High-activity high-titanium ore slag micro-powder and preparation method thereof

Abstract

This invention discloses a highly active high-titanium slag micro-powder and its preparation method, belonging to the field of industrial solid waste resource utilization technology. The preparation method includes: compounding alkaline industrial solid waste with an alkaline activator to form a composite alkaline modifier; grinding high-titanium slag raw material and mixing it with the modifier, followed by high-temperature calcination; carbonizing the calcined product in a hot simmering tank with a 20-40 g / L sodium bicarbonate solution; and finally, obtaining the product through pressure filtration, drying, and grinding. This invention, through the synergistic effect of "high-temperature modification-alkali fusion activation-carbonization treatment," reconstructs the inert mineral phase in high-titanium slag into a highly active mineral phase and effectively eliminates free calcium oxide. The resulting high-titanium slag micro-powder has a 28-day activity index of not less than 105%, a free calcium oxide content of less than 0.5%, and excellent stability. It can be used as a mineral admixture to replace cement in a large proportion, realizing the high-value utilization of high-titanium slag.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization technology, specifically to a highly active high-titanium slag powder and its preparation method. Background Technology

[0002] High-titanium slag is a large-scale industrial solid waste generated during the smelting of vanadium-titanium magnetite, characterized by its large output, high stockpiles, and low resource utilization rate. The chemical composition of high-titanium slag is similar to that of blast furnace slag. However, due to its high TiO2 content and rich content of inert mineral phases such as perovskite and diopside, its cementing activity is far lower than that of blast furnace slag, making it difficult to use as a cementing material or mineral admixture, thus severely restricting its large-scale resource utilization. Large stockpiles of high-titanium slag not only occupy land resources, but the heavy metals they contain can also pollute surrounding soil and water bodies through rainwater leaching, causing significant environmental harm.

[0003] Existing methods for enhancing the cementitious activity of high-titanium slag mainly include mechanical activation and chemical activation. Mechanical activation typically increases the specific surface area of ​​high-titanium slag through physical grinding, thereby improving its reactivity. Chemical activation often uses strongly alkaline solutions (such as sodium hydroxide or water glass) to activate the high-titanium slag, promoting the dissolution and reaction of the silicon and aluminum components in the slag. However, existing technologies do not fundamentally change the mineral phase composition of high-titanium slag and have significant limitations: mechanical activation has limited ability to disrupt the inert crystal structure in high-titanium slag, resulting in an increase in activity that is disproportionate to the high grinding energy consumption, leading to poor economic efficiency; while chemical activation, although it can promote the dissolution of silicon and aluminum components in high-titanium slag to some extent, still has limited activation efficiency and faces risks such as high cost of alkaline activators and rapid loss of the working performance of the cementitious system.

[0004] Alkali fusion activation can utilize alkaline substances to disrupt the crystal lattice of inert minerals at high temperatures, generating active aluminosilicates. However, for materials like high-titanium slag with high inert component content, the alkali fusion method alone consumes a large amount of alkali, is costly, and struggles to effectively control the overall mineral phase composition. Therefore, developing a low-cost, synergistic treatment technology that can simultaneously achieve modification and activation is crucial for the high-value utilization of high-titanium slag. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a highly active high-titanium slag micro powder and its preparation method. By utilizing alkaline industrial solid waste and alkaline activators as composite alkaline modifiers, high-temperature modification and alkaline fusion activation of high-titanium slag are simultaneously achieved during calcination. Furthermore, the cementitious activity and stability of the high-titanium slag are further enhanced by carbonizing the calcined products.

[0006] The technical solution of this invention is achieved as follows: a method for preparing highly active, high-titanium slag micro powder, comprising the following steps: S1. Alkaline industrial solid waste is compounded with an alkaline activator to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material, then mix it evenly with the composite alkaline modifier described in step S1, and calcine it at high temperature. S3. Spray sodium bicarbonate solution onto the product of step S2 for carbonization treatment. After the reaction is complete, discharge the carbonized slurry and filter it under pressure. S4. The filter residue obtained from step S3 is dried and ground to obtain the high-activity high-titanium slag micro powder.

