Steel slag powder for solid waste-based cementitious materials and its preparation method

Abstract

This invention provides steel slag powder for solid waste-based cementitious materials and its preparation method, belonging to the field of solid waste resource utilization technology. The method includes: Step 1, ingredient preparation: detecting C3S in the molten phase of the iron ore and limestone mixture during ironmaking. f -CaO, C 12 The content of the three components A7 was determined; based on the measured content of the three components, modifiers CaCO3, bauxite, and silica fume were selectively added to adjust the mass percentage of the three components to achieve a C3S content of 40%~55%. f -CaO content 6%~15%, C 12 A7 content is 4%~13%, and other components are <50%, resulting in a molten steel slag powder mixture. Step two involves separating the molten iron from the impurity layer, and then rapidly cooling the impurity layer to obtain coarse steel slag. Step three involves determining the specific surface area of ​​the steel slag powder. The prepared steel slag powder is then mixed with other raw materials to obtain a solid waste-based cementitious material with high early strength, reasonable setting time, and excellent later strength growth.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology, specifically relating to a steel slag powder for solid waste-based cementitious materials and its preparation method. Background Technology

[0002] During the steel production process, downstream waste such as steel slag is generated, which causes serious damage to the ecological environment. Therefore, the resource utilization of downstream waste such as steel slag is of great significance. At present, steel slag can partially replace cement in building materials, thus realizing resource utilization.

[0003] With the implementation of GB 175-2023, the standard for general-purpose Portland cement, the use of steel slag in cement has been strictly limited, making its resource utilization more difficult. However, the emergence of solid waste-based cementitious materials has provided a new avenue for the resource utilization of steel slag. However, solid waste-based cementitious materials have high requirements for the quality of steel slag, such as its chemical composition, fineness, and pH value. The traditional steel smelting industry focuses primarily on improving the quality of the steel itself, paying less attention to the quality of the steel slag. This results in inconsistent steel slag quality, leading to low early strength, long setting time, and weak later strength development in solid waste-based cementitious materials made from steel slag, thus hindering the resource utilization of steel slag. Summary of the Invention

[0004] This invention provides a method for preparing steel slag powder for solid waste-based cementitious materials, aiming to solve the problems of low early strength, reasonable setting time, and weak strength growth in solid waste-based cementitious materials made from steel slag.

[0005] Firstly, to achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for preparing steel slag powder for solid waste-based cementitious materials, the method comprising:

[0006] Step 1, Ingredients:

[0007] Detection of C3S in the molten phase of iron ore and limestone mixture during ironmaking process. f -CaO, C 12 The content of the three components of A7;

[0008] Based on the measured content of the three components, regulators CaCO3, bauxite, and silica fume were selectively added, and the reaction was carried out at 1300℃~1535℃ for 15min~30min. The mass percentage of the three components was then directionally adjusted to achieve a C3S content of 40%~55%. f -CaO content 6%~15%, C 12 A7 content is 4%~13%, and other component content is <50%, resulting in a molten steel slag powder mixture; the process for adjusting the mass percentage of the three components is as follows:

[0009] When the C3S content is insufficient, use formula 0.26 ( XM - X 1 M The calculated value is obtained by adding silica fume to the iron ore and limestone mixture, where, X For the target C3S content, X 1 represents the actual measured C3S content;

[0010] when f When the CaO content is insufficient, use formula 1.78 ( YM - Y 1 M The calculated value is obtained by adding CaCO3 to a mixture of iron ore and limestone, where, Y For the goal f -CaO content, Y 1 represents the actual measurement. f -CaO content;

[0011] When C 12 When the A7 content is insufficient, use formula 0.56 ( ZM - Z 1 M The calculated value is obtained by adding bauxite to a mixture of iron ore and limestone, wherein... Z For target C 12 A7 content, Z 1 represents the actual measured C 12 A7 content;

[0012] in, M For the quality of iron ore and limestone.

