A slag recycling secondary treatment process

Abstract

The present application relates to the technical field of slag resource processing, more particularly, it relates to a slag recycling secondary treatment process. It comprises the following steps: titanium-containing blast furnace slag recycling and processing, titanium-containing blast furnace slag resource processing, composite adsorbent preparation, resource secondary treatment and composite phase change heat storage material preparation. In the present application, through the resource processing of the titanium-containing blast furnace slag, the titanium-silicon composite matrix material and the mixture powder can be separated from the titanium-containing blast furnace slag, and the titanium-silicon composite matrix material and the mixture powder can be used for preparing the composite adsorbent and used as the matrix material of the composite phase change heat storage material respectively, so as to achieve the purpose of efficient resource utilization of the titanium-containing blast furnace slag and play the characteristics of each component in the titanium-containing blast furnace slag.

Description

Technical Field

[0001] This invention relates to the field of slag resource utilization technology, and more specifically, to a secondary treatment process for slag recycling. Background Technology

[0002] Blast furnace slag is a byproduct formed during the blast furnace smelting process from gangue in the ore, ash in the fuel, and non-volatile components in the flux. It is a solid waste generated in the metallurgical industry. Because it contains abundant iron, calcium, silicon, titanium, and magnesium, it has potential reuse value. However, without effective utilization and treatment, blast furnace slag will pollute the environment and waste a significant amount of resources.

[0003] Comprehensive utilization of blast furnace slag can transform waste into valuable resources. Currently, my country's treatment and utilization of blast furnace slag mainly focuses on its use as a raw material for cement, building materials, and road base materials. These applications are primarily simple physical uses, characterized by limited utilization methods, low utilization rates, and low efficiency. They fail to effectively leverage the characteristics of the various components in blast furnace slag and cannot realize its full social and economic benefits. Furthermore, current slag treatment technologies are not yet perfect, lacking comprehensive, applicable, and cost-effective technologies. For example, the utilization methods for titanium-containing blast furnace slag are relatively limited, with low recycling rates, high difficulty in resource utilization, and low efficiency, thus restricting the widespread application of comprehensive utilization of titanium-containing blast furnace slag. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a secondary treatment process for slag recycling.

[0005] A secondary treatment process for slag recycling includes the following steps:

[0006] S1: Titanium-containing blast furnace slag recycling and processing, including crushing, ball milling, screening and magnetic separation of titanium-containing blast furnace slag;

[0007] S2: Resource utilization of titanium-containing blast furnace slag. The titanium-containing blast furnace slag after magnetic separation is added to a nitric acid solution. After water bath heating, stirring reaction and filtration, leaching residue and filtrate are obtained. The leaching residue is washed, dried, cooled and ground to obtain titanium-silicon composite matrix material. The filtrate is collected for later use.

[0008] S3: Preparation of composite adsorbent: β-cyclodextrin aqueous solution is stirred and reacted with titanium-silicon composite matrix material, then a crosslinking agent is added, and stirring is continued until the liquid solidifies to obtain a solidified substance. After drying and grinding, the composite adsorbent is obtained.

[0009] S4: Secondary processing for resource recovery. The filtrate collected in step S2 is stirred and reacted with sodium carbonate solution, filtered, and precipitate A and reaction mixture filtrate are obtained. Sodium hydroxide solution is added to the reaction mixture filtrate, stirred and reacted, filtered, and precipitate B is obtained. Precipitate A and precipitate B are mixed, heated at high temperature in air atmosphere, and ground to obtain mixture powder.

[0010] S5: Preparation of composite phase change thermal storage material: Mixed powder, inorganic salt phase change material and binder are ball-milled, and then molded, pressed, demolded, heated at high temperature and kept warm to obtain composite phase change thermal storage material.

[0011] Furthermore, step S2: resource utilization treatment of titanium-containing blast furnace slag, specifically includes the following steps:

[0012] S2.1: Add the titanium-containing blast furnace slag after magnetic separation to a nitric acid solution with a mass fraction of 12-15%. The solid-liquid weight ratio of the titanium-containing blast furnace slag after magnetic separation to the nitric acid solution is 1:(6-10). After stirring evenly, place it in a constant temperature water bath at 70-80℃ and stir to react for 1-2 hours.

[0013] S2.2: After the reaction is completed, the leaching residue and filtrate are obtained by filtration. The leaching residue is washed with deionized water 2 to 5 times, and the filtrate is collected for later use.

[0014] S2.3: Subsequently, the washed leaching residue is placed in an oven at 60-80℃ and dried for 8-10 hours. After cooling and grinding, the titanium-silicon composite matrix material is obtained.

