Abstract:
The coal measure graphite is the product of graphitization stage of coal under the action of magmat ic thermal metamorphism and tectonic stress,develops different degree of graphite structure,has graphite or similar physical chemistry characteristics and technological properties,which is an important supplement to the strategic deposit of crystalline graphite.In order to provide a reliable basis for the mineral resources evaluation,development and utilization of coal measure graphite,the metallogenic mechanism and evolution process of coal measure graphite are studied,the applicability of related testing techniques is analyzed in depth,and a lot of test data from typical coal measure graphite mining areas in China are statistically analyzed,to formulate the scientific and reasonable identification index and establish the classification and grading system of coal measure graphite.The results show that the coal measures graphite is composed of graphitized components with different evolution degree and residual coal macerals,having the dual properties of mineralogy and petrology or ore,which is different from the crystalline flake graphite mineral of regional metamorphism,therefore,it is difficult to identify by single index.The formation of coal measure graphite is the evolution of chemical composition simplification and molecular structure ordering,so,the identification index should include two kinds of composition parameters and structure parameters.The volatile component and reflectivity change obviously in coalification stage,and the sensitivity decreases in the graphitization stage,which can be comprehensively used to distinguish coal and coal measure graphite in a preliminary way.The essence of graphitization of coal is the process of the transition from disorder to order,i.e.the increase of crystallinity and the disappearance of defect;thus,the structural parameters such as XRD and Raman are reliable indicators for distinguishing and classifying of coal measure graphite.Based on the statistical analysis of the test data,two kind ores,coal and coal measure graphite can be distinguished by d002=0.344 nm,G peak position=1 590 cm-1 and R2=0.6.Coal measure graphite is divided into semi graphite and graphite,the identification indexes of semi graphite are d002=0.338~0.344 nm,G peak position=1 585~1 590 cm-1,R2=0.5~0.6,and that for graphite are d002<0.338 nm,G peak position<1 585 cm-1,and R2<0.5.In addition,the component index of fixed carbon has no direct relationship with coal metamorphism,as a grade parameter of graphite ore,it can be used to evaluate the quality grade of coal measure graphite ore.