Flotation response of coal washery reject fines: Characteristics,process optimization,and oxidation |
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Authors: | Gayatri Deepaksingh Hazare Soumya Sucharita Pradhan Nilima Dash Ranjan Kumar Dwari |
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Affiliation: | 1. Mineral Processing Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar, India;2. Mineral Processing Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar, India
Contribution: Investigation, Methodology;3. Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
Central Characterization Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar, India
Contribution: Formal analysis, Investigation, Methodology, Writing - original draft |
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Abstract: | The present paper outlines the characterization, electrokinetic behaviour, and flotation response of rejected coking coal fines with 32.5% ash generated in a coal washery in Eastern India. The response methodology and central composite rotatable design (RSM-CCRD) were used for the process modelling and optimization of the flotation process using diesel, methyl isobutyl carbinol (MIBC), and sodium hexametaphosphate as a collector, frother, and depressant to maximize ash reduction, yield, and combustible recovery. At optimum condition, a 9.7% clean ash coal was achieved with a 63% yield at collector, frother, and depressant dosages of 0.78, 0.31, and 0.80 kg/ton, respectively. The model prediction and experimental data corroborated sufficiently. Subsequently, within 1 year, the fines oxidized and did not float with the collector. Fourier-transform infrared spectroscopy (FTIR) confirmed surface oxidation on oxidized coal. The oxidized coal responded favourably to acid oil, a vegetable oil refinery waste. With acid oil as a collector, the oxidized coal can upgrade to 12% clean ash coal with a 60% yield; the combustible recovered is 80%. The work indicates successful upgradation of fresh and oxidized coal using the froth flotation process. |
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Keywords: | coal washery rejects froth flotation oxidation petrography response surface methodology |
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