Method for preparing Portland cement clinker raw material by synergistically carbonizing Bayer process red mud and electrolytic manganese residues at normal temperature, carbonized material and application of carbonized material

Abstract

The invention provides a method for preparing a Portland cement clinker raw material through normal-temperature synergistic carbonization of Bayer process red mud and electrolytic manganese residues, a carbonized material and application of the carbonized material. The method comprises the following steps: mixing Bayer process red mud, electrolytic manganese residues and water, and adding an alkaline material into the mixture; introducing COtail gas into the mixed system under a stirring condition, and stirring to react; filtering the reaction liquid; and drying the solid substance to obtain the Portland cement clinker raw material. The technical problem to be solved is how to synchronously solve the problem of alkali precipitation caused by high free alkali of Bayer process red mud and the harm of ammonia nitrogen release and excessive sulfate radicals of electrolytic manganese residues, meanwhile, resource utilization of industrial CO-rich tail gas is achieved, and a product meeting the requirements of raw material components of Portland cement clinker is prepared. Furthermore, the dependence of the cement industry on natural mineral resources is reduced, the synergistic goal of solid waste reduction, COemission reduction and cement raw material substitution is achieved, and the treatment energy consumption and cost are reduced through a normal-temperature process, so that the method is more suitable and practical.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a method for preparing silicate cement clinker raw materials by room temperature synergistic carbonization of Bayer process red mud and electrolytic manganese slag, the carbonization materials and their applications. Background Technology

[0002] With rapid economic growth, the industrial demand for manganese and aluminum continues to increase. However, the extraction of these two materials generates a large amount of solid waste, such as Bayer red mud and electrolytic manganese slag. Therefore, in order to ensure the healthy and sustainable development of these two industries, it is urgent to find a safe and effective way to utilize their resources.

[0003] Bayer process red mud is a solid waste product generated after alumina extraction from bauxite using the Bayer process. Its main components include silica, iron minerals, sodium hydroxide, and potassium hydroxide, and its most notable characteristic is its high free alkali content. In current resource utilization processes, the high alkali nature of Bayer process red mud easily leads to alkali precipitation in building materials, manifesting as surface whitening and a loose internal structure. This directly affects the long-term durability and mechanical properties of the products, severely limiting its application in mainstream building materials such as cement and concrete.

[0004] Electrolytic manganese slag is a waste residue generated during the electrolytic preparation of metallic manganese. Its components include gypsum dihydrate, manganese sulfate, and a certain amount of ammonia. If electrolytic manganese slag is used directly as a cement raw material, the ammonia nitrogen in it is easily released into gas during cement preparation and curing, causing pores inside the cement clinker or finished product and leading to a decrease in early strength. At the same time, excessive sulfate substances may react with hydration products in cement, causing volume expansion and further affecting the stability of cement-based materials.

[0005] In addition, industrial production processes generate a large amount of CO2-rich exhaust gas (such as cement kiln and steel plant exhaust gas). The existing treatment methods for such exhaust gas are mainly direct emission or single capture, lacking an effective path to deeply integrate with solid waste resource utilization, and failing to simultaneously achieve the multiple goals of solid waste reduction, resource substitution and CO2 emission reduction. Summary of the Invention

[0006] The main objective of this invention is to provide a method for preparing silicate cement clinker raw materials by room-temperature co-carbonization of Bayer process red mud and electrolytic manganese slag, as well as the carbonization materials and their applications. The technical problem to be solved is how to simultaneously address the problem of alkali precipitation caused by high free alkali in Bayer process red mud and the hazards of ammonia nitrogen release and excessive sulfate from electrolytic manganese slag, while realizing the resource utilization of industrial CO2-rich tail gas, and preparing products that meet the composition requirements of silicate cement clinker raw materials. This reduces the cement industry's dependence on natural mineral resources, achieving the synergistic goals of solid waste reduction, CO2 emission reduction, and cement raw material substitution. Furthermore, the room-temperature process reduces energy consumption and costs, making it more suitable for practical application.

