Fluctuations in Graphitization of Coal Seam-Derived Natural Graphite upon Approaching the Qitianling Granite Intrusion, Hunan, China

Abstract

The Lutang graphite deposit in Chenzhou, Hunan province, China, is a well-known coal seam-derived graphite (graphite formed from coal during its natural evolution) deposit with proven reserves of 9.5 million tons and prospective reserves of around 20 million tons (2015 data). The graphite occurs at an andalusite bearing sericite quartz chlorite metamorphic mudstone around a c. 530 km2 Qitianling granite intrusion. A set of coal seam-derived graphite samples from the Lutang graphite deposit in Hunan was examined by geochemical, crystallographic, and spectroscopic techniques to assess changes in the degree of graphitization approaching the intrusion. The carbon content, degree of graphitization, and Raman spectral parameters of series coal seam-derived natural graphite samples show a fluctuating increase with increasing proximity to the granite intrusion. The profile of geological structural features has a close spatial correlation with the variations in the degree of graphitization of series coal seam-derived natural graphite, and a strain-enhanced graphitization model is proposed. Moreover, the geographical distribution and the degree of graphitization are positively related to changes in the iron content of chlorite, suggesting a graphitization process promoted by mineral catalysis during metamorphism. A close spatial relationship exists between graphite mineral and chlorite occurrences when approaching the intrusive mass. The results of this research are important for understanding the role of tectonic stress and mineral catalysis on the genesis of coal-derived graphite.

Impact of Organic Sulfur on Coal Graphitization

“…In the process of artificial graphitization of coal, the fixed carbon in coal provides the material basis for coal‐based graphite, [71–72] and it can also be seen from Figure 1 that the yield of coal‐based graphite has a very significant positive correlation with the fixed carbon content of coal. As the fixed carbon of BYH series coal samples is abnormally low (all below 20.00 %), the yield of coal‐based graphite obtained is also very low, only close to 10.00 %.…”

Electrolytic Conversion of Natural Graphite into Carbon Nanostructures with Enhanced Electrical Conductivity and Na-ion Storage Performance

“…Preparation of carbon nanostructures.-In this research, the electrolytic erosion of flaky natural graphite sourced from Hunan province, China (with the proven reserves of around 10 million tons 14 ) was employed to prepare the electrolytic carbon nanostructure (ECN), based on the method discussed elsewhere. 15 Briefly, the graphite mineral samples were cut and polished to form cylindrical electrodes (H = 10 cm, D = 1.5 cm), which were subsequently used as the cathode in molten LiCl (164 g)-NaCl (86 g), where a graphite crucible (ID = 6 cm, H = 15 cm) was used as both the container, and the anode during the electrolysis process.…”

The Study on the Purification of Waste Graphite Thermal Field Material of FZ-Si Crystal

“…Because of the impurities in the waste graphite thermal field, such as silicon carbide (SiC) (which has similar properties, including excellent corrosion resistance, to graphite), the alkali-acid method was selected to obtain HPG. With the method, HPG products were prepared by removing the impurity of SiC in the waste graphite thermal field [41][42][43]…”