Cementing material and preparation method thereof

Abstract

The invention provides a cementing material and a preparation method thereof, and belongs to the technical field of cementing materials. The cementing material is prepared from the following raw materials in percentage by mass: 28 to 42 percent of calcium solid waste material, 30 to 42 percent of phosphogypsum and 25 to 30 percent of red mud. According to the invention, by optimizing the types and proportions of the raw materials, on one hand, an all-solid-waste system is constructed, the cementing material with high mechanical properties and high environmental safety can be prepared without correction of other raw materials, and comprehensive resource utilization of industrial solid wastes is realized; on the other hand, a buffer chemical library is formed by constructing a'three-phase buffer-self-steady state 'raw material formula, so that the overall alkalinity coefficient from raw materials to clinker can be kept stable, and production equipment damage, cementing material deterioration or uncontrollable quality caused by adverse components brought by solid waste and extreme pH are avoided. In addition, the requirement of the raw material formula of the cementing material for the calcination temperature is low, the cementing material with high performance can be prepared through low-temperature calcination, and the cementing material is low-carbon and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cementitious materials, and particularly relates to a cementitious material and a preparation method thereof. BACKGROUND

[0002] With the acceleration of industrialization, a large amount of solid waste (referred to as solid waste) is generated, such as carbide slag, red mud, phosphogypsum and the like. The large accumulation of solid waste not only occupies land, but also causes potential harm to the environment, safety and the like. Therefore, it is necessary to vigorously promote the resource utilization of solid waste.

[0003] Cementitious materials are one of the important materials of modern buildings, and the demand is extremely large. The preparation of cementitious materials consumes limestone, bauxite, silicon dioxide and the like, resulting in a large consumption of natural resources.

[0004] Under this situation, the combination of industrial solid waste and the production of cementitious materials not only helps to reduce the amount of solid waste, but also meets the needs of social production, and has high economic benefits.

[0005] However, due to the presence of many adverse components (such as sulfur elements, heavy metal components, and many impurity components) in industrial solid waste, and the great difference in pH, when it is used as a raw material for cementitious materials, it is easy to affect the overall stability of the cementitious system, and the performance of the sintered cementitious material is significantly deteriorated or difficult to control. Therefore, in actual application, it is usually necessary to pretreat the industrial solid waste, and use the industrial solid waste as part of the raw material for the cementitious material when preparing the raw material, and at the same time, by adding other non-solid waste raw materials (such as limestone, bauxite, siliceous materials and the like) to modify the system, so as to improve the performance of the cementitious material. The utilization efficiency of industrial solid waste is low in this application mode, and further breakthrough is needed. SUMMARY

[0006] In view of the technical problems in the background art, the present application provides a cementitious material and a preparation method thereof, aiming to provide a full-solid waste system and a cementitious material with excellent performance.

[0007] In the first aspect, the embodiments of the present application provide a cementitious material, and the raw materials of the cementitious material are composed of 28-42% calcium solid waste material, 30-42% phosphogypsum and 25-30% red mud, in terms of mass percentage.

[0008] In some embodiments, the calcium solid waste material includes at least one of carbide slag, marble waste and limestone waste.

[0009] In some embodiments, the calcium solid waste material is carbide slag.

[0010] In the second aspect, the present application further provides a preparation method of a cementitious material, comprising the following steps: The calcareous solid waste material, phosphogypsum and red mud are respectively ground and treated, and then mixed to obtain raw material; The raw material is calcined to obtain cementitious material; According to the mass percentage, the raw material is composed of 28-42% calcareous solid waste material, 30-42% phosphogypsum and 25-30% red mud.

[0011] In some embodiments, the step of calcining includes heating the raw material to 1150-1200℃ at a heating rate of 5-15 ℃ / min, and calcining for 20-40 min.

[0012] In some embodiments, the step of calcining the raw material to obtain cementitious material includes: The raw material is pressed to obtain pressed material; The pressed material is calcined, and after cooling, it is ground to obtain cementitious material.

[0013] In some embodiments, the pressure of the pressing treatment is 5-10 MPa, and the time is 30-90 s.

[0014] In some embodiments, the specific surface area of the cementitious material is greater than or equal to 300 m 2 / kg.

[0015] In some embodiments, in the step of grinding and treating the calcareous solid waste material, phosphogypsum and red mud respectively, and then mixing to obtain raw material: In some embodiments, the D50 particle size of the raw material is less than 18 microns.

