Fly ash is the fine ash collected from the flue gas after coal combustion. Fly ash is the main solid waste discharged from coal-fired power plants. If a large amount of fly ash is not treated, it will produce dust and pollute the atmosphere. However, after processed, fly ash can be used as a resource, such as concrete admixture etc.
In the following part, we mainly introduce how to process fly ash and what is it used for.
The fly ash processing system is composed of dryer, elevator, silo, grinding mill, fan, powder concentrator, dust collector, pipeline device, etc. The system structure is simple, the layout is compact, the process is smooth, and the negative pressure and closed cycle are used to avoid secondary pollution.
The fly ash grinding process can be divided into open circuit and closed circuit systems.
Open circuit grinding process
The system takes the ash from the coarse ash silo, and after it is measured by the spiral electronic scale, the coarse ash is continuously and stably fed into the grinding mill by the elevator. The coarse ash fed into the mill is directly ground into Grade I and Grade II ash with fineness meeting the standard, without further screening or separation. The finished products from the mill are stored in the finished product ash silo.
Closed circuit grinding process
The grinding system feeds materials from the raw material warehouse. After quantitative feeding and metering by the speed regulating electronic belt weigher, the fly ash is fed by the elevator to the grinding mill for sorting, and the sorted fine ash enters the fine ash warehouse while the coarse ash is sent to the mill by the air conveyor for grinding. The pulverized fine powder is fed to the separator by the original ash elevator for separation, and then the pulverized fine powder is separated in the separator. The fine powder selected by the powder concentrator enters the fine ash silo, and the coarse powder is reground to form a loop flow mill system.
The fly ash processing system can be divided into the coal ash sorting system and grinding system.
In the sorting system, the coal ash is sorted by the separator to separate the qualified pulverized coal and large particles in the coal ash; in the grinding system, the grinding mill grind coarse fly ash into qualified fine powder.
According to different application fields of fly ash, fly ash processing equipment can be configured with different production processes:
Front stage
Raw material storage: the fly ash raw materials in the flue gas of the power plant are collected by the electrostatic dust collector or the pulse dust collector and transported to the powder tank for storage.
Grinding stage
The fly ash in the powder tank is sent to the fly ash grinding mill through the electromagnetic vibration feeder for grinding.
Collecting stage
The fine pulverized fly ash is collected by the dust collector and dust collecting device.
Finished product transportation stage
The collected finished products are sent to the downstream or finished product warehouse, and then the finished products are loaded and transported.
1, the fineness of finished fly ash is fine, which is a new type of grinding;
2, by adopting open flow production process, which can reach the fineness of commercial ash without further sorting;
3, the silo pump or jet pump can be used for conveying fly ash in and out of the mill. The layout is flexible and convenient. The fine ash silo is far away from the mill workshop and can also realize barrier free conveying;
4, each dust raising point is equipped with a bag dust collector, which will not produce secondary pollution;
5, high automation of production management;
6, compared with traditional cement grinding system, this system has high equipment configuration and more reliable operation;
7, large production capacity.
Fly ash is a kind of active mineral fine powder resource. The research shows that different fineness of fly ash has different effects on silicate hydration products. SBM manufactures different types of grinding equipment for fly ash grinding process. They can grind fly ash into different fineness for different applications.
Adding fly ash to concrete can save a lot of cement and fine aggregate;
Reduce water consumption;
The workability of concrete mixture is improved;
Enhance the pumpability of concrete;
The creep of concrete is reduced; Reduce hydration heat and thermal expansion;
Improve the impermeability of concrete;
Increase the decoration of concrete;
Reduce the cost of concrete.
From the perspective of chemical composition, fly ash is mainly composed of silica aluminate materials such as SiO2 and Al2O3, which has the characteristics of clay, so it can replace clay to produce cement. At the same time, the remaining carbon from fly ash can be put into the fuel for burning cement clinker, which can save a lot of fuel.
Compared with ordinary Portland cement, fly ash type cement has greater advantages, such as low hydration heat, good sulfate resistance, low early strength and rapid growth in late strength.
In the rubber industry, when the silicon content of fly ash reaches 30%~40%, it can be used as filler and carbon black reinforcement. When the amount of active fly ash increases, the stiffness of rubber is increasing, and the shrinkage of products is reduced. At the same time, due to the good compatibility of fly ash, it is evenly distributed in the rubber mixture, and its mold filling is good, which can be applied to various types of rubber products. In general, after add fly ash in the rubber material, the waterproof material produced has the advantages of low cost, pollution-free, safe and non-toxic.
With fly ash, quicklime or other alkaline activators as the main raw materials, a certain amount of gypsum can also be added, and a certain amount of coal cinder or water quenched slag and other aggregates can be added, after processing, mixing, digestion, wheel milling, pressing molding, atmospheric or high-pressure steam curing, the steamed fly ash brick can be formed.
Fly ash has good physical and chemical properties, and can be widely used to transform heavy clay, raw soil, acid soil and saline alkali soil to make up for the defects of its acid thin board adhesion. Fly ash contains a large amount of water-soluble silicon calcium magnesium phosphorus and other essential nutrients for crops, so it can be used as agricultural fertilizer.
Fly ash can be used to manufacture molecular sieve, flocculant, adsorption material and other environmental protection materials.
Fly ash is one of the raw materials for the production of inorganic fireproof insulation board, and the raw materials for green energy inorganic fireproof insulation board are 70% ordinary cement and 30% fly ash.
Some researchers have taken fly ash as a new raw material for paper making, and analyzed the principle of improving the tensile strength and internal bonding strength of paper with fly ash through electron microscope.
Feel free to contact SBM if you need the above mentioned fly ash processing equipment.
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