A river and lake silt solidification and heavy metal consolidation agent and preparation method thereof

Abstract

The invention discloses a river and lake sludge solidification and heavy metal consolidating agent and a preparation method thereof. The weight percentages of the components in the agent are: 40-50% of granulated blast furnace slag powder, 10-20% of high titanium steel slag, 10-15% of lithium slag, 15-20% of limestone waste slag, 10-15% of phosphogypsum, 0.005%-0.01% of modified polymer, 0.1-0.2% of foaming agent and 25%-35% of water. The agent is mixed and stirred with the river and lake sludge in proportion to prepare an unconfined cubic compression test piece. The invention is prepared from all solid waste materials, has a wide range of raw materials, can effectively solve the problem that industrial solid waste cannot be consumed, replaces traditional materials such as cement, can achieve the purpose of energy saving and emission reduction, meets the current green and low-carbon theme, has low preparation cost, can effectively solidify river and lake sludge, consolidate harmful ions such as heavy metals in it, and the solidified sludge can form a porous structure, which is conducive to the growth of vegetation.

Description

Technical Field

[0001] The invention relates to the field of environmental engineering, and in particular to a river and lake sludge solidification and heavy metal consolidation agent and a preparation method thereof. Background Art

[0002] Dredging and clearing of rivers and lakes has brought about a large amount of accumulated dredged sludge while improving navigation, flood prevention and control capabilities, and solving water pollution and water embankment elevation. Since sludge has the characteristics of high water content, high porosity, rich organic matter, low permeability, and high compressibility, it cannot be directly used in engineering. River and lake sludge contains organic matter, heavy metals, high water content and is acidic. The porosity of the backfilled sludge solidified soil is low after hardening, which is not conducive to plant growth and ecological environment restoration. Therefore, the problem of how to solidify river and lake sludge, consolidate heavy metal ions, and make secondary use of river and lake sludge needs to be solved urgently. Summary of the invention

[0003] The technical problem to be solved by the present invention is: in order to overcome the deficiencies in the prior art, a river and lake silt solidification and heavy metal consolidation agent and a preparation method thereof are provided.

[0004] The technical solution adopted by the present invention is: a river and lake silt solidification and heavy metal consolidating agent, the weight percentage of the components in the agent is: 40-50% of granulated blast furnace slag powder, 10-20% of high titanium steel slag, 10-15% of lithium slag, 15-20% of limestone waste slag, 10-15% of phosphogypsum, 0.005%-0.01% of modified polymer, 0.1-0.2% of foaming agent and 25%-35% of water;

[0005] The granulated blast furnace slag powder is of S95 grade, in which the silicon-aluminum components account for 43.6% of the total oxides and the calcium oxide accounts for 38.1%. It is rich in hydraulically active silicon (aluminum) oxygen tetrahedrons, and under the synergistic stimulation of high-titanium steel slag and phosphogypsum, through the "silicon tetracoordinate isomorphism effect" and "complex salt effect", while forming nanometer diameter needle-rod-shaped complex salt crystals, it also forms nearly amorphous and tightly packed hydrated calcium silicate CSH gel and zeolite-like phases, and tightly wraps the needle-rod-shaped complex salt crystals, providing strength for solidified silt soil, thereby greatly improving the stability of the entire system.

[0006] Furthermore, the high titanium steel slag of the present invention is a byproduct produced during the smelting of high titanium steel, and its components are Fe2O3 and CaO;

[0007] CaO, hydrated to generate Ca(OH)2, provides an alkaline environment for system hydration, accelerates the hydration reaction process, and promotes the formation of hydration products such as ettringite and CSH gel.

[0008] Fe2O3 has a high adsorption capacity and can adsorb heavy metal ions in the soil, causing them to physically adsorb to the surface. Fe2O3 reacts with some heavy metal ions (such as lead, chromium, etc.) to form insoluble precipitates, thereby fixing the heavy metal ions on the solid surface and reducing their migration and biological effectiveness in the soil. In addition, the hydroxyl or oxygen groups on the surface of Fe2O3 can form chemical complexes with heavy metal ions to reduce the activity and toxicity of heavy metals. It can effectively solidify heavy metal ions and reduce their harm to the environment and organisms.

[0009] Furthermore, the lithium slag described in the present invention is waste slag generated from the production of lithium products, and its components are SiO2 and Al2O3.

[0010] Furthermore, the limestone waste residue of the present invention is a byproduct of limestone extraction and processing, and its component is CaO;

[0011] Limestone waste can form insoluble metal hydroxide or metal carbonate precipitates with some heavy metal ions (such as lead, cadmium, chromium, etc.). These precipitates can effectively fix heavy metal ions in the soil, reducing their dissolution and migration. The alkalinity of lime can exchange ions with acidic ions in the soil, increasing the pH value of the soil. Under highly alkaline conditions, some heavy metal ions will precipitate or form insoluble compounds, thereby reducing their solubility and bioavailability in the soil.

