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Fly ash modifying method based on passivation of heavy metals in stored sludge

A fly ash and heavy metal technology, applied in chemical instruments and methods, sludge treatment, sludge detoxification, etc., can solve soil and groundwater pollution hazards, threats to the health of surrounding residents, etc.

Inactive Publication Date: 2017-05-10
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the stored sludge contains a large amount of heavy metals (Cu, Zn seriously exceeding the standard), and the direct stacking in the environment is extremely harmful to soil and groundwater pollution, and even threatens the health of surrounding residents. At the same time, it limits the direct application of stored sludge to farmland soil

Method used

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  • Fly ash modifying method based on passivation of heavy metals in stored sludge
  • Fly ash modifying method based on passivation of heavy metals in stored sludge

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specific Embodiment approach 1

[0011] Embodiment 1: In this embodiment, a method for modifying fly ash based on heavy metals in passivation storage sludge is carried out in the following steps:

[0012] 1. Soak the fly ash in the acidic solution for 4 hours, then place it in an air bath constant temperature oscillator and shake it for 90 minutes at a temperature of 20°C and 250r / min. The H in the acidic solution + The concentration is 4mol / L, and the acid-ash ratio is 3ml:1g;

[0013] 2. Centrifuge at 10,000r / min for 10min, remove the acid solution and wash the acid-modified fly ash repeatedly with ultrapure water until neutral;

[0014] 3. Dry at 105±2°C to constant weight, crush and pass through a 100-mesh sieve, and then heat at 105±2°C for 2 hours to complete the fly ash modification.

[0015] Sludge is different from wastewater. Heavy metals in sludge exist in four forms: acid-soluble, reducible, oxidizable, and residue; while heavy metals in wastewater are basically in the ion state. The principles ...

specific Embodiment approach 2

[0018] Embodiment 2: The difference between this embodiment and Embodiment 1 is that step 1 is soaked in an acidic solution and subjected to microwave radiation, and then placed in an air bath constant temperature oscillator to vibrate; wherein the microwave power is 400W, and the microwave time is 10min. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 1

[0020] Fly Ash Modification:

[0021] 1. Soak the fly ash in the acidic solution for 4 hours, then place it in an air bath constant temperature oscillator and shake it for 90 minutes at a temperature of 20°C and 250r / min. The H in the acidic solution + The concentration is 4mol / L, and the acid-ash ratio is 3ml:1g;

[0022] 2. Centrifuge at 10,000r / min for 10min, remove the acid solution and wash the acid-modified fly ash repeatedly with ultrapure water until neutral;

[0023] 3. Dry at 105°C to constant weight, crush and pass through a 100-mesh sieve, and then heat at 105°C for 2 hours to complete the fly ash modification.

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Abstract

A fly ash modifying method based on passivation of heavy metals in stored sludge relates to a fly ash modifying method. The invention overcomes the prejudices of the prior art, and acid modification method is used to treat fly ash to arrive at the same excellent passivation effect for heavy metals. The modifying method comprises: I, adding fly ash into an acidic solution for soaking; II, centrifugally leaching; III, drying. The fly ash modified by using the method has greatly reduced proportion of acid-soluble and oxidizable heavy metals and greatly increased proportion of reducible and residual heavy metals; it is indicated that the fly ash modified by using the method is capable of well passivating heavy metals in stored sludge, and the prejudices from those skilled in the art are overcome.

Description

technical field [0001] The invention relates to a method for modifying fly ash. Background technique [0002] With the acceleration of industrialization, the annual discharge of sludge from sewage plants in my country is about (3.8-5.5)×10 6 tons, and the emissions are expected to reach 3.0×10 by 2020 7 tons or so. The increase in sludge production leads to an increase in the production of stored sludge, and a large amount of stored sludge is directly piled into the environment without treatment. During the sewage treatment process, due to adsorption or precipitation, about 70% to 90% of heavy metals are transferred to the sludge. Therefore, the stored sludge contains a large amount of heavy metals (Cu, Zn seriously exceeding the standard), and the direct stacking in the environment is extremely harmful to soil and groundwater pollution, and even threatens the health of surrounding residents. At the same time, it limits the direct application of stored sludge to farmland ...

Claims

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Application Information

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IPC IPC(8): B01J20/10B01J20/28B01J20/30C02F11/00C02F101/20
CPCB01J20/10B01J20/28019B01J20/28054C02F11/004C02F2101/20
Inventor 刘甜甜赫俊国唐建崔崇威
Owner HARBIN INST OF TECH
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