Red mud-based cementitious material based on efficient drying-component homogenization-activity enhancement and preparation method

Abstract

The present application belongs to the field of building materials and solid waste resource utilization, and relates to a red mud-based cementing material and a preparation method based on efficient drying-component homogenization-activity promotion. A filter aid is added to the red mud for sedimentation, and then pressure filtration is performed to obtain a solid material with a moisture content of 14-16%, which is then dried to a moisture content of less than 4%, and finally ground to obtain the red mud-based cementing material. The filter aid comprises the following raw materials: 10-30 parts of polyaluminum chloride, 5-15 parts of polyaluminum sulfate, 1000-1200 parts of blast furnace slag or fly ash, 700-900 parts of steel slag, 400-600 parts of carbide slag or alkali slag, and 300-400 parts of desulfurization gypsum or phosphogypsum or fluorogypsum. The present application not only improves the dewatering efficiency of the red mud, but also simplifies the preparation process of the red mud-based cementing material by preparing the red mud-based cementing material in one step, and the prepared red mud-based cementing material has the advantages of high mechanical strength, high durability and erosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of building materials and solid waste resource utilization, and relates to red mud-based cementitious materials and their preparation methods based on efficient drying, component homogenization and activity enhancement. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Currently, red mud is mainly used in the preparation of building materials, soil remediation, and environmental protection. The preparation of cementitious materials is the most effective way to realize the high-value-added utilization of red mud in large quantities. Current research shows that red mud can be prepared into concrete admixtures, grouting materials, and road engineering materials. However, the key obstacle to the large-scale application of red mud lies in its high water content. Red mud in stockpiles has a water content of approximately 30%, while the preparation of cementitious materials requires a water content of less than 4%. Therefore, the problem of red mud dehydration and its high cost have become technical challenges restricting the large-scale engineering application of red mud.

[0004] In terms of red mud dewatering, the reported technologies are mainly drying and pressure filtration, which generally suffer from drawbacks such as high cost and low dewatering efficiency. In recent years, relevant researchers have conducted a lot of research on new technologies for efficient red mud dewatering. Among them, the patent "A dehydration and preheating device for Bayer red mud before sintering" discloses a method and process for dehydrating red mud, but the water content of the red mud after dehydration is still 20%, which does not meet the performance requirements for preparing cement-based cementitious materials; the patent "A dehydrating agent and its preparation method and application, a method for dehydrating red mud" discloses a preparation method and dehydration process for a new type of red mud dehydrating agent, but after dehydration using this technology, the water content of the red mud is 6.5-18.5%, which still does not meet the performance requirements for preparing cement-based cementitious materials; the patent "A method for dehydrating Bayer red mud during dry feeding sintering of alumina in series" discloses a technology that mainly uses mechanical dehydration to reduce the water content of the separated and washed Bayer red mud to 35-45%, and then pumps it into the red mud drying yard or existing red mud stockpile for natural drying and mechanical turning to further reduce the water content of the red mud. When the moisture content of red mud drops below 15%, it is transported back to the alumina plant for batching and calcination. This technology is time-consuming, costly, and the moisture content does not meet the performance requirements for preparing cement-based cementitious materials.

[0005] In summary, current red mud dewatering processes do not meet the moisture content requirements for preparing cement-based cementitious materials. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a red mud-based cementitious material and its preparation method based on an integrated system of efficient drying, component homogenization, and activity enhancement. This invention not only improves the dehydration efficiency of red mud but also enables the one-step preparation of red mud-based cementitious materials, simplifying the preparation process. Furthermore, the prepared red mud-based cementitious material possesses advantages such as high mechanical strength, high durability, erosion resistance, and environmental friendliness, making it suitable for construction fields such as bridge engineering, road engineering, tunnel engineering, and municipal engineering.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] On one hand, a method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement involves adding the filter aid to the red mud at a mass ratio of 1 to 3:1 for sedimentation, followed by pressure filtration to a moisture content of 14 to 16%. Then, waste heat from the alumina plant is introduced into a grinding equipment to grind and dry the solid material after pressure filtration. The final red mud-based cementitious material has a moisture content of less than 4% and a specific surface area of ​​350 to 450 m². 2 / kg, that is, the result;

[0009] The filter aid comprises, by weight percentage, the following raw materials:

[0010] 10-30 parts of polyaluminum chloride, 5-15 parts of polyaluminum sulfate, 1000-1200 parts of blast furnace slag or fly ash, 700-900 parts of steel slag, 400-600 parts of calcium carbide slag or alkali slag, and 300-400 parts of desulfurized gypsum, phosphogypsum or fluorogypsum.