[0016] In some embodiments, the calcareous solid waste material is carbide slag.

[0017] The cementitious material proposed in the embodiments of the present application optimizes the types and proportions of raw materials. On the one hand, a full solid waste system is constructed, and the cementitious material with high mechanical properties and high environmental safety can be prepared without the modification of other raw materials, realizing the comprehensive resource utilization of industrial solid waste. On the other hand, by constructing a raw material formula of "three-phase buffer-self-stable state", a buffer chemical library is formed, so that the overall alkalinity coefficient from raw material to clinker can be kept stable, avoiding the damage of production equipment, the deterioration of cementitious material or the uncontrollable quality caused by adverse ingredients and extreme pH of solid waste. In addition, the raw material formula of the cementitious material proposed in the present application has a low requirement for calcination temperature, and high-quality cementitious material can be prepared by low-temperature calcination, which is low-carbon and environmentally friendly. DETAILED DESCRIPTION

[0018] The embodiments of the present application will be described below in detail. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot be used to limit the protection scope of the present application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the terms "comprising" and "having," and any variations thereof, as used herein are intended to cover a non-exclusive inclusion.

[0020] Various embodiments of the present application can exist in a range of forms; it should be understood that the description in a range form is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the described range has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single values within the described range, such as 1, 2, 3, 4, 5 and 6, which applies to any range. In addition, whenever a numerical range is indicated in this text, it refers to any cited number (fraction or integer) within the indicated range.

[0021] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive or alternative embodiments. It is explicitly contemplated that embodiments described herein can be combined with other embodiments.

[0022] In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this text generally represents an "or" relationship between the associated objects before and after it.

[0023] In the description of the embodiments of the present application, the term "at least one" refers to one or more, "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces). "At least one", "at least one of the following" or the like refers to any combination of these items, including any combination of single item (s) or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can mean a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0024] In a first aspect, the embodiments of the present application propose a cementing material, and the raw material of the cementing material is composed of calcium solid waste material, phosphogypsum and red mud. The mass percentage of the calcium solid waste material is 28-42%, for example, it can be 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42% and a value between any two of the above values. The mass percentage of the phosphogypsum is 30-42%, for example, it can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42% and a value between any two of the above values. The mass percentage of the red mud is 25-30%, for example, it can be 25%, 26%, 27%, 28%, 29%, 30% and a value between any two of the above values.

[0025] The calcium solid waste material, the phosphogypsum and the red mud are all common industrial solid wastes, which are produced in large quantities in industrial production. The calcium solid waste material refers to a material with calcium compounds as the main component in industrial solid waste, for example, it can include but is not limited to at least one of carbide slag, marble waste and limestone waste. Further, the carbide slag is an industrial waste residue with calcium hydroxide (Ca(OH)2) as the main component obtained by hydrolyzing calcium carbide when preparing acetylene gas. The red mud is a red muddy waste produced in the production process of aluminum oxide, and the main components include aluminum oxide, iron oxide, etc. The phosphogypsum is a byproduct produced in the production process of phosphate fertilizer, and the main component is calcium sulfate.

[0026] However, the red mud is alkaline and rich in heavy metals, which can affect the performance of cementitious materials and have environmental hazards; the phosphogypsum contains a large amount of impurities and has strong acidity (pH about 3-4), which can easily corrode equipment, shorten the service life of equipment, affect the quality of cementitious materials, and cause the strength of the material to decrease; the calcium solid waste material, such as carbide slag (pH about 10-12), contains a large amount of sulfur and halogen elements and other fluxing elements, which can easily cause problems such as skinning in the kiln. Moreover, the pH of the three is quite different, and if they are randomly mixed into the traditional Portland or sulphoaluminate cementitious system, the balance of the system can be easily destroyed, leading to a significant decrease in product performance. These obstacles limit the application of industrial solid waste in cementitious materials, making it difficult to achieve a cementitious system that takes into account both high performance and full solid waste.

