Preparation method of heavy metal contaminated soil solidification and stabilization remediation agent and application thereof

Abstract

The application discloses a heavy metal contaminated soil solidification and stabilization remediation agent, a preparation method and application thereof, and belongs to the technical field of heavy metal contaminated soil remediation. The steel slag particles are dried and then ball milled into steel slag powder; and a mixture of an activator, a grinding aid and a hydrophilic agent is uniformly mixed to obtain an activating agent. The heavy metal contaminated soil solidification and stabilization remediation agent produced by the application has high efficiency, large specific surface area, good stability, strong acid buffering capacity, and a wide adaptability to use conditions such as pH, temperature and humidity of the environment, can realize secondary utilization of industrial solid waste, and has good economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of environmental materials, specifically relating to a solidification and stabilization remediation agent for heavy metal contaminated soil, and more particularly to a preparation method and application of the solidification and stabilization remediation agent for heavy metal contaminated soil. Background Technology

[0002] With industrial development, industrial emissions, and the use of gasoline, paint, fertilizers, and pesticides, heavy metal contamination of soil has become one of the most serious environmental problems worldwide. A national soil survey in China found that 16.1% of the surveyed land exceeded national standards, and 19.4% of the tested agricultural land and 34.9% of the tested former industrial land were contaminated. Highly toxic pollutants such as cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn), once accumulated in soil, can cause severe ecosystem damage and potentially lead to human health problems. For example, heavy metals can accumulate in internal organs, causing renal insufficiency, cardiovascular and cerebrovascular diseases, nervous system damage, and chronic bodily harm. Therefore, developing effective remediation technologies for heavy metal-contaminated soil is of great significance to human health and the ecological environment.

[0003] Generally, the stabilization / solidification (S / S) of heavy metals in contaminated soil is one of the most widely used traditional remediation techniques, originating in the 1970s for hazardous waste management. This method involves using binders to immobilize heavy metal elements in contaminated soil through a combination of encapsulation, chemical reactions, and adsorption, thereby reducing toxicity and improving the engineering and physicochemical properties of the contaminated soil. Previous studies have highlighted the effectiveness of highly alkaline binders, such as Portland cement (PC), MgO-based materials, and lime-fly ash mixtures for solidification / stabilization applications. However, the production of these traditional binder materials is associated with intensive consumption of energy and non-renewable resources; for example, 5%–8% of anthropogenic greenhouse gas emissions from PC production are released into the atmosphere. Furthermore, highly alkaline binders have several significant drawbacks, including a high pH in the treated soil and enhanced heavy metal leaching upon exposure to external conditions such as acid rain, freeze-thaw cycles, wet-dry cycles, and UV radiation, limiting their effectiveness. Contaminated soil, especially with relatively high concentrations of heavy metals, is particularly problematic. Furthermore, certain heavy metals such as copper (Cu), zinc (Zn), and lead (Pb) can significantly hinder the hydration of cement-based binders present in soil, thus affecting the immobilization of heavy metals in stabilized soils. Therefore, it is necessary to develop efficient, stable, low-cost, and environmentally friendly alternative binders for the remediation of contaminated soils. Steel slag has attracted widespread attention due to its advantages in remediating heavy metal-contaminated soils while avoiding the aforementioned drawbacks.

[0004] One well-explored technique is alkali activation, designed to improve the activation of steel slag. Commonly used alkali activators include water glass, sodium hydroxide (SH), sodium silicate, and sodium sulfate. However, alkali-activated steel slag production may present other environmental problems, such as human toxicity and freshwater and marine ecotoxicity, primarily stemming from the production of the alkali activators. Furthermore, due to its high economic cost, alkali-activated steel slag is difficult to apply to the treatment of heavy metal pollution in soil. Additionally, because of the high alkalinity of alkali activators and the large quantities required for alkali-activated steel slag, the addition of alkali activators can increase soil alkalinity, damaging the soil's ecological environment.

[0005] Patent application CN 110624498B discloses a composite steel slag-based heavy metal adsorbent consisting of 60-70 parts steel slag, 5-10 parts straw, 15-25 parts furnace ash, and 5-10 parts binder. The preparation process of this adsorbent is quite complicated, the NaOH reagent is expensive, and it requires high-temperature calcination, which will greatly increase energy consumption, which is not in line with the concept of economic and environmental protection.