[0012] The hydroxyl group (OH - ) can coordinate with heavy metal ions to form stable complexes or precipitates. These complexes or precipitates can reduce the activity and mobility of heavy metal ions.

[0013] Furthermore, the phosphogypsum described in the present invention is an industrial solid waste generated during the wet process of producing phosphoric acid, and its component is CaSO4;

[0014] PO4 in phosphogypsum 3- It can form insoluble metal phosphate precipitates with some heavy metal ions. These precipitates can effectively fix heavy metal ions in the soil and reduce their dissolution and migration. 3- The negative charge of phosphogypsum can coordinate with heavy metal ions to form stable complexes. These complexes can reduce the activity and mobility of heavy metal ions. The surface of phosphogypsum has a certain adsorption capacity and can exchange ions with heavy metal ions in the soil, so that heavy metal ions are fixed on the surface or in the internal structure of phosphogypsum.

[0015] Furthermore, the foaming agent of the present invention is at least one of a protein-based foaming agent and hydrogen peroxide;

[0016] After decomposition, the foaming agent can release gases such as oxygen and hydrogen, and form pores in the process of foaming slurry formation, so that the river and lake sludge solidified soil has a porous structure, which is conducive to the growth of vegetation.

[0017] Furthermore, the lithium slag described in the present invention generates calcium sulfonate and hydrated calcium silicate in an alkaline environment, wherein the hydrated aluminosilicate can bind almost all heavy ions, and polymer materials such as blast furnace slag have good acid and alkali corrosion resistance and weather resistance, and the consolidated heavy ions will not cause new pollution to the environment.

[0018] The modified polymer used in river and lake silt solidification and heavy metal consolidation agent has good chemical stability, improves the internal structure of river and lake silt solidification soil, and increases the internal bonding force.

[0019] A method for preparing a river and lake silt solidification and heavy metal consolidating agent comprises the following steps:

[0020] A. Mix the materials in proportion and grind them to an average particle size of 5 μm;

[0021] B. Mix the river and lake silt with the agent in step A at a weight ratio of 1:0.2 and stir evenly for 10 minutes;

[0022] C. forming the material obtained in step B into an unconfined cubic compression specimen;

[0023] D. Seal the compression test piece in step C with a film and leave it to cure for 15 days.

[0024] Compared with the prior art, the present invention has the following advantages: the river and lake silt solidification and heavy metal consolidating agent of the present invention is a clinker-free agent, which is prepared from all solid waste materials. 1. Solid waste materials are reused, energy is saved and emissions are reduced, and the economy is good; 2. Various solid waste raw materials are used to produce hydration reactions, and the hydration products can effectively solidify river and lake silt; 3. The solid waste materials used can effectively consolidate heavy metal ions in silt soil; 4. By using a foaming method, a porous structured solidified silt soil is obtained, which has good vegetation performance. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below. The embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0026] Embodiment 1:

[0027] A river and lake sludge solidification and heavy metal consolidation agent, wherein the weight percentage of the components in the agent is: 40% granulated blast furnace slag powder, 15% high titanium steel slag, 15% lithium slag, 15% limestone waste slag, 10% phosphogypsum, 0.005% modified polymer, 0.1% foaming agent and 30% water;

[0028] The granulated blast furnace slag powder is of S95 grade, in which the silicon-aluminum components account for 43.6% of the total oxides and the calcium oxide accounts for 38.1%. It is rich in hydraulically active silicon (aluminum) oxygen tetrahedrons, and under the synergistic stimulation of high-titanium steel slag and phosphogypsum, through the "silicon tetracoordinate isomorphism effect" and "complex salt effect", while forming nanometer diameter needle-rod-shaped complex salt crystals, it also forms nearly amorphous and tightly packed hydrated calcium silicate CSH gel and zeolite-like phases, and tightly wraps the needle-rod-shaped complex salt crystals, providing strength for solidified silt soil, thereby greatly improving the stability of the entire system.

[0029] Among them, high-titanium steel slag is a by-product produced in the process of smelting high-titanium steel, and its components are Fe2O3 and CaO; lithium slag is waste slag produced in the production of lithium products, and its components are SiO2 and Al2O3; limestone waste slag is a by-product in the extraction and processing of limestone, and its component is CaO; phosphogypsum is an industrial solid waste produced in the wet production of phosphoric acid, and its component is CaSO4.

[0030] The foaming agent is at least one of a protein-type foaming agent and hydrogen peroxide.

