Experimental study on crushing coal by electric and heat in the process of high- voltage breakdown in the air condition

In order to study the feasibility of crushing coal by electric and heat in the process of high-voltage break- down in air environment,as well as the macroscopic and microscopic characteristics of coal,an high-voltage breakdown testing system of coal is built,and the anthracite coal of Linhua coal mine in Guizhou province was selected for the test. Under the needle electrode-needle electrode,the experimental results show that the air dielectric breakdown field strength from 18． 0 to 18. 3 kV / cm,the breakdown field strength of coal body is 0. 3-0. 8 kV / cm,the breakdown volt- age of anthracite coal is less than the breakdown voltage of air. Under the same conditions,the breakdown voltage and damage characteristics of coal samples are not the same,the breakdown voltage ranges between 20 kV and 41 kV,and there are three main types of damage on coal samples. In the process of the crushing coal by high-voltage,the coal samples of plasma channel presents a burning state,formed a large number of cracks and pores. At the same time,the oxidation reaction happened in the coal around the plasma channel under the condition of high temperature,formed new oxidation products.