Elaborate on the role and advantages of fly ash

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Concept: from the flue gas after combustion of coal in the closing down of fine ash catch called fly ash, coal-fired power plant fly ash is discharged from the main solid waste. Combustion fly ash: coal in the furnace combustion in suspension, in the vast majority of combustible coal can be burned in the furnace, and pulverized in a non-combustible material (mainly ash) mixed in a large temperature the flue gases. These non-combustible by partially melted by the high temperature, and due to the action of surface tension, form a large number of small spherical particles. In the rear of the boiler exhaust fan lead role, contains a lot of ash in the flue gas flow to the furnace tail. With decreasing flue gas temperature, in part due to the molten fine particles was quenched by a certain degree of vitreous state to a higher potential activity. Before the flue gas into the Autoclaved kettle, these small spherical particles, after dust is separated, and collect the ash. Fly ash is one of the larger of China's current emissions of industrial waste, the amount of slag at this stage in our country has reached 30 million t. With the development of power industry, fly ash emissions from coal-fired power plants every year. A lot of fly ash not addressed, it will generate dust, pollution of the atmosphere; into the water if the river will cause blockage of toxic chemicals which can also cause harm to humans and creatures. Therefore, processing and utilization of fly ash caused widespread attention. The advantages of using fly ash mixed with fly ash in concrete saves a lot of cement and fine aggregate; reduce water consumption; improve the workability of concrete mixture; reinforced concrete pumpability; reduced concrete Creep; reduce heat of hydration, thermal expansion; improve concrete impermeability; increase concrete modification. Use of fly ash grading standards: GB level: high quality fly ash and superplasticizer concrete composite technology to produce high-grade modern concrete technology is developing rapidly in China. GB two: high-quality fly ash is especially suitable for pumping concrete, mass concrete, structural concrete impermeability, resistance to sulfate concrete softener and anti-erosion concrete and underground, underwater engineering concrete, grouting concrete and RCC. GB three: fly ash concrete with good workability, pumpability strong finishes improvement, improved impact resistance, frost resistance enhancement advantages. Fly Ash: Fly Ash particles. According ash particle morphology, fly ash particles can be divided into: glass beads; spongy vitreous (including particles smaller, more dense, small pores and particles larger vitreous, vitreous porous); carbon particles . Ash content in the beads of power plant emissions are not high, most of the sponge-like vitreous, particle distribution is extremely uneven. By polishing process, morphology and structure of the original fly ash damage, making it more uniform particle size crushing polyhedron increase its surface area and thus increase the surface activity, improve the performance differences. Fly ash used as a cement, mortar, concrete admixtures and become cement component of concrete, fly ash as a raw material instead of clay to produce cement clinker raw materials, manufacturing sintered bricks, autoclaved aerated concrete, foam concrete, hollow brick, sintered and non-sintered ceramic, paving roads; build a dam, the construction of ports, potholes lowland farmland, coal mine subsidence area and backfill; sorting can drift from beads, beads, iron fine powder, carbon, aluminum and other useful substances, including floating beads, the beads were used as the insulation material may be, refractory materials, plastics, rubber and filler. State coal as its main energy, 76% of electricity is generated by the coal, up more than 400 million tons of coal annually, accounting for 1/3 of the country's coal production in 1997 the country has more than 100 million tons of fly ash emissions to become the world ash largest country, causing serious environmental pollution and take up a lot of land. The chemical composition of fly ash. High silica content, followed by aluminum to form a complex salt complex, less acid soluble. Relatively low iron content, in the form of oxides, acid resistance. Addition of unburned carbon particles, CaO and small amounts of MgO, Na2O, K2O, SO3 and the like. Fly harmful ingredients are unburned carbon particles, water absorption, low strength, easy weathering, is not conducive to Fly resource. Fly in SiO2, Al2O3 on the nature of fly ash ash contributed significantly beneficial in reducing ash melting point of Al2O3, making it easy to form glass beads, both resource beneficial ingredients. The fly ash used in the construction industry, CaO content of the higher bound, can improve their self-hardening, its activity is much higher than the low calcium fly ash, to improve the early strength of concrete is helpful. Ash emissions of power plants for more than 90% of the low-calcium fly ash, fly ash may well improve the development of high calcium ash resource characteristics pathway. Fly Color: Ash looks like cement, due to the combustion conditions and a change in color between the milky gray and black. Ash color is an important indicator of quality, it can not only reflect differences in the number and carbon content. And to some extent also reflects the fineness of fly ash, the deeper the color, the finer ash particle size, the higher the carbon content. Fly ash and calcium fly ash have low calcium points. Usually calcium fly ash color yellow, low calcium fly ash gray color bias. Ingredients Fly: State coal as its main energy, 76% of electricity generated by coal, up more than 400 million tons of coal annually, accounting for 1/3 of the country's coal production in 1997 has exceeded the national emissions of ash. 100 million tons, the world's largest country ash, causing serious environmental pollution and take up a lot of land. The chemical composition of fly ash. High silica content, followed by aluminum to form a complex salt complex, less acid soluble. Relatively low iron content, in the form of oxides, acid resistance. Addition of unburned carbon particles, CaO and small amounts of MgO, Na2O, K2O, SO3 and the like. Fly harmful ingredients are unburned carbon particles, water absorption, low strength, easy weathering, is not conducive to Fly resource. Fly in SiO2, Al2O3 on the nature of fly ash ash contributed significantly beneficial in reducing ash melting point of Al2O3, making it easy to form glass beads, both resource beneficial ingredients. The fly ash used in the construction industry, CaO content of the higher bound, can improve their self-hardening, its activity is much higher than the low calcium fly ash, to improve the early strength of concrete is helpful. Ash emissions of power plants for more than 90% of the low-calcium fly ash, fly ash may well improve the development of high calcium ash resource characteristics pathway. Fly ash particles. According ash particle morphology, fly ash particles can be divided into: glass beads; spongy vitreous (including particles smaller, more dense, small pores and particles larger vitreous, vitreous porous); carbon particles . Ash content in the beads of power plant emissions are not high, most of the sponge-like vitreous, particle distribution is extremely uneven. By polishing process, morphology and structure of the original fly ash damage, making it more uniform particle size crushing polyhedron increase its surface area and thus increase the surface activity, improve the performance differences. Fly ash used as a cement, mortar, concrete admixtures and become cement component of concrete, fly ash as a raw material instead of clay to produce cement clinker raw materials, manufacturing sintered bricks, autoclaved aerated concrete, foam concrete, hollow brick, sintered and non-sintered ceramic, paving roads; build a dam, the construction of ports, potholes lowland farmland, coal mine subsidence area and backfill; sorting can drift from beads, beads, iron fine powder, carbon, aluminum and other useful substances, including floating beads, the beads were used as the insulation material may be, refractory materials, plastics, rubber and filler. Fly Price: Fly now the most commonly used cement and concrete which can be divided into three grade-level ash prices in Hebei bagged 120 yuan / ton, bulk 105 yuan / ton, two bags of 90. / ton, bulk 76 yuan / ton. Three gray very common, and many plants not three gray, prices probably bagged 80 yuan / ton, bulk 67 yuan / ton. Index level Ⅰ Ⅱ Ⅲ 1, fineness (0.045mm square empty sieve),% ≤ 12 20 452, water demand ratio,% not more than 951,051,153, LOI,% not more than 58,154, moisture content, not more than 11% does not require 5, sulfur trioxide,% not more than 333 References: GBJ146-90