Iron and steel slag smothering and pretreatment process

Abstract

The present application relates to steel slag treatment technical field, specifically to a kind of steel slag and pretreatment process.Its preparation process includes the following steps: the high-temperature steel slag just out of furnace is transferred to hot stifling pool, bottom water stifling slag, while adding composite fly ash flux, introduce carbon dioxide gas;In closed environment, continue to inject water cooling, composite stabilizer is added therein, by spraying method spray cold water to cool steel slag to room temperature, complete steel stifling process;The steel stifling that completes hot stifling is magnetically selected, and the iron element in it is recycled.The present application forms flux by boric acid, aluminium hydroxide through fly ash compound, adds in the link of steel slag hot stifling, boric acid is decomposed into oxide under certain temperature, fly ash provides glass state, and both form low-temperature eutectic, substantially improve slag layer fluidity, then through aluminium hydroxide heat absorption, form heat absorption-heat release "thermal buffer-thermal compensation" coupling, to improve the solidification efficiency of free calcium oxide and free magnesium oxide.

Description

Technical Field

[0001] This invention relates to the field of steel slag treatment technology, specifically to a steel slag curing process and pretreatment technology. Background Technology

[0002] In the steel production process, steel slag is a major byproduct. Steel slag quenching, also known as hot quenching, is a process for stabilizing high-temperature molten steel slag during steel smelting. It aims to eliminate harmful components such as free calcium oxide and free magnesium oxide in the steel slag through controlled cooling, hydration, and chemical reactions, thereby improving its volume stability and resource utilization rate. Free calcium oxide and free magnesium oxide are prone to hydration expansion during subsequent storage or resource utilization, leading to unstable steel slag volume and severely affecting its application in building materials, roadbeds, and other fields. Therefore, traditional hot quenching processes mainly promote the hydration reaction of free calcium oxide and free magnesium oxide through high-temperature steam or water spraying.

[0003] Traditional hot quenching relies on high-temperature steam, but the hydration rate of free calcium oxide and free magnesium oxide is slow, resulting in long processing cycles and high energy consumption. Therefore, people use chemical additives such as CO2, organic acids, or mechanical activation such as ultrafine grinding and stirring during hot quenching to improve the stabilization efficiency of steel slag. Although CO2-enhanced hot quenching can promote the carbonation reaction, it requires an external gas source and involves large equipment investment. Organic acid treatment may introduce harmful residues, affecting the resource utilization of steel slag. It can be seen that hot quenching of steel slag still has problems such as high cost, complex process, or environmental risks. Therefore, there is an urgent need to develop a steel slag quenching and pretreatment process that can improve the solidification efficiency of free calcium oxide and free magnesium oxide and the iron recovery rate in steel slag to solve the problems existing in the above-mentioned technologies. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a steel slag slag treatment process.

[0005] A process for pretreatment of steel slag includes the following steps:

[0006] The freshly produced high-temperature steel slag is transferred to a hot quenching tank and allowed to cool down to 900-950℃. Then, cold water with a volume of 5-6 times that of the steel slag is injected from the bottom of the tank using the bottom water quenching method. At the same time, a composite fly ash flux with a mass of one-twentieth of the steel slag is added, and the gas in the tank is discharged and carbon dioxide gas is introduced simultaneously.

[0007] In a closed environment, water is continuously injected to cool the slag until the temperature in the hot slag-quenching pool drops to 250-300℃. Then, a composite stabilizer with a mass ratio of one-tenth of the steel slag is added. Instead of injecting cold water from the bottom of the pool, cold water is sprayed to cool the steel slag to room temperature, thus completing the steel slag-quenching process. The composite stabilizer is obtained by mixing urease / urea coated particles with paraffin composite hollow microcapsules at a mass ratio of 1:(4-5) and stirring at a speed of 120-130 r / min for 15-20 min.

[0008] The hot-quenched steel slag is subjected to magnetic separation to recover the iron element. The product after magnetic separation is ball-milled for 20-30 minutes to obtain fine steel slag powder. The fine steel slag powder can be reused in the preparation of composite stabilizers.

