Experimental Study On The Electrical Parameters Of Coal

This paper systematically studies on the electrical parameters of variation coal in type and structure by using laboratory experiments combined with theoretical analysis. The research results show that there are distinctive differences of electric resistivity between hard coal and tectonic coal in the same mining area. In order to study on the influence factors on measuring the electrical parameters of coal, design and process a test system of electrical parameters of coal samples based on the previous research results and test principle of LCR meter, which can be able to measure the electrical parameters in the course of uniaxial compression and the parameters under various conditions such as different temperature, water content and test frequency as well. The test results show as following:①The electric resistivity of different rank coal samples decreases as the experiment temperature increases, the anthracite coal samples of which has distinct regularity, and the dielectric constant of the anthracite coal samples increases as the temperature increases, while that of the soft coal decreases slightly as the temperature increases.②As the soaking time increases, the electric resistivity of all the different rank coal samples tremendously decreases, and reversely the dielectric constant of those coal samples increases.③The higher the test frequency, the lower the value of the electrical parameters tested.④In the course of uniaxial compression, when the Hebi coal samples of relatively large compressive strength reached the certain value of maximum compressive strength, its electric resistivity abruptly deceases, while the electric resistivity of the other coal samples of relatively small compressive strength such as Jiaozuo and Huainan coal samples gently decreases without abrupt changes, while the dielectric constant changes and the stress-strain curve can achieve the better fitting.⑤the change amplitude of the electrical parameters of tectonic coal samples decreases as loading speed increases in the loading speed tested range, while the electrical parameters change regularity of hard coal is not obvious. This paper explains the above experimental phenomenon by using physical-chemical structure of coal and dielectric physics.