[0013] It should be noted that the percentage content of the components mentioned above is an absolute content. If the addition of one regulator causes a decrease in the content of the other two components, resulting in an undesirable ratio, no additional regulator is needed to adjust it. For example, when the C3S content is insufficient, adding silica fume will... f - If the CaO content does not meet the requirement of 6%~15%, there is no need to further adjust it. f - The CaO content is adjusted.

[0014] The other components mentioned above include one or more of dicalcium silicate, dicalcium ferrite, iron oxide, magnesium oxide, and manganese oxide.

[0015] Step two: the molten iron is separated from the impurity layer, and the impurity layer is rapidly cooled to obtain coarse steel slag. The molten iron then enters the next refining process to continue refining without affecting the refining process of the molten iron.

[0016] Step 3, when the specific surface area S of the steel slag powder is less than 450 m² 2At a rate of / kg, the obtained coarse steel slag is ground, and steel slag powder for solid waste-based cementitious materials is obtained by determining the specific surface area of ​​the steel slag powder.

[0017] Firstly, in one feasible manner, step three, determining the specific surface area of ​​the steel slag powder, includes:

[0018] (1) When the specific surface area S of steel slag powder is less than 450 m² 2 When the steel slag is 1 kg, the coarse steel slag is first ground, and samples are taken every 10 min to 20 min and recorded as fine steel slag.

[0019] The specific surface area of ​​each sample of fine steel slag was measured, and the procedure is as follows:

[0020] Fine steel slag and water are mixed in a certain proportion, and the mass of the resulting mixture is denoted as . m 1. Unit: kg;

[0021] The mixture of fine steel slag and water was stirred once, and the pH value of the supernatant was tested and recorded as follows: a ;

[0022] Carbon dioxide gas was injected into the supernatant for a certain period of time; after aeration, the pH value was tested and recorded, and denoted as pH. b ;

[0023] The mixture of fine steel slag and water was stirred twice, and the pH value of the mixture was tested in real time until the pH value returned to normal. a Record the stirring time at this point, denoted as . t ;

[0024] When the fine steel slag was measured a, b, t The specific surface area of ​​steel slag powder is defined as the fineness range when the following requirements are met:

[0025] a It is between 12.0 and 12.5. b ≥11.5, t If the time is 180 s to 360 s, then steel slag powder for solid waste-based cementitious materials is obtained.

[0026] (2) When the specific surface area S of fine steel slag is greater than or equal to 450 m² 2 When / kg, test according to (1) a When the value is still <12.0, the mass of fine steel slag used is recorded as follows: m 2. Unit: kg; Add quicklime gradually under stirring conditions, and test the pH value in real time until the pH value is ≥12.0. The amount of quicklime added at this point is recorded as: m 3, unit kg; steel slag powder for solid waste-based cementitious materials is obtained.

[0027] In one feasible manner, in step two, the separation of molten iron from the impurity layer and the rapid cooling of the impurity layer to obtain coarse steel slag is as follows: A mixture of molten steel slag powder in a molten state is ultrasonically vibrated at 0.29 m... 3 / min~0.57 m 3 The collected impurities were poured into the condenser at a flow rate of / min, and then discharged at a flow rate of 0.26 m. 3 / min~0.52 m 3 Cooling medium is introduced into the condensation device at a flow rate of / min, and the flow direction of the cooling medium is opposite to the flow direction of the impurities.

[0028] The impurities are rapidly cooled to a temperature of 25℃~35℃ to obtain coarse steel slag.

[0029] In one feasible manner, in step two, the reaction is continued at 1400°C to 1550°C for 20 min to 25 min before utilizing the molten steel slag powder mixture in an ultrasonically vibrated state.

[0030] In one feasible manner, in step three, fine steel slag is mixed with water at a mass ratio of 1:(10~15).

[0031] In one feasible manner, in step three, the mixture of fine steel slag and water is stirred at a rate of 120-180 r / min for 30-35 s and then allowed to stand for 5-10 min.

[0032] Firstly, in one feasible manner, in step three, the concentration of carbon dioxide gas injected into the upward-flowing supernatant is 17%~23%, and the flow rate is (0.03) m 1 / 1397) ~ (0.1) m 1 / 1397), unit m 3 / min, duration 5min~10min.