[0011] On the other hand, a red mud-based cementitious material based on efficient drying, component homogenization, and activity enhancement is obtained by the above preparation method.

[0012] Thirdly, the application of the aforementioned red mud-based cementitious material based on efficient drying, component homogenization, and activity enhancement in bridge engineering, road engineering, tunnel engineering, or municipal engineering.

[0013] The beneficial effects of this invention are as follows:

[0014] 1) In the preparation method of the present invention, a filter aid is added, which contains polyaluminum chloride and polyaluminum sulfate. In the process of red mud dewatering, it not only has a flocculation effect and improves the dewatering efficiency, but also the aluminum element can participate in the geopolymerization reaction process of red mud-based cementitious materials, thereby improving the working performance of red mud-based cementitious materials. Secondly, the chloride ions and sulfate ions therein have a salt activation effect on solid wastes such as red mud, blast furnace slag, and steel slag, thereby promoting the hydration process of the red mud-based cementitious material system. Furthermore, polyaluminum chloride and polyaluminum sulfate can solidify and treat heavy metals such as lead, arsenic, and chromium present in red mud, thereby ensuring the green and environmentally friendly characteristics of red mud-based cementitious materials.

[0015] 2) This invention utilizes components such as blast furnace slag, fly ash, steel slag, carbide slag, alkali slag, and desulfurized gypsum in the filter aid to act as a framework in the red mud slurry. By forming a rigid mesh framework, it maintains the porous structure of the red mud filter cake, thus effectively solving the compressibility problem of red mud and improving its dewatering efficiency. Furthermore, the blast furnace slag, fly ash, steel slag, carbide slag, alkali slag, and desulfurized gypsum in the filter aid are also key components in the preparation of red mud-based cementitious materials. Synergistically with red mud, they can produce red mud-based cementitious materials with short setting time, high mechanical strength, strong durability, environmental friendliness, and low cost through geopolymerization reactions. These materials can completely replace silicate cement in construction fields such as bridge engineering, road engineering, tunnel engineering, and municipal engineering.

[0016] 3) In the original drying process, the red mud had a high moisture content. As drying progressed, the red mud agglomerated, hindering further evaporation and requiring more energy to reduce the moisture content to below 4%. This invention adds a filter aid, which forms a mesh framework to maintain the porous structure of the red mud filter cake. This not only improves the dewatering efficiency of the pressure filtration process but also facilitates moisture evaporation during drying, thereby increasing dewatering efficiency and reducing energy consumption. Furthermore, the filter aid and red mud undergo a slight geopolymerization reaction under the alkaline conditions of the red mud, forming a hydration product with a three-dimensional framework structure, further enhancing the dewatering efficiency of the red mud. During the drying process, this invention utilizes industrial waste heat to further dry and grind the red mud-filter aid composite system after pressure filtration, thereby obtaining a red mud-based cementitious material. It can utilize the industrial waste heat of alumina enterprises to dry the red mud-filter aid composite system, improve the gelling activity of solid waste such as red mud, reduce energy consumption and production costs, promote the coordinated development of alumina enterprises and building material production enterprises, reduce the transportation links of raw materials such as red mud in the production process, save costs, and reduce environmental pollution.

[0017] 4) In the preparation method of the present invention, the red mud has a high utilization rate and other solid wastes are utilized in conjunction, enabling large-scale utilization of solid wastes and realizing the resource utilization of red mud and other solid wastes.

[0018] 5) In previous technologies, the filter aids used remained in the red mud filter cake, which led to an increase in the volume and weight of the red mud, increasing the cost of subsequent treatment and disposal. This invention selects industrial solid waste that can be used in conjunction with red mud to prepare cementitious materials as a filter aid, giving full play to the dual functions of red mud dewatering and cementitious material preparation, and the process is simple. Detailed Implementation

[0019] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, 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 invention pertains.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] Given that one of the bottlenecks in preparing cement-based cementitious materials from red mud is the high water content and high dehydration cost of red mud, this invention proposes a red mud-based cementitious material and its preparation method based on efficient drying, component homogenization, and activity enhancement.

