An experimental research on ultrasonic parameters of coal

Ultrasonic velocity, attenuation coefficient, time domain and frequency domain features in anthracite coal of Daanshan and fat coal of Sanhejian were studied by acoustic emission experimental techniques. Research results indicate that affected by voidage and moisture content, the mean wave velocity in anthracite coal is larger than that of the average velocity in fat coal, and the mean value of its attenuation coefficient is lower than that of attenuation coefficient in fat coal.Time domain and frequency domain features of ultrasonic are influenced by coal quality and waveform frequency,anthracite has greater amplitudes of main frequency and shorter decay period than fat coal.When the wave frequency increases, the decay time decreases and energy of transmission waveform is more gathered in main frequency. These conclusions can provide theory basis for determination of coal quality and type before coal mining.