[0033] In one feasible manner, the CaCO3 is industrially pure, the bauxite contains ≥50% Al2O3, and the silica fume contains ≥85% SiO.

[0034] In one feasible manner, in step three, the added quicklime contains ≥85% CaO and has a residue of ≤7.0% on a 90 μm sieve.

[0035] Secondly, the present invention also provides steel slag powder for solid waste-based cementitious materials, which is prepared by the aforementioned method for preparing steel slag powder for solid waste-based cementitious materials.

[0036] The steel slag powder and preparation method for solid waste-based cementitious materials provided by this invention have the following advantages compared with the prior art:

[0037] (1) Based on the hydration mechanism of steel slag powder in solid waste-based cementitious materials, this invention reverse-engineers the composition of steel slag powder in solid waste-based cementitious materials with excellent strength and durability, and directionally adjusts the content of the main active components to improve the various properties of solid waste-based cementitious materials. This is based on the principle that under specific conditions, active silicon in silica fume generates C3S, calcium carbonate generates CaO, and bauxite generates C... 12 The reaction process of A7 was precisely determined through extensive experimental research by identifying the proportional relationships in the reaction equation and the side reactions, and the formulas for the addition amounts of silica fume, calcium carbonate, and bauxite were accurately determined, thus achieving precise ingredient proportioning.

[0038] Specifically, adjusting the content of tricalcium silicate (C3S) can provide sustained momentum for the strength growth in the later stages of the system; adjusting the content of free calcium oxide (C3S) can also provide sustained momentum for the strength growth in the later stages of the system. f The content of α-CaO can maintain the strength of the system, activate the activity of other components in solid waste cementitious materials, and improve strength and density; adjusting the content of dodecacalcium heptaaluminate (C 12 The content of A7 can improve the early strength of solid waste-based cementitious materials and shorten the setting time. Therefore, the steel slag powder prepared using this invention can effectively solve the problems of low early strength, long setting time, and weak later strength growth in solid waste-based cementitious materials.

[0039] (2) This invention is an improvement on the existing iron and steel smelting process. It directly detects the main components that can play a role in solid waste-based cementitious materials, namely tricalcium silicate (C3S) and free calcium oxide, in the mixture that has reached a molten state during the ironmaking process. f -CaO), dodecacalcium heptaluminate (C 12 The content of A7 was adjusted to the level required for it to function in solid waste-based cementitious materials. Without affecting iron smelting and steel quality, the separated impurities were processed to obtain steel slag, which significantly improved the quality of steel slag and solved the problem of large differences in the quality of steel slag produced by different enterprises and the difficulty in its utilization.

[0040] (3) The specific surface area of ​​steel slag powder is very important for the rate at which free calcium oxide is converted into calcium hydroxide. By controlling the specific surface area of ​​steel slag powder, the rate of pH change of the system can be indirectly adjusted. The rate of pH change should be controlled within a certain range so that the steel slag powder can provide sufficient alkalinity to the system, while preventing the calcium hydroxide from being generated too quickly, which would cause poor stability of the hardened slurry. At the same time, the grinding cost and energy consumption of steel slag powder should also be taken into account.

[0041] Therefore, based on the inventor's long-term research experience, a method of using 450 m is proposed. 2Using / kg as a limit, the optimal specific surface area range of steel slag powder was determined by controlling the pH increase rate, carbon dioxide neutralization resistance, and secondary pH increase rate after carbon dioxide neutralization of the slag powder slurry.

[0042] When the specific surface area S of fine steel slag is ≥ 450 m² 2 / kg, and after grinding test a Value < 12.0, still not satisfied a When the requirement is 12.0~12.5, in order to avoid excessive grinding and increase costs and energy consumption, quicklime is added for adjustment, so as to control the overall cost and energy consumption.