[0022] A typical embodiment of the present invention provides a method for preparing a red mud-based cementitious material based on efficient drying, component homogenization, and activity enhancement. The method involves adding the filter aid to the red mud at a mass ratio of 1 to 3:1 for sedimentation, followed by pressure filtration to a moisture content of 14-16%. Waste heat from the alumina plant is then introduced into a grinding equipment to grind and dry the filtered solid material. The final red mud-based cementitious material has a moisture content of less than 4% and a specific surface area of ​​350-450 m². 2 / kg, that is, the result;

[0023] The filter aid comprises, by weight percentage, the following raw materials:

[0024] 10-30 parts of polyaluminum chloride, 5-15 parts of polyaluminum sulfate, 1000-1200 parts of blast furnace slag or fly ash, 700-900 parts of steel slag, 400-600 parts of calcium carbide slag or alkali slag, and 300-400 parts of desulfurized gypsum, phosphogypsum or fluorogypsum.

[0025] In some embodiments, the filter aid comprises, by weight percentage, the following raw materials:

[0026] The composition includes 10-30 parts polyaluminum chloride, 5-15 parts polyaluminum sulfate, 1000-1200 parts blast furnace slag, 700-900 parts steel slag, 400-600 parts calcium carbide slag or alkaline slag, and 300-400 parts desulfurized gypsum, phosphogypsum, or fluorogypsum. Studies have shown that in the filter aid system of this invention, blast furnace slag is more advantageous in improving the setting rate and mechanical properties of red mud-based cementitious materials compared to fly ash.

[0027] In some embodiments, the filter aid comprises, by weight percentage, the following raw materials:

[0028] The composition includes 10-30 parts polyaluminum chloride, 5-15 parts polyaluminum sulfate, 1000-1200 parts blast furnace slag, 700-900 parts steel slag, 400-600 parts calcium carbide slag or alkali slag, and 300-400 parts fluorogypsum. Studies have shown that, compared to gypsum, the red mud-based cementitious material prepared using fluorogypsum in the filter aid system of this invention has a shorter initial setting time and higher mechanical properties in the latter.

[0029] In some embodiments, the mass ratio of red mud to filter aid is 1 to 1.5:1. Studies have shown that under these conditions, the obtained red mud-based cementitious materials have better mechanical properties.

[0030] In some embodiments, the polyaluminum chloride is in a liquid state, with a neutrality n of 1 to 3 and a basicity > 70%.

[0031] Polyaluminum chloride (PAC) not only has a flocculation effect during the dehydration of red mud, but its aluminum element can also participate in the geopolymerization reaction of red mud-based cementitious materials, thereby improving the workability of these materials. Secondly, chloride ions have a salt-activating effect on solid wastes such as red mud, blast furnace slag, and steel slag, thereby promoting the hydration process of cement-based cementitious material systems. Furthermore, PAC can treat heavy metals such as lead, arsenic, and chromium present in red mud, thus ensuring the green and environmentally friendly characteristics of red mud-based cementitious materials.

[0032] In some embodiments, the polyaluminum sulfate is a liquid with an aluminum content of 7-17%.

[0033] Polyaluminum sulfate not only has a flocculation effect during the dehydration of red mud, but the aluminum element in it can also participate in the geopolymerization reaction process of red mud-based cementitious materials, thereby improving the working performance of red mud-based cementitious materials. Secondly, sulfate ions have a salt activation effect on solid wastes such as red mud, blast furnace slag, and steel slag, thereby promoting the hydration process of cement-based cementitious material systems.

[0034] The red mud described in this invention is a residue discharged from the Bayer process for aluminum production. Its main components are Al2O3, SiO2, Fe2O3, Na2O, etc. It has a large specific surface area, has the function of micro-aggregate filling and potential cementitious activity, and after activation treatment, it has the potential to prepare mortar / concrete / road structure admixtures.

[0035] The blast furnace slag described in this invention has a main chemical composition of Al2O3, SiO2, and CaO, and a mineral phase composition of glassy aluminosilicate components. It exhibits high cementitious activity, can supplement the calcium source in red mud-based cementitious materials, and can provide skeletal support for red mud filter cakes, improving their incompressibility. The blast furnace slag needs to be ground to a specific surface area of ​​350-450 m² / g.2 / kg.