[0007] The objective of this invention and the technical problem it solves are achieved by the following technical solution. A method for preparing silicate cement clinker raw materials by co-carbonization of Bayer process red mud and electrolytic manganese slag, according to this invention, includes the following steps: S1 mixes Bayer process red mud, electrolytic manganese slag and water, and adds alkaline materials to it; S2 introduces CO2 tail gas into the mixed system under stirring conditions and stirs the reaction; S3 filters the reaction liquid; the solid material is dried to obtain carbonized material, which is the raw material for silicate cement clinker.

[0008] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0009] Preferably, in the method, the mass ratio of Bayer red mud to electrolytic manganese slag is 2~9:1; the water-solid mass ratio is 5~10:1.

[0010] Preferably, in the method, the alkaline material is selected from at least one of lime, ammonia, sodium hydroxide, and potassium hydroxide; the amount of alkaline material added is 1% to 8%, with the mass of Bayer red mud and electrolytic manganese slag being 100%.

[0011] Preferably, in the method, the CO2 exhaust gas is CO2-rich waste gas from cement kilns, steel plants, and / or power plants; the reaction time is 0.5 to 6 hours.

[0012] Preferably, in the method, the reaction is carried out at room temperature.

[0013] The objective of this invention and the technical problem it solves are achieved by the following technical solution. A carbonized material prepared according to the aforementioned method, based on this invention, comprises calcium carbonate, iron-based compounds, silicon dioxide, and gypsum dihydrate as its main chemical components; the free alkali content in the carbonized material is ≤0.5% (based on Na2O); the ammonia nitrogen residue in the carbonized material is ≤0.1% (based on NH4⁺); and the sulfate content in the carbonized material is ≤8% (based on SO4²⁻).

[0014] The objective of this invention and the technical problem it solves are achieved through the following technical solution. An application of the aforementioned carbonized material according to this invention includes the following steps: S1 mixes the carbonized material with limestone, sandstone, and wet ash to obtain silicate cement raw meal; S2 is calcined; after cooling, it is ground to obtain silicate cement clinker; the clinker includes tricalcium silicate, dicalcium silicate, tetracalcium aluminoferrite and tricalcium aluminate; the clinker has the following ratio values: KH is 0.72~0.95, SM is 1.7~2.3 and IM is 1.0~1.4.

[0015] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0016] Preferably, in the application, the calcination is carried out by heating to 1250-1450°C at a rate of 5-50°C / min and holding at that temperature for 0.1-1 h; the cooling is air cooling.

[0017] Preferably, in the application, the grinding is performed to make the specific surface area of ​​the clinker 200-400 m2 / kg.

[0018] Preferably, in the application, 3.5% by weight of gypsum dihydrate is added to the clinker, and the compressive strength is tested according to the method of GB / T17671-2021; the 3-day compressive strength is ≥25MPa, and the 28-day compressive strength is ≥52MPa.

