Review on the attribute cognition and carbon-ash-water separation of coal gasification fine slag

Coal gasification fine slag (CGFS), as a typical solid waste, the annual production is increasing. At present, the main disposal methods of CGFS are landfill and storage, which have considerable potential for environmental pollution. Therefore, many researchers have devoted to exploring suitable ways for resource utilization of CGFS, but its high water and ash content restrict its resource utilization, so dewatering and carbon-ash separation should be emphasized. The physicochemical properties of CGFS also affect the dewatering and carbon ash separation process. Under the trend of carbon emission reduction, how to choose efficient and low energy consumption dewatering method according to the water occurrence characteristics of CGFS should be the future research direction. Based on the gasification fine slag surface properties, the development and design of combined flocculants-surfactants is a promising direction to improve the dewatering effect. Moreover, it is worth noting that froth flotation is an effective path to separate carbon and ash from CGFS. Flotation reagent molecular design, process optimization and flotation cost control are the development directions of froth flotation technology. Dewatering of carbon and ash components also need to be developed after the flotation separation process. The comprehensive consideration of the separation of carbon, ash and water from gasification fine slag is a promising idea to realize the harmless disposal and promote the resource utilization of components. This paper systematically summarizes the physical and chemical properties of CGFS and compares the research progress of CGFS dewatering and carbon-ash separation methods. The research direction of CGFS efficient dewatering and large-scale carbon-ash separation methods are clarified, which will provide a basis for its efficient resource utilization.