[0036] The steel slag described in this invention is a solid waste generated during the steelmaking process in the iron and steel industry, including converter steel slag, open-hearth furnace steel slag, and electric furnace steel slag. The main components of steel slag are Al₂O₃, SiO₂, and CaO, and its mineral phase composition contains dicalcium silicate and tricalcium silicate. It possesses high cementitious activity, which can improve the cementitious activity of red mud-based cementitious materials and provide skeletal support for red mud filter cakes, thereby improving the incompressibility of the red mud filter cakes. The steel slag needs to be ground to a specific surface area of ​​350-450 m². 2 / kg.

[0037] The fly ash described in this invention is a solid waste generated during the combustion of coal in coal-fired power plants. The main chemical components of fly ash are Al2O3 and SiO2. It possesses micro-aggregate filling properties, morphological effects, and pozzolanic effects, and can be used in conjunction with red mud to prepare cement-like geopolymer cementitious materials. The fly ash needs to be ground to a specific surface area of ​​350-450 m² / g. 2 / kg.

[0038] The alkali slag described in this invention is a waste residue discharged during the production of sodium carbonate and sodium bicarbonate in the chemical industry, mainly composed of calcium and magnesium components. This invention primarily utilizes the Ca(OH)₂ and Mg(OH)₂ in the alkali slag to provide activation and a pozzolanic effect. Furthermore, the alkali slag has strong adsorption properties and exhibits good adsorption and solidification effects on heavy metals. The alkali slag needs to be ground to a specific surface area of ​​350-450 m² / g. 2 / kg.

[0039] The desulfurization gypsum, phosphogypsum, or fluorogypsum described in this invention are primarily composed of CaSO4·2H2O. The main chemical composition of various solid waste gypsums is CaSO4·2H2O, which can provide a calcium source in red mud-based cementitious material systems and also provide salt activation for sulfate ions. Furthermore, it can provide skeletal support for red mud filter cakes, improving their incompressibility. The desulfurization gypsum, phosphogypsum, or fluorogypsum needs to be ground to a specific surface area of ​​350-450 m² / g. 2 / kg.

[0040] In this invention, various filter aids can undergo slight geological polymerization reactions under the alkaline conditions of red mud slurry to generate Na2O-CaO-SiO2-Al2O3-H2O gel with a three-dimensional network structure. Based on the single-component framework support, this further increases the water passage channels in the red mud filter cake and further improves the dewatering efficiency of red mud.

[0041] In some embodiments, firstly, according to the raw material ratio in the filter aid, polyaluminum chloride, polyaluminum sulfate, fly ash, alkaline slag or carbide slag, desulfurized gypsum or phosphogypsum or fluorogypsum are mixed and added to the red mud as component 1 and stirred evenly. After 0.5 to 1 hour, steel slag is added to the red mud slurry as component 2, and stirred for another 0.2 to 0.5 hours. After settling for 0.4 to 0.6 hours, the mixture is immediately pressure filtered.

[0042] Alternatively, according to the raw material ratio in the filter aid, first mix polyaluminum chloride, polyaluminum sulfate, alkaline slag or carbide slag, desulfurized gypsum or phosphogypsum or fluorogypsum as component 1 and add it to the red mud and stir evenly. After 0.5 to 1 hour, mix blast furnace slag and steel slag as component 2 and add it to the red mud slurry. Stir for another 0.2 to 0.5 hours, let it settle for 0.4 to 0.6 hours, and then immediately perform pressure filtration.

[0043] First, polyaluminum chloride and polyaluminum sulfate have a settling effect on red mud slurry and can be added in advance. Second, filter aids such as fly ash, alkaline slag, carbide slag, desulfurized gypsum, phosphogypsum, and fluorogypsum have low gelling activity and can be added to the red mud slurry in advance to ensure sufficient contact with the alkaline components in the red mud, thereby improving gelling activity. Furthermore, under the action of alkaline components, they can form a three-dimensional geopolymer gel, enhancing the filtration effect. Finally, because other filter aids such as blast furnace slag and steel slag have high gelling activity, they react rapidly in the alkaline environment of red mud slurry. Controlling the reaction time within 0.2–0.5 hours can both produce hydration products to improve dewatering efficiency and avoid excessively long reaction times, preventing deterioration of the performance of red mud-based gelling materials. Additionally, uniform stirring facilitates better contact between the filter aid and the red mud, thus reducing settling time.

[0044] In some embodiments, industrial waste heat is used as a heat source for drying. Industrial waste heat can dry residual moisture in the red mud-filter aid composite system and can also heat-treat raw materials such as red mud, steel slag, and fly ash to improve their gelling activity. Furthermore, it can save drying costs and improve waste heat utilization efficiency.

