Waste titanium slag-metakaolin-based geopolymer thermoelectric material and preparation method thereof
By preparing waste titanium slag-metakaolin-based geopolymer thermoelectric materials, the problem of waste titanium slag utilization was solved, thermoelectric performance was improved while mechanical properties were maintained, and efficient utilization of Ti resources and environmental protection were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-14
AI Technical Summary
Existing technologies are unable to effectively utilize waste titanium slag, leading to waste of Ti resources and environmental pollution. Furthermore, conventional geopolymer thermoelectric materials experience a decline in mechanical properties when improving thermoelectric performance.
Geopolymer thermoelectric materials were prepared using waste titanium slag and metakaolin. The mixture was activated by an alkali activator to form a mixed slurry. After curing in a mold, the waste titanium slag-metakaolin-based geopolymer thermoelectric material was prepared. The performance was improved by combining TiO2 to form a conductive network in the matrix.
This approach enables high-value utilization of waste titanium slag, improves the thermoelectric properties of geopolymers, maintains the mechanical properties of the materials, and reduces energy consumption.
Smart Images
Figure CN121850418A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of geopolymer thermoelectric materials and solid waste resource utilization technology, specifically to waste titanium slag-metakaolin-based geopolymer thermoelectric materials and their preparation methods. Background Technology
[0002] In the process of titanium metal processing or titanium ore smelting, grayish-black granular or lumpy waste titanium slag is often generated. The accumulation of waste titanium slag exacerbates land and environmental pollution, hindering the sustainable development of the mining industry. Although waste titanium slag is industrial solid waste, it still contains a certain amount of TiO2. Depending on the tailings treatment process, the TiO2 content in waste titanium slag is generally around 10% to 30%. Therefore, theoretically, Ti extraction from waste titanium slag is possible. However, current titanium extraction technology from waste titanium slag is not mature. The tailings and industrial wastewater generated by the commonly used acid leaching method are difficult to treat, while pyrometallurgical titanium extraction is not only more expensive but also energy-intensive. Therefore, achieving the recycling of waste titanium slag through titanium extraction has certain limitations. Currently, waste titanium slag is mainly utilized as concrete aggregate, cement admixture, and roadbed filling material. While the above methods can achieve recycling and reuse of waste titanium slag to a certain extent, the amount of waste titanium slag that can be disposed of is limited (generally not exceeding 20%), and the effective utilization of TiO2 in waste titanium slag cannot be achieved, resulting in a waste of Ti resources and low added value of waste titanium slag recycling.
[0003] Geopolymers are a class of three-dimensional network cementitious materials formed by a series of chemical reactions, including dissolution, depolymerization, and condensation, of aluminosilicate materials (such as metakaolin, fly ash, and slag) under the action of an alkaline activator. Compared with cement-based materials, geopolymers have a thermoelectric figure of merit that is 3-4 orders of magnitude higher, showing potential for the preparation of thermoelectric materials. Currently, the internal conductive pathways of geopolymer-based thermoelectric materials are often optimized by adding conductive fillers or metal oxides to further improve their thermoelectric performance (JingmingCai, Jiawei Tan, et al. Thermoelectric behaviors of flyash and metakaolin based geopolymer[J]. Construction and Building Materials,2020, 237: 117757). Although the above methods can effectively improve the thermoelectric performance of geopolymers, the addition of conductive fillers or metal oxides introduces a large number of defects, leading to a decrease in the mechanical properties of geopolymers. The main components of waste titanium ore slag are CaO, SiO2, and Al2O3. Except for a certain amount of TiO2, its composition is basically similar to that of ore slag, so it can be used as a raw material for preparing geopolymers. In addition, the TiO2 in waste titanium ore slag can improve the thermoelectric properties of geopolymers by overlapping the internal conductive network of the matrix and increasing the carrier concentration.
[0004] In summary, the preparation of waste titanium slag-metakaolin-based geopolymer thermoelectric materials using waste titanium slag can, on the one hand, consume a large amount of waste titanium slag and realize high-value-added utilization of industrial solid waste, and on the other hand, improve the thermoelectric performance of geopolymer thermoelectric materials. Summary of the Invention
[0005] The purpose of this invention is to provide a waste titanium slag-metakaolin-based geopolymer thermoelectric material and its preparation method, overcoming the shortcomings and deficiencies of the prior art.
[0006] This invention is achieved through the following technical solution: This invention provides a method for preparing a waste titanium slag-metakaolin-based geopolymer thermoelectric material, the specific steps of which are as follows: (1) Place the waste titanium slag powder and metakaolin in a mixer and pre-mix for 120 seconds to make the raw materials evenly mixed; (2) After mixing the well-mixed raw materials with the alkali activator, place them in a mixer and stir to make a mixed slurry; (3) Pour the prepared mixed slurry into the mold, place the mold in an environment with a temperature of 20℃ and a humidity of ≥60%RH for 1 day, then demold and cure at room temperature to obtain the waste titanium slag-meta-kaolin base polymer thermoelectric material.
[0007] Furthermore, in step (1), the raw material composition of waste titanium slag powder and metakaolin is as follows by mass parts: 0-50 parts of waste titanium slag powder and 50-100 parts of metakaolin.
