Study on flotation behavior of high carbon coal gasification fine slag

Gasification fine slag is a kind of solid waste with high carbon content produced in the process of coal gasification. At present, it is mainly treated by landfill, which not only occupies a lot of land, pollutes soil and water, but also causes energy waste. The separation of residual carbon and ash in gasification fine slag is the key to realize its high value, reduction and harmless utilization. Taking Yulin high carbon coal gasification fine slag as the research object, based on the analysis of the basic characteristics, the flotation method was used to carry out the carbon and ash separation test. When the diesel oil dosage was 12 kg/t and the secondary octanol dosage was 12 kg/t, the ash content of concentrate product was 35.74%, the ash content of tailings product was 57.07%, the combustible recovery was 43.28%, that the reagent consumption was large, with the poor separation index. The XPS analysis shows that the content of oxygen in flotation feed is high, the content of hydrophobic group is low, and the content of hydrophilic group is high. The induction time decreases with the decrease of particle size. In the flotation process, the coarse particles are not easy to adhere to the bubbles, and easy to drop out and become tailings products after adhesion under turbulent flow condition. The fine particles are easy to adhere to the bubbles, and a large number of fine ash particles are easily “agglomerated” in the adhesion process, resulting in a poor flotation separation effect of carbon and ash components in the coal gasification fine slag. Low field nuclear magnetic resonance analysis shows that both polar and nonpolar reagents are easy to be adsorbed into the pores of coal gasification fine slag. There are sodium oleate and n-hexadecane in micropores, transition pores, mesopores and macropores, resulting in a large consumption of flotation reagents. © 2022 China Coal Society. All rights reserved.