[0019] By employing the above technical solution, the method for preparing silicate cement clinker raw materials by room-temperature synergistic carbonization of Bayer process red mud and electrolytic manganese slag, the carbonization materials, and their applications proposed in this invention have at least the following beneficial effects: The present invention discloses a method for preparing silicate cement clinker raw materials by room-temperature co-carbonization of Bayer process red mud and electrolytic manganese slag. This method utilizes a core process combination of mixing red mud and manganese slag with water and adding alkaline materials, stirring, introducing CO2 exhaust gas, and filtering and drying. This combination achieves multiple technical benefits: firstly, it simultaneously disposes of Bayer process red mud and electrolytic manganese slag, reducing the environmental pressure of solid waste storage, while simultaneously utilizing CO2 exhaust gas as a resource, reducing carbon emissions and aligning with carbon peaking and carbon neutrality policies; secondly, the reaction can be completed at room temperature, eliminating the need for... Additional heating significantly reduces energy consumption, and the alkaline materials promote the dissolution efficiency of CO2 in water, accelerating the conversion of gypsum in manganese slag to calcium carbonate and the dissolution of potassium and sodium in red mud. This solves the problem of cement porosity defects caused by ammonia release from manganese slag and eliminates the hidden danger of red mud alkali precipitation affecting the long-term durability of cement. The final product obtained through filtration and drying can be directly used as a raw material for cement clinker, providing a simple and feasible technical path for solid waste resource utilization and industrial emission reduction. The carbonized materials prepared by the above method are characterized by containing calcium carbonate, iron-based compounds, and other components. The composite composition of silica and gypsum dihydrate features low free alkali, low ammonia nitrogen, and low sulfate, giving it a key advantage in cement clinker production. On one hand, its calcium carbonate, iron-based compounds, and silica can be used as calcium, iron, and silicon raw materials required for cement clinker, respectively, without additional purification, providing the cement industry with a new source of raw materials and reducing dependence on natural minerals. On the other hand, the characteristics of low free alkali, low ammonia nitrogen residue, and low sulfate can avoid the decrease in durability caused by alkali precipitation and the porosity defects caused by ammonia release during cement preparation, ensuring the stability of subsequent cement products and meeting the basic requirements of silicate cement clinker for raw material purity and performance. When the aforementioned carbonized material is applied to the preparation of silicate cement clinker, the process of mixing the carbonized material with limestone, sandstone, and wet ash to form raw meal, followed by calcination, cooling, and grinding, allows the calcium, silicon, and iron components in the carbonized material to be efficiently compatible with other raw materials. After calcination, key cement clinker minerals such as tricalcium silicate, dicalcium silicate, tetracalcium aluminoferrite, and tricalcium aluminate are formed, and the clinker yield values ​​(KH, SM, IM) meet the basic requirements of ordinary silicate cement, ensuring that the clinker has qualified cementitious properties. Moreover, the entire application process does not require significant modifications to the existing cement production process, and industrial solid waste derivatives can be integrated into the traditional process. This not only expands the sources of cement raw materials but also indirectly reduces carbon emissions and natural resource consumption in the cement industry through the early resource utilization of solid waste and CO2, taking into account both practicality and environmental protection.

[0020] Furthermore, through the optimization of the production process, the clinker prepared by the method of this invention can achieve a specific surface area of ​​200-400 m² / kg, a 3-day compressive strength ≥25 MPa, and a 28-day compressive strength ≥52 MPa, meeting the strength requirements of cement mortar. At the same time, due to the resource utilization of solid waste and waste CO2, the consumption of natural resources, carbon emissions, and sulfur emissions in the cement industry can be further reduced, promoting the development of the cement industry towards a circular economy and energy conservation and carbon reduction.

[0021] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0022] Figure 1 These are XRD patterns of carbonization products of manganese slag, manganese slag and red mud mixture under different water-cement ratios and ammonia contents. Figure 2 This is the XRD pattern of cement clinker prepared from carbonized materials. Detailed Implementation

[0023] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the appendix and preferred embodiments, details the method for preparing silicate cement clinker raw materials by room-temperature synergistic carbonization of Bayer process red mud and electrolytic manganese slag, the carbonization materials and their applications, and their specific implementation methods and effects. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, the results of one or more embodiments can be combined in any suitable manner. These embodiments are provided to make the invention thorough and complete, and to fully express the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions and values ​​described in these embodiments should be interpreted as merely exemplary and not as limiting.

