Content area
Full Text
Introduction
Coal gangue is a solid waste generated during coal mining and processing, accounting for approximately 10–20% of original coal production [1]. China, India, and the United States are the leading coal-consuming countries [1]. In 2021, over 50% of energy consumption in both China and India was derived from coal [2]. Notably, the cumulative stockpile of coal gangue in China has reached 7 billion tons and continues to grow at an alarming rate of 2–4 billion tons annually [3]. In Europe, 175 million tons of coal waste have been deposited in landfills over decades. In developed countries, such as those in Europe and North America, the comprehensive utilization rate of coal gangue exceeds 90%. In contrast, the average utilization rate in developing countries like China remains relatively low, with a predominant reliance on storage [4]. The substantial accumulation of coal gangue in mining areas has resulted in severe environmental, social, and economic challenges [5]. Open-air storage presents significant environmental concerns due to the presence of heavy metals and organic pollutants [6]. These harmful substances can leach into surface water or soil through rainfall, disrupting the ecological balance [7, 8]. Moreover, the spontaneous combustion of coal gangue releases hazardous gases, contributing to air pollution. The accumulation of pollutants poses a threat to the environment and increases the risk of landslides and explosions, further exacerbating the detrimental effects on mining areas [9].
Coal gangue possesses diverse functional characteristics, including low calorific value, suitability as a chemical raw material, use in building materials, and inert properties [10]. Research into the comprehensive utilization of coal gangue is immense practical significance for fostering sustainable development in environmental, social, and economical terms [11]. Over the past two decades, many countries have actively sought to utilize coal gangue in various industries. This versatile resource has been applied in sectors such as power generation [1], road construction [12], building materials [13], underground filling [14, 15], alumina preparation, and agricultural production [16]. In eastern China, coal gangue has been used in the production of building materials and fuels. However, in the western regions, where coal gangue production is relatively high, the demand for building materials remains comparatively low. The application of comprehensive utilization technologies for coal gangue is influenced by various economic factors, thus...