Froth flotation beneficiation and physiochemical characterization of coal from Achibo-Sombo-Dabaso area, southwestern Ethiopia

Abstract

This study was carried out with one of the physiochemical techniques of coal sample beneficiation using froth flotation technique for upgrading the quality of Achibo-Sombo-Dabaso coal, southwestern Ethiopia. The investigations aimed to beneficiate high impure Ethiopian coal and to minimize its impurities present, so that it can replace the imported coal and the environmental pollution generated during combustion is reduced. The proximate and ultimate characterization studies show that the raw coal samples contain 11.81–20.27% moisture, 22.47–36.58% ash, 22.74–34.85% volatile matter, 23.85–38.31% fixed carbon, 1.22–1.44% nitrogen, 0.57–1.9% sulfur with 3243.59–5295.34 kcal/kg calorific value. Froth flotation experiments were carried out on the raw coal samples at varying parameters of collector dosages (0.0095 kg/ton, 0.0283 kg/ton, 0.0472 kg/ton, 0.0661 kg/ton and 0.085 kg/ton of diesel oil), frother dosages (0.0922 kg/ton, 0.1845 kg/ton, 0.2767 kg/ton, 0.3689 kg/ton and 0.4611 kg/ton of n-octanol) and particle size (500–250, 250–125, 125-63 μm). The experimental results for the treated coal samples are 8.12–14.02% moisture, 7.49–13.62% ash, 21.92–30.64% volatile matter, 44.47–55.87% fixed carbon, 0.52–0.92% nitrogen, 0.25–0.41% sulfur content with 5243.40–6531.46 kcal/kg of calorific value. The results of this study indicate that the treated coal samples are relative with high calorific value, fixed carbon and low ash content compared to the raw samples. The coal samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) to understand the flotation and size distribution of coal. Therefore, the froth flotation technique at parameters of collector dosages (0.0472 kg/ton of diesel oil), frother dosages (0.3689 kg/ton of n-octanol) and particle size (125-63 μm) is effective to increase the calorific value above 5000 kcal/kg and increment carbon content of Achibo-Sombo-Dabaso coal that suitable as an energy source in cement and steel industries.