Extractant for treating heavy metals in fly ash and method for extracting heavy metals with the extractant

Abstract

Belonging to the technical field of environmental engineering, the invention discloses an extractant for treating heavy metals in fly ash and a method for extracting heavy metals with the extractant. The extractant of the invention comprises the following components by volume: 50-80% of kerosene and 20-50% of di(2-ethylhexyl)phosphate. The preparation method of the extractant in the invention includes the step of mixing the raw materials in the above ratio uniformly. The invention also discloses a method for extracting heavy metals with the extractant, and the method consists of the steps of:mixing the extractant for treating heavy metals in fly ash with the fly ash in a mass ratio of 1:1-5:1, placing the mixture in a stirrer at room temperature and stirring the mixture continuously for 12-24h, then leaving it for standing and layering. The extractant provided in the invention has wide source, low price and high treating efficiency, and the fly ash after extraction has zinc and lead leaching concentrations lower than the limit value prescribed by domestic waste landfill pollution control standards.

Description

Technical field

[0001] The invention belongs to the technical field of environmental engineering and relates to an extractant for treating heavy metals in fly ash and a method for extracting heavy metals. Background technique

[0002] Heavy metals are the primary indicators for the risk assessment of fly ash, among which mercury is the most toxic, followed by cadmium, lead, chromium and arsenic. These heavy metals can produce obvious toxic effects as long as there are traces. The incineration fly ash of domestic waste concentrates more heavy metals in the waste. It is a recognized and statutory hazardous waste and must be treated and disposed of safely. At present, domestic waste incineration fly ash is mainly used for safe landfill, but safe landfill occupies a large area and high disposal cost. The main mineral components in fly ash are silicates and aluminosilicates, belonging to SiO 2 -Al 2 O 3 -Metal oxide system, the fly ash after harmless treatment can be recycled. [000...

Examples

Embodiment 1

[0030] The kerosene with a volume percentage of 50% and P204 with a volume percentage of 50% are uniformly mixed to prepare the extractant.

[0031] After the above-mentioned extractant and the fly ash of the municipal solid waste incineration plant are uniformly mixed according to a liquid-solid mass ratio of 1:1, they are placed in a mixer at room temperature for continuous stirring for 24 hours, and then they are allowed to stand for layering. The heavy metals in fly ash include zinc or lead. The standing layer is divided into upper and lower layers. The upper unsaturated extractant can be recycled to saturation. The saturated extractant can also be recycled after stripping with hydrochloric acid solution, and the heavy metals in it can be recovered as a mixture. The leaching concentration of heavy metals in the lower fly ash is lower than the concentration limit for the toxic equivalent of fly ash in the pollution control standard of the domestic waste landfill. The leaching ...

Embodiment 2

[0037] 80% of kerosene by volume and 20% of P204 by volume are uniformly mixed to prepare the extractant.

[0038] After the above-mentioned extractant and the fly ash of the municipal solid waste incineration plant are uniformly mixed according to a liquid-solid mass ratio of 5:1, they are placed in a stirrer at room temperature for continuous stirring for 12 hours, and then left to stand for layering. The heavy metals in fly ash include zinc or lead. The standing layer is divided into upper and lower layers. The upper unsaturated extractant can be recycled to saturation. The saturated extractant can also be recycled after stripping with hydrochloric acid solution, and the heavy metals in it can be recovered as a mixture. The leaching concentration of heavy metals in the lower fly ash is lower than the concentration limit for the toxic equivalent of fly ash in the pollution control standard for domestic waste landfills. The leaching toxicity of heavy metals is shown in Table 2. ...

Embodiment 3

[0043] The extractant is prepared by mixing kerosene with a volume percentage of 65% and P204 with a volume percentage of 35%.