[0006] Patent application CN108554379A discloses an adsorbent for waste steel slag with a mass ratio of steel slag tailings: calcium lignosulfonate: glycerol = 5:3:2. The preparation process of this adsorbent is relatively complicated, the iron selection mechanism is complex, the HCl reagent is expensive and environmentally harmful, and high-temperature calcination is required, which increases energy consumption. Summary of the Invention

[0007] This invention provides a method for preparing a solidification and stabilization remediation agent for heavy metal contaminated soil and its application. The method uses steel slag waste from the steel industry, mixes it with a certain proportion of activator, and then uses a planetary ball mill to ball mill it at a certain speed for a certain time to obtain a highly efficient solidification and stabilization remediation agent for heavy metal contaminated soil with strong acid resistance and long-term stability.

[0008] A method for preparing a remediation agent for heavy metal contaminated soil, comprising the following steps:

[0009] Step 1: Dry 100 parts of steel slag granules, ball mill them, and then pass them through a 1000-1500 mesh sieve to obtain steel slag powder;

[0010] Step 2: Weigh 1-15 parts of activator, 1-10 parts of grinding aid, and 0.1-3 parts of hydrophilic agent, mix them evenly to obtain the activator;

[0011] Step 3: Add 0.01-5 parts of activator to 100 parts of steel slag powder and mix evenly to obtain pre-activated steel slag powder;

[0012] Step 4: Use a planetary ball mill to ball mill the pre-activated steel slag powder obtained in Step 3 at 100-400 r / min for 10-60 min to obtain activated steel slag powder.

[0013] In the technical solution of the present invention, the activator is at least one of triethanolamine (TEA), diethanolamine (DEA), triisopropanolamine (TIPA), hydroxyethyl diisopropanolamine (EDIPA), diethanol monoisopropanolamine (DEIPA), methyl diethanolamine (MDEA), and dimethyl ethanolamine (DMEA);

[0014] In the technical solution of this invention, the grinding aid is at least one selected from ethylene glycol, ethanol, propylene glycol, glycerol, and sodium fatty acid.

[0015] In the technical solution of this invention, the hydrophilic agent is at least one of polysorbate, sorbitan monosilicone, polyoxyethylene lauryl ether, polyoxyethylene fatty alcohol ether, glyceryl monooleate, and glyceryl monostearate.

[0016] In the technical solution of the present invention, the activator in step two is 5-10 parts, the grinding aid is 1-3 parts, and the hydrophilic agent is 0.3-0.8 parts.

[0017] In the technical solution of the present invention, the activator added in step three is 0.01-0.1 parts.

[0018] In the technical solution of the present invention, the ball milling speed in step four is 200-250 r / min; the ball milling time in step four is 20-40 min.

[0019] A soil stabilization and remediation agent for heavy metal contaminated soil is prepared by the above method.

[0020] In the technical solution of this invention: the application of the heavy metal contaminated soil remediation agent in the solidification and stabilization remediation of heavy metal contaminated soil.

[0021] Beneficial effects:

[0022] (1) Steel slag and activator have a good synergistic effect on the remediation of heavy metal contaminated soil. After the activator reacts with the steel slag, it can stimulate its reactivity and promote the hydration of the steel slag. The steel slag with added activator can form hydrated calcium silicate (CSH) more quickly through hydration to achieve the effect of encapsulation and solidification, and the strength after hydration is higher; in addition, the activator has a grinding aid effect on the steel slag, which can be ball-milled more finely, increasing its specific surface area. The increased specific surface area can allow more heavy metal ions to be fixed on the surface of the steel slag through ion exchange.

[0023] (2) The preparation process is simple and effective, and easy to apply in practice. The preparation of the reagent does not require drying, reducing energy consumption for drying, and it can be directly applied in practice. The reagent can be prepared with only one step of ball milling, making the process simple and easy to apply in industrial production.

