A method and system for treating domestic waste incineration fly ash wet mold bag

Abstract

The invention discloses a method and system for treating domestic waste incineration fly ash wet mold bags. Through the three links of fly ash pulping, fly ash slurry transportation, and fly ash slurry dehydration / hydration consolidation, it can fully and simultaneously realize Fly ash homogenization, heavy metal and dioxin detoxification, desalination, and spontaneous hydration consolidation molding; the consolidated mold bag body can be landfilled, or the fly ash can be taken out of the mold bag for resource utilization; The liquid discharged from the mold bag is used for natural evaporation and concentration in the landfill space, and is recycled after heavy metal and dioxin recovery and filtration and impurity removal, or after further salt extraction. The invention can avoid the shortcomings of the traditional dry landfill and water washing pretreatment technologies of fly ash, and can realize the integrated treatment of fly ash homogenization, detoxification, desalination, spontaneous hydration consolidation and landfilling, and is also a follow-up fly ash resource. The chemical utilization has laid the foundation, the processing cost is low, and it can be applied to large-scale industrial production.

Description

technical field [0001] The invention belongs to the technical field of solid waste treatment and disposal, and in particular relates to a method and a system for treating domestic waste incineration fly ash wet mold bags. Background technique [0002] Domestic waste incineration fly ash is a kind of gray-white or dark gray fine powder with low moisture content, generally rod-shaped, horny, cotton-wool, spherical and other irregular shapes, uneven particle size, high porosity and large specific surface area. specialty. Fly ash is rich in high concentrations of chloride salts, high levels of easily leached heavy metals and dioxins, and is classified as hazardous waste by countries around the world (China, code HW18). Therefore, fly ash must be strictly disposed before landfill and resource utilization. In recent years, a variety of fly ash disposal technologies have been studied at home and abroad, including solidification stabilization, separation and extraction, heat treat...

AI Technical Summary

Problems solved by technology

The dry landfill disposal of fly ash has the following problems: (1) The composition of fly ash fluctuates greatly, dry mixing cannot achieve a better homogenization effect, the effect of chelating agent cannot be effectively exerted, the dosage is not easy to control stably, and the detoxification effect is unstable ; or in order to ensure the chelating effect, adding excessive chelating agent will increase the cost of the agent; (2) Fly ash contains a large amount of fine dust, which can easily form PM 2.5 pollution sources when exposed to the environment. Although the conventional dry landfill treatment has water spraying Humidification, mechanical rolling, pre-forming and other dust suppression measures, but still cannot avoid the impact on the surrounding environment of the landfill; (3) New ash landfills are often accompanied by a pungent ammonia smell, causing adverse effects on nearby residents (4) Due to the strength of the stabilized fly ash, only the space below the ground can be used for landfill disposal in pits, and the space above the ground cannot be used, resulting in a low utilization rate of storage capacity; (5) In summer and autumn rainy seasons, landfill Slurry may be formed in the pit, making the landfill operation impossible; (6) There will inevitably be problems with the treatment of landfill leachate, which will increase additional treatment costs

The problem is that the concentration of the supernatant liquid entering the evaporative crystallization system has not been concentrated, resulting in large equipment investment and high operating costs in the evaporative crystallization salt extraction process; if the supernatant liquid entering the evaporative crystallization system is concentrated by natural evaporation, There is basically no treatment cost, and it is technically feasible, but this method occupies a large amount of land. The implementation site of the water washing pretreatment technology is generally in the cement factory, which cannot provide the land area required for the natural evaporation and concentration of the supernatant, so the actual implementation is not feasible; If the chlorine salt is not extracted and recycled directly, the cost of evaporation crystallization can be saved, but the removal effect of fly ash washing chlorine salt is extremely poor, and the effect of fly ash washing pretreatment cannot be exerted

[0007] Since municipal sludge and mine tailings are general solid wastes, while MSW incineration fly ash is hazardous waste (China, code HW18), if the above technology is simply transplanted to the disposal field of MSW incineration fly ash, it will The following problems arise: (1) Environmental protection issues: the products after hazardous waste disposal and the waste residue and waste water generated during the disposal process have strict standard requirements, which are strictly different from general solid waste such as sludge and tailings; (2 ) Technical issues: 1) Sludge and tailings contain 50-95% water, which are water-containing materials. They are treated with mold bags, and only need to consider the problem of dehydration and capacity reduction; while fly ash contains 1-2% water, which belongs to dry materials, and mold bags are used. Pulping and dehydration treatment must be considered at the same time, and the pulping process has a greater impact on the subsequent dehydration effect, and it is required to complete the harmless disposal of fly ash as hazardous waste during the entire treatment process; 2) Sludge Mold bags used for solid waste treatment such as or tailings are susceptible to rainwater penetration, which affects the strength of sludge or tailings consolidation in the mold bag

[0008] Due to the above-mentioned defects and deficiencies in the large-scale industrial application of the traditional dry landfill of fly ash and the pretreatment technology of fly ash washing, and the simple transplantation of mold bags to the field of domestic waste incineration fly ash disposal will lead to technical and environmental protection problems. The problem

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