[0043] When measuring the specific surface area of ​​steel slag powder, the purpose of introducing carbon dioxide gas and controlling its concentration and flow rate is as follows: Through extensive experiments and data analysis, the inventors clarified the carbonation situation of solid waste-based cementitious materials prepared from steel slag powder under actual service conditions after being used in concrete, and determined the use of carbon dioxide for testing and the determination of its concentration and flow rate, so that the fineness of the steel slag powder is more reasonable and closer to the actual application.

[0044] (4) By rapidly cooling the separated impurity layer, the activity and grindability of the steel slag formed after cooling can be improved.

[0045] Therefore, this invention is an improvement on the existing iron and steel smelting process. It can simultaneously refine molten iron and treat the impurities separated during the refining process, thereby significantly improving the quality of downstream steel slag and making it more suitable for solid waste-based cementitious materials. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the condensation device provided in an embodiment of the present invention. Detailed Implementation

[0047] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0048] The steel slag powder used in the solid waste-based cementitious material provided by this invention will now be described.

[0049] Example 1:

[0050] Step 1, Ingredients:

[0051] Quantitative XRD was used to detect tricalcium silicate (C3S) and free calcium oxide (C4S) in the molten phase of mixtures of iron ore and limestone during ironmaking.f -CaO), dodecacalcium heptaluminate (C 12 The actual contents of A7 were 36%, 9%, and 6%, respectively, compared to the target content of C3S 40%~55%. f -CaO content 6%~15%, C 12 If the A7 content is between 4% and 13%, then the tricalcium silicate (C3S) content in the mixture is insufficient, and silica fume needs to be added to adjust the C3S content.

[0052] The measured mass of the iron ore and limestone mixture is 96 t. If the target C3S content is set at 46%, then 0.26 (t / t) of C3S needs to be added. XM - X 1 M =0.26 (0.45×96-0.36×96) = 2.24 t of silica fume for adjustment.

[0053] After adding silica fume, the mixture was reacted at 1485°C for another 20 minutes.

[0054] To explain, quantitative XRD detection: X-ray diffraction (XRD) is an analytical method that uses X-rays to detect the structure and content of crystals or molecules.

[0055] Step two involves using ultrasonic vibration to rapidly separate the molten iron from impurities, forming an iron layer and an impurity layer. The upper impurity layer, separated using a skimmer, is then collected and processed at a speed of 0.32 m. 3 Impurities are poured from top to bottom into a condensing device at a flow rate of 0.28 m / min. The condensing device contains flowing quenching oil, which flows from bottom to top at a velocity of 0.28 m / min. 3 / min. After rapid cooling, coarse steel slag is obtained, and the molten iron enters the next refining process.

[0056] See Figure 1 As shown, quenching oil enters through f1, flows upwards to exchange heat with high-temperature impurities, and is discharged through f2 after heating. When condensation of impurities is not required, the cooled quenching oil is discharged from s1 at the bottom of the condensation device. Impurities enter through e1 at the top of the condensation device, are cooled, and flow out through e2 at the bottom. When condensing high-temperature impurities, valve p at the inlet of s1 is closed, and is opened when the cooled quenching oil is discharged. Valve p1 is located at the inlet of e1, and valve p2 is located at the outlet of e2. To facilitate the discharge of slag after condensation, a guide cone is provided at the bottom of the impurity cooling chamber in the condensation device.

[0057] The internal structure of the condensing device is not shown. The present invention can utilize existing condensers or heat exchangers for cooling; the condensing device is not the inventive point of this invention. For example, a shell-and-tube or jacketed condenser, or a tower condenser, can be used.

[0058] Step 3: The rapidly cooled coarse steel slag is ground into finer particles using a laboratory mill. Samples are taken every 10 minutes and recorded as fine steel slag. The following tests are performed on the fine steel slag:

[0059] Fine steel slag and water were mixed at a mass ratio of 1:10 at 25℃, and the mass of the mixture was measured. m 1 is 2.0 kg;

[0060] Stir for 30 seconds initially, let stand for 5 minutes, then test the pH value of the supernatant and record it as follows. a ;

[0061] Then, 18% carbon dioxide gas is injected into the supernatant, with the flow rate adjusted to (0.041 × 2 / 1397) = 5.87 × 10⁻⁶. -5 m 3 The ventilation rate was 90°C / min, lasting for 5 minutes. The pH value was measured after ventilation ended and recorded as follows: b ;

[0062] The mixture of fine steel slag and water was stirred a second time, and the pH value of the mixture was tested in real time until it recovered to a normal level. a At that time, the recorded duration is t ; and conditions a It is between 12.0 and 12.5. b ≥11.5, t The comparison was conducted over a period of 180 s to 360 s.

