The Effects of Temperature and Mineral Acids on the Demineralization Degree of Nallihan Lignite

Abstract

Demineralization of lignites from Nallihan, Turkey, was investigated using various aqueous acids, such as HCl, HNO3, and H2SO4, which were used at the concentrations of 5 and 10 vol%, hydrofluoric acid (HF) acid solutions of 5, 10, 20, 30, and 40 vol%. The experiments were done at 20, 40, 50, and 60 degrees C temperatures in order to observe the heating effect on the removal yields. The best result was found for the sample being done experimentally with 5% HF. The ash content is decreased from 17.12 to 6.98 wt% and heating value is increased from 16,652 to 23,950 kJ/kg according to the original lignite. The yields are 59.23 and 44%, respectively. Fourier transform infrared and X-ray diffraction were used to observe the leaching effect of the mineral acids on the demineralization degree of Nallihan lignite.