CN114644929A - Novel composite curing agent for heavy metal Cd-polluted soil and use method thereof - Google Patents
Novel composite curing agent for heavy metal Cd-polluted soil and use method thereof Download PDFInfo
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- CN114644929A CN114644929A CN202011497101.6A CN202011497101A CN114644929A CN 114644929 A CN114644929 A CN 114644929A CN 202011497101 A CN202011497101 A CN 202011497101A CN 114644929 A CN114644929 A CN 114644929A
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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
- C09K17/02—Soil-conditioning materials or soil-stabilising materials containing inorganic compounds only
- C09K17/12—Water-soluble silicates, e.g. waterglass
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- 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
Abstract
The invention provides a novel composite curing agent for heavy metal Cd contaminated soil and a use method thereof, wherein the components comprise red mud, blast furnace slag and an alkali activator or red mud, fly ash and an alkali activator, the mixing ratio of the red mud to the blast furnace slag is 7:3, and the mixing ratio of the red mud to the fly ash is 1: 1. NaOH and Na as alkali activator2SiO3In a ratio of 9: 1. Crushing and screening the soil to be repaired to obtain fine soil, fully mixing the blast furnace slag mixture or the fly ash mixture with the fine soil, and uniformly stirring to obtain a fine soil compound. And uniformly spraying the aqueous solution of the alkaline excitant into the fine-grained soil compound to enable the water content to reach 15-20%, and fully and uniformly mixing. And standing the mixed soil for 7-28 days to solidify the soil polluted by the heavy metal ions. The curing agent of the invention can not only obviously reduce the content of heavy metal in soil, but also improve the bearing capacity of soil body, thereby achieving the purposes of treating wastes with processes of wastes against one another and changing wastes into valuables"is used in the above-mentioned manner.
Description
Technical Field
The invention belongs to the technical field of contaminated soil treatment, and particularly relates to a novel composite curing agent for heavy metal Cd contaminated soil and a using method thereof.
Background
In recent years, the urban industrialization of China is rapidly developed, but the environmental pollution problem is also followed. Among them, soil pollution has reached a considerable degree, and heavy metals are one of the main pollution sources, and are directly related to human production and life and health problems. At present, not only the heavy metal polluted soil needs to be effectively treated, but also the treatment needs to be carried out in the same direction as the national relevant environmental treatment policy, and an economic, efficient and environment-friendly treatment method is explored according to local conditions.
Heavy metal, meaning a density of greater than 4.5g/cm3The heavy metals include gold, silver, copper, iron, mercury, lead, cadmium and the like, and in the aspect of environmental pollution, the heavy metals mainly refer to mercury (mercury), cadmium, lead, chromium, metalloid arsenic and other heavy elements with remarkable biological toxicity. It is mainly from the industries of smelting, mining, electroplating, production of pesticides and fertilizers, batteries, fuels and the like. A large amount of heavy metals are diffused and discharged, so that a large area of soil is polluted, and investigation shows that the soil pollution conditions of a plurality of countries show a trend of increasing year by year.
The soil pollution remediation technology is to apply chemical, physical and biological technologies and methods to reduce the concentration of pollutants in soil, fix soil pollutants, convert the soil pollutants into low-toxicity or non-toxic substances, and block the transfer path of the soil pollutants in an ecosystem. Theoretically feasible restoration techniques include phytoremediation, microbial restoration, chemical restoration, physical restoration, and comprehensive restoration.
Physical repair method: the soil remediation method has the advantages of obvious remediation effect, obvious remediation effect on the soil with serious pollution degree and small area, and wide adaptability. But the environmental disturbance to the soil itself is large, which may cause the structural damage and the decrease of fertility of the soil.
Chemical repairing method: by adding the additive into the soil, the heavy metal ions in the soil are adsorbed, precipitated, ion exchanged and the like, so that the existing form of the metal ions is changed, and the biological effectiveness and the mobility of the soil are reduced. The common additives include cement, lime, fly ash, zeolite, calcium phosphate, silicate and organic matters which can promote the reduction reaction. However, this remediation technique does not fundamentally remove the pollutants from the soil.
The bioremediation method comprises the following steps: the treatment technology utilizes the characteristics of various organisms (including microorganisms, animals and plants) to absorb, degrade and transform pollutants in soil, so that the toxicity of the polluted soil is improved. The biological treatment technology can be carried out on site, the transportation cost is reduced, the chance of direct contact of human beings with pollutants is reduced, and the problem of secondary pollution is avoided. However, bioremediation methods have limitations and long periods, and improper use can aggravate soil contamination.
According to the position of the restored soil, the in-situ restoration technology and the ex-situ restoration technology can be divided.