[0024] This invention proposes a method for preparing silicate cement clinker raw materials through the co-carbonization of Bayer process red mud and electrolytic manganese slag. It achieves co-treatment of solid waste and preparation of silicate cement clinker raw materials through three steps: mixing, carbonization, and separation. The core principle is to utilize an alkaline environment to promote CO2 resource utilization and eliminate solid waste defects. Specifically, it includes the following steps: First, the raw materials are mixed and an alkaline environment is constructed. In some specific embodiments of the present invention, two types of solid waste are preferably weighed at a mass ratio of Bayer process red mud to electrolytic manganese slag of 2-9:1 and added to a stirred reactor. Industrial water is added, and the water-to-solid mass ratio is controlled at 5-10:1. Stirring is started to fully disperse the solid waste. Then, an alkaline material is added, which can be selected from at least one of lime, ammonia, sodium hydroxide, and potassium hydroxide, as long as it can construct an alkaline environment to promote the carbonization reaction. Ammonia is preferred to complement the synergistic effect of ammonia in manganese slag. The amount added is 1%-8% of the total mass of red mud and manganese slag. Stirring is continued until the system is homogeneous to obtain a mixed solution. The water-to-solid ratio is set to 5-10:1 to ensure that the solid waste particles are fully suspended and to avoid incomplete local reactions. The alkaline material increases the pH value of the solution, which can significantly increase the solubility of CO2 in water, generating HCO3⁻ and CO3²⁻. At the same time, the potassium and sodium in the red mud and the ammonia in the manganese slag can help enhance the alkalinity, forming a synergistic catalytic system of exogenous and endogenous alkali. The above-mentioned technical design can effectively solve the problem of low reactivity of single solid waste, creating an efficient environment for subsequent CO2 carbonization reaction; by dispersing solid waste materials evenly, the solution is alkaline and stable, with no obvious precipitation or stratification, thus creating conditions for subsequent carbonization reaction. Then comes the room-temperature stirring carbonization reaction. In some specific embodiments of the present invention, it is preferred to keep the reactor at room temperature, the temperature is not particularly limited, and no additional heating is required. Concentrated CO2 waste gas is continuously introduced through the gas distributor at the bottom of the reactor. The flow rate of CO2 waste gas can be adaptively adjusted according to the volume of the reactor. At the same time, stirring is maintained to ensure that the gas, liquid, and solid phases in the system can be fully contacted. The present invention preferably lasts for 0.5 to 6 hours for the carbonization reaction. The longer the carbonization time, the higher the proportion of dihydrate gypsum in the manganese slag converted into calcium carbonate and the less residual dihydrate gypsum. The carbonization reaction mechanism described above is as follows: At room temperature, CO3²⁻ and HCO3⁻ in the alkaline solution react with Ca²⁺ from gypsum dihydrate in the manganese slag to form calcium carbonate (CaSO4・2H2O + CO2 + 2OH⁻ → CaCO3↓ + SO4²⁻ + 3H2O). Simultaneously, potassium and sodium (Na⁺, K⁺) in the red mud react with SO4²⁻ in the solution to form soluble salts. Ammonia (NH3) in the manganese slag reacts with CO2 to form NH4HCO3, further promoting CO2 dissolution. Stirring breaks up the gas film resistance, preventing CO2 accumulation on the liquid surface and improving carbonization efficiency. To further improve carbonization efficiency, this invention preferably concentrates the CO2 waste gas before the carbonization reaction, preferably with a CO2 concentration of over 50%. The above-mentioned technical design can simultaneously realize CO2 resource utilization, conversion of manganese slag gypsum into calcium raw materials for cement, and red mud alkali removal (potassium and sodium dissolve in water), avoiding the increase in energy consumption caused by high-temperature reaction; during the reaction process, ammonia is fully utilized, there is no odor, the solution gradually becomes turbid and white calcium carbonate precipitate is formed, and the pH of the system decreases after the reaction is completed, indicating that CO2 is fully absorbed. Finally, filtration, drying, and raw material molding are performed. In some specific embodiments of the present invention, it is preferable to stop aeration and stirring, filter the reacted slurry to separate the solids and filtrate. The filtrate contains soluble potassium and sodium salts, which can be further recovered or discharged in compliance with standards; this invention does not specifically limit this step. The filter cake is placed in a hot air drying oven and dried at 80-100°C for 2-3 hours to obtain dried carbonized material, which is a directly usable silicate cement clinker raw material. The above filtration removes water-soluble potassium and sodium, trace amounts of unreacted ammonia, and sulfate ions, thereby reducing the content of harmful impurities in the product. Drying removes free moisture to prevent clumping during subsequent raw material preparation. By purifying the carbonized material, the present invention ensures its stable composition and meets the requirements of cement raw materials for moisture and impurities. The carbonized material obtained by the above technical solution is a light gray powder with no obvious clumping and uniform particle size, which can be directly used for the next step of raw material preparation.

