A method for preparing soil solidifying agent from nickel alloy refined slag of AOD furnace

Abstract

The present invention belongs to the technical field of building materials, and specifically relates to a method for preparing a soil solidifier from nickel alloy refined slag from an AOD furnace. AOD furnace nickel alloy refined slag, ferric sulfate and water are mixed in a certain ratio, and then ground and sieved; the solution under the sieve is dried to form a powder, and then fly ash is added to the powder for calcination and cooling. After cooling to room temperature, sodium metasilicate nonahydrate and ferrous sulfate are added to the dry material, and the mixture is ground to prepare a soil solidifier. The present invention uses AOD furnace nickel alloy refined slag to prepare a low-carbon inorganic soil solidifier that can be directly used, thereby realizing its high-value recycling.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to a method for preparing a soil solidifying agent from nickel alloy refined slag from an AOD furnace. Background Art

[0002] AOD furnace nickel alloy refining slag is the slag produced when nickel alloy and molten iron are refined in AOD furnace. Its main chemical components include SiO2, Al2O3, CaO and Fe2O3, among which the content of CaO is relatively high, about 45%-60%. Compared with blast furnace slag, electric furnace slag, etc., AOD furnace nickel alloy refining slag has low activity and poor grindability. Therefore, there are not many applications of AOD furnace nickel alloy refining slag, and most applications are still mainly for recycling slag.

[0003] Soil stabilizer is a new type of green building material. It can be added to the soil to consolidate soil particles through physical, chemical or biological effects to achieve the performance indicators required by the project. It can be used for roadbed, foundation and deep soil reinforcement projects. It has been widely used in highway, railway, water conservancy, construction and other fields.

[0004] Currently, there are three classification methods for soil solidifiers: according to the form of the material, they can be divided into liquid soil solidifiers and powder soil solidifiers; according to the properties, they can be divided into Class A soil solidifiers and Class B soil solidifiers. Class A soil solidifiers cannot be used directly for soil solidification and need to be used in conjunction with cementitious materials such as cement, while Class B can; according to the different action mechanisms, they can be divided into inorganic soil solidifiers, ionic soil solidifiers, organic soil solidifiers, bio-enzyme soil solidifiers, etc.

[0005] Traditional soil stabilizers are made of cement and lime as the main raw materials, mixed with surfactants, alkaline substances and other stimulants. However, the cement production process is energy-intensive and costly, and emits a large amount of CO2 gas to pollute the environment. Currently, the only resources that can be reused include granulated blast furnace slag, carbide slag, copper slag, etc., resulting in poor economic and environmental benefits. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing a soil solidifier from nickel alloy refined slag in an AOD furnace. The present invention utilizes nickel alloy refined slag in an AOD furnace to prepare a low-carbon inorganic soil solidifier that can be directly used, thereby realizing its high-value recycling.

[0007] The present invention is achieved in that:

[0008] The present invention first provides a method for preparing a soil solidifying agent from nickel alloy refined slag from an AOD furnace, comprising the following steps:

[0009] (1) mixing AOD furnace nickel alloy refining slag, ferrous sulfate and water in a certain ratio, and then grinding and sieving;

[0010] (2) drying the undersize solution of step (1) to obtain a powder, adding fly ash to the powder, calcining, cooling, and obtaining a dry material;

[0011] (3) After cooling to room temperature, sodium metasilicate nonahydrate and ferrous sulfate are added to the dry material, and the mixture is ground to prepare a soil stabilizer.

[0012] The AOD furnace nickel alloy refining slag, ferric sulfate and water are as follows in weight percentage:

[0013] AOD furnace nickel alloy refined slag 55-75%;

[0014] Ferrous sulfate 2.75-3.75%;

[0015] Water 21.25-42.25%;

[0016] The total of the above weight percentages is 100%.

[0017] Furthermore, the screening in step (1) is to pass the ground slurry through a 0.08 mm sieve.