[0007] Based on the above technical solutions, preferably, in step S1, the alkaline industrial solid waste is one or more of red mud, steel slag and carbide slag; the alkaline activator is one or more of sodium hydroxide, sodium carbonate, sodium silicate or potassium hydroxide.

[0008] More preferably, in step S1, the mass percentage of the alkaline industrial solid waste to the alkaline activator is (75~90%):(10~25%), and the sum of the mass percentages is 100%.

[0009] Based on the above technical solution, preferably, in step S2, the mass percentage of high-titanium slag raw material and the composite alkaline modifier is (70~90%):(10~30%), and the sum of the mass percentages is 100%.

[0010] In a further preferred embodiment, in step S2, the high-titanium slag raw material is ground to a particle size of less than 0.075 mm.

[0011] More preferably, in step S2, the high-temperature calcination treatment is carried out at a temperature of 1000~1200℃ for a holding time of 60~120 min. Regarding the synergistic effect of high-temperature modification and alkali fusion activation, during the high-temperature calcination process, the alkaline components in the modifier decompose and ionize to generate a large amount of OH-. - The modifier contains active metal cations, which break the chemical bonds of inert crystalline phases such as Si–O–Ti and Si–O–Al in high-titanium slag, promoting the depolymerization and reconstruction of the original crystal structure and generating soluble aluminosilicate intermediate phases. At the same time, oxides such as CaO, SiO2, and Al2O3 in the modifier can undergo solid-phase reactions at high temperatures, regulating the calcium-silicon ratio of high-titanium slag and promoting the formation of active mineral phases (such as dicalcium silicate), thereby enhancing the hydration activity of high-titanium slag.

[0012] Based on the above technical solutions, preferably, the concentration of the sodium bicarbonate solution is 20~40 g / L, and the liquid-to-solid ratio of the spray is 0.5~1.0:1; the carbonization treatment is carried out under the autogenous pressure caused by the thermal decomposition of the sodium bicarbonate solution, and the carbonization treatment time is 60~90 min. For carbonization treatment, since steel slag has a high content of free calcium oxide and the main component of carbide slag is calcium hydroxide, which is easily decomposed to produce calcium oxide during calcination, carbonization treatment can not only consume the unreacted free calcium oxide in the modifier and solve the hidden danger of its poor stability, but also the nano-sized calcium carbonate generated by the reaction can be uniformly distributed in the material, serving as crystal nuclei and micro-aggregates for hydration reaction, further enhancing the cementitious activity of high-titanium slag. In addition, compared with traditional gas-phase or liquid-phase carbonization methods, on the one hand, when sodium bicarbonate solution comes into contact with high-temperature calcined products, it will rapidly vaporize and thermally decompose to release a large amount of CO2 gas, forming a self-pressurized environment in the closed hot slag container; on the other hand, the pulverization effect of rapid cooling of calcined products will significantly increase the carbonization reaction interface, and the pressurized environment will promote the deep mass transfer and penetration of CO2 into the particle interior, thereby achieving uniform carbonization.

[0013] Further preferably, the selection of process parameters for carbonation treatment in step S3 of the present invention has a decisive influence on the performance of the final product. Specifically, the concentration of sodium bicarbonate solution, liquid-to-solid ratio, and carbonation time must be strictly controlled within the range described in the present invention, i.e., concentration 20~40 g / L, liquid-to-solid ratio 0.5~1.0:1, and time 60~90 min. If the above parameters are lower than the lower limit of the range, the degree of carbonation reaction will be insufficient, and the free calcium oxide component in the modifier cannot be fully converted. This will not only lead to poor volume stability of the product, but also limit the further improvement of gelling activity because the nano carbonate with crystal nucleation function cannot be effectively generated. Conversely, if the above parameters exceed the upper limit of the range, it will cause over-carbonation, the adverse consequences of which are: first, it may continuously consume the active mineral phase calcium silicate phase; second, it will cause the carbonate product to crystallize and coarse, and form a dense coating layer on the surface of the active particles, producing a passivation effect, hindering the subsequent hydration reaction, and thus reducing the gelling activity.

[0014] Based on the above technical solution, preferably, in step S4, the drying temperature is 100~110℃, and the drying time is 8~12 h; the grinding is carried out until the specific surface area of ​​the obtained high-titanium slag powder is 500±20 m². 2 / kg.

