CN112961679A - Repairing agent and method for stably repairing mercury-polluted soil by adopting same - Google Patents

Repairing agent and method for stably repairing mercury-polluted soil by adopting same Download PDF

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CN112961679A
CN112961679A CN202110136399.6A CN202110136399A CN112961679A CN 112961679 A CN112961679 A CN 112961679A CN 202110136399 A CN202110136399 A CN 202110136399A CN 112961679 A CN112961679 A CN 112961679A
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soil
mercury
calcium polysulfide
agent
ferrous salt
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李宁
薛立勇
田媛
郭伟
温旭
张建平
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Bochuan Environmental Restoration Beijing Co ltd
Poten Environment Group Co Ltd
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Bochuan Environmental Restoration Beijing Co ltd
Poten Environment Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K17/00—Soil-conditioning materials or soil-stabilising materials
    • C09K17/40—Soil-conditioning materials or soil-stabilising materials containing mixtures of inorganic and organic compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09C—RECLAMATION OF CONTAMINATED SOIL
    • B09C1/00—Reclamation of contaminated soil
    • B09C1/08—Reclamation of contaminated soil chemically
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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  • Life Sciences & Earth Sciences (AREA)
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  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
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  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

The application provides a repairing agent and a method for stably repairing mercury-polluted soil by adopting the repairing agent. The repairing agent comprises calcium polysulfide, ferrous salt and humic acid powder, wherein the mass percent of the calcium polysulfide, the ferrous salt and the humic acid powder is (16-23%) based on the total mass of the repairing agent: (56-63%): (19-28%). The method for restoring mercury contaminated soil, which adopts the restoring agent, comprises the following steps: (1) calculating the total mercury pollution amount of the soil in the remediation area; (2) adding calcium polysulfide and ferrous salt into soil, stirring, mixing, and stacking for 2-4 days; (3) adding humic acid powder into the soil, stirring and mixing uniformly, keeping the water content of the soil at 30-50%, and stacking and maintaining for 6-8 days. By adopting the method, the mercury toxicity leaching of the soil in the mercury-polluted site can be effectively reduced.

Description

Repairing agent and method for stably repairing mercury-polluted soil by adopting same
Technical Field
The application relates to the technical field of polluted soil treatment and restoration, in particular to a restoration agent and a method for stably restoring mercury-polluted soil by adopting the restoration agent.
Background
Mercury is the only heavy metal existing in liquid state at normal temperature, and the mercury-polluted soil is widely concerned by the public due to the characteristics of mercury different from other heavy metals and the characteristics of high durability, high biotoxicity and high migration in soil. The process of chlor-alkali industry, coal chemical industry and electronic fluorescence industry which are applied by a large amount of accompanying mercury and mercury is updated and iterated, so that more and more mercury pollution sites are generated.
According to land planning, farmland polluted soil is generally conditioned by applying a passivator in a scattering way, so that the ecological activity of mercury is reduced, and the absorption of crops to mercury is reduced; in contrast, the mercury pollution of industrial sites is more serious, and needs to be treated by thermal desorption or solidification/stabilization methods, and according to the recommendation of the United states Environmental Protection Agency (EPA), the mercury polluted soil of more than 260mg/Kg is recommended to be treated by heat treatment, and the mercury polluted soil of less than 260mg/Kg is recommended to be treated by solidification/stabilization methods.
At present, the remediation of mercury-polluted soil in China mainly focuses on the passivation remediation of mercury-polluted farmland soil, and from the perspective of domestic remediation projects, the stabilization technology has a relatively low technical threshold, high economic benefit and is convenient for construction management, but the stabilization technology is often applied to projects with small mercury-polluted soil volume, low mercury content concentration and tight operation cycle. How to apply the stabilization restoration method to the treatment and restoration of the mercury pollution site becomes a problem to be solved urgently by technical personnel in the field.
Disclosure of Invention
In view of the above problems in the prior art, the present application aims to provide a remediation agent and a method for stabilizing and remediating mercury-contaminated soil by using the remediation agent, so as to effectively reduce mercury toxicity leaching of soil in a mercury-contaminated site.
