What is coal gangue?
Coal gangue is an abandoned rock discharged during coal mining and processing. When mining coal, the rock layers or bottom plates from the roof of the coal seam, as well as the various types of rock excavated and blasted from around the coal seam during the excavation are all called coal gangue.
Generally, the comprehensive discharge of coal gangue accounts for 15% to 20% of the original coal production.
Long-term accumulation of coal gangue not only occupies a large amount of land, but also causes atmospheric and groundwater contamination due to spontaneous combustion and sewage leakage.
Coal gangue utilization is an important part of comprehensive utilization of resources. The utilization of coal gangue can increase the economic benefits of coal enterprises, improve coal mine production structure and environmental quality.
What are the uses of coal gangue?
The applications of coal gangue
1. Energy field
In China, the total installed capacity of generators of low calorific value fuel such as coal gangue reached 28 million kW, and the single unit capacity was from 6 to 300 MW. The annual utilization of coal gangue was 140 million tons, and the annual power generation was 160 billion kW·h.
France has an annual output of about 8.5 million tons and a stockpile of 1 billion tons. The coal gangue with an ash content of 65-70% is washed for power generation.
Since the 1970s, the US Bureau of Mines has sampled and analyzed all coal gangue hills and made comprehensive plans for coal gangue utilization. For example, the heat energy is directly recovered from the burning coal gangue mountain for both recovering the heat and controlling pollution.
2. Building materials field
It includes the production of coal gangue bricks, instead of clay to produce cement, ceramics, and concrete lightweight aggregates.
Because coal gangue brick products have characteristics of lightweight, high strength, good load-bearing seismic performance, excellent thermal insulation, heat insulation and sound insulation, so it is a broad market.
3. Engineer packing materials
It includes coal gangue road construction, land reclamation, backfilling goaf and subsidence area.
Road construction and backfilling are also important ways for comprehensive utilization of coal gangue. The use of coal gangue as engineering packing materials do not require an increase in cost and need a large amount of use, which brings good economic efficiency to the coal mine.
4. Chemical products field
Coal gangue contains various elements, especially rare elements, and the highest content of chemical components is SiO2 and Al2O3.
There are three main types of coal gangue for chemical use: the first is to extract a rare element in coal gangue by various methods, such as Ga, Se, Ti, Co, etc. The second is to recover beneficial mineral products such as kaolin; the third is the production of silicon, aluminum, sulfur and other inorganic chemical products.
5. Agricultural field
Using coal gangue to produce organic compound fertilizer, microbial fertilizer or soil amendment.
The use of coal gangue fertilizer is mainly based on the fact that coal gangue contains rich organic carbon, and the organic matter content in the soil can be greatly increased after being applied to the soil.
Why use a roll crusher for coal gangue crushing?
1. From the perspective of characteristics of coal gangue and roll crusher
- In general, coal gangue contains a variety of rocks, the matrix of which is mostly composed of clay minerals, mixed with varying amounts of detrital minerals and carbon, so coal gangue can be regarded as a medium hardness clay mineral.
- For the roll crusher, it relies on the friction generated by two rollers who rotate in opposite directions, and the material is brought into the crevice between the two rollers and is crushed by continuous extrusion. It is mainly used to crush materials below medium hardness, such as bauxite, phosphate rock, zirconium quartz, clay, shale, coal gangue and so on.
2. From the perspective of the main use of the roll crusher and coal gangue
- Coal gangue sintered porous bricks and hollow bricks are kinds of energy-saving wall materials, mainly replacing solid clay bricks for permanent buildings. Most of the coal gangue components are clay rock and gray rock which contains a certain amount of calorific value.
- When roasting, it does not need to use the heat of the outside coal. Therefore, coal gangue as a raw material to burn building materials products - coal gangue sintered porous bricks, hollow bricks, which is an energy-saving project.
- The roll crusher is the most used crushing equipment in the brick and tile industry. It is also the oldest crushing machine. Almost as long as there is a brick factory, you can see the roll crushers.