[0015] A further preferred embodiment of the method for preparing the high-activity high-titanium slag powder includes step S5: drying the filtrate obtained from the pressure filtration in step S3 to obtain a carbonization byproduct.

[0016] Further preferably, the carbonization byproduct is recycled in step S1 to partially replace the composite alkaline modifier. Regarding the recycling of the carbonization byproduct, since the thermal decomposition products of sodium bicarbonate are sodium carbonate, CO2, and water, the main components of the carbonization byproduct are sodium carbonate, incompletely reacted sodium bicarbonate, and soluble silicate and aluminate ions dissolved during carbonization. This byproduct is essentially a composite alkaline material rich in alkali metal carbonates and silicon-aluminum components. Its alkaline components can replace part of the alkaline activator in the original formula, while the contained silicon-aluminum components can participate in the reaction during high-temperature modification, generating more active mineral phases. Therefore, this byproduct can be directly recycled at the upstream stage, partially replacing the original composite alkaline modifier, thereby further reducing raw material consumption and waste emissions.

[0017] More preferably, the carbonization byproducts replace 10% to 30% of the mass of the composite alkaline modifier.

[0018] The present invention also provides a highly active high-titanium slag powder prepared according to the above method, which has a 28-day activity index of not less than 105% and a free calcium oxide content of less than 0.5%.

[0019] The preparation method of the high-activity high-titanium slag micro powder of the present invention has the following advantages over the prior art: (1) This invention improves the gelling activity of high-titanium slag by high-temperature modification and synergistic alkaline fusion activation. While effectively destroying and reconstructing its internal inert crystalline phase structure, it also promotes the generation of highly active aluminosilicate mineral phases. This method significantly improves the gelling activity of high-titanium slag and breaks through the technical bottleneck of the limited effect of traditional single activation methods. (2) The present invention uses sodium bicarbonate solution to carbonize the calcined product in a closed hot simmering tank. This method integrates multiple synergistic effects such as "rapid cooling and pulverization", "self-generated pressurization" and "deep carbonization". It not only consumes the unreacted free calcium oxide in the modifier and improves the volume stability of the high titanium slag, but also further improves the gelling activity of the high titanium slag through the in-situ generated nano calcium carbonate.

[0020] (3) This invention uses alkaline industrial solid wastes such as red mud, carbide slag and steel slag as the main raw materials, and combines them with traditional chemical alkali sources to prepare composite alkaline modifiers. This not only effectively reduces the alkali consumption and energy consumption of the alkali fusion activation process, but also reduces the economic and environmental burden caused by the high alkali consumption in the existing alkali fusion activation process, and realizes the high-value utilization of industrial solid wastes. In addition, this invention uses carbonization by-products to partially replace the original composite alkaline modifiers, realizing the closed-loop recycling of resources, which can further reduce raw material consumption and waste emissions.

[0021] (4) The method of the present invention is simple, efficient and convenient to operate. The high titanium slag powder prepared has high cementitious activity and good stability. It can be used as a high-performance mineral admixture to replace cement in a large proportion, which solves the problem of low utilization rate of high titanium slag. While reducing carbon emissions in the cement industry, it provides a reliable way for the large-scale high-value utilization of high titanium slag resources. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] The performance indicators of the raw materials used in the various embodiments of the present invention are as follows: 1. High-titanium slag The high-titanium slag used in the various embodiments of the present invention is taken from a titanium smelter in the Panzhihua area. Its main mineral phases are glass phase, perovskite, diopside and pyroxene, and its chemical composition is shown in Table 1.

[0024] Table 1

[0025] 2. Alkaline industrial solid waste In the embodiments of the present invention, red mud, carbide slag and steel slag are selected as alkaline industrial solid waste raw materials. After drying, each raw material is ground to a particle size of less than 0.075 mm. Its main chemical composition is shown in Table 2.

[0026] Table 2

[0027] 3. Alkali activator The alkaline activators used in the various embodiments of the present invention are all commercially available industrial-grade chemical reagents, including sodium hydroxide, sodium silicate and sodium carbonate, all with a purity of ≥99%.

