Gangue is a solid waste generated during coal mining and washing, mainly composed of a mixture of rocks, coal dust and other minerals. It usually appears as black or gray blocks, with high hardness and density.

The utilization of coal gangue is of great significance. From an environmental protection perspective, a large amount of accumulated coal gangue occupies land resources and may pollute the soil, water and air. Its effective utilization can reduce environmental pollution and improve the ecology. From a resource perspective, coal gangue contains a certain amount of carbon and other useful minerals, which can be extracted and utilized through technical means, turning waste into resources, improving resource utilization, and alleviating the pressure of resource shortage.