The in-situ remediation technology means that the soil is not disturbed too much in the process of treating the unearthed soil. Its advantages are high effect and low cost. Expensive ground environment engineering infrastructure and remote transportation do not need to be built, and the operation and maintenance are simple. In addition, the in-situ remediation technology can be used for remediating deep soil pollution. The disadvantage is that the three wastes generated in the treatment process are difficult to control.
The ectopic remediation technology refers to a process of remediating excavated soil. Ex-situ remediation is divided into in-situ treatment, which refers to a process of treating excavated soil that occurs in situ, and ex-situ treatment. Off-site treatment refers to the process of transporting excavated soil to another location for treatment. The method has the advantages that the method has better control on the conditions of the treatment process, better contact with pollutants and easy control of the discharge of three wastes generated in the treatment process; disadvantages are the need for excavation and transport prior to treatment, the influence on the reuse of the treated soil and the often high costs.
At present, a Solidification Stabilization method (Solidification/Stabilization), referred to as (S/S) for short, is the most widely applied method for repairing polluted soil. S/S is a foundation treatment method which adds a soil curing agent into polluted soil, uniformly stirs the mixture and converts the soil, the pollutant and the curing agent into a whole compact solid with weak fluidity and complete structure after a series of physicochemical reactions are combined. The heavy metal ions in the solidified/stabilized polluted soil body reduce the biological effectiveness and the mobility due to the adsorption or precipitation effect, and further improve the engineering property of the polluted soil. The main action mechanism of the method is physical wrapping, physical adsorption, chemical precipitation, chemical combination and the like.
At present, not only the heavy metal polluted soil needs to be effectively treated, but also the treatment needs to be carried out in the same direction as the national relevant environmental treatment policy, and an economic, efficient and environment-friendly treatment method is explored according to local conditions. Therefore, the research on the novel curing agent which can effectively repair the high-concentration heavy metal polluted soil and is economic and environment-friendly has important significance.
Disclosure of Invention
The invention aims to provide a novel composite curing agent for heavy metal Cd-polluted soil and a using method thereof, and aims to solve the problems in the prior art.
The invention is realized by the following technical scheme:
a novel composite curing agent for heavy metal Cd polluted soil comprises red mud, blast furnace slag and an alkali activator or red mud, fly ash and an alkali activator, wherein the mixing ratio of the red mud to the blast furnace slag is 7:3, and the mixing ratio of the red mud to the fly ash is 1: 1.
The alkaline activator comprises NaOH and Na2SiO3NaOH and Na2SiO3In a ratio of 9: 1.
The red mud is taken from an aluminum factory, dried, ground and sieved by a 2mm sieve, and the novel composite curing agent for the heavy metal Cd-polluted soil comprises the following main components in percentage by mass: 39.2% Fe2O3，25.5％Al2O3，17.2％SiO2，7.8％Na2O and the balance being others.
The blast furnace slag is taken from an iron mill, dried, ground and sieved by a 2mm sieve, and the novel composite curing agent for the heavy metal Cd-polluted soil comprises the following main components in percentage by mass: 57.13% CaO, 17.62% SiO2，11.93％Al2O3，7.25％MgO，1.4％Fe2O3And the balance being others.
The coal ash is taken from a certain coal-fired power plant, is dried and ground by a 2mm sieve, and comprises the following main components in percentage by mass: 37.10% SiO2，13.86％Al2O3，30.31％CaO，0.39％Fe2O3And the balance being others.
A use method of a novel composite curing agent for heavy metal Cd polluted soil comprises the following steps:
(1) drying and grinding the red mud and sieving the ground red mud by a sieve of 2 mm;
(2) drying and grinding blast furnace slag or fly ash, and sieving by a 2mm sieve;
(3) fully mixing the red mud and the blast furnace slag according to the proportion of 7:3 to form a blast furnace slag mixture or fully mixing the red mud and the fly ash according to the proportion of 1:1 to form a fly ash mixture;
(4) mixing NaOH and Na2SiO3Uniformly mixing the components according to a ratio of 9:1, dissolving the components into water to prepare 8mol/L solution which is used as an alkaline activator;
(5) carrying out excavation, crushing and screening treatment on the soil polluted by the heavy metal Cd to be restored to obtain fine-grained soil;
(6) fully mixing the blast furnace slag mixture or the fly ash mixture with fine-grained soil according to a certain mass ratio, and uniformly stirring to form a fine-grained soil compound;
(7) uniformly spraying an aqueous solution of an alkaline activator into the fine-grained soil compound to enable the water content to reach 15-20%, and fully and uniformly stirring;
(8) and standing the mixed soil for 7-28 days to solidify the soil polluted by the heavy metal ions.