[0063] The specific surface area S of the fine steel slag was measured to be 406 m². 2 / kg, a, b, t It begins to meet the interval requirements; at this point... a, b, t The s values ​​were 12.2, 11.7, and 212 s, respectively, when the specific surface area S reached 440 m². 2 / kg, a, b, t The durations were 12.3, 11.8, and 126 s, respectively. t The value exceeds the required range; therefore, the specific surface area range for steel slag powder is 406 m². 2 / kg≤S<440 m 2 / kg, fine steel slag is ground to a specific surface area of ​​435 m² 2 / kg yields steel slag powder for solid waste-based cementitious materials.

[0064] Among them, CaCO3 is industrially pure, the Al2O3 content in bauxite is 63%, and the SiO content in silica fume is 92%.

[0065] Example 2:

[0066] Step 1, Ingredients:

[0067] Quantitative XRD was used to detect tricalcium silicate (C3S) and free calcium oxide (C4S) in the molten phase of mixtures of iron ore and limestone during ironmaking. f -CaO), dodecacalcium heptaluminate (C 12 The actual contents of A7 were 50%, 4%, and 2%, respectively, compared to the target C3S content of 40%~55%. f -CaO content 6%~15%, C 12 A comparison was made between A7 contents ranging from 4% to 13%. f -CaO and C 12 If the A7 content is insufficient, CaCO3 and bauxite need to be added to adjust it. f -CaO and C 12 A7 content.

[0068] The measured mass of the iron ore and limestone mixture was 137 t. Now, the following settings are implemented... f - The target CaO content is 8%, C 12 If the target content of A7 is 5%, then add 1.78 (0.08×137-0.04×137) = 9.75 t of CaCO3 and 0.56 (0.05×137-0.02×137) = 2.30 t of bauxite for adjustment.

[0069] After adding the two materials mentioned above, the mixture was reacted at 1410℃ for another 25 minutes.

[0070] Step two involves using ultrasonic vibration to rapidly separate the molten iron from impurities, forming an iron layer and an impurity layer. The upper impurity layer is collected using a skimmer and then discharged at a depth of 0.43 m. 3 Quenching oil is poured from top to bottom into a condensing device at a flow rate of 0.40 m / min. The condensing device contains flowing quenching oil, which flows from bottom to top at a velocity of 0.40 m / min. 3 / min. After rapid cooling, coarse steel slag is obtained, and the molten iron enters the next refining process.

[0071] Step 3: The rapidly cooled coarse steel slag is ground into finer particles using a laboratory mill. Samples are taken every 10 minutes and recorded as fine steel slag. The following tests are performed on the fine steel slag:

[0072] Fine steel slag and water were mixed at a mass ratio of 1:10 at 25℃, and the mass of the mixture was measured. m 1 is 3.3 kg;

[0073] Stir for 30 seconds initially, let stand for 5 minutes, then test the pH value of the supernatant and record it as follows. a ;

[0074] Then, 21% carbon dioxide gas is injected into the supernatant, with the flow rate adjusted to (0.085 × 3.3 / 1397) = 20.08 × 10⁻⁶. -5 m 3 The ventilation rate was 90°C / min, lasting for 5 minutes. The pH value was measured after ventilation ended and recorded as follows: b ;

[0075] The mixture of fine steel slag and water was stirred again, and the pH value of the mixture was tested in real time until it returned to normal. a The time taken is t .