[0028] Table 3

[0029] Example 1 A highly active, high-titanium slag powder is prepared by the following method: S1. Red mud, carbide slag and sodium hydroxide are compounded in a mass percentage of 65%:20%:15% to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 80%:20%, and calcine the mixture at 1100℃ for 90 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 30 g / L into it at a liquid-to-solid ratio of 0.7:1 for carbonization treatment. The treatment time is 80 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from step S3 at 105℃ for 10 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining highly active high-titanium slag powder; S5. The filtrate obtained from the pressure filtration in step S3 is dried to obtain carbonized byproduct C1.

[0030] Example 2 A highly active, high-titanium slag powder is prepared by the following method: S1. Red mud, carbide slag and sodium hydroxide are compounded in a mass percentage of 65%:20%:15% to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material to below 0.075 mm, and then mix it uniformly with the composite alkaline modifier obtained in step S1 and the carbonization by-product C1 obtained in Example 1 at a mass percentage of 80%:16%:4%, and calcine the mixture at 1100℃ for 90 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 30 g / L into it at a liquid-to-solid ratio of 0.7:1 for carbonization treatment. The treatment time is 80 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from step S3 at 105℃ for 10 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining highly active high-titanium slag powder.

[0031] Example 3 A highly active, high-titanium slag powder is prepared by the following method: S1. Red mud, steel slag, carbide slag and sodium silicate are compounded in a mass percentage ratio of 30%:50%:10%:10% to obtain a composite alkaline modifier. S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 90%:10%, and calcine the mixture at 1000℃ for 120 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 20 g / L into it at a liquid-to-solid ratio of 0.5:1 for carbonization treatment. The treatment time is 90 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from the pressure filtration in step S3 at 100℃ for 12 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining highly active high-titanium slag powder.

[0032] Example 4 A highly active, high-titanium slag powder is prepared by the following method: S1. Red mud, steel slag and sodium carbonate are compounded in a mass percentage ratio of 45%:30%:25% to obtain a composite alkaline modifier. S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 70%:30%, and calcine the mixture at 1200℃ for 60 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray it with a sodium bicarbonate solution with a concentration of 40 g / L at a liquid-to-solid ratio of 1:1 for carbonization treatment. The treatment time is 60 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from step S3 at 110℃ for 8 hours, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining highly active high-titanium slag powder.

[0033] Example 5 Unlike Example 1, the concentration of sodium bicarbonate solution in step S3 of this example is 10 g / L; specifically, this comparative example prepares high-titanium slag powder by the following method: S1. Red mud, carbide slag and sodium hydroxide are compounded in a mass percentage of 65%:20%:15% to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 80%:20%, and calcine the mixture at 1100℃ for 90 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 10 g / L into it at a liquid-to-solid ratio of 0.7:1 for carbonization treatment. The treatment time is 80 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from step S3 at 105℃ for 10 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining high-titanium slag powder.

[0034] Example 6 Unlike Example 1, the concentration of sodium bicarbonate solution in step S3 of this example is 50 g / L; specifically, this comparative example prepares high-titanium slag powder by the following method: S1. Red mud, carbide slag and sodium hydroxide are compounded in a mass percentage of 65%:20%:15% to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 80%:20%, and calcine the mixture at 1100℃ for 90 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 50 g / L into it at a liquid-to-solid ratio of 0.7:1 for carbonization treatment. The treatment time is 80 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from step S3 at 105℃ for 10 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining high-titanium slag powder.

[0035] Example 7 Unlike Example 1, in step S3 of this example, the liquid-to-solid ratio of the calcined product to the sodium bicarbonate solution is 0.3:1; specifically, this comparative example prepares high-titanium slag powder by the following method: S1. Red mud, carbide slag and sodium hydroxide are compounded in a mass percentage of 65%:20%:15% to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 80%:20%, and calcine the mixture at 1100℃ for 90 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 30 g / L into it at a liquid-to-solid ratio of 0.3:1 for carbonization treatment. The treatment time is 80 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from step S3 at 105℃ for 10 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining high-titanium slag powder.

