Research on grinding and flotation decarbonization of coal gasification fine slag

Abstract

Coal gasification fine slag is a solid waste generated during the coal gasification process. Typically, it is mainly disposed of through landfill or stacking and has not yet been widely utilized on a large-scale industrial level. This study focused on the dry coal gasification fine slag obtained from a specific location in the North of China, considering its characteristics such as high ash content, high porosity, and continuous components. In order to fully dissociate the residual carbon and vitreous body, the ALC-1.5 grinder was employed for pre-grinding after identifying the material composition, particle size composition, surface morphology, and internal structure of the slag. Subsequently, flotation was utilized to separate carbon and ash in the gasification fine slag. Experimental results revealed that fine grinding significantly increased the exposure of the slag′s residual carbon surface, greatly enhancing its floatability. Using the secondary flotation process with a grinding time of 3.5 min, the roughing flotation progress employed 14 kg/t of 3# oil and 3 kg/t of Methyl Isobutyl Methanol (MIBC), while the scavenging flotation progress used 14 kg/t of 3# oil and 1.5 kg/t of MIBC. The resulting concentrate exhibited a rate of 3.20% with an ash content of 26.91%. The tailings had a mineral content of 37.67% and an ash content of 91.77%. The loss on ignition (LOI) was measured at 8.23%. Overall, the tailings product met the requirements of Class III fly ash.

Keywords

• coal gasification fine slag
• decarbonization
• grinding
• flotation
• loss on ignition