[0076] The specific surface area S of the fine steel slag was measured to be 388 m². 2 / kg, a, b, t It begins to meet the interval requirements; at this point... a, b, t The s values ​​were 12.0, 11.6, and 308 s, respectively, when the specific surface area S reached 442 m². 2 / kg, a, b, t The times were 12.1, 11.8, and 97 s, respectively. t The value exceeds the required range; therefore, the specific surface area range for steel slag powder is 388 m². 2 / kg≤S<442 m 2 / kg, fine steel slag is ground to a specific surface area of ​​420 m² 2 / kg yields special steel slag powder for solid waste-based cementitious materials.

[0077] Among them, CaCO3 is industrially pure, the Al2O3 content in bauxite is 56%, and the SiO content in silica fume is 95%.

[0078] Example 3:

[0079] Step 1: Quantitative XRD is used to detect tricalcium silicate (C3S) and free calcium oxide (C4S) in the molten phase of a mixture of iron ore and limestone during the ironmaking process. f -CaO), dodecacalcium heptaluminate (C 12 The actual contents of A7 are 35%, 3%, and 13% respectively, and silica fume and CaCO3 need to be added to adjust C3S and... f -CaO content.

[0080] The measured mass of the iron ore and limestone mixture was 74 tons; the target C3S content is now set at 50%. f If the target CaO content is 7%, then add 0.26 (0.50×74-0.35×74) = 2.89 t of silica fume and 1.78 (0.07×74-0.03×74) = 5.27 t of CaCO3 for adjustment.

[0081] After adding the two materials mentioned above, the mixture was reacted at 1505°C for 22 min.

[0082] Step two involves using ultrasonic vibration to rapidly separate the molten iron from impurities, forming an iron layer and an impurity layer. The upper impurity layer, separated using a skimmer, is then collected and processed at a speed of 0.34 m. 3 Quenching oil is poured from top to bottom into a condensing device at a flow rate of 0.30 m / min. The condensing device contains flowing quenching oil, which flows from bottom to top at a velocity of 0.30 m / min. 3 / min. After rapid cooling, coarse steel slag is obtained, and the molten iron layer enters the next refining process.

[0083] (3) The coarse steel slag after rapid cooling was ground into finer particles using an experimental mill. Samples were taken every 10 minutes and recorded as fine steel slag. The following tests were performed on the fine steel slag:

[0084] Fine steel slag and water were mixed at a mass ratio of 1:10 at 25℃, and the mass of the mixture was measured. m 1 is 1.6 kg;

[0085] Stir for 30 seconds initially, let stand for 5 minutes, then test the pH value of the supernatant and record it as follows. a；

[0086] Tests revealed that when the specific surface area of ​​fine steel slag reached 450 m²... 2 / kg, a <12.0, at this point the mass of steel slag in the mixture is 0.15 kg; under stirring conditions, quicklime is gradually added to the mixture to adjust the pH value, and when the amount of quicklime added is 0.01 kg, the pH reaches 12.1; grind to 450 μm 2 / kg fine steel slag m 2 with quicklime m 3. Mix them at a mass ratio of 15:1 to obtain steel slag powder for solid waste-based cementitious materials.

[0087] Among them, CaCO3 is industrially pure, the Al2O3 content in bauxite is 68%, and the SiO content in silica fume is 86%.

[0088] The quicklime used contains 90% CaO, and has a residue of 6.0% on a 90 μm sieve.

[0089] Comparative Example 1:

[0090] The difference from Example 1 is that when the content of tricalcium silicate (C3S) in the mixture is insufficient, a mixture of fly ash and fly ash is added to replace silica fume to adjust the C3S content. The mass ratio of fly ash to fly ash in the mixture is 1:1. Other processes and parameters are the same as in Example 1 and will not be repeated here.

[0091] Among them, CaCO3 is industrially pure, the Al2O3 content in bauxite is 63%, the SiO2 content of fly ash in the mixture is 38%, and the SiO2 content of fly ash is 45%.