The first aspect of the application provides a repairing agent, which comprises calcium polysulfide, ferrous salt and humic acid powder, wherein the mass percentage of the calcium polysulfide, the ferrous salt and the humic acid powder is (16-23%) based on the total mass of the repairing agent: (56-63%): (19-28%).
In some embodiments of the present application, the calcium polysulfide is selected from a calcium polysulfide aqueous or a calcium polysulfide powder.
In some embodiments of the present application, the ferrous salt is selected from ferrous sulfate heptahydrate (also known as ferrous sulfate) or ferrous sulfide.
In some embodiments of the present application, the humic acid powder has a particle size of 0.15 to 0.25 mm.
The application in a second aspect provides a method for repairing mercury-contaminated soil, and the repairing agent provided by the application is adopted, and comprises the following steps:
(1) calculating the total mercury pollution amount in the soil in the remediation area;
(2) adding the calcium polysulfide and the ferrous salt into the soil, uniformly stirring, stacking and maintaining for 2-4 days;
(3) adding the humic acid powder into the soil, uniformly stirring, keeping the water content of the soil at 30-50%, and stacking and maintaining for 6-8 days;
wherein the mass percentages of the calcium polysulfide, the ferrous salt and the humic acid powder are (16-23%) based on the total mass of the repairing agent: (56-63%): (19-28%).
In some embodiments of the present application, in the step (2), when the calcium polysulfide and the ferrous salt are added to the soil, the soil is classified into clay-based soil and sand-based soil according to the particle size of the soil;
adding a calcium polysulfide aqueous agent into the clay soil, keeping the water content of the clay soil at 50-60%, and adding ferrous salt; and
and adding the calcium polysulfide powder and the ferrous salt which are uniformly mixed on the surface of the sandy soil.
In some embodiments of the present application, in step (2), before adding the calcium polysulfide and the ferrous salt to the soil, the method further comprises:
crushing the soil, and carrying out primary screening to obtain soil blocks, wherein the primary screening particle size is 5-15 cm;
and crushing the soil blocks, and screening for the second time, wherein the grain size of the screened soil blocks for the second time is less than 3 cm.
In some embodiments of the present application, after calculating the total amount of mercury contamination of the soil in the remediation zone in step (1), the method further comprises:
the pH, moisture content, density and particulate composition of the soil were determined.
In a third aspect, the application provides the use of the remediation agent of the application for remediation of soil with a mercury concentration of less than 3200 mg/Kg.
In some embodiments of the present application, the use of the remediation agent described above for remediation of soil having a mercury concentration of less than 3000 mg/Kg.
The restoration agent provided by the application has the advantages of easily available raw materials, low price, simple preparation and use methods and easiness in popularization, can be applied to mercury-polluted soil with mercury content concentration less than 3200mg/kg in a large area, has a remarkable use effect, can restore the mercury-polluted soil, and remarkably reduces mercury toxicity leaching. By adopting the method for stably repairing the mercury-contaminated soil by using the repairing agent, the mercury in the mercury-contaminated soil in an effective state is converted into the mercury in an insoluble state, and the mercury stably exists in the soil, so that the acid leaching concentration of the repaired soil is obviously reduced. In addition, the pH value of the soil environment cannot be greatly changed, and the pH value of the repaired soil is maintained at a reasonable level. The method for stabilizing and repairing the mercury-polluted soil by adopting the repairing agent ensures that the repairing effect of the mercury-polluted soil lasts for a long time.
Of course, not all advantages described above need to be achieved at the same time in the practice of any one product or method of the present application.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only one embodiment of the present application, and other embodiments can be obtained by those skilled in the art according to the drawings.
FIG. 1 is a graph comparing the acid leach concentration of untreated, treated samples of example 1 of the present application;
FIG. 2 is a graph comparing the acid leach concentration before and after treatment of the samples of example 2 of the present application;
FIG. 3 is a graph comparing the acid leach concentration before and after treatment of the samples of example 3 of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in this application are within the scope of protection of this application.
The first aspect of the application provides a repairing agent, which comprises calcium polysulfide, ferrous salt and humic acid powder, wherein the mass percentage of the calcium polysulfide, the ferrous salt and the humic acid powder is (16-23%) based on the total mass of the repairing agent: (56-63%): (19-28%).