[0031] Lithium slag generates calcium aluminosilicate and hydrated calcium silicate in an alkaline environment. Hydrated aluminosilicate can combine almost all heavy ions. In addition, polymer materials such as blast furnace slag have good acid and alkali corrosion resistance and weather resistance, and the consolidated heavy ions will not cause new pollution to the environment.

[0032] A method for preparing a river and lake silt solidification and heavy metal consolidating agent comprises the following steps:

[0033] A. Mix the above ingredients according to the weight percentage of the above components and grind them to an average particle size of 5 μm;

[0034] B. Mix the river and lake silt with the agent in step A at a weight ratio of 1:0.2 and stir evenly for 10 minutes;

[0035] C. forming the material obtained in step B into an unconfined cubic compression specimen;

[0036] D. Seal the compression test piece in step C with a film and leave it to cure for 15 days.

[0037] Embodiment 2:

[0038] A river and lake silt solidification and heavy metal consolidating agent, wherein the weight percentages of the components in the agent are set to: 40% granulated blast furnace slag powder, 15% high titanium steel slag, 15% lithium slag, 15% limestone waste slag, 15% phosphogypsum, 0.1% foaming agent, 0.01% modified polymer, and 30% water; other specifications and preparation methods are the same as those in Example 1.

[0039] Embodiment 3:

[0040] A river and lake silt solidification and heavy metal consolidating agent, wherein the weight percentages of the components in the agent are set to: 45% granulated blast furnace slag powder, 10% high titanium steel slag, 10% lithium slag, 15% limestone waste slag, 20% phosphogypsum, 0.1% foaming agent, 0.01% modified polymer, and 30% water; other specifications and preparation methods are the same as those in Example 1.

[0041] Embodiment 4:

[0042] A river and lake silt solidification and heavy metal consolidating agent, wherein the weight percentages of the components in the agent are set to: 50% granulated blast furnace slag powder, 10% high titanium steel slag, 10% lithium slag, 20% limestone waste slag, 10% phosphogypsum, 0.15% foaming agent, 0.01% modified polymer, and 30% water; other specifications and preparation methods are the same as those in Example 1.

[0043] Comparative Example 1:

[0044] A river and lake silt solidification and heavy metal consolidating agent, wherein the weight percentages of the components in the agent are set to: 50% granulated blast furnace slag powder, 15% lithium slag, 15% limestone waste slag, 20% desulfurized gypsum, 0.1% foaming agent, and 30% water; other specifications and preparation methods are the same as those in Example 1.

[0045] Comparative Example 2:

[0046] A river and lake silt solidification and heavy metal consolidating agent, wherein the weight percentages of the components in the agent are set to: 50% granulated blast furnace slag powder, 15% lithium slag, 20% limestone waste slag, 15% phosphogypsum, 0.1% foaming agent, and 30% water; other specifications and preparation methods are the same as those in Example 1.

[0047] Comparative Example 3:

[0048] A river and lake silt solidification and heavy metal consolidating agent, wherein the weight percentages of the components in the agent are set to: 100% P.O42.5 cement, 0.1% foaming agent, and 30% water; other specifications and preparation methods are the same as those in Example 1.

[0049] The properties of the river and lake silt solidification and heavy metal consolidating agents prepared in Examples 1, 2, 3 and 4 of the present invention and Comparative Examples 1, 2 and 3 are shown in the following table:

[0050] <![CDATA[Dry density kg / m 3 > 28d compressive strength / MPa Porosity / % Ph value Example 1 756 1.8 68.5 7.5 Example 2 702 2.6 73.2 7.1 Example 3 784 3.0 67.7 6.8 Example 4 663 2.7 78.9 8.3 Comparative Example 1 825 2.2 63.6 7.0 Comparative Example 2 794 1.9 65.7 8.1 Comparative Example 3 802 1.6 60.9 5.9

[0051] According to the method in "Determination of leaching toxicity of solid waste" (GB / T15555.1-15555.11), the leaching concentration test results of heavy metal elements in river and lake silt are as follows:

[0052] Example 1

[0053]

[0054]

[0055] Example 2

[0056] Heavy metal components in river and lake silt Pb Cd Ni <![CDATA[Original heavy metal content / mg·kg -1 > 40.95 0.33 1.42 <![CDATA[Leaching concentration after curing / mg·kg -1 > 1.68 0.019 0.071 Curing rate / % 95.9 94.2 95.7

[0057] Example 3

[0058] Heavy metal components in river and lake silt Pb Cd Ni <![CDATA[Original heavy metal content / mg·kg -1 > 41.14 0.42 1.39 <![CDATA[Leaching concentration after curing / mg·kg -1 > 1.56 0.019 0.047 Curing rate / % 96.2 95.5 96.6

