Heavy metal stabilization two-step method for treatment of fly ash from urban domestic refuse burning plant

A technology for municipal solid waste and fly ash incineration, which is applied in the field of solid waste treatment and disposal, can solve the problems of complex process and other problems, and achieve the effects of favorable mixing, simple process and low operation cost

Active Publication Date: 2009-12-09
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to improve the effectiveness of phosphate agents, a process of phosphate stabilization after fly ash washing pretreatment has been proposed ('Monitoring the stabilization of municipal solid waste incineration fly ash byphosphation: mineralological and balance approach'Piantonea P et al. al. WasteManagement 23:225-243, 2003), but the secondary pollutants brought by water washing will obviously complicate the process

Method used

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  • Heavy metal stabilization two-step method for treatment of fly ash from urban domestic refuse burning plant
  • Heavy metal stabilization two-step method for treatment of fly ash from urban domestic refuse burning plant
  • Heavy metal stabilization two-step method for treatment of fly ash from urban domestic refuse burning plant

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Please see attached figure 1 And attached figure 2 .

[0026] The pH was adjusted by sulfuric acid treatment, and then phosphate was added to stabilize heavy metals in the fly ash.

[0027] Step 1: add sulfuric acid to water in the acid solution mixing tank, the ratio of sulfuric acid to water, according to the mixed acid solution H + The molar concentration is controlled from 6M to 7M, and the sulfuric acid solution can be obtained after mixing evenly with slow stirring;

[0028] Step 2: Add fly ash to the stirring treatment tank, start stirring, and slowly add the above sulfuric acid solution into the tank at the same time, the mass ratio of the accumulatively added acid solution to fly ash is controlled to be 1:3.5; after the sulfuric acid solution and fly ash are stirred evenly , and then slowly add the stabilizing agent phosphate into the tank while stirring; the stabilizing agent should be ground and passed through a 60-mesh sieve before use, and the active in...

Embodiment 2

[0034] Please see attached figure 1 And attached image 3 .

[0035] The pH was adjusted by natural aging method and phosphate was added to stabilize heavy metals in fly ash.

[0036] Step 1: Add fly ash to the pretreatment tank, start stirring, and slowly add water into the tank at the same time, the mass ratio of the accumulatively added water to fly ash is controlled to be 1:5; after the water and fly ash are stirred evenly, wet fly ash;

[0037] Step 2: Discharge the humidified fly ash from the pretreatment tank, evenly spread (thickness 0.2 to 0.3m) in the air circulation space, and age for 2 days. During this period, turn the pile once every 8 hours to obtain natural aging fly ash;

[0038] Step 3: Add the natural aging fly ash into the mixing treatment tank, start the stirring, and at the same time slowly add the stabilizing agent into the tank while stirring; the stabilizing agent should be ground and passed through a 60-mesh sieve before use, and the active ingredi...

Embodiment 3

[0044] Please see attached figure 1 And attached Figure 4 .

[0045] The pH was adjusted by forced aging method, and then phosphate was added to stabilize heavy metals in fly ash.

[0046] Step 1: same as step 1 of embodiment 2;

[0047] Step 2: Discharge the humidified fly ash from the pretreatment tank, evenly spread (thickness 0.1 to 0.2m) in the forced aging room, and age for 8 hours to obtain the forced aging fly ash; the forced aging room is an airtight space, set The gas port introduces flue gas from the chimney of the incineration plant through the induced draft fan, flows evenly through the forced aging room, and then returns to the chimney of the incineration plant to be discharged; the volume of flue gas flowing through the forced aging room per hour is 6 to 8 times the volume of the aging room, That is, the flue gas exchange rate in the aging chamber is 6 to 8 times / hour.

[0048] Step 3: Except that the natural aging fly ash is replaced by forced aging fly as...

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Abstract

The invention discloses a two-step method for stabilizing heavy metals in fly ash of municipal solid waste incineration, and relates to a chemical agent stabilization technology for heavy metals in fly ash of flue gas purification system of municipal solid waste incineration plant. First choose one of the three methods of sulfuric acid treatment, natural aging, or forced aging to adjust the pH range of the fly ash to 9 to 11. Then the pretreated fly ash and the stabilizing agent are uniformly mixed at a mass ratio of 50 to 80:1 and left to stand for 8 hours to complete the heavy metal chemical stabilization treatment of the fly ash. Based on the direct phosphate heavy metal stabilization treatment process of fly ash, the present invention pre-treats with pre-pH adjustment, so that the leachability of heavy metal elements in fly ash is reduced, and CaO is converted into a compound with low reactivity, thereby ensuring The stabilization effect of heavy metals and the reduction of the dosage of stabilizing agents can save the cost of heavy metal stabilization treatment of incineration fly ash. The treatment process does not generate free water, and there is no sewage treatment problem; the process is simple and the operation is reliable.

Description

technical field [0001] The invention relates to a chemical agent stabilization technology for heavy metals in fly ash of a flue gas purification system of a municipal solid waste incineration plant, and belongs to the technical field of solid waste treatment and disposal. Background technique [0002] During the incineration process, most of the waste in domestic waste incineration plants is discharged into the atmosphere in the form of gas, part of it is left on the grate in the form of non-combustible slag, and a small amount is attached to the outer wall of the waste heat boiler or enters the waste heat boiler in the form of fly ash. The flue gas purification system is collected by the dust collector, which is called flue gas purification system fly ash (referred to as fly ash). According to my country's National Hazardous Waste List, fly ash belongs to hazardous waste and must be stabilized so that the leached concentration of heavy metals is lower than the hazardous was...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B09B3/00A62D3/00
Inventor 何品晶邵立明章骅冯军会
Owner TONGJI UNIV
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