Method for preparing cement auxiliary cementitious material by synergistically activating red mud through coal gangue and application of cement auxiliary cementitious material
By utilizing waste heat to activate red mud in a tunnel kiln and adding coal gangue powder, the problem of high energy consumption in traditional thermal activation was solved, the gelling reaction activity of red mud was improved, and red mud was effectively replaced in cement, thus improving the performance of cement.
Patent Information
- Application Number
- CN202511394657.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-28
- Publication Date
- 2025-11-21
AI Technical Summary
In existing technologies, traditional thermal activation methods for enhancing the activity of red mud are characterized by high energy consumption, large carbon emissions, and limited effectiveness. Red mud has low activity and is difficult to effectively replace traditional cement.
The waste heat of the tunnel kiln is used to thermally activate the red mud, and coal gangue powder is added during the process. Through mixing at specific time points, highly active minerals such as metakaolinite are formed, which destroys the inert phase and improves the cementation reaction activity of the red mud.
It significantly reduces activation energy consumption, improves the gelation reactivity of red mud, and enhances the mechanical strength and workability of cement, making it a viable alternative to traditional silicate cement clinker.
Smart Images
Figure CN120987586A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of cement material preparation, and particularly relates to a method for preparing cement auxiliary cementitious material by activating red mud in cooperation with coal gangue. BACKGROUND
[0002] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general background of the application and does not necessarily constitute an admission by the patent applicant or the like that the information forms part of the prior art that is already known in this field.
[0003] Cement production is one of the main sources of carbon emissions. In order to reduce carbon emissions in the cement industry, auxiliary cementitious materials are usually introduced into the cement production process, which is conducive to the development of cement concrete durability. A large amount of industrial solid waste is produced every year, among which the proportion of industrial red mud is large. The accumulation of red mud not only occupies a large amount of land, but also causes serious environmental pollution. Red mud contains rich aluminum, silicon, iron and other elements, has potential pozzolanic activity, and is an important raw material for preparing cement auxiliary cementitious materials. However, the activity of the original red mud is low.
[0004] Thermal activation is an effective way to improve the pozzolanic activity of red mud, which can make the red mud dehydrate at high temperature, destroy the layered structure of the red mud, and expose more active sites. Al3+ and Si4+ dissolved after being added into cement-based materials can react with Ca(OH)2 generated during cement hydration to form C-A-S-H gel, so the red mud after thermal activation can replace traditional cement as auxiliary cementitious material, thereby reducing carbon emissions. However, the traditional way of using thermal activation to improve the activity of red mud not only has the problems of high energy consumption and large carbon emissions, but also has limited improvement on the activation performance of red mud. 4 SUMMARY
[0005] In view of the above problems, the present application provides a method for preparing cement auxiliary cementitious material by activating red mud in cooperation with coal gangue and its application. The method utilizes the waste heat of the tunnel kiln to not only realize waste heat utilization and reduce the activation energy consumption, but also realize the regulation of the mineral composition of the red mud through thermal activation, thereby greatly improving the cementitious reaction activity of the red mud. Specifically, the technical scheme of the present application is as follows.
[0006] Firstly, the present application provides a method for preparing cement auxiliary cementitious material by activating red mud in cooperation with coal gangue, which comprises the following steps: (1) Placing red mud particles in a tunnel kiln, and using the internal waste heat to perform thermal activation in a protective atmosphere, and adding coal gangue powder into the red mud particles during the process. After completion, quenching to room temperature to obtain an activated composite material.
[0007] (2) The activated composite material is ground to obtain cement auxiliary cementitious material.
[0008] Further, in step (1), the particle size of the red mud particles is no greater than 150 μm. Preferably, the moisture content of the red mud particles is no greater than 30%.
[0009] Further, in step (1), the red mud includes at least one of the following: Bayer process red mud, sintering process red mud, combined process red mud, etc.
[0010] Further, in step (1), the temperature of the thermal activation is controlled between 600 and 900°C, and the thermal activation time is 2 to 4 hours. Through thermal activation and under the action of coal gangue powder, the mineral phases in the red mud undergo sufficient dehydration, crystal phase transformation, and structural reconstruction, thereby improving its cementing activity.
[0011] Further, in step (1), the protective atmosphere includes at least one of nitrogen, argon, etc.
[0012] Furthermore, in step (1), the total amount of coal gangue powder added is 5-20% of the mass of red mud particles.
[0013] Further, in step (1), the coal gangue powder is added as follows: first, 45-55% of the red mud particles are mixed evenly with the coal gangue powder, and then the thermal activation begins. When the thermal activation time reaches half of the preset time, 60-70% of the remaining coal gangue is added and mixed evenly. When the thermal activation time reaches three-quarters of the preset time, the remaining coal gangue is added and mixed evenly, and activation continues until the preset time is reached.