[0045] In one or more embodiments, the temperature of the industrial waste heat is 80–300 degrees Celsius.

[0046] In some embodiments, the powder is ground to a specific surface area of ​​350–450 m². 2 / kg.

[0047] Another embodiment of the present invention provides a red mud-based cementitious material based on efficient drying-component homogenization-activity enhancement, obtained by the above preparation method.

[0048] A third embodiment of the present invention provides an application of the above-mentioned red mud-based cementitious material based on efficient drying-component homogenization-activity enhancement in bridge engineering, road engineering, tunnel engineering or municipal engineering.

[0049] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0050] Example 1

[0051] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0052] (1) First, prepare a filter aid for red mud dewatering by mixing 10 parts of polyaluminum chloride, 5 parts of polyaluminum sulfate, 1000 parts of blast furnace slag, 700 parts of steel slag, 400 parts of calcium carbide slag, and 300 parts of desulfurization gypsum. Among them, calcium carbide slag and desulfurization gypsum are directly mixed, and then mixed with polyaluminum chloride and polyaluminum sulfate to prepare a filter aid, which is component 1. Blast furnace slag and steel slag are directly mixed as component 2.

[0053] (2) According to the ratio of red mud to filter aid of 3:1, first put component 1 into the red mud settling tank and stir for 0.5 hours, then add component 2, stir for 0.2 hours, and let stand for 0.5 hours.

[0054] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0055] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat-grinding co-utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of 4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0056] Example 2

[0057] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0058] (1) A filter aid for red mud dewatering was prepared by mixing 10 parts polyaluminum chloride, 5 parts polyaluminum sulfate, 1000 parts blast furnace slag, 700 parts steel slag, 400 parts calcium carbide slag, and 300 parts desulfurization gypsum. Calcium carbide slag and desulfurization gypsum were directly mixed, and then mixed with polyaluminum chloride and polyaluminum sulfate to prepare the filter aid, which was component 1. Blast furnace slag and steel slag were directly mixed, which was component 2.

[0059] (2) According to the ratio of red mud to filter aid of 1:1, first put component 1 into the red mud settling tank and stir for 0.5 hours, then add component 2, stir for 0.2 hours, and let stand for 0.5 hours.

[0060] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0061] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat-grinding co-utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of <4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0062] Example 3

[0063] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0064] (1) A filter aid for red mud dewatering was prepared by mixing 10 parts polyaluminum chloride, 5 parts polyaluminum sulfate, 1000 parts fly ash, 900 parts steel slag, 600 parts alkaline slag, and 400 parts phosphogypsum. Fly ash, alkaline slag, and phosphogypsum were directly mixed, and then mixed with polyaluminum chloride and polyaluminum sulfate to prepare the filter aid, which was designated as component 1. Steel slag was directly used as component 2.

[0065] (2) According to the ratio of red mud to filter aid of 3:1, first put component 1 into the red mud settling tank and stir for 0.5 hours, then add component 2, stir for 0.2 hours, and let stand for 0.5 hours.

[0066] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0067] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat-grinding co-utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of <4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0068] Example 4

[0069] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0070] (1) A filter aid for red mud dewatering was prepared by mixing 30 parts of polyaluminum chloride, 15 parts of polyaluminum sulfate, 1200 parts of blast furnace slag, 700 parts of steel slag, 600 parts of alkali slag, and 300 parts of fluorogypsum. The alkali slag and fluorogypsum were directly mixed, and then mixed with polyaluminum chloride and polyaluminum sulfate to prepare the filter aid, which was component 1. The blast furnace slag and steel slag were directly mixed, which was component 2.

[0071] (2) According to the ratio of red mud to filter aid of 1:1, first put component 1 into the red mud settling tank and stir for 0.5 hours, then add component 2, stir for 0.2 hours, and let stand for 0.5 hours.

[0072] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0073] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat-grinding co-utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of <4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0074] Example 5

[0075] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0076] (1) A filter aid for red mud dewatering was prepared by mixing 10 parts polyaluminum chloride, 15 parts polyaluminum sulfate, 1200 parts fly ash, 700 parts steel slag, 600 parts carbide slag, and 400 parts phosphogypsum. Fly ash, carbide slag, and phosphogypsum were directly mixed, and then mixed with polyaluminum chloride and polyaluminum sulfate to prepare the filter aid, which was designated as component 1. Steel slag was directly used as component 2.