[0015] Further, step S3: preparation of the composite adsorbent specifically includes the following steps:

[0016] S3.1: Add β-cyclodextrin to deionized water and stir to mix. The solid-liquid weight ratio is 1:(80~100). Stir at 40~65℃ for 20~40min until the β-cyclodextrin is completely dissolved to obtain an aqueous solution of β-cyclodextrin.

[0017] S3.2: Add titanium-silicon composite matrix material to β-cyclodextrin aqueous solution, the solid-liquid weight ratio of titanium-silicon composite matrix material to β-cyclodextrin aqueous solution is 1:(70~90), stir and react at 35~50℃ for 1~2h, then add crosslinking agent, and continue stirring until the liquid is solidified to obtain solidified solid.

[0018] S3.3: The solidified material is dried in an oven at 70-80℃ and then ground to obtain a composite adsorbent.

[0019] Furthermore, the amount of crosslinking agent used is 3 to 7% of the total mass of the titanium-silicon composite matrix material and the β-cyclodextrin aqueous solution.

[0020] Furthermore, the crosslinking agent is a 25% (w / w) aqueous solution of glutaraldehyde.

[0021] Further, step S4: secondary processing of resources, specifically includes the following steps:

[0022] S4.1: Pour the collected filtrate into the reactor and add a sodium carbonate solution with a mass fraction of 10% to the reactor. The weight ratio of the filtrate to the sodium carbonate solution is 1:(1~2). Stir the reaction for 20~30 min, filter, and obtain precipitate A and reaction mixture filtrate.

[0023] S4.2: Add a 15% sodium hydroxide solution to the reaction mixture filtrate, with a weight ratio of 1:(0.4~1) between the reaction mixture filtrate and the sodium hydroxide solution. Stir the reaction for 20~30 min, filter, and obtain precipitate B.

[0024] S4.3: Mix precipitate A and precipitate B to obtain a precipitate mixture;

[0025] S4.4: Place the precipitate mixture in a ceramic crucible, then place the ceramic crucible in a muffle furnace, and heat it from room temperature to 500-540°C at a heating rate of 2-5°C / min in an air atmosphere. Then hold it at that temperature for 30-60 minutes, and grind it to obtain the mixture powder.

[0026] Further, step S5: preparation of composite phase change thermal storage materials, specifically includes the following steps:

[0027] S5.1: Add the mixed powder, inorganic salt phase change material and binder into a planetary ball mill and mix and mill at a speed of 200-400 r / min for 20-30 min, wherein the weight ratio of the mixed powder to the inorganic salt phase change material is (1-2):(1-3) to obtain the mixed powder;

[0028] S5.2: Place the mixed powder into a cylindrical mold, apply a pressure of 30-54 MPa to the mold on a press and hold the pressure for 2-3 minutes, demold to obtain a cylindrical composite material blank with a diameter of 10-18 mm and a thickness of 2-4 mm;

[0029] S5.3: Place the cylindrical composite material blank in a ceramic crucible, then place the ceramic crucible in a muffle furnace, and heat it from room temperature to 90-120°C at a heating rate of 2-5°C / min in an air atmosphere, holding it for 40-60 minutes to remove residual moisture. Then, set the muffle furnace to continue heating to 340-360°C at a heating rate of 2-5°C / min, and then hold it for 1-2 hours to obtain the composite phase change thermal storage material. Subsequently, remove the composite phase change thermal storage material and allow it to cool naturally to room temperature, then store it in a drying oven for later use.

[0030] Furthermore, the inorganic salt phase change material is at least one of lithium carbonate, sodium nitrate, potassium nitrate, magnesium chloride, lithium fluoride, potassium fluoride, and potassium carbonate.

[0031] Furthermore, the amount of binder used is 2 to 5% of the total mass of the mixture powder and the inorganic salt phase change material.

[0032] Furthermore, the binder is at least one of the following: a mixture of polyvinyl alcohol aqueous solution and borax, bentonite, and sodium humate modified bentonite.