[0009] Furthermore, the preparation method of the composite fly ash flux includes the following steps:

[0010] Place fly ash in a ceramic boat, heat the muffle furnace to 800-850℃, and send the ceramic boat containing fly ash into the muffle furnace for calcination for 2-2.5 hours. After the furnace temperature has cooled naturally, crush the calcined fly ash with a crusher for 5-10 minutes to obtain activated fly ash.

[0011] Deionized water and fly ash were mixed and stirred at a material-to-liquid ratio of 1 g:(5-8) mL to obtain a fly ash aqueous solution. NaOH solution and AlCl3 solution were then added to the solution, with a volume ratio of fly ash aqueous solution, NaOH solution and AlCl3 solution of 10:1:(0.5-0.8). The solution was then heated in a water bath to 90-95℃, and 5-6% of the system volume of boric acid was added dropwise while stirring at a speed of 300-350 r / min for 90-100 min. After stirring, the solution was stopped and kept warm for 30-35 min. The solution was then filtered to remove the filtrate. The filter residue was dried at 105-110℃ for 7-8 h and then pulverized and ground for 10-15 min to obtain a composite fly ash flux.

[0012] Furthermore, the preparation method of urease / urea coated particles includes the following steps:

[0013] Add 1-3 parts by weight of urease to 20-40 parts by weight of chitosan solution to obtain chitosan / urease solution. Add urea particles to chitosan / urease solution with a material-to-liquid ratio of 1g:(10-12)mL. Then spray the solution onto a glass plate to form a film with a thickness of 50-55μm. Cure the film with hot air at 60-65℃ to obtain urease / urea coated particles.

[0014] Furthermore, the preparation method of paraffin composite empty shell microcapsules includes the following steps:

[0015] The paraffin wax is melted at 75-80℃, and 10-12% of the system volume of fine steel slag powder is added. The mixture is then homogenized at a speed of 12000-13000 r / min for 10-15 min to obtain composite paraffin wax.

[0016] Mix 1.5-2 wt% polyvinyl alcohol and 0.2-0.4 wt% sodium dodecyl sulfate with deionized water and heat to 70-75℃ to obtain an aqueous phase. Add composite paraffin to the aqueous phase at a volume ratio of 1:(1.5-2). Shear at 10000-11000 r / min for 5 min to obtain a crude emulsion. Homogenize the crude emulsion for 5-10 min, repeating the homogenization process 3 times to obtain an emulsion. Add 20-25% (by weight of the system) of calcium sulfate powder to the emulsion and heat to 80-85℃. Stir at 5000-5100 r / min for 5-8 min and cool in an ice-water bath to 10-15℃ to obtain paraffin composite hollow microcapsules.

[0017] Furthermore, the concentration of the NaOH solution is 0.3-0.35 mol / L.

[0018] Furthermore, the concentration of the AlCl3 solution is 0.15-0.2 mol / L.

[0019] Furthermore, the concentration of the chitosan solution is 5-10 wt%.

[0020] The present invention has the following advantages:

[0021] 1. This invention uses boric acid and aluminum hydroxide to form a flux through fly ash. The flux is added during the hot quenching of steel slag. Boric acid decomposes into oxides at a certain temperature, which react with free calcium oxide in the slag to form low-melting-point calcium borate, forming a melt with good fluidity. Fly ash provides a glassy state, promoting the formation of a low-temperature liquid phase and further reducing the viscosity of the system. The glassy state in the fly ash and the oxides decomposed from boric acid form a low-temperature eutectic, which greatly improves the fluidity of the slag layer. Then, aluminum hydroxide absorbs heat, forming a "thermal buffer-thermal compensation" coupling of endothermic and exothermic processes, thereby improving the curing efficiency of free calcium oxide and free magnesium oxide.

[0022] 2. This invention combines urea and urease to prepare a core material for a stabilizer. The ammonia and carbon dioxide produced by the decomposition of urea can react with the free calcium oxide and magnesium oxide in the steel slag to generate stable compounds, reducing the risk of subsequent hydration expansion. Urease can accelerate the decomposition of urea, improve reaction efficiency, and shorten processing time. The ammonia produced by the reaction can dissolve in the pore water of the steel slag to form an alkaline environment, promoting the dissolution of CO2 into carbonate ions and accelerating the carbonation reaction. Carbonates can fill the pores of the steel slag, enhance density, and improve compressive strength and durability. The alkaline environment can also inhibit the leaching of heavy metals in the steel slag, thereby improving the iron recovery rate in the subsequent steel slag.