[0014] Furthermore, in step (1), the fineness of the coal gangue powder is 200~400 mesh.
[0015] Further, in step (2), the activated composite material is ground and passed through a 200-300 mesh sieve to obtain the cement auxiliary cementitious material.
[0016] Secondly, this invention provides the application of the coal gangue synergistic activation of red mud in the preparation of cement auxiliary cementitious materials in cement-based materials.
[0017] Furthermore, the dosage of the auxiliary cementitious material is 10-30% of the mass of cement clinker in the cement-based material.
[0018] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: This invention utilizes the waste heat within a tunnel kiln as a heat source to thermally activate red mud, avoiding additional energy consumption and significantly reducing energy consumption by eliminating the need for additional heating equipment, thus improving the energy utilization rate of the tunnel kiln. Furthermore, during this process, the mineral phases in the red mud undergo dehydration, crystal phase transformation, and structural reconstruction to form highly active minerals such as metakaolinite, enhancing the gelling reaction activity. Moreover, the activated red mud products can react with cement hydration products to generate CASH gel, improving the mechanical strength of the cement. On the other hand, this invention further significantly enhances the gelling reaction activity of the red mud by utilizing coal gangue powder and its incorporation into the red mud particles at specific time points. This is because the present invention utilizes the organic matter in the coal gangue to form a reducing agent after carbonization, which reduces the iron oxides in the red mud. The reduction product enters the red mud and destroys the original inert phases such as calcium nepheline and hydrated garnet, which have high crystallinity and high alkalinity, and transforms them into low crystallinity anorthite, calcium aluminate and active SiO2-Al2O3 glass. This makes the auxiliary cementitious material prepared by the present invention exhibit better cementitious activity. It can be used to replace traditional silicate cement clinker, while overcoming the problem of high water demand of red mud-based auxiliary cementitious materials and improving its workability. Attached Figure Description
[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0020] Figure 1 The image shows a sample of cementitious auxiliary binder prepared in Example 1 below.
[0021] Figure 2 The graph shows the flowability test results of the cement-aided cementitious material prepared in Example 1 below.
[0022] Figure 3 The image shows a sample of cementitious auxiliary binder prepared in Example 2 below.
[0023] Figure 4 The graph shows the flowability test results of the cement-aided cementitious material prepared in Example 2 below.
[0024] Figure 5 The image shows a sample of cementitious auxiliary binder prepared in Example 3 below.
[0025] Figure 6 The graph shows the flowability test results of the cementitious auxiliary binder prepared in Example 3 below.
[0026] Figure 7 The image shows a sample of cementitious auxiliary binder prepared in Example 4 below.
[0027] Figure 8 The graph shows the flowability test results of the cementitious auxiliary binder prepared in Example 4 below.
[0028] Figure 9 The graph shows the flowability test results of the cementitious auxiliary binder prepared in Example 5 below.
[0029] Figure 10 The graph shows the flowability test results of the cementitious auxiliary binder prepared in Example 6 below. Detailed Implementation
[0030] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.
[0031] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The reagents or raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.
[0032] Example 1: A method for preparing cement auxiliary binder materials by co-activating red mud with coal gangue, comprising the following steps: (1) After crushing the Bayer red mud, pass it through a sieve with a pore size of 75 μm. Dry the resulting red mud particles in an oven to a moisture content of 25% to obtain pretreated red mud particles.
[0033] (2) Prepare two raw material powders according to the ratio of the total amount of coal gangue powder added to 10% of the mass of the pretreated red mud particles, wherein the fineness of the coal gangue powder is 200 mesh.
[0034] (3) First, mix 50% of the total amount of coal gangue powder with the red mud particles and stir evenly. Then, place the resulting mixture in a tunnel kiln and start thermal activation using the residual heat inside the kiln under a nitrogen protective atmosphere, with the temperature controlled at 700±5℃. When the thermal activation time reaches 1.5 hours, add the remaining 65% of the coal gangue to the mixture and mix evenly. When the thermal activation time reaches 2.25 hours, add the remaining coal gangue and mix evenly, and continue activation until 3 hours have been reached. After completion, cool the resulting product to room temperature in air to obtain the activated composite material.
[0035] (4) The activated composite material is ground and then passed through a 200-mesh sieve to obtain cement auxiliary binder, such as...Figure 1 As shown.
