Joint Institute for High Temperatures of the Russian Academy of Sciences (Russia):

Ryabov Yu. V., Ph. D. of Engineering Sciences, Senior Researcher, ryabov1938@yandex.ru

Delitsyn L. M., Doctor of Geology and Mineralogy, Chief Researcher, delitzin@ihed.ras.ru

Ezhova N. N., Ph. D. of Chemical Sciences, Senior Researcher, nnejova@mail.ru

The paper is dedicated to improving reagent regime of carbon flotation (incomplete burning) from fly ash of coal-fired power plants. In flotation experiments on Kashirskaya power plant fly ash samples, the tested petrochemical products featured different content of middle distillate fractions, distillating at boiling point 150–250 °С, — kerosene (content of fractions 100 %), as well as heavy gasoil, produced by Moscow oil refinery plant (content of fractions 10 %). Pine oil was applied as frother. In the experiments with kerosene, effects of reagents consumption and flotation duration upon flotation results were studied. With kerosene consumption from 7.84 to 11.0 kg/t, that of frother – 0.46 kg/t, rougher flotation duration from 5.0 to 8.5 min, and cleaner flotation duration of 5.0 min, concentrates were produced with carbon mass fraction from 67.5 to 68.5 %. Carbon recovery ratio into concentrate amounted from 67.0 to 80.9 %. High kerosene consumption and long duration of unburned carbon flotation may be explained by significant changes in surface properties during burning, decreasing hydrophobicity and flotability. In an effort to decrease reagents consumption and flotation duration, and also increase unburned carbon recovery ratio, a mix of kerosene with heavy vacuum catalytic cracking gasoil (without hydrotreatment), produced by Moscow oil refinery plant, was tested as a collector. Flotation reagent regime with application of flotation reagents mix is characterized by a higher selectivity and lower costs of reagents, if compared with a regime with application of kerosene only. The developed flow sheet is distinguished by simplicity and provides for 100 % of fly ash utilization.

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