[0023] 3. This invention uses paraffin wax and calcium sulfate to composite with steel slag micropowder. The prepared paraffin composite hollow shell microcapsules are used to load urease / urea coated particles. Steel slag micropowder serves as the capsule shell skeleton, enhancing mechanical strength and exhibiting high compatibility with steel slag, thereby improving the solidification efficiency of free calcium oxide and free magnesium oxide. Paraffin wax and calcium sulfate are evenly arranged around the steel slag micropowder to adjust the microporous structure, thereby regulating moisture permeability. During the hot slag quenching or low-temperature stabilization process, moisture is gradually released, activating urease and controlling the release rate of urea and urease. At the same time, the hydrophobic shell formed by the combination of steel slag micropowder and paraffin wax can block moisture and high temperature, preventing urease from losing its activity prematurely, thereby improving the iron recovery rate in steel slag. Attached Figure Description

[0024] Figure 1 This is a flowchart of the preparation method of the composite stabilizer of the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0026] Example 1:

[0027] A process for pretreatment of steel slag includes the following steps:

[0028] The freshly produced high-temperature steel slag is transferred to a hot quenching tank and placed to cool down to 900°C. Then, cold water with a volume of 5 times that of the steel slag is injected from the bottom of the tank using the bottom water quenching method. At the same time, a composite fly ash flux with a mass of one-twentieth of the steel slag is added, and the gas in the tank is discharged and carbon dioxide gas is introduced simultaneously.

[0029] In a closed environment, water is continuously injected to cool the slag until the temperature in the hot slag-cooling pool drops to 250°C. Then, a composite stabilizer of one-tenth the mass of the steel slag is added to the pool. Instead of injecting cold water from the bottom of the pool, cold water is sprayed to cool the steel slag to room temperature, thus completing the steel slag-cooling process.

[0030] The hot-quenched steel slag is subjected to magnetic separation to recover the iron element. The product after magnetic separation is ball-milled for 20 minutes to obtain fine steel slag powder. The fine steel slag powder can be reused in the preparation of composite stabilizers.

[0031] The preparation method of the composite fly ash flux is as follows:

[0032] Fly ash is placed in a ceramic boat, the muffle furnace is heated to 800°C, the ceramic boat containing fly ash is sent into the muffle furnace for calcination for 2 hours, and after the furnace temperature is naturally cooled, the calcined fly ash is crushed for 5 minutes to obtain activated fly ash.

[0033] Deionized water and fly ash were mixed and stirred at a material-to-liquid ratio of 1 g: 5 mL to obtain a fly ash aqueous solution. Then, NaOH solution and AlCl3 solution were added to the solution, with a volume ratio of fly ash aqueous solution, NaOH solution and AlCl3 solution of 10:1:0.5. The concentration of NaOH solution was 0.3 mol / L and the concentration of AlCl3 solution was 0.15 mol / L. The solution was then heated to 90°C in a water bath, and 5% of the system volume of boric acid was added dropwise while stirring at 300 r / min for 90 min. After stirring, the solution was stopped and kept warm for 30 min. The solution was then filtered to remove the filtrate. The filter residue was dried at 105°C for 7 h and then pulverized and ground for 10 min to obtain a composite fly ash flux.

[0034] The preparation method of composite stabilizer is as follows: Figure 1 As shown:

[0035] S1: Preparation of urease / urea coated particles

[0036] One part by mass of urease was added to 20 parts by mass of chitosan solution to obtain a chitosan / urease solution with a concentration of 5 wt%. Urea particles were added to the chitosan / urease solution with a material-to-liquid ratio of 1 g: 10 mL. The solution was then sprayed onto a glass plate to form a film with a thickness of 50 μm. The film was then cured with hot air at 60 °C to obtain urease / urea coated particles.

