Research On The Purification Process Of Raw Materials For High-purity Graphit

As an important strategic resource,graphite is widely used in the fields of silicon carbon anode,photovoltaic pulling crystal and nuclear graphite,etc.And various industries require high quality graphite,especially with the further development of new energy,information and other industries,the demand for high purity graphite resources has increased greatly.However,a large amount of high purity graphite in China depends on imports,and there is an obvious problem of mismatch between graphite purification technology and rapid industrial development.As China is both a large graphite resource country and a large graphite consumer country,how to give full play to the advantages of China’s graphite resources and explore a high-efficiency and low-cost high-purity graphite purification technology is the key to solve the current foreign technological barriers.In this paper,through the study of three raw materials used for the preparation of high-purity graphite: graphite ore,high-sulfur petroleum coke and waste graphite electrode,we explore a reasonable graphite purification process to improve the quality of raw materials and meet the requirements of subsequent high-purity graphite production.The specific research contents are as follows.A microcrystalline graphite from Yunnan Province was used as the research object,the fixed carbon content of the raw ore was 60.37%,and the graphite was purified by using flotation process to explore the influence of several experimental factors on the flotation effect,and the final fixed carbon content of the concentrate was 90.65%.In the process of graphite purification by alkali acid method,the influence of various experimental factors on the graphite purification effect was investigated,and the final product fixed carbon content was 99.48%;while in the process of graphite purification by hydrofluoric acid method,the final product fixed carbon content was as high as 99.946%by optimizing various experimental conditions,which reached the experimental target of fixed carbon content >99.9% was achieved.For the purification study of petroleum coke and waste graphite electrode,the desulfurization study of petroleum coke was first conducted by vacuum-assisted alkali roasting desulfurization process,which reduced the sulfur content of petroleum coke from12.37% to 0.18%,and the desulfurization rate of petroleum coke reached 98.54%,meeting the standard of low sulfur petroleum coke(sulfur content <0.5%)used in the preparation of artificial high purity graphite,Gauss,Multiwfn,VMD and other software were used for the theoretical calculation and analysis of the desulfurization process,and the mechanism of petroleum coke desulfurization was studied,the experimental results were finally analyzed and verified by X-ray electron spectroscopy(XPS),swept surface electron microscopy(SEM)and infrared spectroscopy(FT-IR).In addition,alkaline acid method and hydrofluoric acid method were used to recover and purify the waste graphite electrode,and multiple single-factor exploration experiments were carried out.Under the optimal experimental conditions,the fixed carbon content of graphite electrode was increased from 94.31% to 99.05%.In the hydrofluoric acid purification process,the influence of several experimental factors on the purification effect of graphite electrode was explored,and the fixed carbon content of graphite electrode was increased to 99.34%,which met the requirements of raw materials used in the subsequent preparation of artificial high purity graphite.