A method for modifying steel slag

Abstract

The application relates to a steel slag modification method, which comprises the following steps: providing clean steel slag and a nano-silica dispersion solution; soaking the steel slag in the nano-silica dispersion solution; obtaining the soaked steel slag, and obtaining modified steel slag after drying. The steel slag modification method provided by the embodiment of the application realizes that nano-silica with extremely small particle size fills the surface pores of the steel slag, and a dense calcium silicate gel is generated to wrap the surface of the steel slag, and the surface is roughened, so that the overall strength of the steel slag is improved. The application only uses the technical means of soaking the steel slag in the nano-silica dispersion solution to realize the reduction of the water swelling rate of the steel slag, and has the advantages of being environment-friendly, low in energy consumption, simple in process and good in modification effect.

Description

Technical Field

[0001] This application relates to the field of solid waste utilization technology, and in particular to the reuse of steel slag. Background Technology

[0002] Steel slag has properties such as hardness and abrasion value that are close to or better than those of natural ore, making it a valuable resource that can replace natural ore. However, the problem of its swelling when exposed to water limits the application and promotion of this material.

[0003] The volume expansion of steel slag is mainly due to the hydration reaction of f-CaO, which accounts for about 5% of the steel slag system, to generate calcium hydroxide, resulting in a 98% volume expansion. This leads to insufficient volume stability of steel slag, which in turn limits its large-scale application in road engineering.

[0004] Currently, the main methods for reducing the water immersion expansion rate of steel slag and improving its stability are mechanical grinding, acid modification, and high-temperature reconstruction. Although these modification methods can reduce the content of f-CaO in steel slag and play a certain role in dissolving it, they have problems such as environmental pollution and complex operation processes, which do not conform to the general trend of sustainable development, energy conservation and emission reduction.

[0005] Application content

[0006] This application provides a method for modifying steel slag to solve the technical problems of current steel slag modification methods, such as environmental pollution and complex processes.

[0007] This application provides a method for modifying steel slag, which includes the following steps:

[0008] Provides a clean dispersion of steel slag and nano-silica;

[0009] The steel slag is soaked in the nano-silica dispersion;

[0010] The soaked steel slag is obtained and dried to obtain modified steel slag.

[0011] In some embodiments of this application, the mass percentage concentration of the nano-silica dispersion is 1-3%.

[0012] In some embodiments of this application, the particle size of the nano-silica dispersion is 8-15 nm.

[0013] In some embodiments of this application, the pH value of the nano-silica dispersion is 9.5-11.

[0014] In some embodiments of this application, the steel slag is soaked in the nano-silica dispersion for a duration of 6-48 hours.

[0015] In some embodiments of this application, the steel slag is soaked in the nano-silica dispersion, and during the soaking process, the steel slag is stirred after a predetermined period of time.

[0016] In some embodiments of this application, the predetermined time is 30-40 minutes.

[0017] In some embodiments of this application, the steel slag is soaked in the nano-silica dispersion, and the temperature of the nano-silica dispersion is controlled at 15-25°C during the soaking process.

[0018] In some embodiments of this application, the drying method is air drying.

[0019] The technical solutions provided in this application have the following advantages compared with the prior art:

[0020] The steel slag modification method provided in this application involves immersing the steel slag in a nano-silica dispersion. This process achieves the filling of surface pores with extremely small-sized nano-silica particles, while simultaneously generating a dense calcium silicate gel that coats the steel slag surface. This also roughens the surface and improves the overall strength of the steel slag. This application achieves a reduction in the water immersion swelling rate of steel slag solely through the technique of immersing the steel slag in a nano-silica dispersion. It boasts advantages such as environmental friendliness, low energy consumption, simple process, and good modification effect. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The graph shows the water absorption rate of the modified steel slag obtained in Examples 1-4 and the comparative examples of this application.

[0024] Figure 2 The chart shows the crushing and abrasion values ​​of the modified steel slag obtained in Examples 1-4 and the comparative examples of this application.

