Oil collector flotation of high-ash coal gasification fine slag and the hard-to-float mechanism
Efficient separation of residual carbon and minerals in the gasification fine slag is the premise of its high-value utilization,but the poor floatability of the gasification fine slag has become one of the major issues on its flotation separation.In this paper,the flotation effect and mechanism of the oil collector,dodecane,were studied by using the gasification fine slag from the opposed multi-burner(OMB)coal-water slurry gasifier.Measurements including X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spec-troscopy(FITR)were applied.It is found that the aromatic structure and side chains on the surface of the gasification fine slag are in poor content compared to coal samples,and the existence of rich oxygen-containing groups is found.The pore structures of the gasification fine slag are characterized by low-temperature nitrogen adsorption and mercury intrusion porosimetry measurements.The specific surface area of the sample is 62.03 m2/g,and the pores are widely distributed on nano to micron scale.The liquid-powder wetting measurement and modified Lucas-Washburn equation are applied and wetting processes of gasification fine slag powder by water and dodecane are char-acterized.It is found that the residual carbon of gasification fine slag is more easily wetted by dodecane than that of water,while the miner-als of tailings in gasification fine slag are more easily wetted by water.However,the water wettability of residual carbon and tailings are not in much difference.The adsorption behavior of oil collector in pores is justified by the T2 inversion spectrum of low-field H1 NMR.The ad-sorption behavior of the oil collector in pores increases with the increase of oil dosage and the decrease of oil droplet size.In fine gasifica-tion slag flotation,the oil collector is trapped in the pores in large quantities,which makes it difficult to adsorb on the surface of resi-due carbon,resulting in poor flotation indexes.
gasification fine slagflotationoil collectorlow-filed nuclear magnetic resonanceLucas-Washburn equation
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