[0025] This invention also proposes a carbonized material prepared according to the aforementioned method, the main chemical components of which include calcium carbonate from gypsum carbonization, iron-based compounds from red mud, silica from red mud, and gypsum dihydrate residue from incomplete carbonization; through the filtration process settings and reaction parameter control in the carbonized material preparation method, most of the potassium and sodium in the red mud are removed with the filtrate, and the free alkali content calculated as Na2O is ≤0.5%; ammonia participates in the CO2 reaction or dissolves in the filtrate, and the ammonia nitrogen residue calculated as NH4⁺ is ≤0.1%; after the gypsum is converted into calcium carbonate, the sulfate ions dissolve in the filtrate, and the sulfate ion content calculated as SO4²⁻ is ≤8%. The low free alkali characteristic of the carbonized material of this invention can avoid alkali precipitation during the subsequent cement hardening process, thereby preventing whitening of the material surface and reduction in strength; the low ammonia nitrogen residue characteristic can prevent the generation of air bubbles in the cement paste, avoiding pore defects; the low sulfate characteristic can prevent the reaction with tricalcium aluminate in cement to generate excessive ettringite, thereby preventing volume expansion; this carbonized material meets the composition requirements of ordinary silicate cement clinker for calcium (provided by calcium carbonate), silicon (provided by silicon dioxide), and iron (provided by iron-based compounds), and can be used directly without additional purification, replacing approximately 10% of the amount of natural limestone. This invention also proposes an application of the aforementioned carbonized material in the preparation of silicate cement clinker. This process, involving raw meal preparation, calcination, and grinding, transforms the carbonized material into qualified cement clinker. The core principle is to adapt it to existing cement production processes and ensure clinker performance. Specifically, it includes the following steps: The first step is the preparation of raw materials. In some specific embodiments of the present invention, it is preferable to mix carbonized materials with limestone, sandstone, and wet ash in a mass ratio, and then put them into a mixer and stir evenly to obtain silicate cement raw materials. The proportion of each raw material can be adaptively adjusted according to the three ratios of cement clinker to ensure that the ratio of clinker after calcination of raw materials meets the following requirements: KH (ratio of tricalcium silicate to dicalcium silicate) is 0.72~0.95, SM (ratio of silicon to aluminum and iron) is 1.7~2.3, and IM (ratio of aluminum to iron) is 1.0~1.4. Based on the calcium, silicon, and iron content in the carbonized material, limestone is added to supplement calcium, sandstone is added to supplement silicon, and wet ash is added to adjust the aluminum-iron ratio. The four raw materials work together to ensure that the raw meal composition meets the target ratio requirements for clinker sintering. By controlling the ratio, it can be ensured that sufficient tricalcium silicate is generated after calcination to dominate early strength and dicalcium silicate to dominate later strength, while inhibiting the generation of free calcium, thereby avoiding strength reduction. The raw meal obtained by the above proportions can meet the mixing requirements of industrial cement raw meal and can be directly entered into the calcination process.

[0026] In some specific embodiments of the present invention, by analyzing the composition of the carbonized material, the preferred composition by mass percentage is 75-85% limestone, 5-15% sandstone, 0-1% wet ash content, and 6-10% carbonized material.

