Solidification material and use thereof

Abstract

The present invention relates to the technical field of sediment or sludge treatment of a water body, and provides a solidification material and a use thereof. The solidification material consists of the following components in percentage by mass: 30% of a sediment flocculant, 20% of a high-strength and high-water-resistant earth consolidator, 30%-40% of calcium bentonite, 5%-15% of a clay mineral, and 5% of an engineering admixture. When the solidification material is used in the sediment or sludge treatment of the water body, pollutants in sediments can be well immobilized, and as tested, no leaching of the pollutants occurs after immersion in the water body. Moreover, the usage amount of the solidification material is significantly reduced compared to that of a conventional solidification material, so that the impact on the storage capacity of the water body can be effectively reduced, and the construction cost is also saved.

Description

A curing material and its application Technical Field

[0001] This invention belongs to the field of water body sediment or silt treatment technology, specifically relating to a solidification material and its application. Background Technology

[0002] River and lake silt or sediment is a special type of polluted sediment formed under natural conditions due to pollutants accumulated in the sediment caused by factors such as water flow, water pollution, and human activities. This pollutants gradually worsen over time along the direction of water flow. The sediment contains high levels of heavy metals with significant toxic effects, seriously threatening the river's ecological environment and human health. Sediment solidification / stabilization technology is one of the main methods for treating river sediment. By adding solidifying and stabilizing agents to the sediment, a chemical or physical reaction is initiated, transforming the pollutants into stable substances, thus stabilizing and solidifying the sediment.

[0003] In-situ solidification technology involves placing one or more layers of covering material on contaminated sediment to isolate it from the water, preventing the migration of pollutants from the sediment into the water and the resuspension of the sediment. Commonly used stabilization or covering materials include: uncontaminated sediment, clean sand, gravel, calcareous bentonite, ash, artificial zeolite, cement, and other synthetic materials. This method is an in-situ remediation technology with low engineering costs and can effectively prevent secondary pollution caused by pollutants in the sediment entering the water. However, these traditional stabilization or covering materials have relatively limited functions; they can only prevent the migration of sediment pollutants into the water and the resuspension of sediment, but the pollutants are not eliminated. They are not suitable for waters with a lot of floating silt, and excessive use of materials can change the water volume of the reservoir, while also causing some damage to the benthic ecosystem.

[0004] Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a solidification material for in-situ solidification of contaminated sediment. This solidification material effectively bonds the sediment and the solidified material into a robust whole with high strength and excellent water stability, while simultaneously passivating and sealing contaminants within the sediment.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A solidification material is composed of the following components by mass fraction: 30% silt flocculant, 20% high-strength and high-water-resistant soil consolidation agent, 30%–40% calcareous bentonite, 5%–15% clay minerals, and 5% engineering admixtures.

[0008] Flocculating-settling agent for sediment (FSA) is a powdered solid, a new type of environmentally friendly sludge conditioning and dewatering product. It is a multi-component composite material that can condition dredged sludge and construction mud with different mud qualities, organic matter content, and particle sizes, reducing their specific surface area and improving drainage performance. This flocculant can be used in environmental dredging, land reclamation, and pile foundation shield tunneling projects to reduce sludge moisture content. Its dewatering principle is through ionization, which breaks the capillary action of sludge particles, increasing the filtration rate and improving drainage performance.

[0009] High Strength and High Waterproof Earth Consolidator (HEC) is an inorganic hydraulic cementitious material. HEC hydration products bind the basic units of the consolidator into a strong whole, resulting in high strength and water stability, achieving passivation and sealing of harmful substances. Its consolidation principle is as follows: the active components of the HEC directly penetrate into the phase interface of the basic units of the material being consolidated at room temperature, stimulating the activity of aluminosilicates in the material. Utilizing the superposition effect of multiple components, it forms polycrystalline aggregates.

