Ultrasonic investigations of coals under solvent treatment

摘要

The measurements of density, velocity of ultrasonic longitudinal waves at frequency of 2.5 MHz, and dynamic elastic modulus were made for raw and demineralized bituminous coal, subjected to action of selected solvents such as: methanol, tetrahydrofuran, pyridine and ethylenediamine. It was found that the measured values are different for samples after a treatment of solvents. Ultrasonic velocities and elastic moduli after solvent action are mostly higher in demineralized than raw coal samples. The dependence of elastic modulus on swelling exhibits the same nature as that found for polymers.