[0077] (2) According to the ratio of red mud to filter aid of 1:1, first put component 1 into the red mud settling tank and stir for 0.5 hours, then add component 2, stir for 0.2 hours, and let stand for 0.5 hours.

[0078] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0079] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of <4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0080] Example 6

[0081] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0082] (1) A filter aid for red mud dewatering was prepared by mixing 30 parts of polyaluminum chloride, 5 parts of polyaluminum sulfate, 1200 parts of blast furnace slag, 700 parts of steel slag, 400 parts of alkali slag, and 400 parts of phosphogypsum. The alkali slag and phosphogypsum were directly mixed, and then mixed with polyaluminum chloride and polyaluminum sulfate to prepare the filter aid, which was component 1. The blast furnace slag and steel slag were directly mixed, which was component 2.

[0083] (2) According to the ratio of red mud to filter aid of 1:1, first put component 1 into the red mud settling tank and stir for 0.5 hours, then add component 2, stir for 0.2 hours, and let stand for 0.5 hours.

[0084] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0085] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat-grinding co-utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of <4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0086] Example 7

[0087] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0088] (1) First, prepare a filter aid for red mud dewatering by mixing 10 parts of polyaluminum chloride, 5 parts of polyaluminum sulfate, 1000 parts of blast furnace slag, 700 parts of steel slag, 400 parts of calcium carbide slag, and 300 parts of desulfurization gypsum. Among them, calcium carbide slag and desulfurization gypsum are directly mixed, and then mixed with polyaluminum chloride and polyaluminum sulfate to prepare a filter aid, which is component 1. Blast furnace slag and steel slag are directly mixed as component 2.

[0089] (2) According to the ratio of red mud to filter aid of 3:1, first put component 1 into the red mud settling tank and stir for 0.5 hours, then add component 2, stir for 0.5 hours, and let stand for 0.5 hours.

[0090] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0091] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat-grinding co-utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of 4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0092] Comparative Example 1

[0093] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0094] (1) A filter aid for red mud dewatering was prepared by mixing 10 parts of polyaluminum chloride, 1000 parts of blast furnace slag, 700 parts of steel slag, 400 parts of calcium carbide slag, and 300 parts of desulfurized gypsum. Among them, calcium carbide slag and desulfurized gypsum were directly mixed and then mixed with polyaluminum chloride to prepare the filter aid, which was used as component 1. Blast furnace slag and steel slag were directly mixed as component 2.

[0095] (2) According to the ratio of red mud to filter aid of 3:1, first put component 1 into the red mud settling tank and stir for 0.5 hours, then add component 2, stir for 0.2 hours, and let stand for 0.5 hours.

[0096] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0097] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat-grinding co-utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of 4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0098] Comparative Example 2

[0099] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0100] (1) A filter aid for dewatering red mud was prepared by mixing 5 parts polyaluminum sulfate, 1000 parts blast furnace slag, 700 parts steel slag, 400 parts calcium carbide slag, and 300 parts desulfurized gypsum. Among them, calcium carbide slag and desulfurized gypsum were directly mixed and then mixed with polyaluminum sulfate to prepare the filter aid, which was used as component 1. Blast furnace slag and steel slag were directly mixed as component 2.

[0101] (2) According to the ratio of red mud to filter aid of 3:1, first put component 1 into the red mud settling tank and stir for 0.5 hours, then add component 2, stir for 0.2 hours, and let stand for 0.5 hours.

[0102] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0103] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat-grinding co-utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of 4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0104] Comparative Example 3

[0105] A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement includes the following steps:

[0106] (1) First, prepare a filter aid for red mud dewatering by mixing 10 parts of polyaluminum chloride, 5 parts of polyaluminum sulfate, 1000 parts of blast furnace slag, 700 parts of steel slag, 400 parts of carbide slag and 300 parts of desulfurization gypsum. Among them, carbide slag, desulfurization gypsum, blast furnace slag and steel slag are directly mixed, and then mixed with polyaluminum chloride and polyaluminum sulfate to prepare a filter aid.

[0107] (2) Add red mud to the red mud settling tank at a ratio of 3:1, stir for 1 hour, and let stand for 0.2 hours.