[0025] Figure 3 This is a statistical chart showing the adhesion grades of modified steel slag and asphalt obtained from Examples 1-4 and the comparative examples of this application.

[0026] Figure 4The above is a statistical chart showing the water immersion expansion rate of the modified steel slag obtained in Examples 1-4 and the comparative examples of this application.

[0027] Figure 5 Here is a SEM image of the modified steel slag obtained in Example 1 of this application;

[0028] Figure 6 Here is a SEM image of the modified steel slag obtained in Example 2 of this application;

[0029] Figure 7 Here is a SEM image of the modified steel slag obtained in Example 3 of this application;

[0030] Figure 8 Here is a SEM image of the modified steel slag obtained in Example 4 of this application;

[0031] Figure 9 SEM image of the modified steel slag obtained in the comparative example of this application;

[0032] Figure 10 This is a statistical chart showing the freeze-thaw splitting strength ratio of modified steel slag obtained in Examples 1-4 and the comparative examples of this application;

[0033] Figure 11 This is a statistical chart showing the water immersion expansion rate of the modified steel slag obtained in Examples 1-4 and the comparative examples of this application. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] Unless otherwise specified, the terminology used herein should be understood as having the meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any conflict, this specification shall prevail.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0037] Current methods for modifying steel slag have technical problems such as environmental pollution and complex processes.

[0038] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0039] This application provides a method for modifying steel slag, which includes the following steps:

[0040] S1: Provides a clean dispersion of steel slag and nano-silica;

[0041] S2: Immerse the steel slag in the nano-silica dispersion;

[0042] S3: Obtain the soaked steel slag, and dry it to obtain modified steel slag.

[0043] In practical applications, the surface of the modified steel slag is coated with a layer of white substance.

[0044] The volume expansion of steel slag is mainly due to the hydration reaction of f-CaO, which accounts for about 5% of the steel slag system, to generate calcium hydroxide, resulting in a 98% volume expansion. This leads to insufficient volume stability of steel slag, which in turn limits its large-scale application in road engineering.

[0045] This application involves immersing steel slag in a nano-silica dispersion. During the immersion modification process, the extremely small nano-silica particles fill the surface pores of the steel slag. Simultaneously, the nano-silica reacts with calcium hydroxide, a hydration product of the steel slag, to form a well-bonded calcium silicate (CSH) gel, thereby inhibiting the volume expansion of the steel slag. Furthermore, under the action of the nano-silica, the calcium silicate gel is connected into a dense layered structure, which not only completely coats the surface of the steel slag but also roughens the surface, improving the overall strength of the steel slag.

[0046] The chemical equation for the reaction between nano-silica and calcium hydroxide, a hydration product of steel slag, is as follows:

[0047] SiO2 + Ca(OH)2 → CSH (precipitate) + H2O

[0048] This application achieves the filling of surface pores with extremely small-sized nano-silica by immersing steel slag in a nano-silica dispersion. Simultaneously, it generates a dense calcium silicate gel that coats the steel slag surface, roughens the surface, and improves the overall strength of the steel slag. This application reduces the water immersion swelling rate of steel slag solely through the technique of immersing it in a nano-silica dispersion, offering advantages such as environmental friendliness, low energy consumption, simple process, and good modification effect.

[0049] In some embodiments of this application, the mass percentage concentration of the nano-silica dispersion is 1-3%.

[0050] Setting the mass percentage concentration of the nano-silica dispersion to 1-3% has the advantage of ensuring the modification effect without causing excessive nano-silica to adhere to the surface of the modified steel slag during sludge removal, thus avoiding material waste.

[0051] In some embodiments of this application, the particle size of the nano-silica dispersion is 8-15 nm.

[0052] In some embodiments of this application, the pH value of the nano-silica dispersion is 9.5-11.

[0053] The beneficial effect of having a pH value of 9.5-11 for nano-silica dispersions is that this pH value helps maintain the stability of the nano-silica dispersions.

[0054] In some embodiments of this application, the steel slag is soaked in the nano-silica dispersion for a duration of 6-48 hours.