[0010] The solidification material of this invention contains a sediment flocculant and a high-strength, high-water-resistant soil consolidation agent, which can rapidly dehydrate and solidify contaminated sediment, while simultaneously forming polycrystalline aggregates that serve as the structural framework of the solidified sediment. Calcareous bentonite and clay minerals increase the strength of the solidified sediment and further reduce its moisture content. The engineering admixture is an organic early-strength agent that promotes the hydration reaction of the sediment flocculant, the high-strength, high-water-resistant soil consolidation agent, and clay minerals, thereby increasing the hardening strength of the solidified sediment and providing a certain degree of water-reducing and early-strength properties.

[0011] In a preferred embodiment, the sediment flocculant comprises polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of (14-16):(2-3):(1-2).

[0012] In a preferred embodiment, the high-strength, high-water-resistant soil consolidation agent is at least one of components A, B, C, and D; component A is at least one of the "calcareous materials" in GB / T 16753-1997 "Terminology for Silicate Building Products"; component B is at least one of the "siliceous materials" in GB / T 16753-1997 "Terminology for Silicate Building Products"; component C is at least one of ferric sulfate, polyferric sulfate, aluminum sulfate, polyaluminum sulfate, ferric chloride, polyferric chloride, aluminum chloride, and polyaluminum chloride; and component D is at least one of the "gypsum" in GB / T 16753-1997 "Terminology for Silicate Building Products".

[0013] In a further preferred embodiment, the mass ratio of component A, component B, component C, and component D is (20-50):(5-20):(0-20):(30-60).

[0014] In a further preferred embodiment, the solidification material is composed of the following raw materials by mass percentage: 30% silt flocculant, 20% high-strength, high-water-resistant soil consolidation agent, 30% calcareous bentonite, 15% clay minerals, and 5% engineering admixtures; the silt flocculant comprises polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of 25:4:3; the high-strength, high-water-resistant soil consolidation agent comprises components A, B, and D in a mass ratio of (6-10):(1-2):(6-10); and the engineering admixtures comprise calcium chloride and triethanolamine in a mass ratio of 35:4.

[0015] In a further preferred embodiment, the solidification material is composed of the following raw materials by mass percentage: 30% silt flocculant, 20% high-strength, high-water-resistant soil consolidation agent, 40% calcareous bentonite, 5% clay minerals, and 5% engineering admixtures; the silt flocculant comprises polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of 14:2:1; the high-strength, high-water-resistant soil consolidation agent comprises components A, B, C, and D in a mass ratio of (30-40):(10-20):(10-20):(40-50); and the engineering admixtures comprise calcium chloride and triethanolamine in a mass ratio of 10:1.

[0016] In a further preferred embodiment, the solidification material is composed of the following raw materials by mass percentage: 30% silt flocculant, 20% high-strength, high-water-resistant soil consolidation agent, 35% calcareous bentonite, 10% clay minerals, and 5% engineering admixtures; the silt flocculant includes polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of 16:3:2; the high-strength, high-water-resistant soil consolidation agent is composed of component A, component B, and component D in a mass ratio of (20-40):(5-10):(40-60); and the engineering admixtures include calcium chloride and triethanolamine in a mass ratio of 8:1.

[0017] In a further preferred embodiment, the solidification material is composed of the following raw materials by mass percentage: 30% silt flocculant, 20% high-strength, high-water-resistant consolidating agent, 38% calcareous bentonite, 7% clay minerals, and 5% engineering admixtures; the silt flocculant comprises polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of 12:2:1; the high-strength, high-water-resistant soil consolidating agent is composed of components A, B, C, and D in a mass ratio of (20-30):(10-20):(10-20):(50-60); and the engineering admixtures comprise calcium chloride and triethanolamine in a mass ratio of 33:4.

[0018] In a preferred embodiment, the engineering admixture is an organic early-strength agent, which comprises calcium chloride and triethanolamine in a mass ratio of (30-40):(3-5).

