The formation principle of natural graphite mainly includes two stages: Carbonaceous sedimentation and enrichment stage and metamorphic mineralization stage. First of all, the sources of carbonaceous materials are mainly organic carbon and inorganic carbon, among which organic carbon occupies a dominant position, mainly from algae plants and micro-ancient remains in the primitive ocean; inorganic carbon mainly comes from carbon-containing inorganic substances such as carbonate rocks formed in the marine environment. These carbonaceous materials accumulate and are buried on the seabed, forming carbon-rich sedimentary layers. Subsequently, during the movement of the earth's plates, these sedimentary layers gradually moved to the deep crust. The high temperature and high pressure environment made the scattered carbonaceous materials quickly and orderly form graphite nuclei, and slowly aggregated and grew to form graphite crystals. 1. The formation conditions of natural graphite include temperature and pressure. The closed environment of high temperature and high pressure is the primary condition for the transformation of carbonaceous materials into graphite, and the crystal growth time is an important factor in the degree of graphitization. Specifically, gasification refers to the process in which high-temperature and high-pressure gaseous carbon-containing compounds deep in the earth rise along the cracks in the earth's crust and decompose into high-purity large-crystalline graphite veins in places with lower pressure; deep metamorphism refers to the deep metamorphic products obtained by pyrolysis of coal or asphalt in the stratum under high pressure and abnormally high temperature.
The distribution of natural graphite is also very wide. The world's proven reserves of natural graphite are about 280 million tons, and China's reserves are about 81 million tons, accounting for about 1/4 of the world's total. China's graphite reserves are mainly concentrated in Heilongjiang, Shandong, Inner Mongolia and Hubei. Among them, Heilongjiang is the largest crystalline graphite reserve province in my country, accounting for about 2/3 of the country's crystalline graphite reserves.
In addition, natural graphite often coexists with quartz, feldspar, etc., or is generated in deeply metamorphosed coal seams.