[0055] The beneficial effect of controlling the soaking time to 6-48 hours is that it allows the nano-silica to fully fill the surface pores of the steel slag, enabling the nano-silica to fully react with calcium hydroxide, without taking too long.

[0056] In some embodiments of this application, the steel slag is soaked in the nano-silica dispersion, and during the soaking process, the steel slag is stirred after a predetermined period of time.

[0057] The beneficial effect of stirring the soaking steel slag at predetermined intervals is to ensure that the entire surface of the steel slag is evenly contacted with the nano-silica dispersion.

[0058] In some embodiments of this application, the predetermined time is 30-40 minutes.

[0059] In some embodiments of this application, the steel slag is soaked in the nano-silica dispersion, and the temperature of the nano-silica dispersion is controlled at 15-25°C during the soaking process.

[0060] In some embodiments of this application, the drying method is air drying.

[0061] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0062] Example 1

[0063] This embodiment provides a method for modifying steel slag, including the following steps:

[0064] Sa, Steel slag pretreatment: Put the steel slag into clean water, wash off the dirt and impurities on the surface, and air dry to obtain pretreated steel slag;

[0065] Preparation of Sb-modified solution: The silica gel solution and water were mixed to obtain a 1% nano silica dispersion.

[0066] Sc. Immersion modification: The pretreated steel slag is immersed in the nano-silica dispersion for 6 hours.

[0067] Sd, air drying: After soaking, the steel slag is air dried to obtain modified steel slag.

[0068] The average particle size of the nano-silica in the nano-silica dispersion is 8 nm.

[0069] Step Sc was carried out at room temperature (25°C), and the temperature of the silica gel solution was 20°C during the soaking process; the steel slag was stirred once every 30 minutes during the soaking process.

[0070] The surface of the obtained modified steel slag is coated with a layer of white substance.

[0071] Example 2

[0072] This embodiment provides a method for modifying steel slag, including the following steps:

[0073] Sa, Steel slag pretreatment: Put the steel slag into clean water, wash off the dirt and impurities on the surface, and air dry to obtain pretreated steel slag.

[0074] Preparation of Sb-modified solution: The silica gel solution and water were mixed to obtain a 2% nano silica dispersion;

[0075] Sc. Immersion modification: The pretreated steel slag is immersed in the nano-silica dispersion for 12 hours.

[0076] Sd, air drying: After soaking, the steel slag is air dried to obtain modified steel slag.

[0077] The average particle size of the nano-silica in the nano-silica dispersion is 11 nm.

[0078] Step Sc was carried out at room temperature (25°C), and the temperature of the silica gel solution was 20°C during the soaking process; the steel slag was stirred once every 30 minutes during the soaking process.

[0079] The surface of the obtained modified steel slag is coated with a layer of white substance.

[0080] Example 3

[0081] This embodiment provides a method for modifying steel slag, including the following steps:

[0082] Sa, Steel slag pretreatment: Put the steel slag into clean water, wash off the dirt and impurities on the surface, and air dry to obtain pretreated steel slag.

[0083] Preparation of Sb-modified solution: The silica gel solution and water were mixed to obtain a 3% nano-silica dispersion;

[0084] Sc. Immersion modification: The pretreated steel slag is immersed in the nano-silica dispersion for 24 hours.

[0085] Sd, air drying: After soaking, the steel slag is air dried to obtain modified steel slag.

[0086] The average particle size of the nano-silica in the nano-silica dispersion is 9 nm.

[0087] Step Sc was carried out at room temperature (25°C), and the temperature of the silica gel solution was 20°C during the soaking process; the steel slag was stirred once every 30 minutes during the soaking process.

[0088] The surface of the obtained modified steel slag is coated with a layer of white substance.

[0089] Example 4

[0090] This embodiment provides a method for modifying steel slag, including the following steps:

[0091] Sa, Steel slag pretreatment: Put the steel slag into clean water, wash off the dirt and impurities on the surface, and air dry to obtain pretreated steel slag.