[0027] To this end, the technical solution proposed in this application breaks through the traditional raw material selection concept and coordination mechanism. By optimizing the proportion of calcium solid waste material, phosphogypsum, and red mud, a system that couples acid and base and induces crystal phase is established, and a cementitious material based on full solid waste components is successfully prepared. This cementitious material has high strength and low calcination temperature requirements, which improves the utilization efficiency of industrial solid waste, reduces the cost, energy consumption, and carbon emissions of product production, and also takes into account the high quality of the product. Specifically: (1) The cementitious material formula proposed in this application can form a ternary eutectic point to generate cement mineral phases. The alkaline environment provided by red mud and calcium solid waste material can in-situ neutralize the free acid and trace heavy metals such as fluorine and magnesium in phosphogypsum. The heavy metal elements can be embedded in the crystal structure of clinker during the firing process, which increases the degree of crystal hybridization and improves the hydration activity. At the same time, the chemical solidification of toxic and harmful heavy metals in solid waste is achieved, thereby significantly improving the mechanical properties, durability, and environmental safety of the cementitious material.

[0028] (2) In the production of cementitious materials, the pH of raw materials and clinker has a great impact on the production system and the product. If the alkalinity of the raw material is too high, it can easily lead to the early appearance of liquid phase and skinning in the kiln, product clumping, and failure to fire specific crystal phases. If the acidity of the raw material is too high, it can easily corrode equipment and cause calcium sulfate to decompose too early, causing SO3 to escape prematurely and reducing the generation rate of C4A3Š phase, which in turn affects product performance. At the same time, if the pH control is unstable, such as pH drift during calcination, it can easily cause the crystal type to change from β-C2S to γ-C2S, causing volume expansion. By mixing the three components with different acid-base properties in a specific ratio, a "three-phase buffer-self-stable" system is formed, which can form a buffer chemical library inside, so that the overall alkalinity coefficient from raw materials (the pH of raw materials can be stabilized in the range of 12-13) to clinker (the pH of clinker can be stabilized in the range of 9-10) can remain stable, thereby inhibiting mineral phase abnormalities, product performance fluctuations, and avoiding equipment corrosion or skinning.

[0029] Acidic reservoir: CaSO4·2H2O from phosphogypsum, soluble P2O5, and F - , consume free Ca(OH)2in the initial heating stage: Ca(OH)2+ H⁺ → Ca²⁺ + H2O↑ (pH drop buffer) Basic reservoir: Ca(OH)2, NaOH, KOH in carbide slag and red mud, release OH⁻when SO3, Al2O3are dissolved: OH⁻+ HSO4⁻ → SO4²⁻ + H2O (pH rise buffer) (3) With the help of the synergistic system, the requirement for calcination temperature is reduced, so that the raw material based on the above formula can realize the massive conversion of phosphogypsum in the low temperature range of 1150~1200℃, and the calcium sulfate does not decompose, effectively preventing the massive decomposition and volatilization of pollutants such as sulfurized gas, significantly reducing energy consumption and carbon emissions, and being low-carbon and environmentally friendly.

[0030] Further, as a preferred embodiment, the mass percentage content of the calcareous solid waste material in the raw material is controlled to be 32~38%, and the mass percentage content of the phosphogypsum is controlled to be 33~39%. When the proportion of each component is controlled within the above range, it is helpful to further improve the mechanical properties of the cementitious material.

[0031] Further, as a preferred embodiment, the calcareous solid waste material can be carbide slag, that is, the raw material of the cementitious material is composed of 28~42% carbide slag, 30~42% phosphogypsum, and 25~30% red mud. Compared with marble and limestone, carbide slag is more suitable for being matched with phosphogypsum and red mud to form an acid-base buffer system.

[0032] In a second aspect, the application further provides a preparation method of the cementitious material, which comprises the following steps: S10, the calcareous solid waste material, phosphogypsum and red mud are respectively ground and treated, and then mixed to obtain a raw material; wherein, according to the mass percentage, the raw material is composed of 28~42% calcareous solid waste material, 30~42% phosphogypsum and 25~30% red mud.

[0033] S20, the raw material is calcined to obtain a cementitious material.

[0034] Through the above method, large-scale, high-value and harmless utilization of solid waste can be realized, and a cementitious material with high performance can be prepared.

[0035] In step S10, The calcareous solid waste material can include but is not limited to at least one of carbide slag, marble waste and limestone waste, and is preferably carbide slag.

[0036] Before mixing the three components, the components can be separately ground into powder to improve the mixing effect and promote in-situ neutralization. Specifically, after grinding, the size of each component is controlled to be: the D50 particle size of the raw material is less than 18 microns.

