ABSTRACT
The northwest region is characterized by wide land area and rich resources, and is also the region for important development at the end of this century and for a very long time in the next century (Kang 2011). Particularly in five provinces in northwest region (Shaanxi, Ningxia, Qinghai, Gansu and Xinjiang), there are rich coal resources. In the “Twelfth Five-Year” planning of the coal industry, the coal production in the central and western regions is 2.09 billion ton/year, accounting for 53% of total coal production in China. With the mining of a large amount of coal, the discharge of coal gangue increases year by year. Coal gangue is a hard black rock with low carbon content coexisting with coal during the formation of the coal, and is discharged during the coal mining (Wang 2013), and it is predicted that the coal gangue in China will be about 40 × 108t in 2020 (Lei 2013). A large amount of coal gangue piles up, which invades the land and destroys the ecological environment, and easily results in the geological disaster. Its leachates will pollute the water body and once being burned, will become hazardous gases, which will pollute the environment and have influence on the human health. So it is critically important to realize the utilization of coal gangue as a resource, turn the waste into the treasure, and make full use of the potential values (Qiu 2014). At present, there is low utilization rate of coal gangue in China, and the comprehensive utilization rate in the Western Region is less than 50%. Except that a small amount of coal gangue is used for power generation and brick making, a large amount of
3 UTILIZATION ROUTES FOR COAL GANGUE
Main constituents of coal gangue are Al2O3 and SiO2, as well as C, Fe2O3, CaO, MgO, Na2O, K2O, P2O5 and SO3 in varying amount and rare elements (gallium, vanadium, titanium, cobalt) in trace amount and so on. In addition to traditional utilization of coal gangue for backfill, wasteland filling, lowland filling, filling of the goaf and collapse zone, coal gangue has multiple utilization methods by using the characteristics of the elements in coal gangue.
