Optimization of desulphurization of Artvin–Yusufeli lignite with acidic hydrogen peroxide solutions

In this study in which the Taguchi method was used, the optimization of sulphur removal by H2O2/H2SO4 solutions was carried out over lignite with higher content of sulphur from Artvin/Yusufeli, Turkey. In experiments, the ranges of experimental parameters were between 0.25 and 6.0 mol L−1 for H2O2 concentration, 0.25–4 mol L−1 for H2SO4 concentration, 10–60 °C for reaction temperature, 0.01–0.08 g mL−1 for solid-to-liquid ratio, 15–120 min for reaction time, 200–300 rpm for stirring speed and 710–120 μm for particle size. The optimum conditions for these parameters have found to be 60 °C of temperature, 0.06 g mL−1 of solid-to-liquid ratio, 60 min of reaction time, 250 rpm of stirring speed and −250 + 180 μm of particle size.A statistical experimental arrangement, L25(56) was prepared to determine optimum sulphur removal and ash removal ratios. The obtained yields were 97.85% in removal of total sulphur, 56.54% in removal of pyritic sulphur, 21.33% in removal of organic sulphur and 61.52% in removal of ash. According to variance analysis, it was seen that all parameters were effective in removal of pyritic and total sulphur, reaction temperature, solid-to-liquid ratio, reaction time, stirring speed, H2O2 and H2SO4 concentrations in removal of organic sulphur, and other parameters except acid concentration in removal of ash.