Characteristics of particle size classification and classified separation for coal gasification fine slag

A considerable volume of coal gasification fine slag (CGFS) has hampered the growth of the coal chemical sector. Carbon/ash separation in CGFS is a prerequisite for efficient treatment and resource utilization. This work focuses on the residual carbon classified separation of CGFS. The composition and structural characteristics of CGFS were studied through wet screening, and classified it on the differences in physicochemical properties. And then, it investigates the interface separation and density separation characteristics of different classification components of CGFS. The results show that the CGFS can be divided into high-ash fine-grained (HAFG) component (<0.074 mm), high carbon (HC) component (0.074–0.25 mm), and high-ash coarse-grained (HACG) component (>0.25 mm). The HAFG component is appropriate for interface difference separation, producing a carbon-rich product (fragmented carbon) with an ash of 32.90% and a mineral-rich produce (powdery ash) with an ash of 96.29%. The HC component is appropriate for density difference separation, producing a carbon-rich product (porous carbon) with an ash of 17.41% and a mineral-rich product (sandy ash) with an ash of 92.05%. The HACG component does not need to be decarbonized.