[0037] Further, in some embodiments, the step of calcining comprises: heating the raw material to 1150-1200℃ at a heating rate of 5-15℃ / min, and calcining for 20-40 min. Wherein, the heating rate can be 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, 15℃ / min and a value between any two of the above values; the calcination temperature can be 1150℃, 1160℃, 1170℃, 1180℃, 1190℃, 1200℃ and a value between any two of the above values; the calcination time can be 20 min, 25 min, 30 min, 35 min, 40 min and a value between any two of the above values. It can be understood that the starting temperature of the heating stage can be room temperature or the current temperature of the production site, for example, it can be 10-40℃, etc. Further, as a preferred embodiment, the calcination temperature can be 1180-1200℃, which is more conducive to the reaction of the raw material and improves the product quality.

[0038] The calcination temperature required by the preparation method of the present application is relatively low, and a large amount of phosphogypsum can be converted in the low temperature range of 1150-1200℃, and the calcium sulfate does not decompose, effectively preventing the decomposition and volatilization of a large amount of pollutants such as sulfurized gas, significantly reducing energy consumption and carbon emissions, and being low-carbon and environmentally friendly.

[0039] Further, in some embodiments, step S20 can be implemented as follows: S21, the raw material is pressed to obtain a pressed material; S22, the pressed material is calcined, and after cooling, the calcined material is ground to obtain a cementitious material.

[0040] In the present application, the raw material is pressed into a cake, and the pressing process is used to promote close contact and pre-neutralization reaction of the material at the microscale, thereby activating the inherent acid-base coupling mechanism, achieving active adjustment and dynamic balance of the system pH value, and inhibiting abnormal mineral phase, equipment skinning and performance fluctuations caused by local over-acid / base during the heating stage.

[0041] Specifically, in step S21, the pressure of the pressing treatment can be 5-10 MPa, and the time can be 30-90 s.

[0042] In step S22, the cooling step comprises: after calcination is completed, the calcined clinker is transferred to room temperature for rapid cooling.

[0043] Further, in some embodiments, the calcined clinker is ground in step S22 to regulate its size, and the specific surface area of the cementitious material is controlled to be greater than or equal to 300 m 2 / kg.

[0044] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application and cannot be understood as limiting the present application. If a specific technology or condition is not specified in the examples, the technology or condition described in the literature in the art or according to the product manual is used. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained on the market.

[0045] Example 1 (1) According to the mass percentage, take 35% of carbide slag, 36% of phosphogypsum, and 29% of red mud, respectively, for use. The carbide slag, phosphogypsum, and red mud are ground respectively, and the D50 particle size of the three solid waste powders is controlled to be less than 18 microns. The three powders are mixed uniformly to obtain a mixed raw material.

[0046] (2) The mixed raw material is pressed under a pressure of 8 MPa for 30 s to obtain a cake-shaped pressed material, which is then calcined at a low temperature of 1200°C for 30 min. After the end of the calcination, it is quickly transferred to a room temperature environment (about 25°C) for cooling to obtain a clinker.

[0047] (3) The clinker is ground to a specific surface area of 300 m 2 / kg to obtain a full-solid-waste-based cementitious material powder.

[0048] Example 2 The scheme of this example is basically the same as that of Example 1, except that in this example, the formula of the raw material is: 32% of carbide slag, 40% of phosphogypsum, and 28% of red mud. Except for this, the other steps and conditions remain unchanged.

[0049] Example 3 The scheme of this example is basically the same as that of Example 1, except that in this example, the carbide slag is replaced by a combination of carbide slag and marble waste, and the total mass percentage of the carbide slag and the marble waste is 35%. According to the CaO content, the amount of the carbide slag is equal to that of the marble waste. Except for this, the other steps and conditions remain unchanged.

[0050] Example 4 The scheme of this example is basically the same as that of Example 1, except that in this example, the carbide slag is replaced by a combination of carbide slag and marble waste, and the total mass percentage of the carbide slag and the marble waste is 35%. According to the CaO content, the amount of the carbide slag is equal to that of the marble waste. Except for this, the other steps and conditions remain unchanged.

[0051] Example 5 The scheme of this example is basically the same as that of Example 1, except that the temperature of calcination is changed to 1170℃ in this example. Other steps and conditions remain unchanged.

[0052] Example 6 The scheme of this example is basically the same as that of Example 1, except that the temperature of calcination is changed to 1200℃ and the calcination time is changed to 20 min in this example. Other steps and conditions remain unchanged.