[0092] Preparation of Sb-modified solution: The silica gel solution and water were mixed to obtain a 2% nano silica dispersion;

[0093] Sc. Immersion modification: The pretreated steel slag is immersed in the nano-silica dispersion for 48 hours.

[0094] Sd, air drying: After soaking, the steel slag is air dried to obtain modified steel slag.

[0095] The average particle size of the nano-silica in the nano-silica dispersion is 15 nm.

[0096] Step Sc was carried out at room temperature (25°C), and the temperature of the silica gel solution was 20°C during the soaking process; the steel slag was stirred once every 30 minutes during the soaking process.

[0097] The surface of the obtained modified steel slag is coated with a layer of white substance.

[0098] Comparative Example

[0099] The only difference between this comparative example and Examples 1-4 is that:

[0100] This comparative example only performs step Sa.

[0101] Relevant experimental and effect data:

[0102] First, the modified steel slag obtained in Examples 1-4 and the comparative examples were used to prepare steel slag-asphalt mixtures, as detailed below:

[0103] After the modified steel slag is completely screened, 70# base asphalt is selected and configured according to AC-16 type gradation, as shown in Table 1, to prepare the modified steel slag-asphalt mixture.

[0104] Table 1. Grading pass rate / %

[0105]

[0106] Subsequently, the modified steel slag obtained in Examples 1-4 and the comparative example, as well as the above-mentioned modified steel slag-asphalt mixture, were subjected to the following tests:

[0107] Water immersion expansion rate test of steel slag: According to the "Stability Test Method of Steel Slag" (GB / T 24175-2009), the specimens were prepared and tested. The compacted specimens were placed in a water bath for 10 days. Three parallel specimens were used in each group. The dial gauge reading was taken before heating the specimens each day. The specimens were heated continuously at 90℃ for 6 hours. The specific calculation method is as follows:

[0108]

[0109] In the formula: γ: water swelling rate;

[0110] d10: Final reading of the dial indicator, mm;

[0111] d0: Initial reading of the dial gauge, mm.

[0112] Water stability tests of modified steel slag-asphalt mixtures include freeze-thaw splitting tests and volumetric stability tests.

[0113] Freeze-thaw splitting test: Marshall specimens were formed according to the standard of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). A total of 20 groups of specimens were prepared in the examples and comparative examples of this application, with 3 parallel specimens in each group. The specific process is as follows:

[0114] (1) The first set of specimens for each asphalt mixture was stored at room temperature for later use; the other three sets were vacuum saturated with water under a pressure of 97.3 kPa.

[0115] (2) After the water saturation is complete, the specimen is placed in a refrigerator for heat preservation. The temperature is set to -18℃ and the heat preservation time is 16h.

[0116] (3) Remove the specimen from (2) and place it in a water bath for continued warming. Set the temperature to 60℃ and the warming time to 24h. The first freeze-thaw cycle is then complete. The second and third freeze-thaw cycles are simply a matter of repeating (2) and (3).

[0117] (4) After keeping the first set of specimens and the specimens after each cycle in a water bath at 25°C for 2 hours, take them out and conduct the test. The test loading rate is 50 mm / min.

[0118] The water stability of the specimens in the embodiments and comparative examples of this application was tested using the freeze-thaw splitting strength ratio. The specific calculation method is as follows:

[0119]

[0120]

[0121] Where: RT1—the splitting tensile strength of a single specimen in the first group, MPa;

[0122] PT1—Load value of a single specimen in the first group, in N;

[0123] h1—Height of a single specimen in the first group, in mm;

[0124] RT2—Splitting tensile strength of a single specimen in the second group, in MPa;

[0125] PT2—Load value of a single specimen in the second group, in N;

[0126] h2 — Height of a single specimen in the second group, in mm.

[0127]

[0128] Where: TSR—freeze-thaw splitting strength ratio, %;

[0129] RT2—Splitting tensile strength of a single specimen in the second group, in MPa;

[0130] RT1—Splitting tensile strength of a single specimen in the first group, in MPa;

[0131] Volume stability test: Marshall specimens were prepared according to the "Specifications for Testing Aggregates in Highway Engineering" (JTG E42-2005). The water temperature was controlled at 60℃ and the immersion time was 120h. The volume of the specimen was measured every 24h, and the volume expansion rate was calculated according to the following formula.

