River channel sediment in-situ heavy metal removal and phosphorus control material and preparation method thereof

Abstract

The application discloses a kind of river channel sediment in-situ heavy metal removal, phosphorus control material and preparation method thereof, wherein the in-situ heavy metal removal, phosphorus control material uses the raw material of the following weight parts of ingredients: blast furnace slag 26.7-43.2 parts, limonite 20.2-32.7 parts, water 23.45-37.95 parts, and is prepared by batching, grinding, hydrothermal reaction, solid-liquid separation, washing and drying.The preparation method comprises the following steps: S1, pretreatment;S2, hydrothermal reaction;S3, solid-liquid separation, wherein S2, the hydrothermal reaction step further comprises: S21, precursor preparation;S22, material synthesis.The application utilizes solid waste blast furnace slag for resource utilization, and prepares a material suitable for in-situ heavy metal removal and phosphorus control of sediment.The material can effectively remove heavy metals and phosphorus in sediment, has low cost, stable treatment effect, and is not prone to secondary pollution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of river sediment treatment, and particularly relates to a material for removing heavy metals and controlling phosphorus from river sediment in situ and a preparation method thereof. BACKGROUND

[0002] River sediment, as a key component of the aquatic ecosystem, plays an important role in material circulation and energy flow. However, with the acceleration of industrialization and urbanization, a large amount of pollutants are discharged into rivers, especially in urban rivers, because the pipe network system is not perfect, a large amount of sewage is easily discharged into the river through the rainwater outlet. In the long run, the content of heavy metals and phosphorus in the sediment increases significantly, thereby causing a series of environmental problems.

[0003] In the field of river sediment remediation, in-situ remediation and ex-situ remediation are two core technical routes. In-situ remediation emphasizes treatment at the original position of the sediment, while ex-situ remediation transfers the contaminated sediment to a specific site for treatment. Although ex-situ remediation has obvious effects, it requires large engineering quantity and investment. If the dredged sediment is not further treated or improperly treated, it will cause secondary pollution to the environment. In-situ remediation can prevent pollutants in the sediment from entering the overlying water and cut off the internal pollution source by taking measures. The construction operation is relatively simple, does not require large-scale dredging and transportation of sediment, has little impact on the surrounding environment, is relatively low in cost, and can preserve the original ecological function of the sediment and maintain the stability of the river ecosystem.

[0004] At present, the most promising in-situ remediation technology is sediment capping technology, which has very obvious remediation effect on contaminated sediment and can effectively prevent pollutants in the sediment from entering the water body. Current capping materials are mainly inorganic sand and stone, which are widely available and low in price. However, they have large specific gravity, small specific surface area and poor adsorption performance. In view of this phenomenon, the material for reducing the content of heavy metals and nitrogen and phosphorus in the sediment disclosed in CN119409392A removes phosphorus through physical and chemical adsorption, but the material itself has no effect on removing heavy metals. In addition, the material is obtained by acid leaching of heavy metals in river and lake sediment through fermentation of Aspergillus niger under specific conditions. The removal of heavy metals is relatively harsh, and the effect is unstable. SUMMARY

[0005] To solve the problems of the prior art, the application provides a material for removing heavy metals and controlling phosphorus from river sediment in situ and a preparation method thereof, so as to better apply the material to in-situ remediation of river sediment.

[0006] The technical scheme provided by the application is as follows:

[0007] The application discloses a heavy metal and phosphorus removal material for river sediment in-situ, which is prepared from the following raw materials in parts by weight: 26.7-43.2 parts of blast furnace slag, 20.2-32.7 parts of limonite, and 23.45-37.95 parts of water.

[0008] Preferably, the blast furnace slag is an alkaline blast furnace slag, and main mineral crystal phases include calcium aluminum yellow long stone (Ca2Al (SiAlO7)) and calcium magnesium yellow long stone (Ca2Mg (Si2O7)), wherein the weight percentage of the calcium aluminum yellow long stone (Ca2Al (SiAlO7)) is 30%-45%, and the weight percentage of the calcium magnesium yellow long stone (Ca2Mg (Si2O7)) is 20%-30%.