In the step (6), the blast furnace slag mixture or the fly ash mixture and the fine soil are fully mixed according to the mass ratio of 1:9 and are uniformly stirred;
the novel composite curing agent for the heavy metal Cd-polluted soil is used for curing the heavy metal ion-polluted soil.
The invention has the beneficial effects that: a novel composite curing agent for heavy metal Cd contaminated soil and a using method thereof reduce the bioactivity of heavy metal in the contaminated soil and reduce the leachable amount through multiple actions of adsorption and curing, avoid the heavy metal pollutants from generating continuous secondary pollution on the surrounding surface water and underground water, and improve the foundation bearing capacity of the heavy metal contaminated soil; the curing agent disclosed by the invention can play a more effective stabilizing role in heavy metal pollutants in soil. In addition, the curing agent disclosed by the invention can obviously reduce the content of heavy metals in soil, can improve the bearing capacity of soil, solves the problem of treatment of industrial wastes such as red mud, blast furnace slag and fly ash to a certain extent, achieves the effects of treating wastes with processes of wastes against one another and changing wastes into valuables, and has better economic benefits and engineering application prospects.
Detailed Description
The following description is further described in conjunction with the specific embodiments, but the specific embodiments below should not be construed as limiting the invention. Various changes and modifications obvious to those skilled in the art based on the present invention should be made within the scope of the present invention in order to make the technical problems, technical solutions and advantages solved by the present invention more apparent, and the present invention is further described in detail with reference to the following embodiments.
Example 1
The novel composite curing agent for the heavy metal Cd-polluted soil comprises the following components: mixing red mud and fly ash in a ratio of 1:1 to obtain a fly ash mixture, and alkaline activators NaOH and Na2SiO3In a ratio of 9: 1. Mixing NaOH and Na2SiO3Uniformly mixing the components according to the ratio of 9:1, and dissolving the components into water to prepare 8mol/L solution which is used as an alkaline activator. The red mud is obtained from an aluminum factory, dried, ground and sieved by a 2mm sieve, and the main components and the mass percentage of each component are shown in table 1. The fly ash is taken from a coal-fired power plant, dried, ground and sieved by a 2mm sieve, and the main components of the fly ash are shown in Table 3.
The use method of the novel composite curing agent for the heavy metal Cd-polluted soil comprises the following steps:
(1) excavating, crushing and screening the soil polluted by the heavy metal Cd to be repaired to obtain fine-grained soil;
(2) fully mixing the fly ash mixture with fine-grained soil according to the mass ratio of 1:9, and uniformly stirring to form a fine-grained soil compound;
(3) uniformly spraying an aqueous solution of an alkaline activator into the fine-grained soil compound to enable the water content to reach 15-20%, and fully and uniformly stirring;
(4) and standing the mixed soil for 7-28 days to solidify the soil polluted by the heavy metal ions.
Example 2
The novel composite curing agent for the heavy metal Cd-polluted soil comprises the following components: mixing red mud and blast furnace slag in a ratio of 7:3 to obtain a blast furnace slag mixture, and alkali activators NaOH and Na2SiO3In a ratio of 9: 1. Mixing NaOH and Na2SiO3Uniformly mixing the components according to the ratio of 9:1, and dissolving the components into water to prepare 8mol/L solution which is used as an alkaline activator. The red mud is obtained from a certain iron-making plant, dried, ground and processed as in example 12mm sieve, the main components of which are shown in table 2.
The application method of the novel composite curing agent for heavy metal Cd-polluted soil comprises the following steps:
(1) excavating, crushing and screening the soil polluted by the heavy metal Cd to be repaired to obtain fine-grained soil;
(2) fully mixing the blast furnace slag mixture with fine-grained soil according to the mass ratio of 1:9, and uniformly stirring to form a fine-grained soil compound;
(3) uniformly spraying an aqueous solution of an alkaline activator into the fine-grained soil compound to enable the water content to reach 15-20%, and fully and uniformly stirring;
(4) and standing the mixed soil for 7-28 days to solidify the soil polluted by the heavy metal ions.
TABLE 1 chemical index of red mud for test
The blast furnace slag is taken from a certain iron works, dried, ground and sieved by a 2mm sieve, and the main components of the blast furnace slag are shown in Table 2.
TABLE 2 chemical index of blast furnace slag for test
The fly ash is taken from a coal-fired power plant, dried, ground and sieved by a 2mm sieve, and the main components of the fly ash are shown in Table 3.
TABLE 3 chemical index of fly ash for test
The above description is only illustrative of the preferred embodiments of the present application. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.
Claims (8)
1. A novel composite curing agent for heavy metal Cd contaminated soil is characterized by comprising red mud, blast furnace slag and an alkali activator or red mud, fly ash and an alkali activator, wherein the mixing ratio of the red mud to the blast furnace slag is 7:3, and the mixing ratio of the red mud to the fly ash is 1: 1.