In the application, the repairing agent comprises calcium polysulfide, ferrous salt and humic acid powder, and the three medicament components are low in price, convenient to prepare and easy to operate and implement, and can be widely applied to repairing of soil in a mercury-polluted site. Based on the total mass of the repairing agent, the mass percentages of calcium polysulfide, ferrous salt and humic acid powder are (16-23%): (56-63%): (19-28%). By controlling the contents of calcium polysulfide, ferrous salt and humic acid powder in the above range, the acid leaching concentration of the mercury-polluted soil with lower concentration can reach the national standard, the change range of the soil environment acidity and alkalinity is small, and the soil remediation effect lasts for a long time.
In some embodiments of the present application, the calcium polysulfide is selected from a calcium polysulfide aqueous or a calcium polysulfide powder. In order to fully exert the function of calcium polysulfide, the skilled person in the art can select the calcium polysulfide according to the soil layer characteristics, the particle size or the water content of the mercury polluted soil in actual operation. For example, when the mercury-polluted soil is clay soil, a calcium polysulfide aqueous agent is added; when the mercury-polluted soil is sandy soil, the calcium polysulfide powder can be added in an adjustable manner.
In some embodiments of the present application, there is no particular limitation on the ferrous salt as long as the object of the present application can be satisfied. For example, the ferrous salt is selected from ferrous sulfate heptahydrate or ferrous sulfide, and the like.
In some embodiments of the present application, the humic acid powder has a particle size of 0.15 to 0.25mm (60 to 100 mesh), preferably 0.20mm (80 mesh). The particle size of the humic acid powder is controlled within the range, so that the humic acid powder can play a role in soil to a greater extent, and the pH value of the soil can be better adjusted and eased.
The repairing agent comprises calcium polysulfide, ferrous salt and humic acid powder, wherein the mass percent of the calcium polysulfide, the ferrous salt and the humic acid powder is (16-23%) based on the total mass of the repairing agent: (56-63%): (19-28%). By selecting the components and controlling the content of each component, the repairing agent is used in the low-concentration large-area mercury-polluted soil, so that the mercury in an effective state is converted into the mercury with insolubility so as to stably exist in the soil, and the toxic leaching of the mercury in the mercury-polluted soil can be effectively reduced. The pH change range of the repaired soil is small, and the soil repairing effect lasts for a long time.
The application in a second aspect provides a method for repairing mercury-contaminated soil, and the repairing agent provided by the application is adopted, and comprises the following steps:
(1) calculating the total mercury pollution amount in the soil in the remediation area;
in some embodiments of the present application, the total mercury pollution amount of the soil in the remediation area is calculated, and the total mercury pollution amount of the soil in the remediation area is determined, so as to provide a basis for the amount of the remediation agent used in the soil. In the process of calculating the total mercury pollution amount of the soil in the remediation area, a person skilled in the art can divide a large-area remediation area into a plurality of small-area areas according to actual needs to calculate the total mercury pollution amount respectively. In the present application, the method of calculating the total amount of mercury contamination of the soil in the remediation zone is not particularly limited as long as the object of the present application can be achieved.
In some embodiments of the application, after the total mercury pollution amount of the soil in the remediation area is calculated, basic parameters such as the pH, the water content, the density and the particle components of the mercury-polluted soil can be investigated, so that various data indexes of the soil in the remediation area can be more accurately judged, and data information with higher reference significance and utilization value is provided for the next-step remediation of the mercury-polluted soil.
In the present application, the moisture content refers to the mass percentage content of moisture in the soil.
