Overview of the triple attributes and their connections of coal gasification slag in China: resources, materials, and environment

A large amount of coal gasification slag (CGS) is piled up or landfilled on the ground, causing serious resource waste and environmental risks. The green reuse of CGS is highly concerned. To fully understand the attribute research and utilization status of CGS, this study quantitatively characterizes the resource attribute of CGS, summarizes the material attributes corresponding to resource attributes, and evaluates the environmental attributes of CGS, and finally analyzes the correlation between the environmental attributes and resource attributes, material attributes of CGS. Research showed that coal gasification coarse slag (CGCS) and coal gasification fine slag (CGFS) exhibit general differences and significant resource attribute in particle size, pore parameters, residual carbon and ash content, chemical composition, and rare earth element (REE) concentration. Based on these resource attributes, CGS can be synergistically utilized for the preparation and development of materials with specific functions and uses, achieving high-value and circular utilization. However, this process is constrained by the environmental attributes. Individual heavy metals in some CGS have varying degrees of environmental risks. There is a correlation between resource attributes and environmental attributes, especially the significant correlation between carbon content, particle size, and heavy metal content, leaching concentration. In the future, gradation and classification utilization of CGS with technical efficiency, economically feasible, and environmentally friendly is a potential development direction.