[0009] Preferably, the alkaline blast furnace slag is a slag formed by water quenching and slow cooling of molten slag generated in the blast furnace ironmaking process, and the alkalinity is 1-1.2.

[0010] Preferably, the chemical composition of the slag is that the weight ratio of CaO and SiO2 is 1-1.2, the weight percentage of Al2O3 is 8%-15%, and the weight percentage of MgO is 5%-8%.

[0011] Preferably, the main component of the limonite is hydrated iron oxide, and the iron content is more than 60%.

[0012] Preferably, the raw materials are selected according to the following parts by weight: 37.6 parts of blast furnace slag, 28.43 parts of limonite, and 33.96 parts of water.

[0013] The application further provides a preparation method of the heavy metal and phosphorus removal material for river sediment in-situ.

[0014] S1, pretreatment: 26.7-43.2 parts by weight of blast furnace slag and 6.7-10.8 parts by weight of water are placed in a ball mill for ball milling, and 20.2-32.7 parts by weight of limonite and 5.1-8.2 parts by weight of water are placed in another ball mill for ball milling, the rotating speed is adjusted to 400-800 rpm, and after 1-4 h of grinding, pretreated wet powder is prepared for standby;

[0015] S2, hydrothermal reaction:

[0016] S21, preparation of a precursor: the pretreated blast furnace slag wet powder, limonite wet powder and 11.7-18.9 parts by weight of water are placed in a high-pressure reaction kettle together, the rotating speed is 200-300 rpm, and the reaction time is 24-72 h;

[0017] S22, material synthesis: after the reaction, the high-pressure reactor is heated, the rotating speed is 500-600 rpm, and the reaction time is 12-24 hours;

[0018] S3, solid-liquid separation: after the reaction, the temperature of the high-pressure reactor is cooled, the mixture is taken out and subjected to solid-liquid separation, washed until neutral, and dried at 60-80 DEG C.

[0019] Preferably, in step S1, the blast furnace slag and water in the first ball mill are specifically selected as 37.6 parts by weight, 9.4 parts by weight, the limonite and water in the second ball mill are specifically selected as 28.43 parts by weight, 7.1 parts by weight; in step S21, the amount of water added in the high-pressure reactor is 17.46 parts by weight.

[0020] Preferably, in step S21, the temperature of the high-pressure reactor is 150-200 DEG C, and the pressure is 10 MPa; in step S22, the temperature of the high-pressure reactor is 200-250 DEG C, and the pressure is 10 MPa.

[0021] Preferably, in step S21, the temperature of the high-pressure reactor is 200 DEG C, and the pressure is 10 MPa; in step S22, the temperature of the high-pressure reactor is 250 DEG C, and the pressure is 10 MPa.

[0022] Compared with the prior art, the advantages of the present application are that: the mineral crystal phase Ca2Al (SiAlO7) in the blast furnace slag and the iron montmorillonite hydrothermally generated from the limonite, and the magnesium aluminum / silicic acid gel precursor hydrothermally generated from the mineral crystal phase Ca2Mg (Si2O7) in the blast furnace slag, under the action of low-temperature hydrothermal, the Si-OH, Al-OH on the surface of the iron montmorillonite and the Si-OH, Mg-OH of the gel precursor occur interface bonding reaction, forming a three-dimensional Si-Al-Mg-O porous network with a skeleton structure similar to zeolite or layered double hydroxide, which has high porosity and large specific surface area, not only provides a large number of adsorption sites, and the microporous structure of the three-dimensional network can physically intercept phosphate ions. In addition, the surface is rich in hydroxyl and interlayer exchangeable cations (Mg 2+ , Al 3+ ), which is easy to coordinate and replace with heavy metal ions or phosphate, so as to realize the removal of heavy metals and control of phosphorus.