[0024] (3) Effective utilization of waste raw materials and environmentally friendly solidification and stabilization remediation agents. This invention provides a method for preparing a waste resource-based, low-cost solidification and stabilization remediation agent for heavy metal contaminated soil. Steel slag, as an industrial waste, has accumulated over a large area, causing serious environmental pollution. Activating steel slag effectively improves its utilization value, turning waste into treasure. Secondly, as a cementing material, steel slag can have a good solidification effect on soil, and activated steel slag has a stronger soil solidification ability.

[0025] (4) Good long-term effect. Traditional curing agents are easily affected by carbon dioxide erosion and acid rain erosion, resulting in the degradation and decline of the environmental safety and engineering properties of the solidified soil. However, as an alkaline cementing material, steel slag has a good resistance to acid rain and carbon dioxide erosion. Furthermore, under the encapsulation effect of CSH gel, a hydration product of steel slag, it can effectively reduce the contact between heavy metal precipitation and acidic solutions. At the same time, steel slag itself has a very strong acid buffering capacity. Detailed Implementation

[0026] To better understand the present invention, the present invention will be further described below with reference to specific embodiments, but the scope of the invention is not limited to the embodiments described below.

[0027] Example 1

[0028] A method for preparing a remediation agent for heavy metal contaminated soil:

[0029] Pretreatment of steel slag: The dried steel slag particles were ball-milled using a small cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder.

[0030] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.02 parts by weight of activator and mix evenly. The activator is triisopropanolamine (TIPA), ethylene glycol and polysorbate in a mass ratio of 8:1.5:0.5 to obtain pre-activated steel slag powder.

[0031] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0032] Example 2

[0033] A method for preparing a remediation agent for heavy metal contaminated soil:

[0034] Pretreatment of steel slag: The dried steel slag particles were ball-milled using a small cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder.

[0035] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.05 parts by weight of activator and mix evenly. The activator is triisopropanolamine (TIPA), ethylene glycol and polysorbate in a mass ratio of 8:1.5:0.5 to obtain pre-activated steel slag powder.

[0036] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0037] Example 3

[0038] A method for preparing a remediation agent for heavy metal contaminated soil:

[0039] Pretreatment of steel slag: The dried steel slag particles were ball-milled using a small cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder.

[0040] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.08 parts by weight of activator and mix evenly. The activator is triisopropanolamine (TIPA), ethylene glycol and polysorbate in a mass ratio of 8:1.5:0.5 to obtain pre-activated steel slag powder.

[0041] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0042] Example 4

[0043] A method for preparing a remediation agent for heavy metal contaminated soil:

[0044] Pretreatment of steel slag: The dried steel slag particles were ball-milled using a small cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder.

[0045] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.1 parts by weight of activator and mix evenly. The activator is triisopropanolamine (TIPA), ethylene glycol and polysorbate in a mass ratio of 8:1.5:0.5 to obtain pre-activated steel slag powder.

[0046] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0047] Example 5

[0048] A method for preparing a remediation agent for heavy metal contaminated soil:

[0049] Pretreatment of steel slag: The dried steel slag particles were ball-milled using a small cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder.

[0050] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.05 parts by weight of activator and mix evenly. The activator is triethanolamine (TEA), ethylene glycol and polysorbate in a mass ratio of 8:1.5:0.5 to obtain pre-activated steel slag powder.

[0051] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0052] Example 6

[0053] A method for preparing a remediation agent for heavy metal contaminated soil:

[0054] Pretreatment of steel slag: The dried steel slag particles were ball-milled using a small cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder.

[0055] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.05 parts by weight of activator and mix evenly. The activator is hydroxyethyl diisopropanolamine (EDIPA), ethylene glycol and polysorbate in a mass ratio of 8:1.5:0.5 to obtain pre-activated steel slag powder.

[0056] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0057] Example 7

[0058] A method for preparing a remediation agent for heavy metal contaminated soil:

[0059] Pretreatment of steel slag: The dried steel slag particles were ball-milled using a small cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder.

[0060] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.05 parts by weight of activator and mix evenly. The activator is diethanol monoisopropanolamine (DEIPA), ethylene glycol and polysorbate in a mass ratio of 8:1.5:0.5 to obtain pre-activated steel slag powder.