[0053] Example 7 The scheme of this example is basically the same as that of Example 1, except that the step of pressing is removed in this example, i.e. step (2) is replaced by “low-temperature calcination at 1200℃ for 30 min, and then quickly transferred to room temperature environment for cooling after the end of calcination to obtain clinker”. Other steps and conditions remain unchanged.

[0054] Comparative Example 1 The scheme of this comparative example is basically the same as that of Example 1, except that the formula of raw material is changed to: carbide slag 31%, phosphogypsum 50%, red mud 19% in this comparative example. Other steps and conditions remain unchanged.

[0055] Comparative Example 2 The scheme of this comparative example is basically the same as that of Example 1, except that the formula of raw material is changed to: carbide slag 42%, phosphogypsum 38%, red mud 20% in this comparative example. Other steps and conditions remain unchanged.

[0056] Comparative Example 3 The scheme of this comparative example is basically the same as that of Example 1, except that the formula of raw material is changed to: carbide slag 25%, phosphogypsum 40%, red mud 35% in this comparative example. Other steps and conditions remain unchanged.

[0057] Comparative Example 4 The scheme of this comparative example is basically the same as that of Example 1, except that the temperature of calcination is changed to 1130℃ in this comparative example. Other steps and conditions remain unchanged.

[0058] Comparative Example 5 The scheme of this comparative example is basically the same as that of Example 1, except that the temperature of calcination is changed to 1240℃ in this comparative example. Other steps and conditions remain unchanged.

[0059] Comparative Example 6 The scheme of the present comparative example is basically the same as that of Example 1, except that in the present comparative example, the raw material formulation is: carbide slag 25 parts, phosphogypsum 40 parts, red mud 35 parts, and silicon dioxide 20 parts. Except for this, the other steps and conditions are unchanged.

[0060] Comparative Example 7 The scheme of the present comparative example is basically the same as that of Example 1, except that in the present comparative example, the raw material formulation is: carbide slag 25 parts, phosphogypsum 90 parts, and red mud 35 parts. Except for this, the other steps and conditions are unchanged.

[0061] Comparative Example 8 The scheme of the present comparative example is basically the same as that of Example 1, except that in the present comparative example, the raw material formulation is: carbide slag 25 parts, phosphogypsum 40 parts, and red mud 85 parts. Except for this, the other steps and conditions are unchanged.

[0062] Comparative Example 9 The scheme of the present comparative example is basically the same as that of Example 1, except that in the present comparative example, the raw material formulation is: carbide slag 25 parts, phosphogypsum 40 parts, red mud 35 parts, and sodium hydroxide 10 parts. Except for this, the other steps and conditions are unchanged. The product fired in the present comparative example has a serious problem of expansion and frosting.

[0063] Comparative Example 10 The scheme of the present comparative example is basically the same as that of Example 1, except that in the present comparative example, the raw material formulation is: carbide slag 25 parts, phosphogypsum 40 parts, red mud 35 parts, and sulfuric acid 5 parts. Except for this, the other steps and conditions are unchanged. The product fired in the present comparative example has almost no mineral composition of cement.

[0064] Experimental Example The raw material pH, clinker pH, and 3d compressive strength of the products of each example and comparative example were detected, and the results are recorded in Table 1. The detection method is as follows: pH: tested by a pH meter; 3d compressive strength: the high-quality cementitious material powder was added with water at a liquid-solid ratio of 0.2, and after curing for 3d under standard curing conditions, the compressive strength was detected according to the detection method provided in GB / T 37125-2018.

[0065] Table 1

[0066] Result analysis: (1) The 3D compressive strength of the products of each embodiment is stable at 45.8-55.4 MPa, all reaching the compressive strength index in the national standard of sulphoaluminate cement clinker (GB / T 37125-2018), meeting the engineering requirements, and being much higher than the compressive strength of the products of Comparative Examples 1-3, indicating that the formula proposed in the application can build the optimal matching of industrial solid wastes, improving the utilization efficiency of industrial solid wastes while taking into account the high quality of the products; when the proportion of the three solid wastes is too large or too small (such as the formula of Comparative Examples 1-3), the system balance will be destroyed, leading to a sharp decrease in the compressive strength. Further, by comparing Example 1 and Comparative Example 6, it can be seen that the compressive strength of Comparative Example 6 has decreased significantly, which may be because the formula is designed based on the design concept of acid-base coupling and crystal phase induction synergistic effect, and does not rely on simple element composition or compound composition. In this case, the addition of any exogenous siliceous raw material will block the acid-base coupling and crystal phase induction synergistic effect established among phosphogypsum, red mud and calcareous raw materials, and instead lead to a decrease in product performance.