[0036] Performance testing: (1) The cement auxiliary cementitious material prepared in this embodiment was added to PⅠ42.5 cement (the dosage was 30 wt.%). Then, the 28-day compressive strength and 28-day flexural strength of the obtained specimens were tested according to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)". (2) The flow properties of the cement auxiliary cementitious material prepared in this embodiment were tested according to GB / T2419-2005 "Determination Method for Flowability of Cement Mortar" (e.g., Figure 2 (As shown), the results are shown in the table below:
[0037] Example 2: A method for preparing cement auxiliary binder materials by synergistic activation of red mud with coal gangue, comprising the following steps: (1) After crushing the Bayer red mud, pass it through a sieve with a pore size of 150 μm. Dry the resulting red mud particles in an oven to a moisture content of 30% to obtain pretreated red mud particles.
[0038] (2) Prepare two raw material powders according to the ratio of the total amount of coal gangue powder added to 5% of the mass of the pretreated red mud particles, wherein the fineness of the coal gangue powder is 250 mesh.
[0039] (3) First, mix 45% of the total amount of coal gangue powder with the red mud particles and stir evenly. Then, place the resulting mixture in a tunnel kiln and start thermal activation using the residual heat inside the kiln under a nitrogen protective atmosphere, with the temperature controlled at 605±5℃. When the thermal activation time reaches 1.0 hour, add the remaining 60% of the coal gangue to the mixture and mix evenly. When the thermal activation time reaches 1.5 hours, add the remaining coal gangue and mix evenly, and continue activation until it reaches 2 hours. After completion, cool the resulting product to room temperature in air to obtain the activated composite material.
[0040] (4) The activated composite material is ground and then passed through a 200-mesh sieve to obtain cement auxiliary binder, such as... Figure 3 As shown.
[0041] Performance testing: The 28-day compressive strength, 28-day flexural strength, and flow properties of the cementitious auxiliary binder prepared in this embodiment were tested using the same method as in Example 1 above (e.g., Figure 4 (As shown), the results are shown in the table below:
[0042] Example 3: A method for preparing cement auxiliary binder materials by co-activating red mud with coal gangue, comprising the following steps: (1) After crushing the Bayer red mud, pass it through a sieve with a pore size of 45 μm. Dry the resulting red mud particles in an oven to a moisture content of 20% to obtain pretreated red mud particles.
[0043] (2) Prepare two raw material powders according to the ratio of the total amount of coal gangue powder added to 20% of the mass of the pretreated red mud particles, wherein the fineness of the coal gangue powder is 400 mesh.
[0044] (3) First, mix 55% of the total amount of coal gangue powder with the red mud particles and stir evenly. Then, place the resulting mixture in a tunnel kiln and start thermal activation using the residual heat inside the kiln under a nitrogen protective atmosphere, with the temperature controlled at 895±5℃. When the thermal activation time reaches 2 hours, add the remaining 70% of the coal gangue to the mixture and mix evenly. When the thermal activation time reaches 3 hours, add the remaining coal gangue and mix evenly, and continue activation until 4 hours have been reached. After completion, cool the resulting product to room temperature in air to obtain the activated composite material.
[0045] (4) The activated composite material is ground and then passed through a 300-mesh sieve to obtain cementitious auxiliary binder, such as... Figure 5 As shown.
[0046] Performance testing: The 28-day compressive strength, 28-day flexural strength, and flow properties of the cementitious auxiliary binder prepared in this embodiment were tested using the same method as in Example 1 above (e.g., Figure 6 (As shown), the results are shown in the table below:
[0047] Example 4: A method for preparing cement auxiliary binder materials by synergistic activation of red mud with coal gangue, comprising the following steps: (1) After crushing the Bayer red mud, pass it through a sieve with a pore size of 75 μm. Dry the resulting red mud particles in an oven to a moisture content of 25% to obtain pretreated red mud particles.
[0048] (2) The red mud particles are placed in a tunnel kiln and thermally activated using the residual heat inside the kiln under a nitrogen protective atmosphere. The temperature is controlled at 700±5℃ and the activation time is 3 hours. After completion, the product is cooled to room temperature in air to obtain activated red mud.
[0049] (3) The activated red mud is ground and then passed through a 200-mesh sieve to obtain cement auxiliary binder material, such as... Figure 7 As shown.
[0050] Performance testing: The 28-day compressive strength, 28-day flexural strength, and flow properties of the cementitious auxiliary binder prepared in this embodiment were tested using the same method as in Example 1 above (e.g., Figure 8(As shown), the results are shown in the table below:
[0051] Example 5: A method for preparing cement auxiliary cementitious materials by co-activating red mud with coal gangue, comprising the following steps: (1) After crushing the Bayer red mud, pass it through a sieve with a pore size of 150 μm. Dry the resulting red mud particles in an oven to a moisture content of 30% to obtain pretreated red mud particles.
[0052] (2) Prepare two raw material powders according to the ratio of the total amount of coal gangue powder added to 5% of the mass of the pretreated red mud particles, wherein the fineness of the coal gangue powder is 250 mesh.