[0037] S2: Preparation of paraffin composite hollow microcapsules

[0038] The paraffin wax was melted at 75°C, and 10% of the system volume of fine steel slag powder was added. The mixture was then homogenized at 12000 r / min for 10 min to obtain composite paraffin wax.

[0039] 1.5 wt% polyvinyl alcohol and 0.2 wt% sodium dodecyl sulfate were mixed with deionized water and heated to 70 °C to obtain an aqueous phase. Composite paraffin was added to the aqueous phase at a volume ratio of 1:1.5, and sheared at 10000 r / min for 5 min to obtain a crude emulsion. The crude emulsion was homogenized for 5 min, and homogenized 3 times to obtain an emulsion. 20% of the system mass of calcium sulfate powder was added to the emulsion, and the mixture was heated to 80 °C, stirred at 5000 r / min for 5 min, and cooled to 10 °C in an ice-water bath to obtain paraffin composite hollow microcapsules.

[0040] S3: Mix urease / urea coated particles with paraffin composite hollow microcapsules at a mass ratio of 1:4 and stir at a stirring speed of 120 r / min for 15 min to obtain a composite stabilizer.

[0041] Example 2:

[0042] A process for pretreatment of steel slag includes the following steps:

[0043] The freshly produced high-temperature steel slag is transferred to a hot quenching tank and placed to cool down to 900°C. Then, cold water with a volume of 6 times that of the steel slag is injected from the bottom of the tank using the bottom water quenching method. At the same time, a composite fly ash flux with a mass of one-twentieth of the steel slag is added, and the gas in the tank is discharged and carbon dioxide gas is introduced simultaneously.

[0044] In a closed environment, water is continuously injected to cool the slag until the temperature in the hot slag-cooling pool drops to 250°C. Then, a composite stabilizer of one-tenth the mass of the steel slag is added to the pool. Instead of injecting cold water from the bottom of the pool, cold water is sprayed to cool the steel slag to room temperature, thus completing the steel slag-cooling process.

[0045] The hot-quenched steel slag is subjected to magnetic separation to recover the iron element. The product after magnetic separation is ball-milled for 20 minutes to obtain fine steel slag powder. The fine steel slag powder can be reused in the preparation of composite stabilizers.

[0046] The preparation method of the composite fly ash flux is as follows:

[0047] Fly ash is placed in a ceramic boat, the muffle furnace is heated to 800°C, the ceramic boat containing fly ash is sent into the muffle furnace for calcination for 2 hours, and after the furnace temperature is naturally cooled, the calcined fly ash is crushed for 5 minutes to obtain activated fly ash.

[0048] Deionized water and fly ash were mixed and stirred at a material-to-liquid ratio of 1 g: 8 mL to obtain a fly ash aqueous solution. Then, NaOH solution and AlCl3 solution were added to the solution, with a volume ratio of fly ash aqueous solution, NaOH solution and AlCl3 solution of 10:1:0.8. The concentration of NaOH solution was 0.35 mol / L and the concentration of AlCl3 solution was 0.2 mol / L. The solution was then heated to 90°C in a water bath, and 6% of the system volume of boric acid was added dropwise while stirring at 300 r / min for 90 min. After stirring, the solution was stopped and kept warm for 30 min. The filtrate was then filtered to remove the liquid. The filter residue was dried at 105°C for 7 h and then pulverized and ground for 10 min to obtain a composite fly ash flux.

[0049] The preparation method of composite stabilizer is as follows: Figure 1 As shown:

[0050] S1: Preparation of urease / urea coated particles

[0051] Three parts by mass of urease were added to 40 parts by mass of chitosan solution to obtain a chitosan / urease solution with a chitosan solution concentration of 10 wt%. Urea particles were added to the chitosan / urease solution with a material-to-liquid ratio of 1 g: 12 mL. The solution was then sprayed onto a glass plate to form a film with a thickness of 50 μm. The film was then cured with hot air at 60 °C to obtain urease / urea coated particles.

[0052] S2: Preparation of paraffin composite hollow microcapsules

[0053] The paraffin wax was melted at 75°C, and 12% of the system volume of fine steel slag powder was added. The mixture was then homogenized at 12000 r / min for 10 min to obtain composite paraffin wax.