[0018] Furthermore, the drying in step (2) is carried out in an oven at 100-110°C.

[0019] Furthermore, the calcination in step (2) is performed at 400-600° C. for 30-60 min.

[0020] Furthermore, in step (2), the weight ratio of the powder to the fly ash is 85%:15%-95%:5%.

[0021] Furthermore, in step (3), the weight ratios of the sodium metasilicate nonahydrate and the ferrous sulfate to the dry material are 0.005-0.015% and 0.25-0.75% respectively.

[0022] Furthermore, the grinding in step (3) is to grind the mixture to a size where the residue on an 80 μm sieve does not exceed 10%.

[0023] Specific working principle:

[0024] 1. The ferric sulfate solution is highly acidic. Grinding it with the nickel alloy refined slag from the AOD furnace can improve the mechanical activity on the one hand, and on the other hand, it can destroy the surface morphology of the refined slag particles by acidification. Combined with the mechanical grinding effect, it can increase its surface energy, thereby improving its activity.

[0025] 2. Decompose the residual ferric sulfate solution in the powder by low-temperature calcination to achieve neutralization of the powder;

[0026] 3. Adding ferrous sulfate has weak acidity, which can improve the early strength of the curing agent. Adding nonahydrate metasilicic acid has a setting effect and improves the construction performance of the curing agent.

[0027] The present invention has the following advantages:

[0028] The present invention utilizes AOD furnace nickel alloy refined slag to prepare soil solidifying agent, has high waste utilization rate, reaching more than 95% (the total proportion of solid waste in the solidifying agent, the solid waste is refined slag and fly ash), has a relatively simple preparation process, and has good product performance. DETAILED DESCRIPTION

[0029] Embodiment 1:

[0030]

[0031] The above components are put into a closed ball mill with a stopper and ground for 30 minutes. The slurry is passed through a 0.08mm sieve, and the slurry under the sieve is placed in a 100-110℃ oven for drying and dehydration. The dried and dehydrated powder is mixed with fly ash, and the mass ratio of powder to fly ash is 85%:15%; the powder and fly ash mixture is kept at 600℃ for 45 minutes, and then cooled to room temperature. 0.012% sodium metasilicate nonahydrate and 0.5% ferrous sulfate are added to the dry material, and ground for about 60 minutes to obtain the finished soil solidifier. The product fineness (80μm sieve residue) is 2.2% (that is, the percentage of the total mass remaining after passing through a certain aperture, the smaller the residue, the finer it is).

[0032] After the curing agent is added to the soil, it forms a solidified soil. The curing agent is calculated by the internal mixing method. The amount of curing agent added is 10% of the total powder amount, the water-powder ratio is 0.6, the specimen specification is a cube of 70.7mm*70.7mm*70.7mm, the number of specimens is 6 in a group, the curing condition is 20±1℃, and the curing is carried out to the specified age for unconfined compression. Its 7d unconfined compressive strength is 1.67MPa, and the 28d unconfined compressive strength is 3.1MPa, which meets the index requirements of the current industry standard "Soft Soil Curing Agent" CJ / T 526-2018 strength grade 3.0.

[0033] Embodiment 2:

[0034]

[0035] Put it into a closed ball mill with a stopper and grind it for 20-30 minutes. Pass the slurry through a 0.08mm sieve, take the slurry under the sieve and place it in a 100-110℃ oven for drying and dehydration. Add the dried and dehydrated powder to fly ash, with the mass ratio of powder to fly ash being 85%:15%; keep the powder and fly ash mixture at 480℃-500℃ for 45 minutes, and then cool it to room temperature. Add 0.005% sodium metasilicate nonahydrate and 0.3% ferrous sulfate to the dry material, and grind it for about 35 minutes to obtain the finished soil solidifier. The product fineness (80μm sieve residue) is 3.6%.