(2) Adding the calcium polysulfide and the ferrous salt into the soil in several times, stirring and mixing uniformly, and stacking and maintaining for 2-4 days, preferably 3 days;
in some embodiments of the present application, before adding the calcium polysulfide and the ferrite to the soil, a negative pressure greenhouse can be constructed in a remediation area, the soil is crushed in the negative pressure greenhouse and is sieved for the first time, the first sieved particle size is 5-15cm, preferably 5cm, and large-particle-size non-soil substances such as stones, bricks, plant rhizomes and the like can be sieved out through the first sieving to obtain soil blocks. Crushing the soil blocks, and sieving for the second time to obtain the soil blocks with the particle size of less than 3 cm. Through the first screening, the non-soil impurities in the remediation zone are rejected. Through secondary screening, the particle size of the mercury-polluted soil is controlled to be less than 3cm, the mercury-polluted soil can be more fully reacted with calcium polysulfide and ferrous salt, and the action of the calcium polysulfide and the ferrous salt is effectively exerted, so that the mercury in the effective state in the soil is converted into the mercury in the insoluble state to the maximum extent, the acid leaching concentration of the soil is reduced, and the remediation effect of the mercury-polluted soil is improved.
According to the method, the negative pressure greenhouse is built, the original unorganized emission of the polluted gas generated in the open operation area of the repair area can be changed into organized emission, and the gas emission is controlled within the national emission standard; the dust and the mercury vapor generated in the repair area can be effectively controlled to volatilize. The anti-seepage concrete brick bottom in the negative pressure greenhouse can reduce the groundwater pollution caused by precipitation infiltration in the repair area.
In some embodiments of the present application, when the calcium polysulfide and the ferrous salt are added to the soil, the soil may be classified into clay-based soil and sand-based soil according to the particle size of the soil; adding a calcium polysulfide aqueous agent into the clay soil, keeping the water content of the clay soil at 50-60%, and adding ferrous salt according to the mass percentage; and adding calcium polysulfide powder and ferrous salt which are uniformly mixed according to the mass percentage into the surface of the sandy soil. In the application, when the calcium polysulfide aqueous solution is added into clay soil, the calcium polysulfide aqueous solution can be uniformly sprayed into the soil.
In the present application, the method for classifying clay soil and sand soil is not particularly limited, and those skilled in the art may select clay soil and sand soil according to actual needs, and the object of the present application can be achieved by classifying clay soil and sand soil according to the particle size of soil.
(3) Adding the humic acid powder into the soil, uniformly stirring, keeping the water content of the soil at 30-50%, and stacking and maintaining for 6-8 days, preferably for 7 days;
wherein the mass percentages of the calcium polysulfide, the ferrous salt and the humic acid powder are (16-23%) based on the total mass of the repairing agent: (56-63%): (19-28%).
In some embodiments of the present application, after calculating the mercury content of the soil in the remediation zone, the mercury content may be calculated according to the chemical formula Hg2++S2-Calculating the required S as HgS2-The number of moles of (2) Ns. In soil remediation treatment, S is generally added2-The mole number of (b) is 10-20Ns, and the corresponding calculation is carried outThe added mass of calcium polysulfide (CaS) is obtained. Based on the total mass of the repairing agent, the mass percentages of calcium polysulfide, ferrous salt and humic acid powder are (16-23%): (56-63%): (19-28%), according to the mass of the calcium polysulfide determined by the mercury content, the adding mass of the ferrous salt and the humic acid powder is respectively calculated according to the mass percent of the calcium polysulfide, the ferrous salt and the humic acid powder.
In the application, after the mercury-contaminated soil is repaired by the method for repairing the mercury-contaminated soil, the stationing sampling and the detection treatment effect can be carried out according to the relevant national guide rules.
According to the method for restoring mercury-contaminated soil, the restoring agent provided by the application is adopted to stably restore mercury-contaminated soil with lower concentration, and compared with the 269mg/kg pollution concentration processing limit value of EPA, the limit value of solidifying/stabilizing low-concentration soil is enlarged, so that the method can be used for restoring mercury-contaminated soil with low concentration and large earth volume in China. By adopting the method for restoring the mercury-polluted soil, all components in the restoring agent are fully mixed, stirred and maintained with the mercury-polluted soil in sequence, so that the mercury in the mercury-polluted soil in an effective state is converted into the mercury in an insoluble state, and the mercury stably exists in the soil, and the mercury toxicity leaching of the restored soil is remarkably reduced. In addition, the pH value of the soil environment cannot be greatly changed, and the pH value of the repaired soil is maintained at a reasonable level. The method for stabilizing and repairing the mercury-polluted soil by adopting the repairing agent ensures that the repairing effect of the mercury-polluted soil lasts for a long time.