[0054] 2 wt% polyvinyl alcohol and 0.4 wt% sodium dodecyl sulfate were mixed with deionized water and heated to 70 °C to obtain an aqueous phase. Composite paraffin was added to the aqueous phase at a volume ratio of 1:2, and sheared at 10000 r / min for 5 min to obtain a crude emulsion. The crude emulsion was homogenized for 5 min, and homogenized 3 times to obtain an emulsion. 25% of the system mass of calcium sulfate powder was added to the emulsion, and the mixture was heated to 80 °C, stirred at 5000 r / min for 5 min, and cooled to 10 °C in an ice-water bath to obtain paraffin composite hollow microcapsules.

[0055] S3: Mix urease / urea coated particles with paraffin composite empty shell microcapsules at a mass ratio of 1:5 and stir at a stirring speed of 120 r / min for 15 min to obtain a composite stabilizer.

[0056] Example 3:

[0057] A process for pretreatment of steel slag includes the following steps:

[0058] The freshly produced high-temperature steel slag is transferred to a hot quenching tank and placed to cool down to 950°C. Then, cold water with a volume of 5 times that of the steel slag is injected from the bottom of the tank using the bottom water quenching method. At the same time, a composite fly ash flux with a mass of one-twentieth of the steel slag is added, and the gas in the tank is discharged and carbon dioxide gas is introduced simultaneously.

[0059] In a closed environment, water is continuously injected to cool the slag until the temperature in the hot slag-cooling pool drops to 300°C. Then, a composite stabilizer with a mass of one-tenth the steel slag is added. Instead of injecting cold water from the bottom of the pool, cold water is sprayed to cool the steel slag to room temperature, thus completing the steel slag-cooling process.

[0060] The hot-quenched steel slag is subjected to magnetic separation to recover the iron element. The product after magnetic separation is ball-milled for 30 minutes to obtain fine steel slag powder. The fine steel slag powder can be reused in the preparation of composite stabilizers.

[0061] The preparation method of the composite fly ash flux is as follows:

[0062] Fly ash is placed in a ceramic boat, the muffle furnace is heated to 850°C, the ceramic boat containing fly ash is sent into the muffle furnace for calcination for 2.5 hours, and after the furnace temperature is naturally cooled, the calcined fly ash is crushed by a crusher for 10 minutes to obtain activated fly ash.

[0063] Deionized water and fly ash were mixed and stirred at a material-to-liquid ratio of 1 g: 5 mL to obtain a fly ash aqueous solution. Then, NaOH solution and AlCl3 solution were added to the solution, with a volume ratio of fly ash aqueous solution, NaOH solution and AlCl3 solution of 10:1:0.5. The concentration of NaOH solution was 0.3 mol / L and the concentration of AlCl3 solution was 0.15 mol / L. The solution was then heated to 95°C in a water bath, and 5% of the system volume of boric acid was added dropwise while stirring at 350 r / min for 100 min. After stirring, the solution was stopped and kept warm for 35 min. The solution was then filtered to remove the filtrate. The filter residue was dried at 110°C for 8 h and then pulverized and ground for 15 min to obtain a composite fly ash flux.

[0064] The preparation method of composite stabilizer is as follows: Figure 1 As shown:

[0065] S1: Preparation of urease / urea coated particles

[0066] One part by mass of urease was added to 20 parts by mass of chitosan solution to obtain a chitosan / urease solution with a concentration of 5 wt%. Urea particles were added to the chitosan / urease solution with a material-to-liquid ratio of 1 g: 10 mL. The solution was then sprayed onto a glass plate to form a film with a thickness of 55 μm. The film was then cured with hot air at 65 °C to obtain urease / urea coated particles.

[0067] S2: Preparation of paraffin composite hollow microcapsules

[0068] The paraffin wax was melted at 80℃, and 10% of the system volume of fine steel slag powder was added. The mixture was then homogenized at 13000 r / min for 15 min to obtain composite paraffin wax.