[0033] The present invention has the following advantages:

[0034] 1. In this invention, the titanium-containing blast furnace slag, after acid leaching treatment, yields a titanium-silicon composite matrix material whose main components are SiO2 and TiO2. The surface of this matrix material contains a large number of hydroxyl groups, which facilitates the combination of the titanium-silicon composite matrix material with β-cyclodextrin to form a composite adsorbent, promoting the recovery and resource utilization of titanium and silicon components in the titanium-containing blast furnace slag. The hydroxyl groups on the surface of β-cyclodextrin undergo dehydration condensation with the hydroxyl groups on the surface of SiO2 in the titanium-silicon composite matrix material. Simultaneously, hydrogen bonds are formed between TiO2 in the titanium-silicon composite matrix material and β-cyclodextrin, allowing β-cyclodextrin to intercalate within the titanium-silicon composite matrix material. The resulting composite adsorbent exhibits excellent adsorption properties, effectively adsorbing pollutants. Furthermore, the titanium dioxide in the composite adsorbent undergoes a photocatalytic reaction, degrading pollutants adsorbed on the material surface, maintaining the high adsorption capacity and degradation performance of the composite adsorbent, and promoting the continuous adsorption process.

[0035] 2. In this invention, after resource recovery treatment, the collected filtrate contains soluble salts such as calcium, magnesium, aluminum, and manganese. The filtrate undergoes secondary resource recovery treatment, and the resulting mixed powder mainly consists of calcium carbonate, magnesium oxide, aluminum oxide, and manganese oxide. The mixed powder has good thermal and chemical stability. Using the mixed powder as a substrate or filler in high-temperature environments can ensure that the mixed powder maintains its structural and performance stability under high-temperature conditions. It plays an important role in the storage and utilization of renewable energy, improves the recycling effect of titanium-containing blast furnace slag, and increases the resource utilization efficiency of titanium-containing blast furnace slag.

[0036] 3. In this invention, a mixture of powders is used as the matrix material for inorganic salt phase change materials to prepare composite phase change thermal storage materials. The prepared composite phase change thermal storage materials have good high-temperature thermal stability and thermal cycling stability, which not only reduces the production cost of composite phase change thermal storage materials, but also realizes the value-added utilization of titanium-containing blast furnace slag, promotes the recycling and resource utilization of calcium, magnesium and aluminum components in titanium-containing blast furnace slag, and reduces the environmental harm of titanium-containing blast furnace slag. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] A secondary treatment process for slag recycling specifically includes the following steps:

[0040] S1: Titanium-containing blast furnace slag recycling and processing

[0041] S1.1: Crush, ball mill, and screen titanium-containing blast furnace slag to a particle size of 150 mesh;

[0042] S1.2: The titanium-containing blast furnace slag after screening is sent into a magnetic separator for magnetic separation to remove strongly magnetic substances, such as slag containing magnetic iron and elemental iron. The magnetic field strength of the magnetic separator is 1000GS.

[0043] S2: Resource utilization of titanium-containing blast furnace slag

[0044] S2.1: Add the titanium-containing blast furnace slag after magnetic separation to a nitric acid solution with a mass fraction of 15%. The solid-liquid weight ratio of the titanium-containing blast furnace slag after magnetic separation to the nitric acid solution is 1:10. After stirring evenly, place it in a constant temperature water bath at 80℃ and stir to react for 2 hours.

[0045] S2.2: After the reaction is completed, the leaching residue and filtrate are obtained by vacuum filtration. The leaching residue is washed 5 times with deionized water, and the filtrate is collected for later use.

[0046] S2.3: Subsequently, the washed leaching residue was placed in an 80℃ oven and dried for 10 hours. After cooling and grinding, a titanium-silicon composite matrix material was obtained.

[0047] S3: Preparation of Composite Adsorbents

[0048] S3.1: Add β-cyclodextrin to deionized water and stir to mix. The solid-liquid weight ratio is 1:100. Stir at 65℃ for 40 min until the β-cyclodextrin is completely dissolved to obtain an aqueous solution of β-cyclodextrin.

[0049] S3.2: Add titanium-silicon composite matrix material to β-cyclodextrin aqueous solution, with a solid-liquid weight ratio of 1:90. Stir and react at 50°C for 2 hours. Then, add 25% glutaraldehyde aqueous solution, with the amount of glutaraldehyde aqueous solution added being 5% of the total mass of titanium-silicon composite matrix material and β-cyclodextrin aqueous solution. Continue stirring until the liquid solidifies to obtain a solidified product.

[0050] S3.3: The solidified material is dried in an 80℃ oven and then ground to obtain a composite adsorbent;

[0051] S4: Secondary processing for resource recovery

[0052] S4.1: Pour the filtrate collected in step S2.2 into the reactor, and add a sodium carbonate solution with a mass fraction of 10% to the reactor. The weight ratio of the filtrate to the sodium carbonate solution is 1:2. Stir the reaction for 30 minutes, filter, and obtain precipitate A and reaction mixture filtrate.