In a third aspect, the application provides the use of the remediation agent of the application for remediation of soil with a mercury concentration of less than 3200 mg/Kg.
In some embodiments of the present application, the use of the remediation agent described above for remediation of soil having a mercury concentration of less than 3000 mg/Kg.
Hereinafter, embodiments of the present application will be described in more detail with reference to examples and comparative examples.
Measuring methodAnd equipment:
mercury pollution total:
microwave digestion/atomic fluorescence method for measuring mercury, arsenic, selenium, bismuth and antimony in soil and sediments HJ 680-2013.
Acid leaching concentration:
pretreatment HJT299-2007 (solid waste leaching toxicity leaching method, sulfuric acid and nitric acid method); determination of solid waste mercury, arsenic, selenium, bismuth and antimony microwave digestion/atomic fluorescence method HJ 702-2014.
Example 1
(1) Collecting mercury contaminated soil, removing stones and plant roots, crushing, mixing uniformly, naturally drying (selecting samples to measure the water content), grinding, sieving with a 80-mesh sieve, fully mixing uniformly, weighing 24 samples, taking 3 samples as blank samples, taking 21 samples as treatment samples, and accurately measuring each sample to 200.0g, wherein the test treatment steps are shown in table 1.
(2) Determination of blank CK1、CK2、CK3Mercury contamination full and acid leaching concentration.
(3)CK1、CK2、CK3The average value of the mercury content in the samples is 2403mg/kg, the adding mass of calcium polysulfide, ferrous sulfate and humic acid powder in each sample is calculated according to the molar ratio S to Hg, the empirical parameter ratio and the like, and the effective component content of the calcium polysulfide aqueous solution is about 29 percent, so the mass percentage of the calcium polysulfide, the ferrous sulfate and the humic acid powder treated by SFH is 18 percent, 61 percent and 21 percent, and the particle size of the humic acid powder is 80 meshes.
(4) Adding medicine and mixing, maintaining water content of 30-50%, and curing in self-sealing bag for 7 days (4 days after adding humic acid in SFH).
(5) The acid leaching concentration of each sample was determined and the data are summarized in table 2. FIG. 1 shows a graph of the acid leach concentration of the untreated, treated sample of example 1 in comparison.
Example 2
(1) Excavating 10 square (m) on site3) Mercury contaminated soil, earth density at 1.8g/cm3Measuring, mechanically stirring and uniformly mixing, collecting 6 mixed samples to measure mercury pollutionDye full and acid leaching concentration.
(2) The average concentration of the mercury content in the mercury-contaminated soil is 3187mg/kg according to the data, and the calculation shows that 212kg of calcium polysulfide (730 kg of calcium polysulfide aqueous solution), 540kg of ferrous sulfate and 180kg of humic acid powder are needed, 720kg of calcium polysulfide aqueous solution, 525kg of ferrous sulfate and 175kg of humic acid powder are actually added, the mass percentages of the calcium polysulfide, the ferrous sulfate and the humic acid powder are 23 percent, 58 percent and 19 percent, and the particle size of the humic acid powder is 80 meshes.
(3) CK is added1、CK2、CK3、CK4、CK5、CK6The sample is subjected to primary screening and secondary screening to enable the soil particle size to be 3 cm. Weighing calcium polysulfide aqueous solution according to mercury content proportion, and respectively and uniformly spraying the calcium polysulfide aqueous solution on CK1、CK2、CK3、CK4、CK5、CK6In the samples, after the spreading is finished, the water content of the soil is maintained at about 50%, and then ferrous sulfate is weighed according to the proportion and is respectively added into the samples. Then, the mixture was stirred and mixed for 2 times, and stacked and cured for 3 days.
(4) Weighing humic acid powder according to mercury content proportion, and respectively adding CK1、CK2、CK3、CK4、CK5、CK6And (3) uniformly stirring the mixture in the sample, keeping a certain soil moisture content, and stacking and maintaining for 7 days.
(5) The acid leaching concentrations of the 6 samples were determined and the data are summarized in table 3. Figure 2 shows a graph of acid leach concentration before and after treatment for the sample of example 2.