[0061] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0062] To highlight the synergistic effect of the activator, grinding aid, and hydrophilic agent on steel slag, a comparative experiment was conducted using two of these aids to grind steel slag as a separate example:

[0063] Comparative Example 1

[0064] Pretreatment of steel slag: Steel slag particles are ball-milled using a small-scale cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder;

[0065] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.05 parts of activator and mix evenly. The composition of the activator is: triisopropanolamine (TIPA): ethylene glycol = 8: 1.5, to obtain pre-activated steel slag powder.

[0066] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0067] Comparative Example 2

[0068] Pretreatment of steel slag: Steel slag particles are ball-milled using a small-scale cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder;

[0069] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.05 parts of activator and mix evenly. The composition of the activator is: triisopropanolamine (TIPA): polysorbate = 8: 0.5, to obtain pre-activated steel slag powder.

[0070] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0071] Comparative Example 3

[0072] Pretreatment of steel slag: Steel slag particles are ball-milled using a small-scale cement experimental mill and passed through a 1250-mesh sieve to obtain steel slag powder;

[0073] Preparation of pre-activated steel slag powder: Take 100 parts by weight of steel slag powder, add 0.05 parts of activator and mix evenly. The composition of the activator is: ethylene glycol: polysorbate = 1.5: 0.5, to obtain pre-activated steel slag powder.

[0074] Preparation of activated steel slag powder: Pre-activated steel slag powder was ball-milled in a planetary ball mill for 30 minutes at a speed of 220 r / min to obtain activated steel slag powder.

[0075] The specific experimental items involved in the experiment are as follows:

[0076] Test 1: Unconfined compressive strength test 1

[0077] Sample preparation: Prepare the sample in the laboratory by taking dried soil sample, passing it through a 9.5mm sieve, and adding 12mg / kg Cd. 2+ (32.93mg / kg Cd(NO3)2·4H2O), 2000mg / kg Cu 2+(7603.46mg / kg Cu(NO3)2·3H2O), 500mg / kg Ni 2+ (2024.96mg / kg NiCl2·6H2O), 1400mg / kg Pb 2+ (1879.12mg / kgPbCl2), 1250mg / kg Zn 2+ Dissolve (2604.73 mg / kg ZnCl2) in a specified amount of water, then add the prepared heavy metal solution to the soil sample and mix with a mortar mixer for 30 minutes to make it as homogeneous as possible. Seal the mixture and store it for 7 days to ensure the full distribution of heavy metals in the soil.

[0078] Test Method: The remediation agents corresponding to Examples 1-4 were mixed with the soil samples at a weight ratio of 20:100, and then stirred in a mortar mixer for 10 minutes to ensure homogeneity. The final weight ratio of water to solids (including soil and binder) was determined to be 25:100. Approximately 200 grams of the mixture was then statically compacted using a stainless steel cylindrical mold with a diameter of 50 mm and a height of 50 mm. The sample was then carefully extruded from the mold using a hydraulic jack and sealed in a polyethylene bag for curing under standard conditions (temperature 20 ± 2 °C, relative humidity 99%). Unconfined compressive strength tests were performed at 1, 3, 7, 28, and 90 days of age, and the crushed samples were collected for toxicity leaching tests.

[0079] The test data after 90 days are shown in Table 1 below. The remediation agent has a good effect on improving the unconfined compressive strength of the soil.

[0080]

[0081] Test 2: Unconfined compressive strength test 2

[0082] Sample preparation: Prepare the sample in the laboratory by taking dried soil sample, passing it through a 9.5mm sieve, and adding 12mg / kg Cd. 2+ (32.93mg / kg Cd(NO3)2·4H2O), 2000mg / kg Cu 2+ (7603.46mg / kg Cu(NO3)2·3H2O), 500mg / kg Ni 2+ (2024.96mg / kg NiCl2·6H2O), 1400mg / kg Pb 2+ (1879.12mg / kgPbCl2), 1250mg / kg Zn 2+Dissolve (2604.73 mg / kg ZnCl2) in a specified amount of water, then add the prepared heavy metal solution to the soil sample and mix with a mortar mixer for 30 minutes to make it as homogeneous as possible. Seal the mixture and store it for 7 days to ensure the full distribution of heavy metals in the soil.