[0053] S4.2: Add a 15% sodium hydroxide solution to the reaction mixture filtrate, with a weight ratio of 1:1 between the reaction mixture filtrate and the sodium hydroxide solution. Stir the reaction for 30 minutes, filter, and obtain precipitate B.

[0054] S4.3: Mix precipitate A and precipitate B to obtain a precipitate mixture;

[0055] S4.4: Place the precipitate mixture in a ceramic crucible, then place the ceramic crucible in a muffle furnace, heat it from room temperature to 540°C at a heating rate of 5°C / min in air atmosphere, then hold it at that temperature for 60 min, and then grind it to obtain the mixture powder.

[0056] S5: Preparation of Composite Phase Change Thermal Storage Materials

[0057] S5.1: Add the mixed powder, sodium nitrate and sodium humate modified bentonite into a planetary ball mill and mix and mill at a speed of 400 r / min for 30 min. The weight ratio of the mixed powder to sodium nitrate is 2:3, and the amount of sodium humate modified bentonite is 5% of the total mass of the mixed powder and sodium nitrate to obtain the mixed powder.

[0058] S5.2: Place the mixed powder into a cylindrical mold, apply a pressure of 54MPa to the mold on a press and hold the pressure for 3 minutes, demold to obtain a cylindrical composite material blank with a diameter of 10mm and a thickness of 4mm;

[0059] S5.3: Place the cylindrical composite material blank in a ceramic crucible, then place the ceramic crucible in a muffle furnace, and heat it from room temperature to 120°C at a heating rate of 5°C / min in air atmosphere, hold for 60 min to remove residual moisture. Then set the muffle furnace to continue heating to 360°C at a heating rate of 5°C / min, and hold for 2 h to obtain the composite phase change thermal storage material. Subsequently, remove the composite phase change thermal storage material and allow it to cool naturally to room temperature, then store it in a drying oven for later use.

[0060] Example 2

[0061] A secondary treatment process for slag recycling specifically includes the following steps:

[0062] S1: Titanium-containing blast furnace slag recycling and processing

[0063] S1.1: Crush, ball mill, and screen titanium-containing blast furnace slag to a particle size of 150 mesh;

[0064] S1.2: The titanium-containing blast furnace slag after screening is sent into a magnetic separator for magnetic separation to remove strongly magnetic substances, such as slag containing magnetic iron and elemental iron. The magnetic field strength of the magnetic separator is 1000GS.

[0065] S2: Resource utilization of titanium-containing blast furnace slag

[0066] S2.1: Add the titanium-containing blast furnace slag after magnetic separation to a nitric acid solution with a mass fraction of 15%. The solid-liquid weight ratio of the titanium-containing blast furnace slag after magnetic separation to the nitric acid solution is 1:10. After stirring evenly, place it in a constant temperature water bath at 70℃ and stir to react for 1 hour.

[0067] S2.2: After the reaction is completed, the leaching residue and filtrate are obtained by filtration. The leaching residue is washed twice with deionized water, and the filtrate is collected for later use.

[0068] S2.3: Subsequently, the washed leaching residue was placed in a 60℃ oven and dried for 8 hours. After cooling and grinding, a titanium-silicon composite matrix material was obtained.

[0069] S3: Preparation of Composite Adsorbents

[0070] S3.1: Add β-cyclodextrin to deionized water and stir to mix. The solid-liquid weight ratio is 1:100. Stir at 40℃ for 20 min until the β-cyclodextrin is completely dissolved to obtain a β-cyclodextrin aqueous solution.

[0071] S3.2: Add titanium-silicon composite matrix material to β-cyclodextrin aqueous solution, with a solid-liquid weight ratio of 1:90. Stir and react at 35°C for 1 hour. Then, add 25% glutaraldehyde aqueous solution, with the amount of glutaraldehyde aqueous solution added being 5% of the total mass of titanium-silicon composite matrix material and β-cyclodextrin aqueous solution. Continue stirring until the liquid solidifies to obtain a solidified product.

[0072] S3.3: The solidified material is dried in a 70℃ oven and then ground to obtain a composite adsorbent;

[0073] S4: Secondary processing for resource recovery

[0074] S4.1: Pour the filtrate collected in step S2.2 into the reactor, and add a sodium carbonate solution with a mass fraction of 10% to the reactor. The weight ratio of the filtrate to the sodium carbonate solution is 1:2. Stir the reaction for 20 minutes, filter, and obtain precipitate A and reaction mixture filtrate.

