Remediation method for chromium slag or chromium contaminated soil

A technology of chromium-contaminated soil and remediation method, applied in the restoration of contaminated soil, etc., can solve problems such as limitations, high equipment requirements, and unreasonable economics, and achieve the goals of widely popularizing and using, shortening pyrolysis time, and improving treatment efficiency Effect

Inactive Publication Date: 2017-02-15
BEIJING GEOENVIRON ENG & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although there are some thermal desorption processes and equipment reports in my country at present, they all have deficiencies: CN105642654A adopts the method of synchronously treating blast furnace slag, chromium slag and sludge, but this method needs the cooperation of blast furnace and has certain limitations CN105728443A and CN105772487A use high temperature of pulverized coal to melt and vitrify it, but the temperature of melting and vitrification is very high, the requirements for equipment are also high, and the energy consumption is also high, which is economically unreasonable; CN105521985A combines straw and chromium slag After mixing, pyrolysis uses the tar produced by high-temperature pyrolysis to reduce hexavalent chromium; Zhang Dalei uses cellulose and chromium residue pyrolysis reduction (Zhang D L, Zhang M Y, Zhang CH, et al. Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr (VI) Reduction Behavior[J]. Environmental science & technology, 2016, 50(6): 3111-3118.) These two methods will lead to further contamination of soil with tar produced by pyrolysis, although hexavalent chromium But it may introduce new organic secondary pollution such as PAH, etc.
The above-mentioned chromium slag-contaminated soil treatment process has the disadvantages of high energy consumption; easy to cause secondary pollution; limitations; reduce soil fertility and other shortcomings

Method used

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  • Remediation method for chromium slag or chromium contaminated soil
  • Remediation method for chromium slag or chromium contaminated soil
  • Remediation method for chromium slag or chromium contaminated soil

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Example 1: Raw material (chromium slag polluted soil): the content of hexavalent chromium is 8750mg / kg.

[0031] Mix corn stalk semi-coke with soil polluted by chromium slag evenly (semi-coke accounts for 2-10wt%, based on dry soil), and then put the mixture into a rotary kiln for pyrolysis under a nitrogen atmosphere. The pyrolysis temperature is 600 ° C, angle 2 degrees, rotating speed 2 rev / min, residence time 1 hour, the soil that pyrolysis is completed is cooled to room temperature. The content of hexavalent chromium and the content of participating PAH were analyzed by XANS and EPA method 8015M respectively. The detailed results are shown in Table 1.

[0032] Table 1 Residual hexavalent chromium and quantity

[0033]

[0034] Note: US EPA: 1) Naphthalene; 2) Acenaphthylene; )Acenaphthene; 4) Fluorene; 5) Phenanthrene; 6) Anthracene; anthracene benzo(a) anthracene; 10) Chrysene; 11) Benzo(b)fluoranthene benzo(b) fluoranthene; 12) Benzo(k)fluoranthene benzo(...

Embodiment 2

[0036] The experimental raw materials are the same as in Example 1, the addition of semi-coke is 4wt%, pyrolyzed in a fluidized bed under a nitrogen atmosphere, the pyrolysis temperature is 400-1000 ° C, the residence time is 10 minutes, and the pyrolyzed soil is cooled to room temperature. The content of hexavalent chromium and PAHs, the detailed results are shown in Table 2.

[0037] Table 2 Residual hexavalent chromium and quantity

[0038]

Embodiment 3

[0040] The soil obtained by pyrolysis at 700°C in Example 2 was cultivated at 25°C and humidity 100% (maintained with deionized water) without light for 3 months. After cultivating for three months, sieve the coke with a 5mm sieve. The coke obtained by sieving was washed three times with deionized water and air-dried. The change of C-O group was analyzed by XPS; the long-term oxidation stability of semi-coke was oxidized by hydrogen peroxide.

[0041] Hydrogen peroxide oxidation: 0.1g semi-coke is treated with 7ml 5% hydrogen peroxide at 80 degrees for two days.

[0042] The results showed that: C-O-Cr organometallic complexes could be detected, and the relative content of C-O, C=O and COOH decreased from 35.1% to 18.3%. It shows that the addition of semi-coke increases the oxidation resistance and helps to maintain the stability of the reduced chromium in the environment.

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Abstract

The invention discloses a remediation method for chromium slag or chromium contaminated soil. The remediation method comprises the following steps: mixing the chromium slag or chromium contaminated soil with semi-coke; performing thermal treatment at the temperature of 400 to 1600 DEG C; and allowing pollutants in the chromium slag or chromium contaminated soil to have a reduction reaction at a high temperature to obtain non-contaminated soil, wherein the thermal treatment is performed under the protection of one or both of an inert gas and a reductive gas. According to the remediation method disclosed by the invention, the semi-coke is utilized for strengthened reduction of chromium in the chromium slag or chromium contaminated soil; the semi-coke can play a reduction effect on hexavalent chromium and can also improve soil, sequestrate carbon and treat wastes. The remediation method has the advantages of being high in chromium reduction efficiency, low in energy consumption, economical, feasible, environmentally friendly and the like, and has quite good application prospects.

Description

technical field [0001] The invention belongs to the field of environmental restoration, and in particular relates to a restoration method for chromium slag or chromium-contaminated soil. Background technique [0002] Soil is an important part of the ecosystem and one of the environmental resources on which human beings depend. With the development of modern industrial and agricultural production, large-scale application of chemical fertilizers and pesticides, industrial waste water continuously invades farmland, urban industrial waste and other artificial synthetic substances continuously enter the soil, landfill leakage, oil well mining and atmospheric subsidence cause soil environmental pollution accidents Occurs continuously, polluting the soil with organic matter (including petroleum hydrocarbons (TPH), volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), pesticides) and heavy metals (chromium, lead, cadmium, etc.)...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09C1/08
CPCB09C1/08
Inventor 杨华胡晨刘力奇张绍坤霍成立郑峰郑中华孙晓东郭智洪慧兰贺真虢德威丁仕文
Owner BEIJING GEOENVIRON ENG & TECH
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