, 2}
• Ze Li ³
• Yang Lei ³
• Guiling Wang ^{1, 2}

¹ Key Laboratory of Superlight Materials and Surface Technology of Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, P. R. China, Guiling Wang, Jing Zhao

² b Heilongjiang Hachuan Carbon Materials Technology Co., LTD, National Quality Supervision and Inspection Center Of Graphite Products, No. 88 Kangxin Road, Jiguan District,Jixi City, Heilongjiang Province, 158100, P. R.Chinac

³ Heilongjiang transportation investment group Co., LTD, No. 899, Innovation 3rd Road, Songbei District, Harbin, Heilongjiang Province, 150025, P. R. China

Abstract

Traditional graphite has safety and environmental issues, associated with fluorine purification. To address these issues, an energy-saving and efficient graphite purification process can be explored through the acid leaching method with composite additives. The acid leaching process was studied and optimized in detail using the controlled variable method including the effects of the soaking time and temperature on the graphite purification process. Then the response surface method was used to simulate the orthogonal experiment of graphite purification to verify the correctness of the single-factor, experiment. The purity and micromorphology of the graphite samples at each stage were characterized and tested. The experimental results showed that the optimal liquid-to-solid ratio of the acid solution and graphite was 20:1, which could make the fixed carbon content reach 99.77%. On the basis of these optimal process conditions, the addition types were further explored. The experimental result showed that the best addition was ascorbic acid and EDTA, which could reduce the content of various impurities in the graphite raw material without destroying the microstructure of the graphite. Benefitting from the addition of compound additives in the two-step process, almost all the metal ions were leached from the graphite. After the acid and water leaching, the fixed carbon content of graphite could reach 99.96%. The process parameters proposed in this paper were scientifically verified by both the single-factor and multi-factor experiments, and innovative and effective additives were introduced in different steps to make the graphite purity break through 99.9%, which was difficult to reach by the traditional method. 

Keywords

• graphite
• purification
• alkali-acid process
• response surface methodology
• auxiliary agent

Main Subjects

• Mineral Processing