[0027] Then, the raw materials are calcined and ground. In some specific embodiments of the present invention, calcination is preferably carried out by pressing the raw materials into φ50mm×50mm test blocks (or directly using raw material powder), and placing them in a high-temperature muffle furnace; heating to 1250~1450℃ at a heating rate of 5~50℃ / min and holding for 0.1~1h; after the holding is completed, the blocks are immediately taken out and cooled to room temperature by air cooling to obtain silicate cement clinker blocks. The technical solution of this invention controls the heating rate to 5~50℃ / min to avoid cracking of the test block due to excessive heating rate; 1250~1450℃ is the optimal sintering temperature for cement clinker, which allows CaCO3 in the raw meal to decompose into CaO, and then react with SiO2, Al2O3, and Fe2O3 to generate C3S(3CaO・SiO2), C2S(2CaO・SiO2), C4AF(4CaO・Al2O3・Fe2O3), and C3A(3CaO・Al2O3) (corresponding to the XRD characterization results in Figure 2, the free calcium content is ≤1%); air cooling can rapidly cool it to inhibit the conversion of C3S to C2S, thereby ensuring the clinker strength.

[0028] In some specific embodiments of the present invention, the preferred grinding method is to put the cooled clinker blocks into a ball mill and grind them for 30 to 40 minutes. The specific surface area of ​​the clinker powder is controlled to be 200 to 400 m² / kg by sieving. The purpose of controlling the specific surface area of ​​the clinker to be 200 to 400 m² / kg is to ensure that the hydration rate is moderate when the clinker reacts with water in the future, to avoid cracking caused by excessively rapid early heat release, and to ensure sufficient strength development. According to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)", mortar test blocks were prepared by mixing clinker powder with 3.5% dihydrate gypsum and testing the compressive strength: 3-day compressive strength ≥25MPa, 28-day compressive strength ≥52MPa, which fully meets the strength requirements of ordinary Portland cement clinker (P・I 42.5 grade). As can be seen from the above description, the technical solution of the present invention can form a complete industrial chain of solid waste co-carbonization, raw material preparation and cement application, which can greatly reduce solid waste stockpiling and greenhouse gas emissions; replacing part of the limestone with the above-mentioned carbonization materials can reduce the dependence of cement production on natural minerals; moreover, only room temperature carbonization is required, without heating, saving energy, while solid waste resource utilization reduces raw material costs, which meets the requirements of carbon peaking, carbon neutrality and circular economy policies.

[0029] The present invention will be further described below with reference to specific embodiments, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0030] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0031] The following examples use Bayer process red mud and electrolytic manganese slag for room temperature carbonization, and the carbonization products are used as raw materials to prepare ordinary silicate cement clinker. The Bayer process red mud was sourced from Chinalco Shandong Co., Ltd., the electrolytic manganese slag from Guangxi Southern Manganese Industry, the limestone, sandstone, and wet ash were from Conch Cement Plant, and other reagents were randomly purchased samples from the market.

[0032] The carbonization results of the above-mentioned manganese slag (EMR), red mud (RM), and a mixture of manganese slag in a mass ratio of 3:1 under a water-cement ratio of 5:1, with the addition of 3% and 6% ammonia, were compared for 2 hours. The XRD characterization of the manganese slag raw material and the carbonization products obtained under the above four carbonization conditions is as follows: Figure 1As shown in the attached figures, the carbonization effect of simply carbonizing manganese slag is extremely poor, as indicated by the black and red curves in the figures. However, the carbonization effect of the mixture of red mud and manganese slag is significantly improved after adding red mud, as indicated by the blue and green curves in the figures. Furthermore, after adding red mud, only a small amount of ammonia water is needed to carbonize the gypsum in the manganese slag into calcium carbonate.

[0033] Example 1 1) Preparation of raw materials for silicate cement clinker The mixture consists of 2 parts by weight of Bayer red mud, 1 part by weight of manganese slag, 15 parts by weight of water, and 0.54 parts by weight of ammonia. The specific steps are as follows: Weigh the Bayer red mud and manganese slag; add the weighed Bayer red mud and manganese slag to a reaction vessel, add the measured water and ammonia, stir evenly, and then introduce CO2 tail gas (with a CO2 concentration > 50%) concentrated from a cement kiln, stirring continuously for 2 hours; filter, separate, and dry the prepared mixed slurry to obtain a mixture containing calcium carbonate, iron-based compounds, silica, and gypsum dihydrate, which is the carbonized material.