[0108] (3) The red mud-filter aid composite system is filtered to a moisture content of about 15% by mechanical pressure filtration.

[0109] (4) The red mud-filter aid composite system after pressure filtration is conveyed to the industrial waste heat-grinding co-utilization system via conveyor belt. The industrial waste heat is used to dry the red mud-filter aid composite system to a moisture content of 4%, and the red mud-filter aid composite system is ground to a specific surface area of ​​400 m². 2 / kg, thus obtaining red mud-based cementitious materials.

[0110] Performance testing

[0111] The performance of red mud-based cementitious materials was tested in accordance with GB 175-2023 "General Silicate Cement", and the results are shown in Table 1.

[0112] Table 1. Performance of the red mud-based cementitious materials prepared in each embodiment.

[0113]

[0114] Analysis of test data shows that the smaller the mass ratio of red mud to filter aid, the better the performance of the prepared red mud-based cementitious material; blast furnace slag has a better effect on the system than fly ash, and desulfurized gypsum has a better effect on the system than phosphogypsum and fluorogypsum; alkaline slag has a better effect on the system than carbide slag; polyaluminum chloride and polyaluminum sulfate have little effect on the performance of red mud-based cementitious materials, but they have a certain degree of improvement effect.

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing red mud-based cementitious materials based on efficient drying, component homogenization, and activity enhancement, characterized in that, The filter aid is added to the red mud at a mass ratio of 1 to 3:1 for sedimentation, followed by pressure filtration until the moisture content is 14-16%. The solid material after pressure filtration is then dried until the moisture content is below 4%, and finally ground until the specific surface area is 350-450 m². 2 / kg, that is, the result; The filter aid comprises, by weight percentage, the following raw materials: 10-30 parts of polyaluminum chloride, 5-15 parts of polyaluminum sulfate, 1000-1200 parts of blast furnace slag or fly ash, 700-900 parts of steel slag, 400-600 parts of calcium carbide slag or alkali slag, and 300-400 parts of desulfurized gypsum, phosphogypsum or fluorogypsum. First, according to the raw material ratio in the filter aid, mix polyaluminum chloride, polyaluminum sulfate, fly ash, alkaline slag or carbide slag, desulfurized gypsum or phosphogypsum or fluorogypsum and add them as component 1 to the red mud and stir evenly. After 0.5 to 1 hour, add steel slag as component 2 to the red mud slurry and stir for another 0.2 to 0.5 hours. After settling for 0.4 to 0.6 hours, immediately perform pressure filtration. Alternatively, according to the raw material ratio in the filter aid, first mix polyaluminum chloride, polyaluminum sulfate, alkaline slag or carbide slag, desulfurized gypsum or phosphogypsum or fluorogypsum and add them as component 1 to the red mud and stir evenly. After 0.5 to 1 hour, mix blast furnace slag and steel slag and add them as component 2 to the red mud slurry. Stir for another 0.2 to 0.5 hours, let it settle for 0.4 to 0.6 hours, and then immediately perform pressure filtration. Industrial waste heat is used as a heat source for drying; the temperature of industrial waste heat is 80~300 degrees Celsius.

2. The preparation method of red mud-based cementitious material based on efficient drying-component homogenization-activity enhancement as described in claim 1, characterized in that, The filter aid comprises, by weight percentage, the following raw materials: 10-30 parts of polyaluminum chloride, 5-15 parts of polyaluminum sulfate, 1000-1200 parts of blast furnace slag, 700-900 parts of steel slag, 400-600 parts of calcium carbide slag or alkali slag, and 300-400 parts of desulfurized gypsum, phosphogypsum or fluorogypsum.

3. The preparation method of red mud-based cementitious material based on efficient drying-component homogenization-activity enhancement as described in claim 1, characterized in that, The polyaluminum chloride is in a liquid state, with a neutrality n of 1 to 3 and a basicity > 70%.

4. The preparation method of red mud-based cementitious material based on efficient drying-component homogenization-activity enhancement as described in claim 1, characterized in that, The polyaluminum sulfate is a liquid with an aluminum content of 7-17%.

5. A red mud-based cementitious material based on efficient drying, component homogenization, and activity enhancement, characterized in that: Obtained by the preparation method described in any one of claims 1 to 4.

6. The application of the red mud-based cementitious material based on efficient drying-component homogenization-activity enhancement as described in claim 5 in bridge engineering, road engineering, tunnel engineering or municipal engineering.

Images