Underground Disposal of Coal Gangue Backfill in China

Abstract

China’s total coal production in 2021 exceeded 4.13 billion tons, 52% of the world’s total. Coal gangue, a solid waste of coal mining accounts for 15–20% of coal production, when directly discharged on the ground surface as waste heaps, it occupies large areas of land and cause environmental pollution. This paper summarizes the existing gangue backfilling methods, their working principles, efficiency, and application status. The methods that are meeting Middle and Western China’s mining demands are discussed in detail. The state-of-the-art technologies that can realize high-efficiency, centralized, and large-scale underground backfilling of coal gangue are analyzed. This paper shows that the industrial implementation of these technologies can increase the current maximum disposal capacity of coal gangue by three times, reaching five million tons per year. The equipment innovation and automation are analyzed, and the environmental effect of coal gangue backfilling is discussed. This review offers inspirations and guidelines for coal gangue disposal and the environmental hazard reduction of coal mining.

Separation and Recovery of Valuable Carbon Components and Li/Ga Metals in Coal Gangue by Using a Flotation Flowsheet

“…Coal is one of the main energy sources in many countries, and coal gangue (CG) is a kind of gray-black rock produced in the process of coal processing and washing, with low carbon content and harder than coal, generally accounting for 15%–20% of coal production in China and 25% of industrial waste emissions. − In recent years, with the significant increase in coal mining activities, CG has also become one of the largest industrial wastes. , From 2010 to 2020, China has produced about 5 billion tonnes of CG; thus, CG has become an important environmental issue . Traditional treatment methods are based on piling up and landfilling, which leads to a large amount of land occupation, as well as the release of a large amount of minerals in the CG into the soil, thus causing serious environmental pollution. , At present, a carbon-neutral environment is a common goal of mankind, and the spontaneous combustion and conventional utilization processess of CG produce direct or indirect carbon emissions, so there is a need to improve the comprehensive utilization rate of CG in the context of carbon-neutrality and to promote the multielement, multicomponent gradient utilization of CG. − …”

Research on preparation and related properties of macro–micro porous mullite ceramic skeletons via twice pore-forming technology

“…China alone has stockpiled 6-7 billion tons and is still increasing at the rate of more than 300 million tons per year. [1][2][3][4] Coal gangue waste can cause serious pollution to the water resources, land, air and the ecological, which poses a great threat to human health. How to deal with coal gangue properly is still a serious problem.…”

Experimental Study on Performance Optimization of Grouting Backfill Material Based on Mechanically Ground Coal Gangue Utilizing Urea and Quicklime

“…Coal gangue (CG) is a solid waste generated during coal mining and washing, which accounts for approximately 15% of coal production [ 11 ]. Currently, the accumulated gangue exceeds six billion tons in China, and the annual increase is about 500~800 million tons [ 12 ]. The incorporation of solid waste into underground backfill provides an efficient strategy for the waste utilization and disposal [ 12 , 13 , 14 ], which minimizes problems caused by its exposure to the environment [ 11 , 15 ].…”

“…Currently, the accumulated gangue exceeds six billion tons in China, and the annual increase is about 500~800 million tons [ 12 ]. The incorporation of solid waste into underground backfill provides an efficient strategy for the waste utilization and disposal [ 12 , 13 , 14 ], which minimizes problems caused by its exposure to the environment [ 11 , 15 ]. Grouting backfill materials (GBMs) based on coal gangue (CG) are highly desirable in coal mining in terms of their accessibility to abundant CG and the urgent demand for utilization and disposal of existing and continuously generated CG [ 11 ].…”