[0023] The beneficial effects of the present application are that: the solid waste blast furnace slag is used for resource utilization, and a material suitable for in-situ heavy metal removal and phosphorus control of sediment is prepared, which can effectively remove heavy metals and phosphorus in sediment, has low cost, stable treatment effect, and is not easy to produce secondary pollution. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1The work flow chart of the preparation method of the river sediment in-situ heavy metal removal and phosphorus control material. DETAILED DESCRIPTION

[0025] The application will be further described below in conjunction with the drawings and examples:

[0026] Example 1

[0027] The raw materials of the river sediment in-situ heavy metal removal and phosphorus control material of Example 1 include the following components in parts by weight: blast furnace slag 26.7-43.2 parts, limonite 20.2-32.7 parts, and water 23.45-37.95 parts.

[0028] The blast furnace slag is alkaline blast furnace slag, and the main mineral crystal phases include calcium aluminum melilite (Ca2Al(SiAlO7)) and calcium magnesium melilite (Ca2Mg(Si2O7)), and the secondary minerals include pseudowollastonite (CaSiO3), anorthite (CaO・Al2O3・2SiO2), and picropharmacolite (CaO・MgO・2SiO2), etc., wherein the weight percentage of calcium aluminum melilite (Ca2Al(SiAlO7)) is 30%-45%, and the weight percentage of calcium magnesium melilite (Ca2Mg(Si2O7)) is 20%-30%.

[0029] Due to different chemical compositions of the slag and different cooling processes, different alkaline blast furnace slag crystal phases are produced. In the present application, the alkaline blast furnace slag is the main solid molten waste (slag) produced in the blast furnace ironmaking process, and the slag is formed by water quenching and slow cooling, and the alkalinity is 1-1.2. By controlling the weight ratio of CaO and SiO2 in the slag chemical composition to be 1-1.2, the weight percentage of Al2O3 to be 8%-15%, the weight percentage of MgO to be 5%-8%, and the water quenching and slow cooling process, the generation state of the blast furnace slag crystal phase can be adjusted.

[0030] The limonite is a natural mineral, and the main component is hydrated iron oxide, and the iron content is controlled to be more than 60%, and more preferably 60%-62%.

[0031] The specific manufacturing steps of Example 1 are as follows:

[0032] S1, pretreatment: the blast furnace slag (26.7-43.2 parts) and water (6.7-10.8 parts) are placed in a ball mill for ball milling, and the limonite (20.2-32.7 parts) and water (5.1-8.2 parts) are placed in another ball mill for ball milling, and the rotation speed is adjusted to 400-800 rpm, and after grinding for 1-4 h, the pretreated wet powder is prepared for standby;

[0033] The water in the grinding process is adsorbed by the blast furnace slag and the limonite respectively, and therefore will not cause loss.

[0034] S2, hydrothermal reaction:

[0035] S21, precursor preparation: the pretreated blast furnace slag wet powder, limonite wet powder and water (11.7-18.9 parts) are placed in a high-pressure reaction kettle together, at 150°C, pressure 10 MPa, rotation speed 200-300 rpm, reaction time 24-72 h;

[0036] S22, material synthesis: after the reaction is completed, the high-pressure reaction kettle is heated, the temperature is controlled at 250°C, the pressure is 10 MPa, the rotation speed is 500-600 rpm, and the reaction time is 12-24 h;

[0037] S3, solid-liquid separation: after the reaction is completed and the temperature of the high-pressure reaction kettle is cooled to 85°C, the mixture is taken out and subjected to solid-liquid separation, washed to neutral, and dried at 60-80°C.

[0038] In Example 1, in order to ensure the balanced use of the main components (calcium aluminum melilite, calcium magnesium melilite, hydrated iron oxide and water), the weight parts of the raw materials are specifically selected as follows: blast furnace slag 37.6 parts, limonite 28.43 parts, and water 33.96 parts.

[0039] Further, in step S1, the blast furnace slag and water in the first ball mill are specifically selected as 37.6 parts and 9.4 parts, respectively, the limonite and water in the second ball mill are specifically selected as 28.43 parts and 7.1 parts, respectively, and in step S21, the amount of additional water added in the high-pressure reaction kettle is 17.46 parts, which is beneficial to improve the production quality of the river sediment in-situ heavy metal removal and phosphorus control material.