[0036] Example 8 Unlike Example 1, in step S3 of this example, the liquid-to-solid ratio of the calcined product to the sodium bicarbonate solution is 1.2:1; specifically, this comparative example prepares high-titanium slag powder by the following method: S1. Red mud, carbide slag and sodium hydroxide are compounded in a mass percentage of 65%:20%:15% to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 80%:20%, and calcine the mixture at 1100℃ for 90 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 30 g / L into it at a liquid-to-solid ratio of 1.2:1 for carbonization treatment. The treatment time is 80 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from step S3 at 105℃ for 10 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining high-titanium slag powder.

[0037] Example 9 Unlike Example 1, the carbonization process in step S3 of this example takes 50 minutes; specifically, this comparative example prepares high-titanium slag powder using the following method: S1. Red mud, carbide slag and sodium hydroxide are compounded in a mass percentage of 65%:20%:15% to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 80%:20%, and calcine the mixture at 1100℃ for 90 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 30 g / L into it at a liquid-to-solid ratio of 0.7:1 for carbonization treatment. The treatment time is 50 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from step S3 at 105℃ for 10 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining high-titanium slag powder.

[0038] Example 10 Unlike Example 1, the carbonization treatment time in step S3 of this example is 100 min; specifically, this comparative example prepares high-titanium slag powder by the following method: S1. Red mud, carbide slag and sodium hydroxide are compounded in a mass percentage of 65%:20%:15% to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 80%:20%, and calcine the mixture at 1100℃ for 90 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 30 g / L into it at a liquid-to-solid ratio of 0.7:1 for carbonization treatment. The treatment time is 100 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from step S3 at 105℃ for 10 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining high-titanium slag powder.

[0039] Comparative Example 11: This comparative example did not involve high-temperature modification or alkali fusion activation of the high-titanium slag. Instead, the high-titanium slag raw material was directly ground to a specific surface area of ​​500±20 m² / kg to obtain high-titanium slag micro powder.

[0040] Comparative Example 12: Unlike Example 1, this comparative example did not use alkaline industrial solid waste to perform high-temperature modification of the high-titanium slag; specifically, this comparative example prepared high-titanium slag powder by the following method: S1. Grind the high-titanium slag raw material to below 0.075 mm, then mix it evenly with sodium hydroxide at a mass percentage of 80%:20%, and calcine the mixture at 1100℃ for 90 min. S2. Transfer the high-temperature calcination product obtained in step S1 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 30 g / L into it at a liquid-to-solid ratio of 0.7:1 for carbonization treatment. The treatment time is 80 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. The carbonized slurry is then subjected to pressure filtration treatment, and the filtrate is collected in a storage tank. S3. After drying the filter residue obtained from step S2 at 105℃ for 10 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining high-titanium slag powder.

[0041] Comparative Example 13: Unlike Example 3, the modifier in this comparative example does not contain an alkali activator; specifically, the high-titanium slag powder in this comparative example was prepared by the following method: S1. Red mud, steel slag and carbide slag are compounded in a mass percentage ratio of 30%:50%:10% to obtain a modifier; S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it evenly with the modifier obtained in step S1 at a mass percentage of 90%:10%, and calcine the mixture at 1000℃ for 120 min. S3. Transfer the high-temperature calcination product obtained in step S2 to a hot sealing tank, and spray a sodium bicarbonate solution with a concentration of 20 g / L into it at a liquid-to-solid ratio of 0.5:1 for carbonization treatment. The treatment time is 90 min. After the reaction is completed, release the pressure and discharge the carbonized slurry. Perform pressure filtration on the obtained carbonized slurry and collect the obtained filtrate in a storage tank. S4. After drying the filter residue obtained from the pressure filtration in step S3 at 100℃ for 12 h, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining high-titanium slag powder.

[0042] Comparative Example 14: Unlike Example 4, this comparative example did not involve carbonization treatment of the calcined product. Specifically, this comparative example prepared high-titanium slag powder using the following method: S1. Red mud, steel slag and sodium carbonate are compounded in a mass percentage ratio of 45%:30%:25% to obtain a composite alkaline modifier. S2. Grind the high-titanium slag raw material to below 0.075 mm, then mix it with the composite alkaline modifier obtained in step S1 at a mass percentage of 70%:30%, and calcine the mixture at 1200℃ for 60 min. S3. After the calcined product obtained in step S2 has cooled to room temperature, grind it to a specific surface area of ​​500±20 m². 2 / kg, thus obtaining high-titanium slag powder.

