A novel approach for expeditiously assessing residual carbon recovery from coal gasification slag

Residual carbon recovery from coal gasification slag (CGS) is a promising approach for the cascade utilization of CGS, while the inherent complexity and multistep processes in different separation techniques to achieve high-efficiency extraction hampered the rapid assessment of the residual carbon recovery potential. In this study, a self-designed simple water flow classifier was employed to extract the residual carbon from CGS by adjusting the superficial water flow velocities (SWFV). The results revealed the non-uniform carbon and ash distribution in CGS was the basis of residual carbon recovery, while the fine particles with lower carbon content significantly affected the separation efficiency of residual carbon in the water flow classifier. Based on this, a rapid and efficient method for assessing the residual carbon recovery was proposed by combining screening with water flow classification. Particles coarser than 0.075 mm after screening were subjected to water flow classification for carbon extraction. When the SWFV was 36 × 10⁻³ m/s, the carbon content of the floating slag increased to 78.78 %, the recovery rate of combustible reached 76.69 %, and the carbon content of tailings reduced to 8.57 % simultaneously. This method holds the capacity to evaluate the feasibility of the carbon extraction process from CGS, presenting significant potential for the process optimization and large-scale implementation.