High Temperature And High Pressure Experimental Study On The Response Characteristics Of Minerals And Elements In Coal Deformation

This paper takes the low-rank bituminous coal of Huaibei Qinan Coal Mine in Anhui province as the main research object.Based on the regional structural background and evolution analysis,the deformation experiment on high temperature and pressure conditions of the primary structure coal and SEM-EDX,XRD,ICP-MS,XRF experiments were carried out.In this paper,the occurrence state of minerals and elements of samples were analyzed,and the effects of temperature and differential stress on mineral deformation and element migration and aggregation during coal deformation and their response characteristics to coal deformation were discussed.The results showed that:(1)Based on the analysis of regional tectonic background and its evolution characteristics,the early and middle Yanshan period contributed to forming Xusu arcuate nappe structure is the key tectonic period of coal seam deformation in Qinan Coal Mine,which provides a basis for the selection of conditions for coal hightemperature and high-pressure experiments.According to the actual burial depth,ground pressure and temperature gradient during,the experimental conditions such as confining pressure,temperature and differential stress of coal seam deformation on high temperature and high pressure conditions were determined.The coal deformation experiments on high temperature and high pressure conditions were systematically conducted under the effect of bedding extrusion stress.(2)The macro and micro structure observation and analysis of experimental deformed coal were systematically carried out.With the increase of differential stress,the deformation of the coal sample was promoted,and the degree of deformation of the sample was enhanced.The deformation degree of microscopic fragments,particles and cracks increased.The degree of brittle deformation is increased.The strength of the sample decreased and the plasticity of the sample enhanced with the temperature increased.The fragmented rheological toughness and deformation of the sample are enhanced,leading to the occurrence of traction micro-folds or cleavage zones.Taking calcite minerals as the main research object,it has good response characteristics to coal deformation.(3)The change law of elements during coal deformation were discussed.The low temperature and high stress-strain environment is conducive to the aggregation of the constant elements Ca,Fe,and Mg,while Ti,K,Al,Si,and Na are easily aggregated under the high temperature and high stress-strain environment.Among the trace elements,REE is richer in high temperature and large differential stress conditions in the coal deformation.The high temperature and high stress-strain environment is conducive to the increase of Be,Pb,and Co content.The elements Li and Ga are gathered in high temperature and low stress and strain environments,and the low temperature and high stress and strain environments are beneficial to element Sc.The variation of Ca element is closely related to the deformation and displacement of calcite.