Method for extracting heavy metals from secondary flying ash generated during burning wastes

A secondary fly ash and waste incineration technology, applied in the field of heavy metal extraction, can solve the problem of low leaching efficiency

Active Publication Date: 2010-09-01
刘阳生 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the leaching efficiency is low, and a large amount of metals still remain in the residue (such as the extraction rate of Zn is only 20-30%), and it still needs to be treated as hazardous waste for solidification / stabilization

Method used

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  • Method for extracting heavy metals from secondary flying ash generated during burning wastes
  • Method for extracting heavy metals from secondary flying ash generated during burning wastes

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Such as figure 1 As shown, the secondary fly ash 1 is slowly added into the washing tank 2 through a screw feeder, the mass ratio of gray to water is 1:2, stirred and washed at 80°C for 90 minutes; then naturally settled for 2 hours, and the solid and liquid are separated to obtain Supernatant 3 and washing residue 4. Washing residue and concentrated hydrochloric acid are mixed in equal volumes, heated and extracted in acid extraction reactor 5 for 30 minutes to obtain extract 6 and extraction residue 7, and the extraction residue is mixed with lime with a weight concentration of 10%, and stirred in lime neutralization pool 8 Homogenously, a stabilized solid residue 9 was obtained.

[0018] The supernatant 3 contains high concentrations of copper chloride and zinc chloride, and is evaporated in the evaporator 10 to obtain condensed water 12 and solid powder 13 of copper chloride and zinc chloride. The extract 6 is distilled under reduced pressure in the vacuum still 1...

Embodiment 2

[0020] Such as figure 1 As shown, the secondary fly ash 1 is slowly added into the water washing tank 2 through the screw feeder, the mass ratio of gray to water is 1:3, stirred and washed at 60°C for 30 minutes; then naturally settled for 4 hours, and the solid and liquid are separated to obtain Supernatant 3 and washing residue 4. Washing residue and concentrated hydrochloric acid are mixed in equal volumes, heated and extracted in acid extraction reactor 5 for 1 hour to obtain extract 6 and extraction residue 7, and the extraction residue is mixed with lime with a weight concentration of 10%, and stirred in lime neutralization pool 8 Homogenously, a stabilized solid residue 9 was obtained.

[0021] The supernatant 3 contains high concentrations of copper chloride and zinc chloride, and is evaporated in the evaporator 10 to obtain condensed water 12 and solid powder 13 of copper chloride and zinc chloride. The extract 6 is distilled under reduced pressure in the vacuum sti...

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Abstract

The invention discloses a method for extracting heavy metals from secondary flying ash generated during burning wastes, which comprises the following steps of: adding secondary flying ash generated during burning wastes into water under the condition that the ratio of the secondary flying ash to the water is 1:2-3; stirring and washing with water at 60-80 DEG C for 30-90 minutes; naturally precipitating for 2-4 hours, and separating supernatant liquid from residues; adding an isometric concentrated hydrochloric acid solution into the residues, stirring, refluxing and extracting at 60-80 DEG C for 30 minutes, and centrifugally separating solids from liquid to obtain extraction liquid and residual solid residues; evaporating the supernatant liquid at 100 DEG C to obtain mixed solid powder of CuCl2 and ZnCl2, and condensing the evaporated water vapor for recycling; carrying out vacuum evaporation on the extraction liquid at 60-80 DEG C to obtain PbCl2 powder, and simultaneously, recovering the hydrochloric acid; and adding lime of which the weight concentration is 10% into the residual solid residues for stirring uniformly to form inert solid wastes. In the invention, copper chloride and zinc chloride are separated by heating and water washing firstly, and lead chloride is obtained by adding the concentrated hydrochloric acid for heating, refluxing and extracting secondly, thereby realizing the purpose of recovering heavy metals.

Description

technical field [0001] The invention relates to a method for extracting heavy metals from waste incineration secondary fly ash. Background technique [0002] Waste incineration technology has become one of the main means of domestic waste disposal in economically developed cities in my country. The fly ash produced during the waste incineration process contains high concentrations of heavy metals and dioxins and other pollutants. According to my country's hazardous waste list, it belongs to the category of hazardous waste and should be solidified and stabilized. Not only the disposal cost is high, but also occupies a safe landfill. site. Extracting heavy metals from waste incineration fly ash and realizing resource utilization of heavy metals has attracted extensive attention of researchers at home and abroad. [0003] The methods for recovering heavy metals from fly ash mainly include: acid leaching method (mainly leaching with sulfuric acid or acetic acid solution), alkal...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22B7/02
Inventor 刘阳生曾辉
Owner 刘阳生
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