2. The novel composite curing agent for heavy metal Cd-polluted soil as claimed in claim 1, wherein the alkaline activator comprises NaOH and Na2SiO3NaOH and Na2SiO3In a ratio of 9: 1.
3. The novel composite curing agent for heavy metal Cd-polluted soil according to claim 1, wherein the red mud is obtained from an aluminum factory, dried, ground and sieved by a 2mm sieve, and comprises the following main components in percentage by mass: 39.2% Fe2O3，25.5％Al2O3，17.2％SiO2，7.8％Na2O。
4. The novel composite curing agent for heavy metal Cd-polluted soil as claimed in claim 1, wherein the blast furnace slag is obtained from iron works, dried, ground and sieved by a 2mm sieve, and comprises the following main components in percentage by mass: 57.13% CaO, 17.62% SiO2，11.93％Al2O3，7.25％MgO，1.4％Fe2O3。
5. The novel composite curing agent for heavy metal Cd-polluted soil as claimed in claim 1, wherein the fly ash is obtained from fly ashIn a certain coal-fired power plant, the coal-fired power plant is dried and ground to pass through a 2mm sieve, and comprises the following main components in percentage by mass: 37.10% SiO2，13.86％Al2O3，30.31％CaO，0.39％Fe2O3。
6. A use method of a novel composite curing agent for heavy metal Cd-polluted soil is characterized by comprising the following steps:
(1) drying and grinding the red mud and sieving the ground red mud by a sieve of 2 mm;
(2) drying and grinding blast furnace slag or fly ash, and sieving by a 2mm sieve;
(3) fully mixing the red mud and the blast furnace slag according to the proportion of 7:3 to form a blast furnace slag mixture or fully mixing the red mud and the fly ash according to the proportion of 1:1 to form a fly ash mixture;
(4) mixing NaOH and Na2SiO3Uniformly mixing the components according to a ratio of 9:1, dissolving the components into water to prepare 8mol/L solution which is used as an alkaline activator;
(5) carrying out excavation, crushing and screening treatment on the soil polluted by the heavy metal Cd to be restored to obtain fine-grained soil;
(6) fully mixing the blast furnace slag mixture or the fly ash mixture with fine-grained soil according to a certain mass ratio, and uniformly stirring to form a fine-grained soil compound;
(7) uniformly spraying an aqueous solution of an alkaline activator into the fine-grained soil compound to enable the water content to reach 15-20%, and fully and uniformly stirring;
(8) and standing the mixed soil for 7-28 days to solidify the soil polluted by the heavy metal ions.
7. The use method of the novel composite curing agent for the soil polluted by the heavy metal Cd in the claim 6, wherein in the step (6), the blast furnace slag mixture or the fly ash mixture is fully mixed with the fine soil according to the mass ratio of 1:9, and the mixture is uniformly stirred.
8. The novel composite curing agent for the heavy metal Cd-polluted soil as claimed in any one of claims 1 to 5 is used for curing the heavy metal ion-polluted soil.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114989828A (en) * | 2022-06-27 | 2022-09-02 | 湖北工业大学 | Novel curing agent for curing heavy metal copper polluted soil and use method thereof |
| CN115521787A (en) * | 2022-10-17 | 2022-12-27 | 中国科学院南京土壤研究所 | Lead-zinc smelting site heavy metal compound contaminated soil remediation agent and application thereof |
| CN115634917A (en) * | 2022-09-09 | 2023-01-24 | 江苏省环境科学研究院 | Method for restoring dye-contaminated soil |
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| CN111346903A (en) * | 2020-03-24 | 2020-06-30 | 陕西地建土地工程技术研究院有限责任公司 | Method for solidifying and stabilizing heavy metal contaminated soil by taking fly ash as raw material |
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| CN105294023A (en) * | 2015-11-17 | 2016-02-03 | 中山大学 | Method for repairing heavy metal-polluted soil by using red mud granular material |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114989828A (en) * | 2022-06-27 | 2022-09-02 | 湖北工业大学 | Novel curing agent for curing heavy metal copper polluted soil and use method thereof |
| CN115634917A (en) * | 2022-09-09 | 2023-01-24 | 江苏省环境科学研究院 | Method for restoring dye-contaminated soil |
| CN115634917B (en) * | 2022-09-09 | 2023-11-14 | 江苏省环境科学研究院 | Restoration method for dye-contaminated soil |
| CN115521787A (en) * | 2022-10-17 | 2022-12-27 | 中国科学院南京土壤研究所 | Lead-zinc smelting site heavy metal compound contaminated soil remediation agent and application thereof |
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