Coal gangue industry planning

Gangue is a solid waste discharged during coal mining and coal washing. It is a kind of black gray rock with low carbon content and harder than coal, which is associated with coal seams in the process of coal formation. It includes the driving gangue in the process of roadway excavation, the gangue extracted from roof, floor and interlayer in the process of mining, and the gangue washed out in the process of coal washing. Its main components are Al2O3 and SiO2, in addition, it also contains varying amounts of Fe2O3, CaO, MgO, Na2O, K2O, P2O5, SO3 and trace rare elements (gallium, vanadium, titanium, cobalt).
 
From the perspective of coal mining, China produces 100 million tons of coal every year and discharges about 14 million tons of gangue; From the perspective of coal washing and processing, 20 million tons of gangue will be discharged for every 100 million tons of coking coal washed, and 15 million tons of gangue will be discharged for every 100 million tons of power coal washed. In 2005, various domestic coal mines produced 104.5 billion tons of coal, washed 38.5 billion tons of coal, and discharged 1.9-2 billion tons of gangue. As a result, there are more than 1500 waste dumps in state-owned coal mines in China, with an accumulation of more than 3 billion tons (accounting for more than 40% of China's total industrial solid waste emissions). The massive stacking of coal gangue will not only occupy the land and affect the ecological environment, the leaching water of gangue will pollute the surrounding soil and groundwater, but also contains certain combustibles, which will spontaneously ignite under suitable conditions, and discharge harmful gases such as sulfur dioxide, nitrogen oxides, carbon oxides and smoke and dust to pollute the atmospheric environment and affect the health of residents in the mining area. Therefore, under the influence of national energy conservation and environmental protection policies, comprehensive utilization of coal gangue is extremely urgent.

According to the 13th Five Year Plan for the Development of the Coal Industry issued by the National Development and Reform Commission and the National Energy Administration, the raw coal selection rate in China will reach more than 75% by 2020; The output of coalbed methane (coal mine gas) is 24 billion cubic meters, and the utilization is 16 billion cubic meters; The comprehensive utilization rate of coal gangue is about 75%.
With the development of China's modernization and environmental protection, the development of clean coal technology and the improvement of coal mining mechanization, the emissions of coal gangue and slime will increase. Change“ Waste” For treasure, energy saving and land saving, increase output value, comprehensive utilization of coal gangue is a big“ Money” Jing.

　　 （1） Brick made from coal gangue
The gangue without spontaneous combustion can be used for batching and brick making, and the spontaneous combustion of organic substances contained in it can be used to save raw coal. This method is simple and has been widely used with little investment. Major breakthroughs have been made in the technology and equipment of making bricks from coal and stone, and the manufacturing technology has reached the international advanced level.

　　 （2） Production of light aggregate from coal gangue
The coal gangue suitable for burning light aggregate is mainly carbonaceous shale and washing gangue discharged from the concentrator. The carbon content of gangue should not be too large, and should be less than 13%. There are two firing methods: balling method and non balling method. Non pelletizing method is to crush coal gangue to a certain size and directly roast it.

　　 （3） Coal gangue power generation
Most of the waste discharged during coal mining contains a certain amount of organic matter, which can be used to burn coal gangue in fluidized bed furnace for heating or power generation. The ash after combustion can be used to produce cement and other building materials.

　　 （4） Production of cement with coal gangue as raw material and fuel
Coal gangue and clay have similar chemical composition and can release a certain amount of heat. Using coal gangue to replace clay and some fuels to produce ordinary cement can improve the quality of clinker. This is because the activation energy of raw meal prepared with coal gangue is much lower than that prepared with clay. The pre burning temperature of raw meal can be increased with a small amount of coal, and the combustibles in coal gangue are also conducive to the melting and formation of minerals such as silicate; In addition, the surface energy of raw meal prepared from coal gangue is high, and acid oxides such as silicon and aluminum are easy to absorb calcium oxide, which can accelerate the formation of minerals such as calcium silicate. The production process of coal gangue used as cement raw fuel is basically the same as that of ordinary cement. Mix the raw materials and fuels in a certain proportion, grind them into raw meal, burn them until they are partially melted to obtain clinker with calcium silicate as the main component, and then add appropriate gypsum and mixed materials to grind them into fine powder to make cement.

　　 （5） Coal gangue as cement mixing material
Coal gangue has certain activity after spontaneous combustion or manual calcination, which can be mixed into cement as active admixture, mixed with clinker and gypsum in proportion, and then ground into cement. The amount of coal gangue added depends on the type and grade of cement. Adding 15% coal gangue into cement clinker can produce No. 325 - No. 425 ordinary Portland cement; When the content exceeds 20%, it is pozzolanic Portland cement according to national regulations. When using coal gangue as mixing material, the loss on ignition should be controlled; 5%, S03≤ 3%, the pozzolanic test must be qualified, and the 28 day compressive strength ratio of cement mortar≥ 62%。

　　 （6） Coal gangue as road building and filling material
Gangue filling is an important way to recover. Using coal gangue as filling material in subsidence area can consume a large amount of coal gangue, which can reduce the pollution of coal gangue to the mine environment (polluting water source, polluting atmosphere, affecting environmental health, etc.). While making full use of solid waste in the mining area, it can solve the problem of reclamation of subsidence area, so it has the effect of getting more with one action.