[0075] S4.2: Add a 15% sodium hydroxide solution to the reaction mixture filtrate, with a weight ratio of 1:1 between the reaction mixture filtrate and the sodium hydroxide solution. Stir the reaction for 20 minutes, filter, and obtain precipitate B.

[0076] S4.3: Mix precipitate A and precipitate B to obtain a precipitate mixture;

[0077] S4.4: Place the precipitate mixture in a ceramic crucible, then place the ceramic crucible in a muffle furnace, heat it from room temperature to 500°C at a heating rate of 2°C / min in air atmosphere, then hold it at that temperature for 30 min, and then grind it to obtain the mixture powder;

[0078] S5: Preparation of Composite Phase Change Thermal Storage Materials

[0079] S5.1: Add the mixed powder, sodium nitrate and sodium humate modified bentonite into a planetary ball mill and mix and mill at a speed of 200 r / min for 20 min. The weight ratio of the mixed powder to sodium nitrate is 2:3, and the amount of sodium humate modified bentonite is 5% of the total mass of the mixed powder and sodium nitrate to obtain the mixed powder.

[0080] S5.2: Place the mixed powder into a cylindrical mold, apply a pressure of 30MPa to the mold on a press and hold the pressure for 2 minutes, demold to obtain a cylindrical composite material blank with a diameter of 10mm and a thickness of 4mm;

[0081] S5.3: Place the cylindrical composite material blank in a ceramic crucible, then place the ceramic crucible in a muffle furnace, and heat it from room temperature to 90°C at a heating rate of 2°C / min in air atmosphere, hold for 40 min to remove residual moisture, then set the muffle furnace to continue heating to 340°C at a heating rate of 2°C / min, and then hold for 1 h to obtain the composite phase change thermal storage material. Subsequently, remove the composite phase change thermal storage material and allow it to cool naturally to room temperature, then store it in a drying oven for later use.

[0082] Example 3

[0083] A secondary treatment process for slag recycling specifically includes the following steps:

[0084] S1: Titanium-containing blast furnace slag recycling and processing

[0085] S1.1: Crush, ball mill, and screen titanium-containing blast furnace slag to a particle size of 180 mesh;

[0086] S1.2: The titanium-containing blast furnace slag after screening is sent into a magnetic separator for magnetic separation to remove strongly magnetic substances, such as slag containing magnetic iron and elemental iron. The magnetic field strength of the magnetic separator is 2000GS.

[0087] S2: Resource utilization of titanium-containing blast furnace slag

[0088] S2.1: Add the titanium-containing blast furnace slag after magnetic separation to a nitric acid solution with a mass fraction of 15%. The solid-liquid weight ratio of the titanium-containing blast furnace slag after magnetic separation to the nitric acid solution is 1:6. After stirring evenly, place it in a constant temperature water bath at 80℃ and stir to react for 2 hours.

[0089] S2.2: After the reaction is completed, the leaching residue and filtrate are obtained by vacuum filtration. The leaching residue is washed 5 times with deionized water, and the filtrate is collected for later use.

[0090] S2.3: Subsequently, the washed leaching residue was placed in an 80℃ oven and dried for 10 hours. After cooling and grinding, a titanium-silicon composite matrix material was obtained.

[0091] S3: Preparation of Composite Adsorbents

[0092] S3.1: Add β-cyclodextrin to deionized water and stir to mix. The solid-liquid weight ratio is 1:80. Stir at 65℃ for 40 min until the β-cyclodextrin is completely dissolved to obtain an aqueous solution of β-cyclodextrin.

[0093] S3.2: Add titanium-silicon composite matrix material to β-cyclodextrin aqueous solution, the solid-liquid weight ratio of titanium-silicon composite matrix material to β-cyclodextrin aqueous solution is 1:70, stir and react at 50℃ for 2h, then add 25% glutaraldehyde aqueous solution, the amount of glutaraldehyde aqueous solution added is 3% of the total mass of titanium-silicon composite matrix material and β-cyclodextrin aqueous solution, and continue stirring until the liquid is solidified to obtain solidified solid.

[0094] S3.3: The solidified material is dried in an 80℃ oven and then ground to obtain a composite adsorbent;

[0095] S4: Secondary processing for resource recovery

[0096] S4.1: Pour the filtrate collected in step S2.2 into the reactor, and add a sodium carbonate solution with a mass fraction of 10% to the reactor. The weight ratio of the filtrate to the sodium carbonate solution is 1:1. Stir the reaction for 30 minutes, filter, and obtain precipitate A and reaction mixture filtrate.