[0043] The performance testing methods for the high-titanium slag powders obtained in each embodiment and comparative example are as follows: 1. Cementitious activity test: Mortar specimens were prepared using the methods specified in GB / T 1596-2017. The 28-day compressive strength of each mortar was tested and compared with that of pure cement mortar specimens to calculate the 28-day activity index of the samples.

[0044] 2. The soluble Si and Al contents in each sample were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The specific steps are as follows: (1) Weigh 3.000 g of the high-titanium slag powder to be tested and measure 150 mL of deionized water; (2) Pour the high-titanium slag powder and deionized water into a 300 mL plastic beaker, place the beaker in a constant temperature water bath at 20±1℃, and continuously dissolve it at a stirring rate of 200 rpm for 24 h. (3) After the reaction is complete, the resulting suspension is centrifuged at high speed and the supernatant is collected; (4) Draw 100 ml of supernatant and filter it through a 0.22 μm syringe filter to obtain the test solution; (5) The concentrations of Al and Si in the test solution were tested using an inductively coupled plasma mass spectrometer.

[0045] 3. Free calcium oxide content: The free calcium oxide content in high-titanium slag powder was tested by EDTA titration according to the method specified in GB / T 176-2017.

[0046] The performance test results of the high-titanium slag powder obtained in all embodiments and comparative examples are shown in Table 4.

[0047] Table 4

[0048] Table 4 shows that the 28-day activity index of the high-activity high-titanium slag powders obtained in Examples 1-4 all exceeded 105%, the free calcium oxide content was all below 0.7%, and the soluble Si and Al contents were significantly higher than those of the comparative sample. The results indicate that this invention, through a synergistic process of "alkali fusion-modification-carbonation," significantly improves the cementitious activity of high-titanium slag powder while also addressing the stability concerns arising from the high-temperature modification process. The resulting product exhibits stable and excellent performance and can be used as a high-quality mineral admixture or auxiliary cementitious material to replace cement in a large proportion.

[0049] Comparing the performance results of Example 1 and Comparative Example 11, it can be found that the soluble Si and Al content of the high-titanium slag powder obtained in Comparative Example 11 is significantly lower, and its activity index is only 61.3%. This indicates that the original high-titanium slag has a higher proportion of inert crystalline phase and a lower content of active mineral phase and amorphous glass phase, resulting in poor cementing activity.

[0050] Comparing the performance results of Example 1 and Comparative Example 12, it can be found that the properties of the high-titanium slag powder obtained in Comparative Example 12 are significantly lower than those in Example 1. This is mainly because Comparative Example 12 only uses a single alkali activator for alkali fusion activation of the high-titanium slag, resulting in limited modification effect of the high-temperature calcination process on the high-titanium slag. The system lacks oxide components provided by alkaline industrial solid waste, and the contents of CaO, SiO2, and Al2O3 are insufficient, which is not conducive to the formation of active aluminosilicate mineral phases, resulting in insufficient soluble Si and Al content in the system, thus limiting the subsequent hydration reaction.

[0051] Comparing the performance results of Example 3 and Comparative Example 13, it can be found that the properties of the high-titanium slag powder obtained in Comparative Example 13 are significantly lower than those of Example 3. This is mainly because the modifier used in Comparative Example 13 did not contain an alkali activator, and the system lacked a sufficient alkaline environment at high temperature. The content of OH- and active metal cations was insufficient, making it difficult to effectively break the stable Si-O-Ti and Si-O-Al bonds in the high-titanium slag. The inert crystalline phase could not be fully decomposed, resulting in a low content of soluble Si and Al, and limited improvement in gelling activity.

[0052] Comparing the performance results of Example 4 and Comparative Example 14, it can be found that the 28-day activity index and soluble Si and Al content of the high-titanium slag micropowder obtained in Comparative Example 14 are lower than those of Example 4, but its free calcium oxide content is significantly higher than that of Example 4. This is mainly because the calcined product in Comparative Example 14 was not carbonized, resulting in the free calcium oxide in the calcined product not being effectively consumed and reacted to generate nano-sized calcium carbonate with micro-aggregate filling effect and crystal nucleation effect, thus limiting its activity improvement.

