Properties of flotation residual carbon from gasification fine slag

The purpose of this study was to upgrade the fine slag by a froth flotation kinetics process in order to separate and recycle the residual carbon and tailing ash simultaneously. Fine slag, a kind of solid waste, was obtained from an entrained-flow gasification unit. The carbon content of flotation residual carbon was 64.47% by weight, which is about 3 times of that of gasification fine slag. The results show that when the particle size of fractions is higher ( > 75 mu m), the carbon content is higher, even > 80%. The fine slag and flotation residual carbon were characterized by elemental and proximate analysis in order to compare the H/C, O/C, and element characteristics. The morphology of fine slag was determined by scanning electron microscopy (SEM). It was found the grinding time of 6 min can meet the crushing requirements of large particle flotation residual carbon. The grinding volume ratio of > 80% is < 75 mu m sieving, which is a benefit for further fuel utilization. The non-isothermal thermo-gravimetric analysis (TGA) and loss on ignition (LOI) at 450 degrees C & 550 degrees C methods were used to analyze and compare the oxidation of residual carbon. In conclusion, LOI at 550 degrees C and non-isothermal TGA approaches can be used to determine the carbon content, which provides a reference for the determining LOI of waste-derived fuels in industries.