[0097] S4.2: Add a 15% sodium hydroxide solution to the reaction mixture filtrate, with a weight ratio of 1:0.5 between the reaction mixture filtrate and the sodium hydroxide solution. Stir the reaction for 30 minutes, filter, and obtain precipitate B.

[0098] S4.3: Mix precipitate A and precipitate B to obtain a precipitate mixture;

[0099] S4.4: Place the precipitate mixture in a ceramic crucible, then place the ceramic crucible in a muffle furnace, heat it from room temperature to 540°C at a heating rate of 5°C / min in air atmosphere, then hold it at that temperature for 60 min, and then grind it to obtain the mixture powder.

[0100] S5: Preparation of Composite Phase Change Thermal Storage Materials

[0101] S5.1: Add the mixed powder, sodium nitrate and sodium humate modified bentonite into a planetary ball mill and mix and mill at a speed of 400 r / min for 30 min. The weight ratio of the mixed powder to sodium nitrate is 1:1, and the amount of sodium humate modified bentonite is 2% of the total mass of the mixed powder and sodium nitrate to obtain the mixed powder.

[0102] S5.2: Place the mixed powder into a cylindrical mold, apply a pressure of 54MPa to the mold on a press and hold the pressure for 3 minutes, demold to obtain a cylindrical composite material blank with a diameter of 10mm and a thickness of 4mm;

[0103] S5.3: Place the cylindrical composite material blank in a ceramic crucible, then place the ceramic crucible in a muffle furnace, and heat it from room temperature to 120°C at a heating rate of 5°C / min in air atmosphere, hold for 60 min to remove residual moisture. Then set the muffle furnace to continue heating to 360°C at a heating rate of 5°C / min, and hold for 2 h to obtain the composite phase change thermal storage material. Subsequently, remove the composite phase change thermal storage material and allow it to cool naturally to room temperature, then store it in a drying oven for later use.

[0104] Comparative Example 1

[0105] Compared with Example 1, the difference of Comparative Example 1 is that the titanium-containing blast furnace slag after magnetic separation is directly used in the preparation of the composite adsorbent, and the titanium-silicon composite matrix material in step S3.2 is replaced with the titanium-containing blast furnace slag after magnetic separation. The other steps remain unchanged, and the composite adsorbent is prepared. This is called Comparative Example 1.

[0106] From the composite adsorbents obtained in Examples 1-3 and Comparative Example 1, 60 mg of each was weighed as test samples. Each sample was dispersed in 100 mL of a 0.01 g / L methylene blue solution. The mixture was magnetically stirred for 60 min in the dark to obtain a mixed liquid. The mixed liquid was then irradiated under a 250 W high-pressure mercury lamp and reacted for 30 min. 10 mL of the mixed liquid was taken out and centrifuged. After centrifugation, the concentration of methylene blue solution in the solution was analyzed by UV-Vis diffuse reflectance spectroscopy, and the degradation rate of methylene blue by the sample was calculated. The results are shown in Table 1.

[0107] The formula for calculating the degradation rate is:

[0108] N0 and N1 represent the concentrations of methylene blue before and after degradation, respectively.

[0109] Table 1:

[0110] Group Degradation rate (%) Example 1 68.77 Example 2 65.93 Example 3 62.68 Comparative Example 1 27.31

[0111] As shown in Table 1, during the photocatalytic degradation of methylene blue, the composite adsorbents prepared in Examples 1-3 exhibited significantly stronger degradation capabilities than Comparative Example 1, demonstrating excellent adsorption and degradation effects. This indicates that while directly using titanium-containing blast furnace slag after magnetic separation as a raw material to prepare composite adsorbents can achieve a certain level of pollutant degradation, the resulting adsorption treatment effect is significantly weaker than that of the composite adsorbents in Examples 1-3. By utilizing the titanium-containing blast furnace slag for resource recovery, the resulting titanium-silicon composite matrix material, combined with β-cyclodextrin, can effectively adsorb and degrade pollutants, significantly improving the recovery rate of titanium dioxide and silicon dioxide during the recycling and treatment of titanium-containing blast furnace slag.

[0112] Comparative Example 2

[0113] Compared with Example 1, the difference of Comparative Example 2 is that the titanium-containing blast furnace slag after magnetic separation is directly used in the preparation of composite phase change thermal storage material, and the mixed powder in step S5.1 is replaced with the titanium-containing blast furnace slag after magnetic separation. The other steps remain unchanged, and the composite phase change thermal storage material is prepared. This is referred to as Comparative Example 2.