[0059] Example 4

[0060] Heavy metal components in river and lake silt Pb Cd Ni <![CDATA[Original heavy metal content / mg·kg -1 > 40.88 0.47 1.43 <![CDATA[Leaching concentration after curing / mg·kg -1 > 1.18 0.020 0.038 Curing rate / % 97.1 95.7 97.3

[0061] Comparative Example 1

[0062] Heavy metal components in river and lake silt Pb Cd Ni <![CDATA[Original heavy metal content / mg·kg -1 > 39.87 0.39 1.49 <![CDATA[Leaching concentration after solidification / mg·kg -1 > 5.86 0.052 0.167 Curing rate / % 85.3 86.6 88.8

[0063] Comparative Example 2

[0064] Heavy metal components in river and lake silt Pb Cd Ni <![CDATA[Original heavy metal content / mg·kg -1 > 40.06 0.36 1.38 <![CDATA[Leaching concentration after solidification / mg·kg -1 > 3.36 0.035 0.10 Curing rate / % 91.6 90.2 92.7

[0065] Comparative Example 3

[0066]

[0067]

[0068] It can be seen from the above embodiments and comparative examples that after the river and lake silt solidification and heavy metal consolidation agent solidifies the river and lake silt, the river and lake silt has good strength, and the porosity of the obtained river and lake silt solidification soil can reach 60.9%-78.9%, and the porous structure is conducive to vegetation growth. Most of the PH is neutral, which is suitable for the growth of most plants. The solidification rate of heavy metal Pb ions is 85.3%-97.1%, the solidification rate of heavy metal Cd ions is 86.6%-95.7%, and the solidification rate of heavy metal Cd ions is 88.8%-97.3%. Compared with P.O42.5, the river and lake silt solidification and heavy metal consolidation agent have a good solidification effect on heavy metal ions. The high titanium steel slag, limestone waste residue and phosphogypsum in the river and lake silt solidification and heavy metal consolidation agent play an important role in the solidification of heavy metal ions.

Claims

1. A river and lake silt solidification and heavy metal consolidation agent, characterized in that: The weight percentage of the components in the agent is: 40-50% of granulated blast furnace slag powder, 10-20% of high titanium steel slag, 10-15% of lithium slag, 15-20% of limestone waste slag, 10-15% of phosphogypsum, 0.005%-0.01% of modified polymer, 0.1-0.2% of foaming agent and 25%-35% of water; The granulated blast furnace slag powder contains 43.6% of the total oxides in the silicon and aluminum components, and 38.1% in the calcium oxide. The granulated blast furnace slag powder is rich in hydraulically active silicon (aluminum) oxygen tetrahedrons, which, under the synergistic stimulation of high-titanium steel slag and phosphogypsum, form nanometer diameter needle-rod-shaped complex salt crystals through the "silicon tetracoordination isomorphism effect" and "complex salt effect". At the same time, it also forms nearly amorphous and tightly packed hydrated calcium silicate gel and zeolite-like phases, and tightly wraps the needle-rod-shaped complex salt crystals to provide strength for solidified silt soil.

2. The river and lake silt solidification and heavy metal consolidation agent according to claim 1, characterized in that: The high titanium steel slag is a by-product produced in the process of smelting high titanium steel, and its components are Fe2O3 and CaO.

3. The river and lake silt solidification and heavy metal consolidation agent according to claim 1, characterized in that: The lithium slag is waste slag generated in the production of lithium products, and its components are SiO2 and Al2O3.

4. The river and lake silt solidification and heavy metal consolidation agent according to claim 1, characterized in that: The limestone waste residue is a by-product in the process of limestone extraction and processing, and its component is CaO.

5. The river and lake silt solidification and heavy metal consolidation agent according to claim 1, characterized in that: The phosphogypsum is an industrial solid waste generated during the wet process of preparing phosphoric acid, and its component is CaSO4.

6. The river and lake silt solidification and heavy metal consolidation agent according to claim 1, characterized in that: The foaming agent is at least one of a protein-type foaming agent and hydrogen peroxide.

7. The river and lake silt solidification and heavy metal consolidation agent according to claim 1, characterized in that: The lithium slag generates calcium aluminate and hydrated calcium silicate in an alkaline environment, wherein the hydrated aluminosilicate combines almost all heavy ions, and polymer materials such as blast furnace slag have good acid and alkali corrosion resistance and weather resistance, and the consolidated heavy ions will not cause new pollution to the environment.

8. A method for preparing the river and lake silt solidification and heavy metal consolidating agent according to any one of claims 1 to 7, characterized in that: The following steps are involved: A. Mix the materials in proportion and grind them to an average particle size of 5 μm; B. Mix the river and lake silt with the agent in step A at a weight ratio of 1:0.2 and stir evenly for 10 minutes; C. forming the material obtained in step B into an unconfined cubic compression specimen; D. Seal the compression test piece in step C with a film and leave it to cure for 15 days.

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