Desulfurization of Lignite and Coal Using Alkaline Solution from Biomass Ashes

Abstract

This study has shown the technical potential of biomass ash to contribute to the desulfurization of problematic high sulfur lignites. The alkaline desulfurization is more effective in removing the pyritic sulfur from the coal, which is the less abundant form than the organic sulfur. Lignite and coal samples from Turkish resources were extracted with an aqueous alkaline solution obtained from the water-soluble fraction of biomass ash. By this method, high sulfur removal from lignites was possible. The effect of temperature, the amount of biomass ash used, extraction time, and stirring speed were studied in the range of 10–50 g, 350–550 K, 0.042–1.8 MPa, 15–60 min, and 300–600 rpm, respectively. The effect of pyritic and organic sulfur removal were investigated. This process removed 33.1, 35.3 and 37.2 % of total sulfur contents; 52.3, 53.6 and 60.7 % of pyritic sulfur contents; and 4.6, 22.1 and 18.0 % of organic sulfur contents from the lignite samples, respectively.