[0019] When the solidification material provided in this invention is used to solidify aquatic sediment or silt, 50-110 kg of solidification material is added per ton of sediment or silt. The solidification of aquatic sediment in this invention includes in-situ solidification and dehydration solidification. Dehydration solidification refers to first dehydrating the aquatic sediment to a moisture content of 50%-55%, and then using the solidification material for solidification. The specific ratio of sediment to solidification material can be adjusted according to the characteristics of different aquatic sediments and treatment requirements. Generally speaking, the higher the moisture content of the sediment, the higher the amount of solidification material used; the more severe the organic pollution of the sediment, the higher the amount of solidification material used.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) When the solidification material provided by the present invention is used for in-situ solidification of river or lake bottom sediment with a water content of about 90% in actual engineering applications, the compressive strength of the solidified body reaches more than 80 kPa after 7 days, the water content is reduced to 60% or less, and the pH value is 6 to 9. (2) The solidification material of the present invention can effectively seal the bottom sediment pollutants, and no leaching pollutants are observed after water immersion. (3) Traditional in-situ solidification process materials often use cement, lime, fly ash and other solidification cementitious materials. A large number of traditional cases show (such as the Wuhan East Lake Port Channel Silt In-situ Solidification Project) that the traditional in-situ solidification material dosage ratio is generally 20% to 40% of the bottom sediment or silt to achieve obvious solidification effect. The dosage of the solidification material of the present invention in the in-situ solidification project of river and channel silt (5% to 11%) is significantly reduced compared with the dosage of traditional solidification materials, which can effectively reduce the impact on the water body capacity and save construction costs. Detailed Implementation

[0021] The following description, in conjunction with embodiments, clearly and completely illustrates the technical solutions of the present invention, enabling those skilled in the art to fully understand the invention. Obviously, the described embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Any equivalent modifications or substitutions made by those skilled in the art to the following embodiments without creative effort are within the protection scope of the present invention.

[0022] The high-strength, high-water-resistant soil consolidation agent used in the following examples comprises at least one of components A, B, C, and D. Component A is at least one of the "calcareous materials" listed in GB / T 16753-1997 "Terminology for Silicate Building Products," including cement, lime, carbide slag, and steel slag; component B is at least one of the "siliceous materials" listed in GB / T 16753-1997 "Terminology for Silicate Building Products," including low-calcium fly ash, high-calcium fly ash, coal slag, granulated blast furnace slag, heavy blast furnace slag, coal gangue, self-igniting coal gangue, tailings, fluidized bed slag, liquid slag, oil shale slag, volcanic slag, pumice, zeolite, diatomaceous earth, and silica fume; component C is at least one of ferric sulfate, polyferric sulfate, aluminum sulfate, polyaluminum sulfate, ferric chloride, polyferric chloride, aluminum chloride, and polyaluminum chloride; component D is from GB / T At least one of the "gypsum" in 16753-1997 "Terminology for Silicate Building Products", including natural gypsum (such as dihydrate gypsum, anhydrite), hemihydrate gypsum, and industrial by-product gypsum (such as fluorogypsum, phosphogypsum).

[0023] Example 1

[0024] This embodiment provides a solidification material composed of the following raw materials by mass percentage: 30% silt flocculant, 20% high-strength, high-water-resistant soil consolidation agent, 30% calcareous bentonite, 15% clay minerals, and 5% engineering admixtures. The silt flocculant is a composite powder material that promotes flocculant formation, comprising polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of 25:4:3. The high-strength, high-water-resistant soil consolidation agent is a hydraulic cementitious material with dehydration and good cementing properties, composed of components A, B, and D in a mass ratio of 5:1:5. The engineering admixture is an organic coagulant early-strength agent, comprising calcium chloride and triethanolamine in a mass ratio of 35:4.

[0025] The aforementioned solidification material was used to solidify riverbed sediment (87.9% moisture content) in Lu'an City in situ. The solidification material reacted with the riverbed sediment through hydration to form a solidified body. 55 kg of solidification material was added per ton of sediment. The solidification process was carried out using in-situ mixing and solidification techniques. Testing was conducted according to the "Unconfined Compressive Strength Test" method in JTJ051-93 "Specifications for Geotechnical Testing of Highways". After 7 days, the unconfined compressive strength of the solidified body reached 88.5 kPa, and the sediment moisture content decreased to 52%. Referring to the method in standard HJ 1147-2020 "Electrode Method for Determining pH Value of Water Quality", the pH of the leachate was measured to be 8.5. After the solidified body achieved strength, geotextile and pebbles were laid on it, providing both seepage prevention and aesthetic enhancement.