[0132]

[0133] Where: C—volume expansion rate, %;

[0134] V1—Gross volume of the specimen before immersion in water, cm3;

[0135] V2—Gross volume of the specimen after immersion in water, cm3;

[0136] Physical properties of modified steel slag: including mechanical properties and water immersion expansion rate.

[0137] Mechanical properties of modified steel slag

[0138] According to the current "Specifications for Testing Aggregates in Highway Engineering" (JTG E42-2005), "Steel Slag for Road Use" (GB / T25824-2010), "Steel Slag for Wear-Resistant Asphalt Pavement" (GB / T 24765-2009), and "Specifications for Testing Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), steel slag aggregates for highway engineering should meet the technical requirements in Table 2.

[0139] Table 2 Technical Requirements for Steel Slag Aggregates

[0140]

[0141] Examples 1-4 and the comparative examples were compared and tested according to the test methods of "Test Procedures for Aggregates in Highway Engineering" (JTG JTG E42-2005) and "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The test results are as follows.

[0142] Table 3 Test results of modified steel slag aggregate performance

[0143]

[0144] Figure 1-3 The figures show a comparison of the test results of the physical and mechanical properties of the modified steel slag obtained in Examples 1-4 and the comparative examples of this application. Figure 1 The embodiments of this application show an average water absorption rate of 1.38%, which is 35.2% lower than the comparative example while meeting the standard. Figure 2 The present application embodiment shows that the crushing and abrasion resistance of steel slag is improved, with the crushing value and abrasion value averaging 13.2% and 12.6%, respectively. While meeting the standard, these values ​​are reduced by 11.4% and 12.5% ​​compared to the comparative example. Therefore, the present application embodiment can withstand higher loads and improves its applicability. Figure 3 The embodiments of this application show improved adhesion to asphalt, and the adhesion to asphalt is stronger than that of the comparative examples while meeting the specification requirements.

[0145] Water immersion expansion rate of modified steel slag

[0146] Figure 4These are the volume expansion rate test results of the embodiments and comparative examples of this application after immersion in water for 10 days. From Figure 4 It can be seen that the comparative example, after immersion in water for 6 days, no longer meets the requirement of less than 2% in the specification (JTG E42 T0348). The immersion expansion rate of the embodiments in this application meets the specification requirement. As the immersion time increases, the difference between the embodiments and the comparative example widens. Specifically, the immersion expansion rates of Examples 3 and 4 stabilize on the 7th day, averaging around 1.3%, a decrease of 42.5% compared to the comparative example. This indicates that the silica gel solution modifier has a certain inhibitory effect on the volume expansion of the steel slag.

[0147] Microstructure of modified steel slag

[0148] Figure 5-9 The images shown are SEM images of embodiments and comparative examples magnified 10,000 times. Figure 9 The comparative sample shows that the surface has many pores and a large number of crystalline impurities attached to it. Figure 5 The modified steel slag in Example 1 has a less distinct crystal shape, smaller crystal size, and less uniform distribution. Figure 6 In Example 2, the crystals on the surface of the modified steel slag generally have a plate-like structure. The plate-like crystals are stacked and covered. Although the structure is thick, there are still pores that are not completely covered. Figure 7 and Figure 8 The modified steel slag surface was completely covered by crystals and maintained a certain degree of roughness. This may be because the degree of crystallization on the steel slag surface improved with the increase of modification concentration and modification time during the modification process, and the crystal distribution became more uniform and dense.