[0069] 1.5 wt% polyvinyl alcohol and 0.2 wt% sodium dodecyl sulfate were mixed with deionized water and heated to 75 °C to obtain an aqueous phase. Composite paraffin was added to the aqueous phase at a volume ratio of 1:1.5, and sheared at 11000 r / min for 5 min to obtain a crude emulsion. The crude emulsion was homogenized for 10 min, and homogenized 3 times to obtain an emulsion. 20% of the system mass of calcium sulfate powder was added to the emulsion, and the mixture was heated to 85 °C, stirred at 5100 r / min for 8 min, and cooled to 15 °C in an ice-water bath to obtain paraffin composite hollow microcapsules.

[0070] S3: Mix urease / urea coated particles with paraffin composite empty shell microcapsules at a mass ratio of 1:4 and stir at a stirring speed of 130 r / min for 15 min to obtain a composite stabilizer.

[0071] Comparative Example 1:

[0072] Compared with Example 1, the difference of Comparative Example 1 is that AlCl3 solution is not added when preparing the composite fly ash flux, while the other steps remain the same, and it is referred to as Comparative Example 1.

[0073] Comparative Example 2:

[0074] Compared with Example 1, Comparative Example 2 differs in that boric acid is not added when preparing the composite fly ash flux, while the other steps remain unchanged, and is referred to as Comparative Example 2.

[0075] Comparative Example 3:

[0076] Compared with Example 1, Comparative Example 3 differs in that step S1 is omitted, and urease is used instead of urease / urea coated particles in step S3. The remaining steps remain unchanged, and it is referred to as Comparative Example 3.

[0077] Comparative Example 4:

[0078] Compared with Example 1, Comparative Example 4 differs in that step S1 is omitted, and urea particles are used instead of urease / urea-coated particles in step S3. The remaining steps remain unchanged, and it is referred to as Comparative Example 4.

[0079] Comparative Example 5:

[0080] Compared with Example 1, Comparative Example 5 differs in that steel slag powder is not added in step S2, while the other steps remain unchanged, and it is referred to as Comparative Example 5.

[0081] Comparative Example 6:

[0082] Compared with Example 1, Comparative Example 6 differs in that calcium sulfate powder is not added in step S2, while the other steps remain unchanged, and is referred to as Comparative Example 6.

[0083] High-temperature slag from the same batch of furnace was selected for the slag-sealing process. The contents of free calcium oxide and free magnesium oxide in the steel slag were tested when the slag-sealing process was completed in Examples 1-3, Comparative Examples 1-2, and Comparative Examples 5-6. The results are shown in Table 1.

[0084] High-temperature slag from the same batch of furnaces was selected for the slag-sealing process. The steel slag from Examples 1-3 and Comparative Examples 3-6 that completed the steel slag-sealing process was subjected to magnetic separation, and the iron recovery rate was tested, as shown in Table 2.

[0085] Table 1

[0086]

[0087] Table 2

[0088]

[0089] As can be seen from Table 1, the free calcium oxide content in Examples 1-3 is 0.82-0.85%, and the free magnesium oxide content is 1.21-1.24%, while the free calcium oxide content in the comparative examples is above 1.32%, and the free magnesium oxide content is above 2.51%. It can be seen that the flux prepared by using boric acid and aluminum hydroxide through fly ash in this invention has a solidification effect on free calcium oxide and free magnesium oxide after being added to the hot quenching process of steel slag, which can reduce the content of free calcium oxide and free magnesium oxide. At the same time, the paraffin composite hollow microcapsules prepared in this invention also have a solidification effect on free calcium oxide and free magnesium oxide.

[0090] As can be seen from Table 2, the present invention can improve the iron recovery rate by using urea and urease in combination to prepare the core material of the stabilizer, while the effect of using urea or urease alone is worse. At the same time, the paraffin composite hollow microcapsules prepared by the specific raw material combination of the present invention also have the ability to regulate release, which can have a positive impact on the iron recovery rate.

