The reuse and recycling of coal mining waste with zero-waste approach by technological development and integrated management for sustainable growth and benefits

Coal mining industries generate hundreds of millions of tonnes of waste coal, rock and cleaning waste stream containing fine coal (a by-product of previous coal processing operations), coal gangue, coal sludge, fly-ash, coal mine drainage and coal bed methane (CBM) that contaminate the landscape in the mining areas. Examples of waste coal include fine coal, coal obtained from a refuse bank or slurry dam, anthracite culm, bituminous gob and lignite waste. In 2008, China had produced 2716 Mt of raw coal, accounting for approximately 40% of the total world production and overtook the United States as the world's largest producer of carbon dioxide. In China, about 95% of total coal production is from underground coal mines producing 660 million tonnes of coal mining waste (CMW) annually, out of which about 62% are reused and recycled (Cui et al., 2015). The average production of coal mining waste is about 15% of coal production, which varies from 10 to 15% with the change of geological and mining conditions (Haibin and Zhenling, 2010). Therefore, it is estimated that the annual production of coal mining waste is about 315 million tonnes for underground coal mining since 2007, which accounts for a quarter of the total industrial solid waste. There are about 4.5 billion tonnes of coal mining wastes stockpiled at 1700 waste dumps, occupying 15,000 ha lands (Bian et al., 2009). If the gangue is exposed to air and piled on land, it will pollute the environment considerably. Waste coal piles leach toxic metals—such as iron, manganese, aluminium, mercury and arsenic into waterways—and cause acid drainage that kill neighbouring aquatic ecosystems. These piles sometimes even catch fire through spontaneous combustion. The coal combustion waste constitutes the second largest waste stream after municipal solid waste in the United States (Sturgis, 2009).