Method for low-temperature pyrolysis and resource utilization of household garbage incineration fly ash

Abstract

The invention discloses a household garbage incineration fly ash low-temperature pyrolysis and resource utilization method, which comprises the steps: unloading fly ash from a storage tank, feeding into a pyrolysis furnace, and carrying out low-temperature pyrolysis; discharging from the pyrolysis furnace, detecting the total residual amount of dioxins in the fly ash pyrolyzing product, feeding the fly ash pyrolyzing product with the total residual amount exceeding 50 ng-TEQ / kg back to the pyrolyzing furnace, continuously pyrolyzing, and preparing the qualified fly ash pyrolyzing product withthe total residual amount not exceeding 50ng-TEQ / kg into a mine filler, wherein the mine filler is prepared by stirring a cementing agent, aggregate, water and an additive, and the cementing agent isprepared by homogenizing a qualified fly ash pyrolysis product, slag, slag and industrial byproduct gypsum; and sequentially feeding the flue gas generated in the pyrolysis furnace into a secondary combustion chamber, a waste heat recovery system, a deacidification system and a dust removal system, and discharging until atmospheric pollutants in the flue gas meet the national emission standard. According to the method, resource utilization of the fly ash is achieved, the absorption capacity is high, the cost is low, and environmental safety is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of domestic waste incineration fly ash treatment, and more specifically relates to a method for low-temperature pyrolysis and resource utilization of domestic waste incineration fly ash. Background technique [0002] Waste incineration fly ash (referred to as fly ash) is a powder material with light bulk density and small particle size that is mainly collected in flue gas pipelines, flue gas purification devices, cyclone separators, and bag filters during the process of domestic waste incineration for power generation. . Fly ash is highly toxic. Fly ash not only contains a large amount of heavy metal inorganic harmful substances such as Cd, Cr, Cu, Ni, Pb and Zn, but also enriches high concentrations of organic carcinogens such as dioxin, which is the most toxic. The hazardous waste clearly listed in my country's "National List of Hazardous Wastes" is code-named HW18. In addition, my country's fly ash still...

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Problems solved by technology

From the perspective of environmental risk control, the co-processing of fly ash in cement kilns is not the best feasible solution, and there are even "fatal flaws": fly ash has high content of volatile elements such as chlorine, sulfur, potassium, sodium, etc., and must be processed before entering the cement kiln. Water washing pretreatment to remove volatile elements, especially chlorine (required content less than <0.04%), which will inevitably produce washing wastewater with high concentration of chlorine salt; fly ash, especially lead and cadmium in grate furnace incineration fly ash The content of highly toxic heavy metals such as mercury and mercury is generally 2-3 orders of magnitude higher than that of cement raw materials. In order to control the content of heavy metals in cement to meet the standard requirements, the absorption capacity of cement kiln co-processing fly ash is relatively limited; during the cement calcination process Most of the highly toxic heavy metals such as lead, cadmium, and mercury volatilize into the flue gas, and most of the lead, cadmium and about 50% of the mercury in the flue gas are captured into the kiln dust, but the cement kiln dust does not follow the Waste management, but return to the kiln for recalcination or directly mix with cement clinker to become part of the cement product, which essentially disperses and dilutes heavy metals into the cement product, increasing the risk of its slow release to the environment; cement products They all have a certain lifespan in the environment, and they will become construction waste after their service period expires. The large amount of heavy metals brought in by co-processing fly ash will undoubtedly become a heavy burden for the treatment and utilization of construction waste in the future.

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