[0067] (2) In Examples 1, 5 and 6 and Comparative Examples 4 and 5, the products of the three examples all exhibit better strength, while Comparative Examples 4 and 5 are extremely poor, indicating that the formula provided in the application can realize mineral phase formation in a lower temperature range (1150-1200℃) and a shorter time, and prepare a high-performance cementitious material; at the same time, due to the lower firing temperature and shorter firing time, energy consumption and carbon emissions are reduced, and at the same time, calcium sulfate is not easy to decompose in this temperature range, which inhibits the generation of pollutants such as sulfide gas, and helps to achieve low-carbon environmental protection.

[0068] (3) The raw material pH of each example is basically stable at 12-13, and the clinker pH is basically stable at 9-10, all showing extremely stable pH transition, and in Comparative Examples 1-3 and Comparative Examples 7 and 8, the pH can also be stable in the above range, indicating that the formula proposed in the application can build an acid-base buffer system, and even if the addition amount of each component increases or decreases, the pH stability can be maintained, and at least the overall alkalinity coefficient from raw material to clinker can be kept stable; on the contrary, when a strong acid or a strong base is used to forcibly break the buffer system (for example, Comparative Examples 9 and 10), the pH drifts obviously during the firing process, and the product prepared has problems such as disappearance of mineral phases required by cement, product expansion, frosting, etc., indicating that by maintaining the pH stability, the application can overcome the damage caused by the adverse components and extreme pH of industrial solid wastes, such as avoiding damage to production equipment and deterioration of product cementitious materials.

[0069] (4) The compressive strength of Example 1 is higher than that of Example 7, indicating that the compression treatment of the raw material before firing helps to improve the performance of the product, which may be because one of the mechanisms of the present formulation is the acid-base coupling of the three acid-base components. Compression treatment can promote close contact and pre-neutralization reaction of the material at the microscale, thereby activating its inherent acid-base coupling mechanism.

[0070] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration as the technical idea and exerting the same effects within the scope of the technical solution of the present application are included in the technical scope of the present application. Furthermore, within the scope of the gist of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the configuration elements of the embodiments are also included in the scope of the present application.

Claims

1. A cementitious material, characterized in that, The raw materials of the cementitious material, by mass percentage, consist of 28-42% calcareous solid waste material, 30-42% phosphogypsum and 25-30% red mud.

2. The cementitious material according to claim 1, characterized in that, The calcareous solid waste material includes at least one of carbide slag, marble waste, and limestone waste.

3. The cementitious material according to claim 2, characterized in that, The calcium-based solid waste material is carbide slag.

4. A method for preparing the cementitious material according to any one of claims 1 to 3, characterized in that, Includes the following steps: Calcareous solid waste materials, phosphogypsum, and red mud are ground separately and then mixed to obtain raw materials; The raw materials are calcined to obtain a cementitious material; The raw material, by mass percentage, consists of 28-42% calcareous solid waste, 30-42% phosphogypsum, and 25-30% red mud.

5. The preparation method according to claim 4, characterized in that, The calcination step includes: heating the raw material to 1150-1200℃ at a heating rate of 5-15℃ / min and calcining for 20-40 min.

6. The preparation method according to claim 4, characterized in that, The step of calcining the raw materials to obtain the cementitious material includes: The raw material is pressed to obtain pressed material; The pressed material is calcined, cooled, and then ground to obtain a gelling material.

7. The preparation method according to claim 6, characterized in that, The pressing process is performed at a pressure of 5-10 MPa for 30-90 seconds.

8. The preparation method according to claim 4, characterized in that, The specific surface area of ​​the cementitious material is greater than or equal to 300 m² 2 / kg.

9. The preparation method according to claim 4, characterized in that, In the step of grinding calcareous solid waste materials, phosphogypsum, and red mud separately and then mixing them to obtain raw materials: The D50 particle size of the raw materials is less than 18 micrometers.

10. The preparation method according to claim 4, characterized in that, The calcium-based solid waste material is carbide slag.

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