[0034] Tests showed that the free alkali content in the carbonized material, calculated as Na2O, was 0.2%; the residual ammonia nitrogen, calculated as NH4⁺, was 0.04%; and the sulfate content, calculated as SO4²⁻, was 5%.

[0035] 2) Using the carbonization material of this embodiment as a raw material to prepare silicate cement clinker Weigh the carbonized material, limestone, sandstone, and wet ash according to the formula, and prepare ordinary silicate cement raw meal. The proportions are as follows: 8.9 parts by weight of carbonized material, 79.2 parts by weight of limestone, 11.2 parts by weight of sandstone, and 0.7 parts by weight of wet ash prepared in this embodiment. Press the uniformly mixed raw meal sample into sheets and dry it. Heat it to 1400℃ at a rate of 10℃ / min and keep it at this temperature for 60min to obtain ordinary silicate cement clinker blocks. Cool the ordinary silicate cement clinker blocks with air and then grind them for 30min. The specific surface area of ​​the ground ordinary silicate cement clinker is 380m2 / kg, and ordinary silicate cement clinker powder is obtained.

[0036] The three ratios KH, SM, and IM of the clinker powder prepared in this embodiment were tested and found to be 0.82, 1.82, and 1.17, respectively.

[0037] Appendix Figure 2 This is the XRD pattern of the ordinary silicate cement clinker powder prepared in this embodiment. As can be seen from the pattern, its main components are tricalcium silicate, dicalcium silicate, tetracalcium aluminoferrite, and tricalcium aluminate. The free calcium content is extremely low (almost none), indicating that the cement clinker prepared by this method has good performance, and the carbonized material can be used as a raw material for cement clinker.

[0038] The compressive strength of ordinary silicate cement clinker prepared according to the ISO method (GB / T17671-2021) was determined after mixing with 3.5% dihydrate gypsum. The compressive strength properties at 3d and 28d were 26MPa and 55MPa, respectively.

[0039] Example 2 The preparation of silicate cement clinker raw materials is the same as in Example 1, except that: 3 parts by weight of Bayer red mud, 1 part by weight of manganese slag, 28 parts by weight of water, and 0.2 parts by weight of ammonia water; the carbonization reaction time is 1 hour; and the carbonized material was found to have a free alkali content of 0.3% (calculated as Na2O), ammonia nitrogen residue of 0.03% (calculated as NH4⁺), and sulfate content of 7% (calculated as SO4²⁻).

[0040] The preparation of silicate cement clinker using the carbonized material of this embodiment as raw material is the same as in Example 1, except that the material proportions are as follows: 9 parts by mass of carbonized material, 79.9 parts by mass of limestone, 10.9 parts by mass of sandstone, and 0.2 parts by mass of wet-discharged ash prepared in this embodiment; the heating rate is 5℃ / min; the holding temperature is 1450℃, the holding time is 40min; the grinding time is 40min, and the specific surface area of ​​the ordinary silicate cement clinker after grinding is 400m2 / kg, thus obtaining ordinary silicate cement clinker powder.

[0041] The clinker prepared in this embodiment has three ratios KH, SM, and IM of 0.85, 1.81, and 1.12, respectively, according to the test results.

[0042] The compressive strength of ordinary silicate cement clinker prepared according to the ISO method (GB / T17671-2021) was determined after mixing with 3.5% dihydrate gypsum. The compressive strengths at 3d and 28d were 25MPa and 54MPa, respectively.

[0043] Example 3 The preparation of silicate cement clinker raw materials is the same as in Example 1, except that: 4 parts by weight of Bayer red mud, 1 part by weight of manganese slag, 50 parts by weight of water, and 0.3 parts by weight of ammonia water; the free alkali content in the carbonized material, calculated as Na2O, is 0.2%; the residual ammonia nitrogen, calculated as NH4⁺, is 0.03%; and the sulfate content, calculated as SO4²⁻, is 6%.