[0040] Example 2

[0041] The river sediment in-situ heavy metal removal and phosphorus control material of Example 2 uses the same blast furnace slag and limonite raw materials as Example 1, and includes the following components in weight parts: blast furnace slag 26.7-43.2 parts, limonite 20.2-32.7 parts, and water 23.45-37.95 parts, and the specific production steps are as follows:

[0042] S1, pretreatment: the blast furnace slag (26.7-43.2 parts) and water (6.7-10.8 parts) are placed in a ball mill for ball milling, and the limonite (20.2-32.7 parts) and water (5.1-8.2 parts) are placed in another ball mill for ball milling, the rotation speed is adjusted to 400-800 rpm, and after 1-4 h of grinding, the pretreated wet powder is prepared for standby;

[0043] The water in the grinding process is adsorbed by the blast furnace slag and limonite, respectively, and therefore will not cause loss.

[0044] S2, hydrothermal reaction:

[0045] S21, precursor preparation: the pretreated blast furnace slag wet powder, limonite wet powder and water (11.7-18.9 parts) were placed in a high-pressure reaction kettle together, at 200°C, pressure 10 MPa, rotation speed 200-300 rpm, reaction time 24-72 h;

[0046] S22, material synthesis: after the reaction, the high-pressure reaction kettle was heated, the temperature was controlled at 250°C, the pressure was 10 MPa, the rotation speed was 500-600 rpm, and the reaction time was 12-24 h.

[0047] S3, solid-liquid separation: after the reaction, the temperature of the high-pressure reaction kettle was cooled to 85°C, the mixture was taken out and subjected to solid-liquid separation, washed to neutral, and dried at 60-80°C.

[0048] Example 3

[0049] A river sediment in-situ heavy metal removal and phosphorus control material of Example 3 uses the same blast furnace slag and limonite raw materials as Example 1, including the following components by weight: blast furnace slag 26.7-43.2 parts, limonite 20.2-32.7 parts, water 23.45-37.95 parts, and the specific production steps are as follows:

[0050] S1, pretreatment: the blast furnace slag (26.7-43.2 parts) and water (6.7-10.8 parts) were placed in a ball mill for ball milling, and the limonite (20.2-32.7 parts) and water (5.1-8.2 parts) were placed in another ball mill for ball milling, the rotation speed was adjusted to 400-800 rpm, and the pretreated wet powder was prepared after grinding for 1-4 h;

[0051] The water in the grinding process is adsorbed by the blast furnace slag and limonite, respectively, and therefore does not cause loss.

[0052] S2, hydrothermal reaction:

[0053] S21, precursor preparation: the pretreated blast furnace slag wet powder, limonite wet powder and water (11.7-18.9 parts) were placed in a high-pressure reaction kettle together, at 250°C, pressure 10 MPa, rotation speed 200-300 rpm, reaction time 24-72 h;

[0054] S22, material synthesis: after the reaction, the high-pressure reaction kettle was heated, the temperature was controlled at 250°C, the pressure was 10 MPa, the rotation speed was 500-600 rpm, and the reaction time was 12-24 h.

[0055] S3, solid-liquid separation: after the reaction, the temperature of the high-pressure reaction kettle was cooled to 85°C, the mixture was taken out and subjected to solid-liquid separation, washed to neutral, and dried at 60-80°C.

[0056] Take blast furnace slag, limonite and water, respectively, according to the method of example 1, example 2, example 3, the preparation of river sediment in-situ heavy metal removal and phosphorus control material, then use the initial concentration of 200mg / L Pb 2+ , 100mg / L Cd 2+ and 50mg / L phosphate mixed solution to test the heavy metal removal and phosphorus control material, the specific index is shown in table 1.