[0026] After the construction was completed, the river was soaked in water for one month. There was no floating mud in the river. The solidified body was sampled and tested. The concentration of heavy metals in the leachate met the standard limit in GB5085.3-1996 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification".

[0027] During the experiment, the inventors discovered that when the scheme of Example 1 was adopted, and when the mass ratio of component A, component B and component D in the high-strength and high-water-resistant soil consolidation agent was in the range of (6-10):(1-2):(6-10), the same effect as the above-mentioned effect could be achieved when the same riverbed sediment was treated. The unconfined compressive strength of the solidified body reached a minimum of 88 kPa after 7 days, the water content did not exceed 60%, and the pH of the solidified body varied in the range of 6-9.

[0028] Example 2

[0029] This embodiment provides a curing material composed of the following raw materials by mass percentage: 30% silt flocculant, 20% high-strength, high-water-resistant soil consolidation agent, 40% calcareous bentonite, 5% clay minerals, and 5% engineering admixtures. The silt flocculant is a composite powder material that promotes flocculation, comprising polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of 14:2:1. The high-strength, high-water-resistant soil consolidation agent is composed of components A, B, C, and D in a mass ratio of 35:15:15:35. The engineering admixture is an organic early-strength agent comprising calcium chloride and triethanolamine in a mass ratio of 10:1.

[0030] The aforementioned solidification material was used to perform in-situ solidification of an endogenous lake (90.5% water content) in Wuhan. The solidification material reacted with the riverbed sediment to form a solidified body, with 95 kg of solidification material added per ton of sediment. The solidification process was carried out using in-situ mixing. After 7 days, the unconfined compressive strength of the solidified body reached 84.5 kPa, the sediment water content decreased to 55%, and the pH was 6. Sampling and testing showed that the concentration of heavy metals in the leachate from the solidified body met the standard limits in GB5085.3-1996 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification". Benthic animal diversity indices were observed according to the methods in HJ710.8-2014 "Technical Guidelines for Biodiversity Observation - Freshwater Benthic Macroinvertebrates", and it was found that the benthic ecosystem was not affected in any way.

[0031] During the experiment, the inventors discovered that when the scheme of Example 2 was adopted, and the mass ratio of components A, B, C and D in the high-strength and high-water-resistant soil consolidation agent was in the range of (30-40):(10-20):(10-20):(40-50), the same effect as the above-mentioned effect could be achieved when the same riverbed sediment was treated. The unconfined compressive strength of the solidified body after 7 days reached a minimum of 80 kPa (the unconfined compressive strength generally varies in the range of 80-95 kPa depending on the mass ratio of components A, B, C and D), the moisture content did not exceed 60%, and the pH of the solidified body varied in the range of 6-9.

[0032] Example 3

[0033] This embodiment provides a curing material composed of the following raw materials by mass percentage: 30% silt flocculant, 20% high-strength, high-water-resistant soil consolidating agent, 35% calcareous bentonite, 10% clay minerals, and 5% engineering admixtures. The silt flocculant comprises polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of 16:3:2. The high-strength, high-water-resistant soil consolidating agent is composed of components A, B, and D mixed in a mass ratio of 30:8:50. The engineering admixtures are organic early-strength agents comprising calcium chloride and triethanolamine in a mass ratio of 8:1.

[0034] The above-mentioned solidification material was used to solidify the bottom sediment (85% water content) of a river in Wenzhou City in situ. The solidification material reacted with the river sediment to form a solidified body. 50 kg of solidification material was added to each ton of sediment. The solidification process was carried out by in-situ mixing. After 7 days, the unconfined compressive strength of the solidified body reached 87.5 kPa, the water content of the sediment decreased to 50%, and the pH was 7.5.

[0035] During the experiment, the inventors discovered that when using the scheme of Example 3, when the mass ratio of components A, B and D in the high-strength and high-water-resistant soil consolidation agent is in the range of (20-40):(5-10):(40-60), when used to treat bottom sediments with a water content of 85%-89%, adding 50-80 kg of solidifying material per ton of bottom sediment can achieve the same effect as described above. The unconfined compressive strength of the solidified body reaches a minimum of 87.5 kPa after 7 days, with a water content of 50%-55%, and the pH of the solidified body varies in the range of 6-9.