[0053] Comparing the performance results of Examples 1 and 2, it can be found that after partially replacing the composite alkaline modifier with carbonization byproducts, the performance indicators of the obtained high-titanium slag powder (Example 2) remain at a level comparable to those of Example 1. This result fully demonstrates that the alkali-rich byproducts obtained by this invention can effectively replace part of the composite alkaline modifier, achieving internal resource recycling and reducing consumables while ensuring excellent product performance, highlighting the industrial application potential and environmental value of the closed-loop process of this invention.

[0054] Comparing Examples 1 and 5-10, it is evident that in step S3, the concentration of the sodium bicarbonate solution, the liquid-to-solid ratio, and the carbonation time must be strictly controlled within the ranges described in this invention; otherwise, the desired modification effect cannot be obtained. If the concentration is too low, the liquid-to-solid ratio is too low, or the carbonation time is insufficient, the carbonation reaction will be incomplete, the degree to which free calcium oxide participates in the reaction will be limited, and it will be difficult to generate sufficient nano-sized calcium carbonate crystals, resulting in insufficient pore filling, low structural densification, and limited improvement in material strength. Conversely, if the concentration of the sodium bicarbonate solution is too high, the liquid-to-solid ratio is too large, or the carbonation time is too long, over-carbonation will occur, causing carbonation of potentially active phases such as dicalcium silicate, weakening their subsequent hydration reaction capacity, leading to a decrease in the amount of gelled products generated, and ultimately reducing the activity of the high-titanium slag powder.

[0055] 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, improvements, etc., 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 highly active, high-titanium slag micro powder, characterized in that, Includes the following steps: S1. Alkaline industrial solid waste is compounded with an alkaline activator to obtain a composite alkaline modifier; S2. Grind the high-titanium slag raw material, then mix it evenly with the composite alkaline modifier described in step S1, and calcine it at high temperature. S3. Spray sodium bicarbonate solution onto the product of step S2 for carbonization treatment. After the reaction is complete, discharge the carbonized slurry and filter it under pressure. S4. The filter residue obtained from step S3 is dried and ground to obtain the high-activity high-titanium slag powder. In step S3, the concentration of sodium bicarbonate is 20~40 g / L, the liquid-to-solid mass ratio of the spray is 0.5~1.0:1, and the treatment time is 60~90 min.

2. The preparation method according to claim 1, characterized in that, In step S1, the alkaline industrial solid waste is one or more of red mud, steel slag, and carbide slag; the alkaline activator is one or more of sodium hydroxide, sodium carbonate, sodium silicate, or potassium hydroxide.

3. The preparation method according to claim 2, characterized in that, In step S1, the mass percentage of the alkaline industrial solid waste to the alkaline activator is (75~90%):(10~25%), and the sum of the mass percentages is 100%.

4. The preparation method according to claim 1, characterized in that, In step S2, the mass percentage of the high-titanium slag raw material and the composite alkaline modifier is (70~90%):(10~30%), and the sum of the mass percentages is 100%.

5. The preparation method according to claim 1, characterized in that, In step S2, the high-titanium slag raw material is ground to a particle size of less than 0.075 mm.

6. The preparation method according to claim 1, characterized in that, In step S4, the temperature of the drying is 100-110℃, the drying time is 8-12 h; the powder grinding is performed until the specific surface area of the obtained high titania slag micro-powder is 500±20 m 2 / kg.

7. The preparation method according to claim 1, characterized in that, It also includes step S5: drying the filtrate obtained from step S3 by pressure filtration to obtain carbonized byproducts.

8. The preparation method according to claim 7, characterized in that, The carbonization byproducts described in step S5 are recycled in step S1 to partially replace the composite alkaline modifier, wherein the carbonization byproducts replace 10% to 30% of the mass of the composite alkaline modifier.

9. A highly active, high-titanium slag powder, characterized in that, Prepared by the method described in any one of claims 1-8.

Images