[0083] Test Method: The remediation agents corresponding to Examples 5, 2, 6, and 7 were mixed with the above soil samples at a weight ratio of 20:100, and then stirred in a mortar mixer for 10 minutes to make it as homogeneous as possible. The final weight ratio of water to solids (including soil and binder) was determined to be 25:100. Approximately 200 grams of the mixture was then statically compacted using a stainless steel cylindrical mold with a diameter of 50 mm and a height of 50 mm. The sample was then carefully extruded from the mold using a hydraulic jack and sealed in a polyethylene bag for curing under standard conditions (temperature 20 ± 2 °C, relative humidity 99%). Unconfined compressive strength tests were performed at 1, 3, 7, 28, and 90 days of age, and the crushed samples were collected for toxicity leaching tests.

[0084] The test data after 90 days are shown in Table 2 below. The remediation agent has a good effect on improving the unconfined compressive strength of the soil.

[0085]

[0086] Test 3: Toxicity Leaching Test 1

[0087] Test method: Collect the broken samples after the 1d, 3d, 7d, 28d and 90d unconfined compressive strength test in Experiment 1, leach the heavy metals using SW-846 Test Method 1315, and then test the heavy metal concentration using inductively coupled plasma atomic emission spectrometry (ICP) to calculate the adsorption rate (according to the following formula).

[0088]

[0089] The test data after 90 days of age are shown in Tables 3 to 7 below. The remediation agent has a good adsorption effect on heavy metal ions such as cadmium, copper, nickel, lead and zinc in the soil.

[0090] Table 3. Effects of unactivated steel slag and the adsorbents prepared in Examples 1-4 on heavy metal Cd. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0091]

[0092] Table 4. Effects of unactivated steel slag and the adsorbents prepared in Examples 1-4 on heavy metal Cu. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0093]

[0094] Table 5. Effects of unactivated steel slag and the adsorbents prepared in Examples 1-4 on heavy metal Ni. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0095]

[0096] Table 6. Effects of unactivated steel slag and the adsorbents prepared in Examples 1-4 on heavy metal Pb. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0097]

[0098]

[0099] Table 7. Effects of unactivated steel slag and the adsorbents prepared in Examples 1-4 on heavy metal Zn. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0100]

[0101] Test 4: Toxicity Leaching Test 2

[0102] Test method: Collect the broken samples after the 1d, 3d, 7d, 28d and 90d unconfined compressive strength test in Experiment 2, leach the heavy metals using SW-846 Test Method 1315, and then test the heavy metal concentration using inductively coupled plasma atomic emission spectrometry (ICP) to calculate the adsorption rate (according to the following formula).

[0103]

[0104] The test data after 90 days of age are shown in Tables 8-12 below. This remediation agent has a good adsorption effect on heavy metal ions such as cadmium, copper, nickel, lead, and zinc in the soil.

[0105] Table 8. Effects of unactivated steel slag and the adsorbents prepared in Examples 5, 2, 6, and 7 on the heavy metal Cd. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0106]

[0107] Table 9 shows the effects of unactivated steel slag and the adsorbents prepared in Examples 5, 2, 6, and 7 on heavy metal Cu. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0108]

[0109]

[0110] Table 10 shows the effects of unactivated steel slag and the adsorbents prepared in Examples 5, 2, 6, and 7 on the heavy metal Ni. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0111]

[0112] Table 11. Effects of unactivated steel slag and the adsorbents prepared in Examples 5, 2, 6, and 7 on heavy metal Pb. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0113]

[0114] Table 12 shows the effects of unactivated steel slag and the adsorbents prepared in Examples 5, 2, 6, and 7 on the heavy metal Zn. 2+ Leaching data (mg / kg) before and after 90 days were restored.