[0036] Example 4

[0037] This embodiment provides a curing material composed of the following raw materials by mass percentage: 30% silt flocculant, 20% high-strength, high-water-resistant consolidating agent, 38% calcareous bentonite, 7% clay minerals, and 5% engineering admixtures. The silt flocculant comprises polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of 12:2:1. The high-strength, high-water-resistant soil consolidating agent is a mixture of components A, B, C, and D in a mass ratio of 25:15:15:55. The engineering admixture is an organic early-strength agent comprising calcium chloride and triethanolamine in a mass ratio of 33:4.

[0038] The above-mentioned solidification material was used to solidify the high water content (90%) bottom sediment of a lake in Wuhan. The solidification material reacted with the lake sediment to form a solidified body. 110 kg of solidification material was added to each ton of sediment. The solidification process was carried out by in-situ mixing. After 7 days, the unconfined compressive strength of the solidified body reached 90 kPa, the water content of the sediment decreased to 40%, and the pH was 9.

[0039] During the experiment, the inventors discovered that when using the scheme of Example 3, when the mass ratio of components A, B, C and D in the high-strength and high-water-resistant soil consolidation agent is in the range of (20-30):(10-20):(10-20):(50-60), it can achieve the same effect as the above when used to treat bottom sediments with a water content of 90%-95% and 90-110 kg of solidifying material is added per ton of bottom sediment. The unconfined compressive strength of the solidified body reaches 90-100 kPa after 7 days, the water content is 40-50%, and the pH of the solidified body varies in the range of 6-9.

[0040] As can be seen from the above embodiments, the solidification material of the present invention has a good treatment effect on in-situ solidification of bottom sediment in water bodies. The bottom sediment and the solidification material can form a stable solidified body, which enables heavy metal pollutants to be effectively sealed.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Various modifications and variations can be made to the present invention by any person skilled in the art. Any simple equivalent changes and modifications made based on the scope of protection of the present invention and the content of the specification should be included within the scope of protection of the present invention.

Claims

1. A curing material, characterized in that, It is composed of the following components by mass fraction: 30% silt flocculant, 20% high-strength and high-water-resistant solidifying agent, 30% to 40% calcareous bentonite, 5% to 15% clay minerals, and 5% engineering admixtures.

2. The curing material according to claim 1, characterized in that, The sediment flocculant comprises polyferric sulfate, sodium silicate, and sodium carbonate in a mass ratio of (14-16):(2-3):(1-2).

3. The curing material according to claim 1, characterized in that, The high-strength, high-water-resistant soil consolidation agent is at least one of components A, B, C, and D; component A is at least one of the "calcareous materials" in GB / T 16753-1997 "Terminology for Silicate Building Products"; component B is at least one of the "siliceous materials" in GB / T 16753-1997 "Terminology for Silicate Building Products"; component C is at least one of ferric sulfate, polyferric sulfate, aluminum sulfate, polyaluminum sulfate, ferric chloride, polyferric chloride, aluminum chloride, and polyaluminum chloride; and component D is at least one of the "gypsum" in GB / T 16753-1997 "Terminology for Silicate Building Products".

4. The curing material according to claim 3, characterized in that, The mass ratio of component A, component B, component C, and component D is (20-50):(5-20):(0-20):(30-60).

5. The curing material according to claim 1, characterized in that, The engineering admixture is an organic early-strength agent, which comprises calcium chloride and triethanolamine in a mass ratio of (30-40):(3-5).

6. The application of the solidification material according to any one of claims 1 to 5 in solidifying bottom sediment of aquatic bodies.

7. The application according to claim 6, characterized in that, The solidified sediment in the water body is solidified in situ or dehydrated and solidified.

8. The application according to claim 7, characterized in that, The dehydration and solidification process refers to first dehydrating the sediment in the water body to a moisture content of 50% to 55%, and then using the solidification material for solidification.

9. The application according to claim 6, characterized in that, The mass ratio of the solidified material to the bottom sediment of the water body is (0.05~0.11):1.