[0114] The composite phase change thermal storage materials obtained in Examples 1-3 and Comparative Example 2 were subjected to performance tests. The thermal cycling test conditions were 600℃, and the results are shown in Table 2.

[0115] Table 2:

[0116] Group Thermal conductivity (W / m*K) Latent heat of phase transition (J / g) State after 100 thermal cycles Example 1 2.4 72.53 No deformation, no cracks Example 2 2.3 70.24 No deformation, no cracks Example 3 2.1 69.82 No deformation, no cracks Comparative Example 2 1.3 52.17 Crack formation

[0117] As shown in Table 2, the composite phase change thermal storage materials prepared in Examples 1-3 all have thermal conductivity > 2 W / m*K. The test results of latent heat of phase change and thermal cycling test results are also better than those of Comparative Example 2. This indicates that Comparative Example 2 directly uses titanium-containing blast furnace slag after magnetic separation as raw material to prepare composite phase change thermal storage materials. The high-temperature thermal stability and thermal cycling stability achieved by Comparative Example 2 are weaker than those of the composite phase change thermal storage materials in Examples 1-3. Examples 1-3, through secondary resource recovery treatment of titanium-containing blast furnace slag, obtained mixed powder with good thermal and chemical stability. Its use as the base material of composite phase change thermal storage materials is beneficial to preparing composite phase change thermal storage materials with good high-temperature thermal stability and thermal cycling stability, and greatly improves the recovery rate and resource utilization effect of calcium, magnesium and aluminum components in titanium-containing blast furnace slag.

[0118] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A secondary treatment process for slag recycling, characterized in that, Includes the following steps: S1: Titanium-containing blast furnace slag recycling and processing, including crushing, ball milling, screening and magnetic separation of titanium-containing blast furnace slag; S2: Resource utilization of titanium-containing blast furnace slag. The titanium-containing blast furnace slag after magnetic separation is added to a nitric acid solution. After water bath heating, stirring reaction and filtration, leaching residue and filtrate are obtained. The leaching residue is washed, dried, cooled and ground to obtain a titanium-silicon composite matrix material with SiO2 and TiO2 as the main components. The filtrate is collected for later use. The collected filtrate contains soluble salts of calcium, magnesium, aluminum and manganese. S3: Preparation of composite adsorbent: β-cyclodextrin aqueous solution is stirred and reacted with titanium-silicon composite matrix material, then a crosslinking agent is added, and stirring is continued until the liquid solidifies to obtain a solidified substance. After drying and grinding, the composite adsorbent is obtained. The hydroxyl groups on the surface of β-cyclodextrin undergo dehydration condensation with the hydroxyl groups on the surface of SiO2 in the titanium-silicon composite matrix material. At the same time, hydrogen bonds are formed between TiO2 in the titanium-silicon composite matrix material and β-cyclodextrin, so that β-cyclodextrin is intercalated in the titanium-silicon composite matrix material. S4: Secondary processing for resource recovery. The filtrate collected in step S2 is stirred and reacted with sodium carbonate solution, filtered, and precipitate A and reaction mixture filtrate are obtained. Sodium hydroxide solution is added to the reaction mixture filtrate, stirred and reacted, filtered, and precipitate B is obtained. Precipitate A and precipitate B are mixed and heated from room temperature to 500-540°C at a heating rate of 2-5°C / min under air atmosphere, and kept at the temperature for 30-60min. After grinding, a mixture powder with calcium carbonate, magnesium oxide, aluminum oxide and manganese oxide as the main components is obtained. S5: Preparation of composite phase change thermal storage material: Mixed powder, inorganic salt phase change material and binder are ball-milled. Then, after being placed into a mold, pressed and formed, and demolded, the mixture is heated from room temperature to 90-120°C at a heating rate of 2-5°C / min in air atmosphere and held for 40-60 min. Then, it is heated to 340-360°C at a heating rate of 2-5°C / min and held for 1-2 h to obtain composite phase change thermal storage material.

2. The secondary treatment process for slag recycling according to claim 1, characterized in that, Step S2: Resource utilization treatment of titanium-containing blast furnace slag, specifically including the following steps: S2.1: Add the titanium-containing blast furnace slag after magnetic separation to a nitric acid solution with a mass fraction of 12-15%. The solid-liquid weight ratio of the titanium-containing blast furnace slag after magnetic separation to the nitric acid solution is 1:(6-10). After stirring evenly, place it in a constant temperature water bath at 70-80℃ and stir to react for 1-2 hours. S2.2: After the reaction is completed, the leaching residue and filtrate are obtained by filtration. The leaching residue is washed with deionized water 2 to 5 times, and the filtrate is collected for later use. S2.3: Subsequently, the washed leaching residue is placed in an oven at 60-80℃ and dried for 8-10 hours. After cooling and grinding, the titanium-silicon composite matrix material is obtained.

