It is sedimentary rock, which was formed at the same time as the formation of coal seam. Mostly limestone. Because of the long-term infiltration and diffusion of coal seam, it also has low carbon content and dark gray.
It is difficult to burn coal gangue alone. It can be made into powder and blended coal for combustion in pulverized coal boilers, and can also be used as fuel in specially designed fluidized bed boilers. Fly ash can be used as a raw material for building materials.
The pulverized coal gangue can also play the role of internal combustion brick making.
bone coal
A sedimentary combustible organic rock formed in early Proterozoic and early Paleozoic. It's black or black-gray. Most of them have the characteristics of high ash, high sulfur, low calorific value and high hardness. Stone coal is a highly metamorphic sapropelic coal or algal coal. Besides organic carbon, it also contains silicon oxide, calcium oxide and a small amount of iron oxide, aluminum oxide and magnesium oxide. There are many classifications of stone coal. According to ash content and calorific value, it can be divided into ordinary stone coal and high-quality stone coal: the ash content of ordinary stone coal is 40% ~ 90%, and the calorific value is below 16.7 kJ/g; The ash content of high-quality stone coal is 20% ~ 40%, and the calorific value is16.7 ~ 27.1kj/g. According to the structure, it can be divided into lump stone coal, granular stone coal, scaly stone coal and powdery stone coal. According to the primary and secondary mineral impurities in stone coal, it can be divided into siliceous stone coal and calcareous stone coal. Stone coal is widely distributed in China, with the most abundant reserves in South Qinling. Stone coal can be used as fuel, burnt slag can be made into building materials such as carbonized bricks and cement, and metal elements such as vanadium, uranium, molybdenum, nickel, copper and cobalt can also be extracted from stone coal.