[0044] The preparation of silicate cement clinker using the carbonized material of this embodiment as raw material is the same as in Example 1, except that the material proportions are as follows: 8.5 parts by weight of the carbonized material prepared in this embodiment, 79.2 parts by weight of limestone, 12.2 parts by weight of sandstone, and 0.1 parts by weight of wet-discharged ash; the heat preservation temperature is 1450℃; the specific surface area of ​​the ordinary silicate cement clinker after grinding is 380m2 / kg, and ordinary silicate cement clinker powder is obtained.

[0045] The clinker powder prepared in this embodiment had three strength values ​​(KH, SM, and IM) of 0.79, 1.93, and 1.16, respectively. The compressive strength of ordinary silicate cement clinker prepared according to the ISO method (GB / T17671-2021) mixed with 3.5% dihydrate gypsum was determined; the 3-day and 28-day compressive strengths were 27 MPa and 58 MPa, respectively.

[0046] The technical features in the claims and / or specification of this invention can be combined, and the combination is not limited to the combinations obtained through reference in the claims. Technical solutions obtained by combining the technical features in the claims and / or specification are also within the scope of protection of this invention.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing silicate cement clinker raw materials by co-carbonization of Bayer process red mud and electrolytic manganese slag, characterized in that, It includes the following steps: S1 mixes Bayer process red mud, electrolytic manganese slag and water, and adds alkaline materials to it; S2 introduces CO2 tail gas into the mixed system under stirring conditions and stirs the reaction; S3 filters the reaction liquid; the solid material is dried to obtain carbonized material, which is the raw material for silicate cement clinker.

2. The method according to claim 1, characterized in that, The mass ratio of Bayer red mud to electrolytic manganese slag is 2~9:1; the water-solid mass ratio is 5~10:

1.

3. The method according to claim 1, characterized in that, The alkaline material is selected from at least one of lime, ammonia, sodium hydroxide and potassium hydroxide; with the mass of Bayer red mud and electrolytic manganese slag being 100%, the amount of alkaline material added is 1% to 8%.

4. The method according to claim 1, characterized in that, The CO2 exhaust gas is CO2-rich waste gas from cement kilns, steel plants, and / or power plants; the reaction time is 0.5 to 6 hours.

5. The method according to claim 1, characterized in that, The reaction was carried out at room temperature.

6. A carbonized material prepared according to any one of claims 1 to 5, characterized in that, Its main chemical components include calcium carbonate, iron-based compounds, silicon dioxide, and gypsum dihydrate; the free alkali content in the carbonized material is ≤0.5% based on Na2O; the ammonia nitrogen residue in the carbonized material is ≤0.1% based on NH4⁺; and the sulfate content in the carbonized material is ≤8% based on SO4²⁻.

7. An application of the carbonized material according to claim 6, characterized in that, It includes the following steps: S1 mixes the carbonized material with limestone, sandstone, and wet ash to obtain silicate cement raw meal; S2 is calcined; after cooling, it is ground to obtain silicate cement clinker; the clinker includes tricalcium silicate, dicalcium silicate, tetracalcium aluminoferrite and tricalcium aluminate; the clinker has the following ratio values: KH is 0.72~0.95, SM is 1.7~2.3 and IM is 1.0~1.

4.

8. The application according to claim 7, characterized in that, The calcination is carried out by heating to 1250-1450℃ at a rate of 5-50℃ / min and holding at that temperature for 0.1h-1h; the cooling is by air cooling.

9. The application according to claim 7, characterized in that, The grinding process aims to reduce the specific surface area of ​​the clinker to 200-400 m². 2 / kg.

10. The application according to claim 7, characterized in that, Add 3.5% by weight of dihydrate gypsum to the clinker and test its compressive strength according to GB / T 17671-2021; the 3-day compressive strength is ≥25MPa and the 28-day compressive strength is ≥52MPa.

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