[0092] Solid waste-based cementitious materials were prepared by using steel slag powder from Examples 1, 2, 3 and Comparative Example 1, combined with slag powder and desulfurized gypsum, with the following mass percentage ratio: 75% slag powder, 10% steel slag powder, and 15% desulfurized gypsum.

[0093] Comparative Example 2:

[0094] The solid waste-based cementitious material was prepared by replacing ordinary steel slag powder with steel slag powder and combining it with slag powder and desulfurized gypsum.

[0095] The compressive and flexural strengths at 3 days, 7 days, and 28 days were tested according to GB / T 17671 "Test Method for Strength of Cement Mortar (ISO Method)". The setting time and soundness were tested according to GB / T 1345 "Test Method for Standard Consistency Water Requirement, Setting Time and Soundness of Cement". See Table 1 for details.

[0096] Table 1 Strength Test Results

[0097]

[0098] The experimental results of Examples 1, 2, 3 and Comparative Example 2 show that the solid waste-based cementitious material prepared using the steel slag powder of the present invention has significantly higher strength than the solid waste-based cementitious material prepared using ordinary steel slag powder.

[0099] The test results of Examples 1, 2, 3 and Comparative Example 1 show that the solid waste-based cementitious material prepared by using the steel slag powder in this invention has significantly higher strength than the steel slag powder prepared by using other materials to replace the corresponding reaction raw materials, and the setting time is significantly shortened, with qualified stability.

[0100] For example, as can be seen from Example 1 and Comparative Example 1, the addition of silica fume in this invention, compared with the addition of a mixture of fly ash and fly ash to adjust the C3S content, results in higher flexural strength and compressive strength, and a shorter setting time.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing steel slag powder for solid waste-based cementitious materials, characterized by, The method comprises: Step one, batching: detecting C3S in a molten phase of a mixture of iron ore and limestone in an iron-making process, f -CaO, C 12 A7 content of the three components; According to the measured content of the three components, the adjusting agent CaCO3, bauxite and silica ash are selectively added to adjust the mass percentage of the three components to: C3S content 40%~55%, f -CaO content 6%~15%, C 12 A7 content 4%~13%, other component content <50%, to obtain a molten steel slag powder mixture, the sum of the mass percentages of all the above components is 100%; the adjustment process of the mass percentages of the three components is as follows: When the C3S content is insufficient, silica fume is added to the mixture of iron ore and limestone according to the calculated value of 0.26 (0.26 x (target C3S content - actual measured C3S content) + actual measured C3S content). XM - X 1 M X X 1​​ When f - the CaO content is insufficient, CaCO3 is added to the mixture of iron ore and limestone according to formula 1.78 (CaO content of the limestone) - (1.78 x CaO content of the iron ore) = CaCO3 to be added YM - Y 1 M - the CaO content of the limestone is determined by formula 1.78 x CaO content of the iron ore, wherein Y is the target f -CaO content, Y 1 is the actually measured f -CaO content; When C 12 A7 content is insufficient, bauxite is added to the mixture of iron ore and limestone according to the formula 0.56 (C ZM - Z 1 M ) calculated value, wherein, Z is the target C 12 A7 content, Z 1 is the actual measured C 12 A7 content; wherein, M mass and of iron ore and limestone; Step two, separating the molten iron from the impurity layer and rapidly cooling the impurity layer to obtain crude steel slag, and the molten iron enters the next smelting process; Step three, when the steel slag powder specific surface area S < 450 m 2 / kg, the obtained crude steel slag is ground, and the steel slag powder for solid waste-based cementitious materials is obtained through determination of the steel slag powder specific surface area.