[0091] 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 steel slag slag treatment process, characterized in that, Includes the following steps: The freshly produced high-temperature steel slag is transferred to a hot quenching tank and allowed to cool down to 900-950℃. Then, cold water with a volume of 5-6 times that of the steel slag is injected from the bottom of the tank using the bottom water quenching method. At the same time, a composite fly ash flux with a mass of one-twentieth of the steel slag is added, and the gas in the tank is discharged and carbon dioxide gas is introduced simultaneously. In a closed environment, water is continuously injected to cool the slag until the temperature in the hot slag-quenching pool drops to 250-300℃. Then, a composite stabilizer with a mass ratio of one-tenth of the steel slag is added. Instead of injecting cold water from the bottom of the pool, cold water is sprayed to cool the steel slag to room temperature, thus completing the steel slag-quenching process. The composite stabilizer is obtained by mixing urease / urea coated particles with paraffin composite hollow microcapsules at a mass ratio of 1:(4-5) and stirring at a speed of 120-130 r / min for 15-20 min. The hot-quenched steel slag is subjected to magnetic separation to recover the iron element. The magnetically separated product is ball-milled for 20-30 minutes to obtain fine steel slag powder. The fine steel slag powder can be reused in the preparation of composite stabilizers. The preparation method of the composite fly ash flux includes the following steps: Place fly ash in a ceramic boat, heat the muffle furnace to 800-850℃, and send the ceramic boat containing fly ash into the muffle furnace for calcination for 2-2.5 hours. After the furnace temperature has cooled naturally, crush the calcined fly ash with a crusher for 5-10 minutes to obtain activated fly ash. Deionized water and fly ash were mixed and stirred at a material-to-liquid ratio of 1 g:(5-8) mL to obtain a fly ash aqueous solution. NaOH solution and AlCl3 solution were then added to the solution, with a volume ratio of fly ash aqueous solution, NaOH solution and AlCl3 solution of 10:1:(0.5-0.8). The solution was then heated in a water bath to 90-95℃, and 5-6% of the system volume of boric acid was added dropwise while stirring at a speed of 300-350 r / min for 90-100 min. After stirring, the solution was stopped and kept warm for 30-35 min. The solution was then filtered to remove the filtrate. The filter residue was dried at 105-110℃ for 7-8 h and then pulverized and ground for 10-15 min to obtain a composite fly ash flux.

2. The steel slag slag treatment process according to claim 1, characterized in that, The preparation method of urease / urea coated particles includes the following steps: Add 1-3 parts by weight of urease to 20-40 parts by weight of chitosan solution to obtain chitosan / urease solution. Add urea particles to chitosan / urease solution with a material-to-liquid ratio of 1g:(10-12)mL. Then spray the solution onto a glass plate to form a film with a thickness of 50-55μm. Cure the film with hot air at 60-65℃ to obtain urease / urea coated particles.

3. The steel slag slag treatment process according to claim 2, characterized in that, The preparation method of paraffin composite empty shell microcapsules includes the following steps: The paraffin wax is melted at 75-80℃, and 10-12% of the system volume of fine steel slag powder is added. The mixture is then homogenized at a speed of 12000-13000 r / min for 10-15 min to obtain composite paraffin wax. Mix 1.5-2 wt% polyvinyl alcohol and 0.2-0.4 wt% sodium dodecyl sulfate with deionized water and heat to 70-75℃ to obtain an aqueous phase. Add composite paraffin to the aqueous phase at a volume ratio of 1:(1.5-2). Shear at 10000-11000 r / min for 5 min to obtain a crude emulsion. Homogenize the crude emulsion for 5-10 min, repeating the homogenization process 3 times to obtain an emulsion. Add 20-25% (by weight of the system) of calcium sulfate powder to the emulsion and heat to 80-85℃. Stir at 5000-5100 r / min for 5-8 min and cool in an ice-water bath to 10-15℃ to obtain paraffin composite hollow microcapsules.

4. The steel slag slag treatment process according to claim 1, characterized in that, The concentration of the NaOH solution is 0.3-0.35 mol / L.

5. The steel slag slag treatment process according to claim 1, characterized in that, The concentration of the AlCl3 solution is 0.15-0.2 mol / L.

6. The steel slag slag treatment process according to claim 2, characterized in that, The concentration of the chitosan solution is 5-10 wt%.

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