[0036] After the curing agent is added to the soil, it forms a solidified soil. The curing agent is calculated by the internal mixing method. The amount of curing agent added is 10% of the total powder amount, the water-powder ratio is 0.6, the specimen specification is a cube of 70.7mm*70.7mm*70.7mm, the number of specimens is 6 in a group, the curing condition is 20±1℃, and the curing is carried out to the specified age for unconfined compression. Its 7d unconfined compressive strength is 1.09MPa, and the 28d unconfined compressive strength is 2.3MPa, which meets the index requirements of the current industry standard "Soft Soil Curing Agent" CJ / T 526-2018 strength grade 2.0.

[0037] Embodiment 3:

[0038]

[0039] Put it into a closed ball mill with a stopper and grind it for 20-30 minutes. Pass the slurry through a 0.08mm sieve, take the slurry under the sieve and place it in a 100-110℃ oven for drying and dehydration. Add the dried and dehydrated powder to fly ash, with the mass ratio of powder to fly ash being 90%:10%; keep the powder and fly ash mixture at 550℃ for 45 minutes, and then cool it to room temperature. Add 0.008% sodium metasilicate nonahydrate and 0.5% ferrous sulfate to the dry material, and grind it for about 45 minutes to obtain the finished soil solidifier. The product fineness (80μm sieve residue) is 2.3%.

[0040] After the curing agent is added to the soil, it forms a solidified soil. The curing agent is calculated by the internal mixing method. The amount of curing agent added is 10% of the total powder amount, the water-powder ratio is 0.6, the specimen specification is a cube of 70.7mm*70.7mm*70.7mm, the number of specimens is 6 in a group, the curing condition is 20±1℃, and the curing is performed to the specified age for unconfined compression. Its 7d unconfined compressive strength is 1.23MPa, and the 28d unconfined compressive strength is 2.6MPa (this performance is the performance of the solidified soil after being added to the soil), which meets the index requirements of the current industry standard "Soft Soil Curing Agent" CJ / T 526-2018 strength grade 2.0.

[0041] The results of each example are shown in Table 1.

[0042] Table 1: Performance of each embodiment

[0043]

[0044] As shown in Table 1, the solidified soil obtained in Example 1 has the highest strength. This is because the iron sulfate content in the components of Example 1 is relatively high, the surface is highly damaged, and the powder is finer after grinding and has a small surface area.

[0045] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a soil solidifying agent from nickel alloy refined slag from an AOD furnace, characterized in that: The steps include: (1) mixing AOD furnace nickel alloy refining slag, ferrous sulfate and water in a certain ratio, and then grinding and sieving; (2) drying the undersize solution of step (1) to obtain a powder, adding fly ash to the powder, calcining, cooling, and obtaining a dry material; (3) After cooling to room temperature, sodium metasilicate nonahydrate and ferrous sulfate are added to the dry material, and the mixture is ground to prepare a soil solidifying agent; The AOD furnace nickel alloy refining slag, ferric sulfate and water are as follows in weight percentage: AOD furnace nickel alloy refined slag 55-75%; Iron sulfate 2.75-3.75%; Water 21.25-42.25%; The total of the above weight percentages is 100%.

2. The method according to claim 1, characterized in that: The sieving in step (1) is to pass the ground slurry through a 0.08 mm sieve.

3. The method according to claim 1, characterized in that: The drying in step (2) is carried out in an oven at 100-110°C.

4. The method according to claim 1, characterized in that: The calcination in step (2) is carried out at 400-600° C. for 30-60 min.

5. The method according to claim 1, characterized in that: The weight ratio of the powder material to the fly ash in step (2) is 85%:15%-95%:5%.

6. The method according to claim 1, characterized in that: In step (3), the weight proportions of the sodium metasilicate nonahydrate and the ferrous sulfate in the dry material are 0.005-0.015% and 0.25-0.75% respectively.

7. The method according to claim 1, characterized in that: The grinding in step (3) is to grind the mixed material to a size where the residue on an 80 μm sieve does not exceed 10%.

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