3. The secondary treatment process for slag recycling according to claim 1, characterized in that, Step S3: Preparation of the composite adsorbent, specifically including the following steps: S3.1: Add β-cyclodextrin to deionized water and stir to mix. The solid-liquid weight ratio is 1:(80-100). Stir at 40-65℃ for 20-40 minutes until the β-cyclodextrin is completely dissolved to obtain a β-cyclodextrin aqueous solution. S3.2: Add titanium-silicon composite matrix material to β-cyclodextrin aqueous solution, the solid-liquid weight ratio of titanium-silicon composite matrix material to β-cyclodextrin aqueous solution is 1: (70-90), stir and react at 35-50℃ for 1-2 hours, then add crosslinking agent, and continue stirring until the liquid is solidified to obtain solidified solid. S3.3: The solidified material is dried in an oven at 70-80℃ and then ground to obtain a composite adsorbent.

4. The secondary treatment process for slag recycling according to claim 3, characterized in that, The amount of crosslinking agent used is 3 to 7% of the total mass of the titanium-silicon composite matrix material and the β-cyclodextrin aqueous solution.

5. The secondary treatment process for slag recycling according to claim 3, characterized in that, The crosslinking agent is a 25% (w / w) aqueous solution of glutaraldehyde.

6. The secondary treatment process for slag recycling according to claim 1, characterized in that, Step S4: Secondary processing of resources, specifically including the following steps: S4.1: Pour the collected filtrate into the reactor and add a sodium carbonate solution with a mass fraction of 10% to the reactor. The weight ratio of the filtrate to the sodium carbonate solution is 1:(1~2). Stir the reaction for 20~30 min, filter, and obtain precipitate A and reaction mixture filtrate. S4.2: Add a 15% sodium hydroxide solution to the reaction mixture filtrate, with a weight ratio of 1:(0.4~1) between the reaction mixture filtrate and the sodium hydroxide solution. Stir the reaction for 20~30 min, filter, and obtain precipitate B. S4.3: Mix precipitate A and precipitate B to obtain a precipitate mixture; S4.4: Place the precipitate mixture in a ceramic crucible, then place the ceramic crucible in a muffle furnace, and heat it from room temperature to 500-540°C at a heating rate of 2-5°C / min in an air atmosphere. Then hold it at that temperature for 30-60 minutes, and grind it to obtain the mixture powder.

7. The secondary treatment process for slag recycling according to claim 1, characterized in that, Step S5: Preparation of composite phase change thermal storage materials, specifically including the following steps: S5.1: Add the mixed powder, inorganic salt phase change material and binder into a planetary ball mill and mix and mill at a speed of 200-400 r / min for 20-30 min, wherein the weight ratio of the mixed powder to the inorganic salt phase change material is (1-2):(1-3) to obtain the mixed powder; S5.2: Place the mixed powder into a cylindrical mold, apply a pressure of 30-54 MPa to the mold on a press and hold the pressure for 2-3 minutes, demold to obtain a cylindrical composite material blank with a diameter of 10-18 mm and a thickness of 2-4 mm; S5.3: Place the cylindrical composite material blank in a ceramic crucible, then place the ceramic crucible in a muffle furnace, and heat it from room temperature to 90-120°C at a heating rate of 2-5°C / min in an air atmosphere, holding it for 40-60 minutes to remove residual moisture. Then, set the muffle furnace to a heating rate of 2-5°C / min and continue heating to 340-360°C, then hold it for 1-2 hours to obtain the composite phase change thermal storage material. Subsequently, remove the composite phase change thermal storage material and allow it to cool naturally to room temperature, then store it in a drying oven for later use.

8. The secondary treatment process for slag recycling according to claim 7, characterized in that, The inorganic salt phase change material is at least one of lithium carbonate, sodium nitrate, potassium nitrate, magnesium chloride, lithium fluoride, potassium fluoride, and potassium carbonate.

9. The secondary treatment process for slag recycling according to claim 8, characterized in that, The amount of binder used is 2-5% of the total mass of the mixture powder and inorganic salt phase change material.

10. The secondary treatment process for slag recycling according to claim 9, characterized in that, The binder is at least one of the following: a mixture of polyvinyl alcohol aqueous solution and borax, bentonite, and sodium humate modified bentonite.