[0053] (3) The red mud particles are mixed with all the coal gangue powder and stirred evenly. The resulting mixture is then placed in a tunnel kiln and thermally activated using the residual heat inside the kiln under a nitrogen protective atmosphere. The temperature is controlled at 605±5℃ and the activation time is 2 hours. After completion, the product is cooled to room temperature in air to obtain the activated composite material.
[0054] (4) Grind the activated composite material and then pass it through a 200-mesh sieve to obtain cement auxiliary cementitious material.
[0055] Performance testing: The 28-day compressive strength, 28-day flexural strength, and flow properties of the cementitious auxiliary binder prepared in this embodiment were tested using the same method as in Example 1 above (e.g., Figure 9 (As shown), the results are shown in the table below:
[0056] Example 6: A method for preparing cement auxiliary cementitious materials by co-activating red mud with coal gangue, comprising the following steps: (1) After crushing the Bayer red mud, pass it through a sieve with a pore size of 75 μm. Dry the resulting red mud particles in an oven to a moisture content of 25% to obtain pretreated red mud particles.
[0057] (2) Prepare two raw material powders according to the ratio of the total amount of coal gangue powder added to 10% of the mass of the pretreated red mud particles, wherein the fineness of the coal gangue powder is 200 mesh.
[0058] (3) First, mix 50% of the total amount of coal gangue powder with the red mud particles and stir evenly. Then, place the resulting mixture in a tunnel kiln and start thermal activation using the residual heat inside the kiln under a nitrogen protective atmosphere, with the temperature controlled at 700±5℃. When the thermal activation time reaches 1.5 hours, continue to add the remaining coal gangue to the mixture and mix evenly, continuing activation until 3 hours have been reached. After completion, cool the resulting product to room temperature in air to obtain the activated composite material.
[0059] (4) Grind the activated composite material and then pass it through a 200-mesh sieve to obtain cement auxiliary cementitious material.
[0060] Performance testing: The 28-day compressive strength, 28-day flexural strength, and flow properties of the cementitious auxiliary binder prepared in this embodiment were tested using the same method as in Example 1 above (e.g., Figure 10 (As shown), the results are shown in the table below:
[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing cement auxiliary cementitious materials by synergistic activation of red mud with coal gangue, characterized in that, Includes the following steps: (1) The red mud particles are placed in a tunnel kiln and thermally activated using the residual heat inside in a protective atmosphere, and coal gangue powder is added to the red mud particles during the process; after completion, the material is rapidly cooled to room temperature to obtain activated composite material. (2) The activated composite material is ground to obtain cement auxiliary cementitious material.
2. The method for preparing cement auxiliary binder materials by co-activating red mud with coal gangue according to claim 1, characterized in that, In step (1), the particle size of the red mud particles is no greater than 150 μm; preferably, the moisture content of the red mud particles is no greater than 30%.
3. The method for preparing cement auxiliary binders using coal gangue and synergistic activation of red mud according to claim 1, characterized in that, In step (1), the red mud includes at least one of Bayer process red mud, sintering process red mud, and combined process red mud.
4. The method for preparing cement auxiliary cementitious materials by co-activating red mud with coal gangue according to claim 1, characterized in that, In step (1), the temperature of the thermal activation is controlled between 600 and 900°C, and the thermal activation time is 2 to 4 hours; Optionally, in step (1), the protective atmosphere includes at least one of nitrogen and argon.
5. The method for preparing cement auxiliary binders using coal gangue and synergistic activation of red mud according to claim 1, characterized in that, In step (1), the total amount of coal gangue powder added is 5-20% of the mass of red mud particles.
6. The method for preparing cement auxiliary cementitious materials by co-activating red mud with coal gangue according to claim 1, characterized in that, In step (1), the coal gangue powder is added by first mixing 45-55% of the red mud particles with the coal gangue powder evenly, and then starting the thermal activation. When the thermal activation time reaches half of the preset time, add 60-70% of the remaining coal gangue and mix evenly; when the thermal activation time reaches three-quarters of the preset time, add the remaining coal gangue and mix evenly, and continue activation until the preset time is reached.
7. The method for preparing cement auxiliary binder materials by co-activating red mud with coal gangue according to any one of claims 1-6, characterized in that, In step (1), the fineness of the coal gangue powder is 200~400 mesh.
8. The method for preparing cement auxiliary binder materials by co-activating red mud with coal gangue according to any one of claims 1-6, characterized in that, In step (2), the activated composite material is ground and passed through a 200-300 mesh sieve to obtain the cement auxiliary cementitious material.
9. The application of the cement-aided cementitious material obtained by the method according to any one of claims 1-6 in cement-based materials.
10. The application according to claim 9, characterized in that, The dosage of the auxiliary cementitious material is 10-30% of the mass of cement clinker in the cement-based material.