- The range of adaptability of the roll crusher to the raw material is very wide. For materials with a moisture content of more than 25%, the roller can also be handled easily and freely, which is unmatched by much other crushing equipment. It is for these reasons that the roll crusher is so favored by brick factories.
Advantages of roll crusher
Advantages of roll crusher
The roll crusher is mainly suitable for fine crushing operations with a feed size of less than 150 mm and a finished product size of 100 mesh to 2 mm. What are the advantages of the roll crusher in use?
- 1 It has a simple and compact structure with small occupation and convenient operation and maintenance.
- 2 The cost is low and the operation is stable, with high energy and crushing efficiency, and adjustable discharge port.
- 3 It has a light weight, small size, significantly saving investment.
- 4 The roller crusher is equipped with safety protection devices. When metal pieces enter the crushing chamber, the protective device works and lets the metal leak out of the machine without stopping it.
- 5 The inside is equipped with dustproof board, which has good sealing performance, avoids splashing of fine materials after crushing, with less dust, low working noise, largely improving the working environment.
- 6 The gap of the abrasive roller can be adjusted arbitrarily between 1mm and 20mm. After adjusting the roll gap according to the requirements, the crushing particle size can be reliably controlled, and all of them are discharged from the lower part of the crushing cavity with the ideal size.
- 7 The roller crusher is working in low speed and high pressure with extruding materials which fall vertically into the crushing chamber from the upper part, and are crushed by the strong pressure generated between the two rolls.
- Most of the material has become powdery, and a large number of cracks have been generated in the interior of the small granular material. Thus, in the further pulverization process, the grinding energy consumption can be greatly reduced and the yield can be increased.
- 8 The roller crusher is equipped with a replaceable wear-resistant lining plate which adopts domestic advanced technology, and has the advantages of long service life, easy damage and convenient maintenance.
- The continuous service life can be more than one year, and can be easily changed when the wear is seriously damaged. The maintenance quantity is small and the cost is low, which is unmatched by other types of crushers.
How to crush coal gangue by using a roll crusher
1. Crushing step by step
Compared with the striking type crushing equipment, the biggest disadvantage of the roll crusher is that the "crushing ratio" is relatively small, the particle size of the product changes with the wear of the gap of the roller, and the crushing effect on the sheet-like material is poor.
It is necessary to make efforts to avoid its shortness and give full play to the advantages of high output, low power consumption and wide adaptability to moisture.
Therefore, the most important thing about using the roll crusher is the method of stepwise crushing. When crushing coal gangue, it should go through three processes of "coarse-middle-fine crushing".
2. Grinding and maintaining frequently
The surface of the roll crusher is easily worn to grooves and makes the gap between the rolls larger, thereby reducing the crushing effect. When the roller is new, the gap between the two rollers is the smallest, and the fineness of the crushing is the best.
However, after the groove is ground, the gap between the two rolls becomes large, and the particle size of the raw material becomes coarse, which is a peculiar phenomenon for the roll crusher.
Therefore, to obtain a good coal gangue crushing product, the work we have to do is to minimize the variation value from fine to coarse, and to control the crushing particle size within the allowable range to ensure the quality of the product.
To achieve this goal, it is necessary to continuously grind the roll surface, maintain the flatness between the two rolls and a certain gap, thereby ensuring the fineness of the raw material.
Configuration for coal gangue crushing production line
When crushing coal gangue, to achieve the target particle size, three processes of "coarse-middle-fine crushing" are usually carried out. According to the previous configuration experience, we configure a detailed crushing production line for the 10t/h coal gangue:
Raw material warehouse→GZD650×2300 vibrating feeder→PE400×600 jaw crusher→2PG0640 roll crusher→3YK1237 vibrating screen→DMC64 dust collector→finished silo (also several B500 conveyors of different lengths).
Finished product specifications: 0-10 mm, 10-50 mm, 50-80 mm
It can be seen from the above that when there are three specifications of the finished coal gangue, the jaw crusher can be used as the first crush, and the roll crusher is used for the medium and fine crushing.
Due to the adjustable particle size of the roll crusher, when the discharge size is finer, the user can also configure different numbers of pairs of roll crusher meet their needs.
Roll crusher on site