[0044] After the above-mentioned extractant and the fly ash of the municipal solid waste incineration plant are uniformly mixed according to a liquid-solid mass ratio of 3:1, they are placed in a stirrer at room temperature for continuous stirring for 20 hours, and then left to stand for layering. The heavy metals in fly ash include zinc or lead. The standing layer is divided into upper and lower layers. The upper unsaturated extractant can be recycled to saturation. The saturated extractant can also be recycled after stripping with hydrochloric acid solution, and the heavy metals in it can be recovered as a mixture. The leaching concentration of heavy metals in the lower fly ash is lower than the concentration limit for the toxic equivalent of fly ash in the pollution control standard for domestic waste landfills. The leaching toxicity of heavy metals ...

Technical field

[0001] The invention belongs to the technical field of environmental engineering and relates to an extractant for treating heavy metals in fly ash and a method for extracting heavy metals. Background technique

[0002] Heavy metals are the primary indicators for the risk assessment of fly ash, among which mercury is the most toxic, followed by cadmium, lead, chromium and arsenic. These heavy metals can produce obvious toxic effects as long as there are traces. The incineration fly ash of domestic waste concentrates more heavy metals in the waste. It is a recognized and statutory hazardous waste and must be treated and disposed of safely. At present, domestic waste incineration fly ash is mainly used for safe landfill, but safe landfill occupies a large area and high disposal cost. The main mineral components in fly ash are silicates and aluminosilicates, belonging to SiO 2 -Al 2 O 3 -Metal oxide system, the fly ash after harmless treatment can be recycled. [000...

Examples

Embodiment 1

[0030] The kerosene with a volume percentage of 50% and P204 with a volume percentage of 50% are uniformly mixed to prepare the extractant.

[0031] After the above-mentioned extractant and the fly ash of the municipal solid waste incineration plant are uniformly mixed according to a liquid-solid mass ratio of 1:1, they are placed in a mixer at room temperature for continuous stirring for 24 hours, and then they are allowed to stand for layering. The heavy metals in fly ash include zinc or lead. The standing layer is divided into upper and lower layers. The upper unsaturated extractant can be recycled to saturation. The saturated extractant can also be recycled after stripping with hydrochloric acid solution, and the heavy metals in it can be recovered as a mixture. The leaching concentration of heavy metals in the lower fly ash is lower than the concentration limit for the toxic equivalent of fly ash in the pollution control standard of the domestic waste landfill. The leaching ...

Embodiment 2

[0037] 80% of kerosene by volume and 20% of P204 by volume are uniformly mixed to prepare the extractant.

[0038] After the above-mentioned extractant and the fly ash of the municipal solid waste incineration plant are uniformly mixed according to a liquid-solid mass ratio of 5:1, they are placed in a stirrer at room temperature for continuous stirring for 12 hours, and then left to stand for layering. The heavy metals in fly ash include zinc or lead. The standing layer is divided into upper and lower layers. The upper unsaturated extractant can be recycled to saturation. The saturated extractant can also be recycled after stripping with hydrochloric acid solution, and the heavy metals in it can be recovered as a mixture. The leaching concentration of heavy metals in the lower fly ash is lower than the concentration limit for the toxic equivalent of fly ash in the pollution control standard for domestic waste landfills. The leaching toxicity of heavy metals is shown in Table 2. ...

Embodiment 3

[0043] The extractant is prepared by mixing kerosene with a volume percentage of 65% and P204 with a volume percentage of 35%.

[0044] After the above-mentioned extractant and the fly ash of the municipal solid waste incineration plant are uniformly mixed according to a liquid-solid mass ratio of 3:1, they are placed in a stirrer at room temperature for continuous stirring for 20 hours, and then left to stand for layering. The heavy metals in fly ash include zinc or lead. The standing layer is divided into upper and lower layers. The upper unsaturated extractant can be recycled to saturation. The saturated extractant can also be recycled after stripping with hydrochloric acid solution, and the heavy metals in it can be recovered as a mixture. The leaching concentration of heavy metals in the lower fly ash is lower than the concentration limit for the toxic equivalent of fly ash in the pollution control standard for domestic waste landfills. The leaching toxicity of heavy metals ...