Example 3
(1) Excavating 10 square (m) on site3) Mercury contaminated soil, earth density at 1.8g/cm3And (3) measuring, mechanically stirring and uniformly mixing, and collecting 6 mixed samples to measure the total mercury pollution amount and the acid leaching concentration.
(2) The average concentration of the mercury content in the mercury-contaminated soil is 2209mg/kg according to the data, and the calculation shows that 147kg of calcium polysulfide (506 kg of calcium polysulfide aqueous solution), 540kg of ferrous sulfate and 180kg of humic acid powder are needed, 500kg of calcium polysulfide aqueous solution, 500kg of ferrous sulfate and 150kg of humic acid powder are actually added, the mass percentage of the calcium polysulfide aqueous solution, the mass percentage of the ferrous sulfate and the mass percentage of the humic acid powder are 18 percent, 63 percent and 19 percent, and the particle size of the humic acid powder is 80 meshes.
(3) CK is added1、CK2、CK3、CK4、CK5、CK6The sample is subjected to primary screening and secondary screening to enable the soil particle size to be 3 cm. Weighing calcium polysulfide aqueous solution according to mercury content proportion, and respectively and uniformly spraying the calcium polysulfide aqueous solution on CK1、CK2、CK3、CK4、CK5、CK6In the samples, after the spreading is finished, the water content of the soil is maintained at about 50%, and then ferrous sulfate is weighed according to the proportion and is respectively added into the samples. Then, the mixture was stirred and mixed for 2 times, and stacked and cured for 3 days.
(4) Weighing humic acid powder according to mercury content proportion, and respectively adding CK1、CK2、CK3、CK4、CK5、CK6And (3) uniformly stirring the mixture in the sample, keeping a certain soil moisture content, and stacking and maintaining for 7 days.
(5) The acid leaching concentrations of the 6 samples were determined and the data are summarized in table 4. Figure 3 shows a graph of acid leach concentration before and after treatment for the sample of example 3.
Example 4
(1) 144 soil mixed samples with different depths are collected at a project site, and the average value is calculated by carrying out mathematical statistical analysis on the total mercury pollution, and the average value is shown in table 5.
(2) Excavation, batch dosing, stirring, water adding maintenance, backfilling and other construction sequences are carried out on sites in different areas, the dosing quality of calcium polysulfide water agent, ferrous sulfate and humic acid powder of every 12 polluted soils is respectively 600kg (content is 29%), 600kg and 300kg, and the mass percentage of the calcium polysulfide water agent, the ferrous sulfate and the humic acid powder is 16%: 56%: 28 percent, and the particle size of the humic acid powder is 80 meshes.
(3) And (3) subjecting the sample to primary screening and secondary screening to enable the soil to have a particle size of 3 cm. Weighing calcium polysulfide aqueous solution according to the mercury content proportion, respectively and uniformly spraying the calcium polysulfide aqueous solution in a sample, after the spreading is finished, maintaining the water content of the soil at 55%, then weighing ferrous sulfate according to the proportion, and respectively adding the ferrous sulfate into the sample. Then, the mixture was stirred and mixed for 2 times, and stacked and cured for 3 days.
(4) And (3) weighing humic acid powder according to the mercury content proportion, respectively adding the humic acid powder into the samples, uniformly stirring, keeping a certain soil water content, and stacking and maintaining for 7 days.
(5) After the curing, the acid leaching concentration was measured in 27 samples of 500 square samples, and the data are summarized in Table 6.