[0115]

[0116] As shown in Tables 3-7, the unconfined compressive strength of the soil increases with the increase of the activator dosage, and the remediation agent has a positive effect on Cd. 2+ Cu 2+ Ni 2+ Pb 2+ With Zn 2+ The remediation capacity of soil contaminated with heavy metals also increases accordingly. Heavy metals in untreated contaminated soil exhibit extremely high mobility and toxicity; the leaching amounts of heavy metals cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) are far higher than the risk screening values ​​for agricultural land soil pollution in the "Soil Quality and Environmental Protection Standard for Risk Control of Agricultural Land Soil Pollution" (GB 15618-2018). However, after adding the remediation agent of this invention and curing for 90 days, the stability of heavy metals cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) is greatly improved, and their leaching amounts are far lower than the risk screening values ​​for agricultural land soil pollution in the "Soil Quality and Environmental Protection Standard for Risk Control of Agricultural Land Soil Pollution" (GB 15618-2018).

[0117] As shown in Tables 8-12, the four activators used—triethanolamine (TEA), triisopropanolamine (TIPA), hydroxyethyl diisopropanolamine (EDIPA), and diethanol monoisopropanolamine (DEIPA)—significantly improved the unconfined compressive strength of the soil after incorporation, and also exhibited excellent solidification and stabilization effects on heavy metals cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Furthermore, after incorporating the remediation agent of this invention and curing for 90 days, the stability of heavy metals cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) was greatly improved, and their leaching amounts were far lower than the risk screening values ​​for agricultural land soil pollution in the "Soil Quality Environmental Standard for Risk Control of Agricultural Land Soil Pollution" (GB 15618-2018).

[0118] Ball milling with an activator increases the hydration rate and degree of steel slag, significantly increasing the quantity and rate of calcium silicate (CSH) formed during hydration that encapsulates and solidifies heavy metals. Furthermore, the activator effectively dissolves more environmentally friendly ions (Ca) from the steel slag. 2+ Fe 2+ Fe 3+ (e.g., ion exchange) significantly increases the capacity for fixing heavy metals on the surface, achieving solidification and remediation. Secondly, it allows for finer grinding of steel slag powder, increasing the specific surface area and enhancing the contact surface for heavy metal adsorption, complexation, and precipitation, thus improving the solidification and remediation effect of steel slag-based solidification agents on heavy metal-contaminated soil. Furthermore, the alkaline substances generated from steel slag hydration, after solidifying the soil, increase its buffering capacity against acidic environments, enhancing the stability and acid resistance of this remediation agent. In practical applications, the prepared remediation agent can be directly applied to soil remediation without the need for drying or calcination, greatly reducing energy consumption and making it both environmentally friendly and cost-effective.

Claims

1. A method for preparing a remediation agent for heavy metal contaminated soil, characterized by: The preparation steps of this method are as follows: Step 1: Dry 100 parts of steel slag granules, ball mill them, and then pass them through a 1000-1500 mesh sieve to obtain steel slag powder; Step 2: Weigh 5-10 parts of activator, 1-3 parts of grinding aid, and 0.3-0.8 parts of hydrophilic agent and mix them evenly to obtain an activator; the activator is composed of an activator, grinding aid, and hydrophilic agent; wherein, the activator is at least one of triethanolamine, diethanolamine, triisopropanolamine, hydroxyethyl diisopropanolamine, diethanol monoisopropanolamine, methyldiethanolamine, and dimethylethanolamine; the grinding aid is at least one of ethylene glycol, ethanol, propylene glycol, and glycerol; and the hydrophilic agent is at least one of polysorbate, sorbitan monolaurate, polyoxyethylene lauryl ether, polyoxyethylene fatty alcohol ether, and glyceryl monooleate. Step 3: Add 0.01-0.1 parts of activator to 100 parts of steel slag powder and mix evenly to obtain pre-activated steel slag powder; Step 4: Use a planetary ball mill to ball mill the pre-activated steel slag powder obtained in Step 3 at 100-400 r / min for 10-60 min to obtain a heavy metal contaminated soil remediation agent.

2. The method for preparing the agent for remediation of heavy metal contaminated soil according to claim 1, wherein The ball milling speed in step four is 200-250 r / min; the ball milling time in step four is 20-40 min.

3. A reagent for remediation of heavy metal contaminated soil, characterized by: The agent is prepared by the method described in any one of claims 1 to 2.

4. The application of the heavy metal contaminated soil remediation agent according to claim 3 in the solidification and stabilization remediation of heavy metal contaminated soil.

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