Review on resource utilization of coal gasification slag

With the promotion of the “carbon peaking and carbon neutrality” goals, the social’s concern and demand for the treatment of coal gasification slag is becoming more and more urgent. Based on previous research, this paper introduces the main sources and discharge methods of coal gasification slag, and compares the properties and characteristics of coarse and fine slag in terms of morphology, particle size composition, mineral phase, chemical composition, etc, which providing a theoretical basis for the realization of its “reduction, resourcefulness and harmlessness” utilization. According to the obvious differences in properties between coarse slag and fine slag in entrained-flow gasification, this paper explores the different resource treatment methods both of them, and analyzes the limitations of the current utilization methods. Coarse slag has excellent hydration activity and volcanic ash activity, and is widely used in mine backfilling, roadbed filling, cement and concrete aggregate, ceramic materials, wall materials and other low-value utilization fields, but there are problems such as the risk of heavy metal leaching and low economic benefits. Fine slag contains rich carbon residue, and gravity separation and flotation are mainly used for combustible recovery and ash separation. However, the high fine-grained content reduces the precision of gravity separation, and the complex carbon-ash combination morphology increases the difficulty of flotation recovery. At the same time, the pore structure of fine slag is developed, with a specific surface area as high as 258.29 m2/g and certain adsorption capacity. Fine slag has great application potential in fields such as soil improvement, catalyst carrier, chemical raw materials, ceramic materials, adsorption materials, etc. But the complex high-value treatment process and high cost make industrial applications more difficult. In order to address these problems, it is necessary to explore the way of combing large-scale elimination with high-value utilization based on the physical and chemical properties of coal gasification slag, and realize the classified and graded resource utilization of coal gasification slag. It is necessary to explore the treatment method of on-site solution of coal gasification slag, combined with field production practice, which benefits to reduce the transportation cost. As well as the induction of physical and chemical properties to improve the treatment in the process of its generation.