2. The method for preparing steel slag powder for solid waste-based cementitious materials according to claim 1, characterized in that, In step three, the determination of the specific surface area of the steel slag powder includes: (1) when the specific surface area S of the steel slag powder is less than 450 m 2 / kg, the obtained crude steel slag is ground, and a sample is taken every 10 min~20 min, which is recorded as fine steel slag; The specific surface area of each sample of fine steel slag is determined, and the process is as follows: The fine steel slag and water are mixed in proportion, and the mass of the obtained fine steel slag and water mixture is denoted as m 1, unit kg; The mixture of fine steel slag and water is stirred once, the pH value of the supernatant is tested and recorded, denoted as pH1. a ; Carbon dioxide gas is injected into the supernatant and left for a certain period of time; after the end of aeration, the pH is tested and recorded, denoted as b ; The mixture of fine steel slag and water is stirred for the second time, and the pH value of the mixture of fine steel slag and water is tested in real time until the pH value of the mixture of fine steel slag and water returns to a , and the stirring time at this time is recorded as t ; When the measured specific surface area of the fine steel slag is a, b, t The fineness interval of the steel slag powder is the specific surface area when the following requirements are met: a is 12.0~12.5, b ≥11.5, t is 180 s~360 s; then the steel slag powder for solid waste-based cementitious materials is obtained; (2) When the specific surface area S of fine steel slag is greater than or equal to 450 m² 2 When / kg, test according to (1) a When the value is still <12.0, the mass of fine steel slag used is recorded as follows: m 2. Unit: kg; Add quicklime gradually under stirring conditions, and test the pH value in real time until the pH value is ≥12.

0. The amount of quicklime added at this point is recorded as: m 3, unit kg; steel slag powder for solid waste-based cementitious materials is obtained.

3. The method of producing steel slag fines for solid waste-based cementitious materials according to claim 2, characterized by, In step two, the molten iron is separated from the impurity layer, and the impurity layer is rapidly cooled to obtain crude steel slag, and the process is as follows: The molten steel and the impurity layer are quickly separated by using ultrasonic oscillation to melt the mixture of the steel slag powder, and the impurity layer formed is floated on the molten steel, and the impurity layer is poured into a condensing device at a flow rate of 0.29 m 3 / min~0.57 m 3 / min, and a cooling medium is introduced into the condensing device at a flow rate of 0.26 m 3 / min~0.52 m 3 / min, and the flow direction of the introduced cooling medium is opposite to the flow direction of the impurity. Rapidly cool the impurities to a temperature of 25-35 DEG C to obtain crude steel slag.

4. The method of producing steel slag powder for solid waste-based cementitious materials according to claim 3, characterized by, In step two, before the steel slag powder mixture in a molten state is mixed by ultrasonic oscillation, the reaction is continued at 1400-1550 DEG C for 20-25 min.

5. The method for preparing steel slag powder for solid waste-based cementitious materials according to claim 2, characterized by, In step three, the fine steel slag is mixed with water at a mass ratio of 1: (10-15).

6. The method of producing steel slag powder for solid waste-based cementitious materials according to claim 2, characterized by, In step three, the mixture of fine steel slag and water is stirred at a rate of 120-180 r / min for 30-35 s, and is left to stand for 5-10 min.

7. The method of producing steel slag fines for solid waste-based cementitious materials according to claim 2, characterized by, In step three, the carbon dioxide gas concentration injected into the supernatant is 17%~23%, the flow rate is (0.03 m 1 / 1397)~(0.1 m 1 / 1397) m 3 / min, and the duration is 5 min~10 min.

1. The method of claim 1, wherein the step of introducing the carbon dioxide gas into the supernatant is performed at a flow rate of about 0.05 mL / min.

2. The method of claim 1, wherein the step of introducing the carbon dioxide gas into the supernatant is performed at a flow rate of about 0.1 mL / min.

3. The method of claim 1, wherein the step of introducing the 8. The method of producing steel slag powder for solid waste-based cementitious materials according to claim 2, characterized by, In step three, the CaO content of the added quicklime is ≥ 85%, and the sieve residue of the 90 μm sieve is ≤ 7.0%.

9. The method for preparing steel slag powder for solid waste-based cementitious materials according to claim 1, characterized by, The CaCO3 is industrial pure, the Al2O3 content of the bauxite is ≥ 50%, and the SiO2 content of the silica ash is ≥ 85%.

10. Steel slag powder for solid waste-based cementitious materials, characterized by, The steel slag powder for solid waste-based cementitious materials is prepared by the method according to any one of claims 1-9.

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