[0149] Water stability of modified steel slag-asphalt mixture

[0150] Freeze-thaw splitting test

[0151] Figure 10 The figure shows the variation of splitting strength ratio (TSR) after three freeze-thaw cycles in the embodiments and comparative examples of this application. As can be seen from the figure, the TSR of the comparative example after the first freeze-thaw cycle meets the requirement of greater than 75% in the specification. However, as the test progresses, after the second and third cycles, the TSR of the comparative example has decreased to 59.21%, a decrease of 28% compared to the first cycle. Furthermore, after three freeze-thaw cycles, most of the comparative example specimens showed bulging on their surface, indicating that the freeze-thaw cycle exacerbated the volume expansion of the steel slag, causing cracking in the comparative example specimens. Figure 10The results show that the splitting tensile strength ratio of the embodiments in this application meets the specification requirements and is significantly higher than that of the comparative examples. After three freeze-thaw cycles, the splitting tensile strength ratios of the four sets of embodiments decreased by 13.06%, 12.0%, 11.6%, and 11.8% respectively. Among them, Examples 3 and 4 had the highest splitting tensile strength ratios and the smallest decrease in splitting tensile strength ratios after three freeze-thaw cycles, indicating the best water stability. The reasons for this are twofold: firstly, the modified steel slag surface is coated with a large amount of silica, which enhances the alkalinity of the steel slag itself and can produce a stronger chemical coupling effect with the weakly acidic asphalt, thereby improving the adhesion to the asphalt; secondly, the modified layer on the surface of the modified steel slag effectively wraps the pores on the surface of the steel slag, reduces the contact between the steel slag and water, and reduces the hydration reaction of the steel slag, thereby effectively reducing the freeze-thaw damage of the mixture and improving water stability.

[0152] Volume stability test

[0153] Figure 11 The graph shows the volume expansion rate changes of the embodiments and comparative examples after immersion in water for 120 hours. As shown in the figure, the volume expansion rate of the comparative example after immersion in water for 72 hours meets the specification requirements. Its volume expansion rate curve generally shows a trend of first leveling off and then rising rapidly, with the rate of volume expansion decreasing first and then increasing rapidly. This is because in the initial stage of immersion, the asphalt film on the surface of the steel slag is uniformly coated, and its hydration possibility is low. As the immersion time increases, water continuously erodes the steel slag-asphalt interface, causing the asphalt film to gradually detach from the steel slag surface, increasing the contact area between the steel slag and water, thereby accelerating volume expansion. In the figure, the volume expansion changes of the embodiments of this application are more consistent, all gradually stabilizing as the immersion time increases. This is because after the asphalt film detaches, the modified layer on the surface of the modified steel slag plays a further water-blocking role, effectively reducing the volume expansion rate of the steel slag and improving volume stability.

[0154] In summary, this application utilizes silica gel solution as a modifier to perform immersion modification treatment on steel slag, which effectively enhances the mechanical properties of steel slag, reduces the volume expansion rate, and improves the water stability of steel slag-asphalt mixture.

[0155] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0156] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. For associations involving three or more related objects described using "and / or", it indicates that any one of the three related objects can exist alone, or at least two of them can exist simultaneously. For example, for A, and / or B, and / or C, it can mean that any one of A, B, and C exists alone, or any two of them exist simultaneously, or all three of them exist simultaneously. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or multiple.

[0157] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for modifying steel slag, characterized in that, The steel slag modification method includes the following steps: Provides a clean dispersion of steel slag and nano-silica; The steel slag is soaked in the nano-silica dispersion; The steel slag after soaking is obtained and then dried to obtain modified steel slag; The mass percentage concentration of the nano-silica dispersion is 1-3%; In the nano-silica dispersion, the particle size of the nano-silica is 8-15 nm; The pH value of the nano-silica dispersion is 9.5-11; The steel slag is soaked in the nano-silica dispersion for a duration of 6-48 hours. The steel slag is soaked in the nano-silica dispersion, and the steel slag is stirred after a predetermined period of time during the soaking process. The predetermined time is 30-40 minutes; The steel slag is soaked in the nano-silica dispersion, and the temperature of the nano-silica dispersion is controlled at 15-25℃ during the soaking process. The drying method is air drying; The modified steel slag has a dense calcium silicate gel coating layer formed by the reaction of nano-silica with the hydration products of free calcium oxide in the steel slag. The coating layer is used to suppress the volume expansion of the steel slag.

Images