[0057] Example 4

[0058] A kind of river sediment in-situ heavy metal removal and phosphorus control material of example 4, raw materials include the following weight parts of ingredients: blast furnace slag 46.9-75.9 parts, water 23.45-37.95 parts, blast furnace slag is the same as example 1, the specific production steps are as follows:

[0059] S1, pretreatment: blast furnace slag (46.9-75.9 parts) and water (23.45-37.95 parts) are placed in the ball mill together for ball milling, the speed is adjusted to 400-800 rpm, after grinding for 1-4 h, the pretreated wet powder is prepared for standby;

[0060] The water in the grinding process is adsorbed by blast furnace slag and will not cause loss.

[0061] S2, hydrothermal reaction:

[0062] S21, the pretreated blast furnace slag wet powder is placed in a high-pressure reaction kettle, at 200℃, pressure 10 MPa, speed 200-300 rpm, reaction time 24-72 h;

[0063] S22, after the reaction is completed, the high-pressure reaction kettle is heated, the temperature is controlled at 250℃, the pressure is 10 MPa, the speed is 500-600 rpm, and the reaction time is 12-24 h.

[0064] S3, solid-liquid separation: after the reaction is completed, the temperature of the high-pressure reaction kettle is cooled to 85℃, the mixture is taken out and subjected to solid-liquid separation, washed to neutral, and dried at 60-80℃.

[0065] Take blast furnace slag and water, according to the method of example 4, the preparation of river sediment in-situ heavy metal removal and phosphorus control material, then use the initial concentration of 200mg / L Pb 2+ , 100mg / L Cd 2+ and 50mg / L phosphate mixed solution to test the heavy metal removal and phosphorus control material, the specific index is shown in table 1.

[0066] Example 5

[0067] The in-situ heavy metal and phosphorus removal and control material of river channel sediment of example 5, the raw materials include the following ingredients by weight: limonite 46.9-75.9 parts, water 23.45-37.95 parts, limonite is the same as example 1, the specific manufacturing steps are as follows:

[0068] S1, pretreatment: put limonite (46.9-75.9 parts) and water (23.45-37.95 parts) together in a ball mill for ball milling, adjust the speed to 400-800 rpm, grind for 1-4 h, and then prepare the pretreated wet powder for standby;

[0069] The water in the grinding process is adsorbed by limonite and will not cause loss.

[0070] S2, hydrothermal reaction:

[0071] S21, put the pretreated limonite wet powder into a high-pressure reaction kettle, at 200℃, pressure 10 MPa, speed 200-300 rpm, reaction time 24-72 h;

[0072] S22, after the reaction is completed, the temperature of the high-pressure reaction kettle is raised to 250℃, the pressure is 10 MPa, the speed is 500-600 rpm, and the reaction time is 12-24 h;

[0073] S3, solid-liquid separation: after the reaction is completed, the temperature of the high-pressure reaction kettle is cooled to 85℃, the mixture is taken out and subjected to solid-liquid separation, washed to neutral, and dried at 60-80℃.

[0074] Take limonite and water, prepare the in-situ heavy metal and phosphorus removal and control material of river channel sediment according to the method of example 5, and then test the heavy metal and phosphorus removal and control material using a mixed solution with an initial concentration of 200 mg / L Pb 2+ , 100 mg / L Cd 2+ and 50 mg / L phosphate, the specific indicators are shown in table 1.

[0075] Table 1 data of removing heavy metals and phosphorus from mixed solution and specific surface area of each example

[0076]

[0077] From the experimental data in table 1, it can be concluded that compared with examples 4 and 5, the heavy metal and phosphorus removal and control material obtained by a series of hydrothermal treatment of blast furnace slag and limonite in examples 1-3 has high porosity and large specific surface area, which significantly improves the removal degree of heavy metals and phosphorus in the mixed solution, and the effect of example 2 is the best. Therefore, the in-situ heavy metal and phosphorus removal and control material prepared by examples 1-3 can be added to the river channel sediment to effectively adsorb and remove heavy metals and phosphorus, thereby reducing the pollution of the sediment in the river and other water bodies.

