Coal Pretreatment Technologies for Clean and Efficient Utilization: A Review

Abstract

As a cornerstone of global energy consumption, coal is extensively utilized in power generation, iron and steel, building materials, chemical industries, and heating. It has made significant contributions to the global economy and will remain indispensable in the energy sector for the foreseeable future. However, coal utilization is accompanied by emissions of high ash, sulfur, heavy metals, and other harmful elements. Thus, implementing effective and viable pretreatment prior to its use is crucial. This review summarizes the current research progress, classification, underlying principles, and challenges of coal pretreatment technologies. It examines the influence of the physicochemical properties of coal on pretreatment processes and subsequent utilization, with particular emphasis on a comparative analysis of relevant processes oriented toward three primary objectives: deashing, desulfurization, and graded efficiency utilization. Physical pretreatment technologies feature mature processes, large treatment capacities, and low cost, but they struggle to remove intrinsic impurities that are chemically bonded or finely dispersed. Chemical pretreatment technologies can achieve deep desulfurization, deashing, and structural modification, yet they generally face severe challenges such as high reagent consumption, high energy intensity, equipment corrosion, and secondary pollution. Biological pretreatment technologies offer mild operating conditions and environmental friendliness, but they suffer from slow reaction rates, difficulties in process scale-up, and narrow adaptability to different coal types. Future advances in coal pretreatment technologies are expected to focus on intelligent process control, multitechnology integration, recovery of value-added components, and application-oriented pretreatment strategies, aiming to enable the clean and efficient utilization of coal and support the sustainable development of the energy sector.