TABLE 1 Experimental treatment table of example 1
Figure BDA0002927108220000091
TABLE 2 summary of data from example 1
Figure BDA0002927108220000092
Figure BDA0002927108220000101
TABLE 3 comparison of data before and after treatment for each sample in example 2
Figure BDA0002927108220000102
TABLE 4 comparison of data before and after treatment for each sample in example 3
Figure BDA0002927108220000103
TABLE 5 summary of data averages for example 4 samples
Index (I) pH Water content% Mercury full dose (mg/kg) Mercury leaching mg/L
Mean value 8.77 13.8 2318.5 2.867
TABLE 6 comparison of the data processed in example 4
Figure BDA0002927108220000111
From examples 1 to 4, it is seen that, in the method for remediating mercury contaminated soil adopted in the present application, after the components in the remediation agent provided in the present application are fully mixed, stirred and maintained with mercury contaminated soil in sequence, the mercury in the effective state is converted into mercury in an insoluble state, so that the acid leaching concentration of the mercury contaminated soil is significantly reduced, and the treatment efficiency of the method for remediating mercury in the effective state can reach more than 99%. In addition, the method for restoring mercury-polluted soil provided by the application can not greatly change the acidity and alkalinity of the soil environment, so that the acidity and alkalinity of the restored soil can be maintained at a reasonable level. The method can be used for stably repairing the mercury-polluted soil with lower concentration, the limit value of the solidification/stabilization treatment of the low-concentration soil is enlarged relative to the treatment limit value of the 269mg/kg pollution concentration of EPA, and the method is simple and easy to implement and can be widely applied to the mercury-polluted soil with the mercury content concentration of less than 3200 mg/kg.
The above description is only for the preferred embodiment of the present application and is not intended to limit the scope of the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims (10)

1. A repairing agent comprising calcium polysulfide, ferrous salt and humic acid powder, wherein the mass percentage of the calcium polysulfide, the ferrous salt and the humic acid powder is (16-23%) based on the total mass of the repairing agent: (56-63%): (19-28%).
2. The repairing agent according to claim 1, wherein the calcium polysulfide is selected from a calcium polysulfide aqueous agent or a calcium polysulfide powder agent.
3. The healant according to claim 1, wherein the ferrous salt is selected from ferrous sulfate heptahydrate or ferrous sulfide.
4. The repairing agent of claim 1, wherein the particle size of the humic acid powder is 0.15-0.25 mm.
5. A method of remediating mercury contaminated soil using the remediation agent of any one of claims 1 to 4, comprising the steps of:
(1) calculating the total mercury pollution amount in the soil in the remediation area;
(2) adding the calcium polysulfide and the ferrous salt into the soil, uniformly stirring, stacking and maintaining for 2-4 days;
(3) adding the humic acid powder into the soil, uniformly stirring, keeping the water content of the soil at 30-50%, and stacking and maintaining for 6-8 days;
wherein the mass percentages of the calcium polysulfide, the ferrous salt and the humic acid powder are (16-23%) based on the total mass of the repairing agent: (56-63%): (19-28%).
6. The method according to claim 5, wherein in the step (2), when the calcium polysulfide and the ferrous salt are added to the soil, the soil is classified into clay-based soil and sand-based soil according to a particle size of the soil;
adding a calcium polysulfide aqueous agent into the clay soil, keeping the water content of the clay soil at 50-60%, and adding ferrous salt; and adding the calcium polysulfide powder and the ferrous salt which are uniformly mixed on the surface of the sandy soil.
7. The method of claim 5, wherein in step (2), prior to adding the calcium polysulfide and the ferrous salt to the soil, the method further comprises:
crushing the soil, and carrying out primary screening to obtain soil blocks, wherein the primary screening particle size is 5-15 cm;
and crushing the soil blocks, and screening for the second time, wherein the grain size of the screened soil blocks for the second time is less than 3 cm.
8. The method of claim 5, wherein after calculating the total amount of mercury contamination of the soil in the remediation zone in step (1), the method further comprises:
the pH, moisture content, density and particulate composition of the soil were determined.
9. Use of the remediation agent of any one of claims 1 to 4 as a remediation agent for soil having a mercury concentration of less than 3200 mg/Kg.
10. Use of the remediation agent of any one of claims 1 to 4 as a remediation agent for soil having a mercury concentration of less than 3000 mg/Kg.
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CN107398472A (en) * 2017-08-24 2017-11-28 航天凯天环保科技股份有限公司 A kind of stable method for repairing mercury contaminated soil of low temperature thermal desorption amalgamation
CN107597787A (en) * 2017-08-11 2018-01-19 航天凯天环保科技股份有限公司 A kind of method of waste slag containing mercury efficient stable
CN108690623A (en) * 2018-05-23 2018-10-23 北京润鸣环境科技有限公司 A kind of nickel contamination soil-repairing agent and preparation method thereof and application method

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