[0078] It should be noted that the above-mentioned embodiments are only preferred embodiments of the present application, and are not used to limit the protection scope of the present application. Any equivalent variations made on the basis of the above-mentioned embodiments should all belong to the protection scope of the present application.

Claims

1. A material for in-situ weight removal and phosphorus control of riverbed sediment, characterized in that: The in-situ degrafting and phosphorus control material is made from the following raw materials in parts by weight: 26.7-43.2 parts blast furnace slag, 20.2-32.7 parts limonite, and 23.45-37.95 parts water, which are prepared by batching, grinding, hydrothermal reaction, solid-liquid separation, washing and drying.

2. The in-situ weight removal and phosphorus control material for riverbed sediment according to claim 1, characterized in that: The blast furnace slag is alkaline blast furnace slag, and the main mineral crystal phases include calcium aluminum feldspar (Ca2Al(SiAlO7)) and calcium magnesium feldspar (Ca2Mg(Si2O7)), wherein the weight percentage of calcium aluminum feldspar (Ca2Al(SiAlO7)) is 30%~45%, and the weight percentage of calcium magnesium feldspar (Ca2Mg(Si2O7)) is 20%~30%.

3. The in-situ weight removal and phosphorus control material for riverbed sediment according to claim 2, characterized in that: The alkaline blast furnace slag is a slag formed by water quenching and slow cooling of molten slag produced during the blast furnace ironmaking process, with an alkalinity of 1-1.

2.

4. The in-situ weight removal and phosphorus control material for riverbed sediment according to claim 3, characterized in that: The chemical composition of the slag is as follows: the weight ratio of CaO to SiO2 is 1-1.2, the weight percentage of Al2O3 is 8%-15%, and the weight percentage of MgO is 5%-8%.

5. The in-situ weight removal and phosphorus control material for riverbed sediment according to claim 1, characterized in that: The main component of the goethite is hydrous iron oxide, with an iron content of over 60%.

6. The in-situ weight removal and phosphorus control material for riverbed sediment according to claim 1, characterized in that: Select the raw materials according to the following weight proportions: 37.6 parts blast furnace slag, 28.43 parts limonite, and 33.96 parts water.

7. A method for preparing an in-situ weight removal and phosphorus control material for riverbed sediment, characterized in that, Includes the following steps: S1. Pretreatment: Place 26.7-43.2 parts by weight of blast furnace slag and 6.7-10.8 parts by weight of water in a ball mill for ball milling, and simultaneously place 20.2-32.7 parts by weight of limonite and 5.1-8.2 parts by weight of water in another ball mill for ball milling. Adjust the speed to 400-800 rpm and grind for 1-4 hours to obtain pretreated wet powder for later use. S2, hydrothermal reaction: S21. Precursor preparation: Pretreated wet blast furnace slag powder, wet limonite powder and 11.7-18.9 parts by weight of water are placed together in a high-pressure reactor, the rotation speed is 200-300 rpm and the reaction time is 24-72 h. S22. Material synthesis: After the reaction is completed, the high-pressure reactor is heated at 500-600 rpm for 12-24 hours. S3. Solid-liquid separation: After the reaction is completed, wait for the high-pressure reactor to cool down, take out the mixture and perform solid-liquid separation, wash until neutral, and dry at 60-80℃.

8. The method for preparing an in-situ weight removal and phosphorus control material for riverbed sediment according to claim 7, characterized in that: In step S1, the blast furnace slag and water in the first ball mill are specifically selected as 37.6 parts by weight and 9.4 parts by weight, respectively, and the limonite and water in the second ball mill are specifically selected as 28.43 parts by weight and 7.1 parts by weight, respectively. In step S21, an additional 17.46 parts by weight of water is added to the high-pressure reactor.

9. The method for preparing an in-situ weight removal and phosphorus control material for riverbed sediment according to claim 7, characterized in that: In step S21, the temperature of the high-pressure reactor is 150~200℃ and the pressure is 10MPa; in step S22, the temperature of the high-pressure reactor is 200~250℃ and the pressure is 10MPa.

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