[0008] Furthermore, in step (1), the waste titanium slag powder is obtained by ball milling waste titanium slag. Waste titanium slag includes industrial solid waste generated during the production of titanium dioxide or the smelting of ilmenite. The weight percentage of moisture in the waste titanium slag is less than 1.0%. The TiO2 content in the composition of the waste titanium slag does not exceed 30%, and the activity index of the waste titanium slag is greater than 60%.
[0009] Furthermore, the waste titanium slag is dried in an oven to control its moisture content to be less than 1.0% by weight.
[0010] Furthermore, in step (1), the particle size range of the waste titanium slag powder is 7-15 μm.
[0011] Furthermore, in step (1), the particle size of the metakaolin ranges from 2 to 10 μm; the content of SiO2 and Al2O3 in the metakaolin composition is greater than 30%.
[0012] Furthermore, in step (1), pre-mixing involves adding the weighed waste titanium slag powder and metakaolin to a mixer and mixing them at a speed of 150 rpm.
[0013] Furthermore, in step (2), the alkaline activator solution is prepared with an alkalinity of 10% and a modulus of 1.4.
[0014] Furthermore, after the alkaline activator solution is prepared, it should be allowed to stand for 1 day and cooled to room temperature for later use.
[0015] Furthermore, in step (2), the alkaline activator solution is one or more of the following: water glass + sodium hydroxide, water glass + sodium carbonate, and water glass + sodium hydroxide + sodium carbonate.
[0016] Furthermore, in step (2), the water-cement ratio of the uniformly mixed raw materials and water is 0.4.
[0017] Furthermore, in steps (1) and (2), the mixer speed is 100-200 rpm and the mixing time is 10 min.
[0018] The present invention also provides a waste titanium slag-metakaolin-based polymer thermoelectric material prepared by the above-described method for preparing a waste titanium slag-metakaolin-based polymer thermoelectric material.
[0019] The waste titanium slag-metakaolin-based geopolymer thermoelectric material prepared by this invention can make extensive use of waste titanium slag, reduce the amount of metakaolin used, and save natural resources. By incorporating waste titanium slag, the same purpose of improving the thermoelectric properties of the matrix can be achieved as that of incorporating conductive fillers (such as expanded graphite). This can effectively improve the thermoelectric properties of waste titanium slag-metakaolin-based polymer thermoelectric materials while ensuring mechanical properties.
[0020] Room temperature curing eliminates the need for energy-intensive autoclaving to enhance reactivity, thus reducing energy consumption. This study explores new approaches for the high-value utilization of waste titanium slag, the development of geopolymers, and the realization of functional utilization. Attached Figure Description
[0021] Figure 1 This is a flowchart of the preparation method of waste titanium slag-metakaolin-based geopolymer thermoelectric material provided by the present invention.
[0022] Figure 2 This is a 28-day Seebeck coefficient diagram of the waste titanium slag-metakaolin-based geopolymer thermoelectric materials prepared in Examples 1-3.
[0023] Figure 3 This is a 28-day thermoelectric figure of merit diagram for the waste titanium slag-metakaolin-based geopolymer thermoelectric materials prepared in Examples 1-3.
[0024] Figure 4 The image shows the 28-day compressive strength of the waste titanium slag-metakaolin-based geopolymer thermoelectric materials prepared in Examples 1-3. Detailed Implementation
[0025] To make the technical solution, objectives, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments.
[0026] In the embodiments of the present invention, the waste titanium slag powder used is obtained by ball milling waste titanium slag. Waste titanium slag includes industrial solid waste generated during titanium dioxide production or ilmenite smelting, etc. The weight percentage of moisture in the waste titanium slag is less than 1.0%; the TiO2 content in the waste titanium slag composition does not exceed 30%, and the activity index of the waste titanium slag is greater than 60%. The waste titanium slag is dried in an oven to control its moisture content to be less than 1.0% by weight; the particle size range of the waste titanium slag powder is 7-15 μm. The metakaolin used has a particle size range of 2-10 μm; the SiO2 and Al2O3 contents in the metakaolin composition are both greater than 30%.
[0027] Raw material proportions are shown in Table 1:
[0028] Note: The water content in water glass is 64.5% (v / v). The water in the table is additional water added to the alkaline activator.
[0029] Figure 1 The present invention illustrates the preparation process of the waste titanium slag-metakaolin-based geopolymer thermoelectric material.
[0030] Example 1 (1) Mix 45.9 g of water glass with a water content of 64.5% (v / v), 7.9 g of NaOH and 11.5 g of water to prepare an alkaline activator with an alkalinity of 10% and a modulus of 1.4 for later use; (2) Mix 100 wt.% metakaolin with the alkali activator at a water-cement ratio of 0.4 to the total water content in the alkali activator solution, and then place the mixture in a mixer and stir at 150 rpm for 10 min to make a mixed slurry; (3) Pour the prepared mixed slurry into the mold, place the mold in an environment with a temperature of 20℃ and a humidity of ≥60%RH for 1 day, then demold and cure at room temperature to obtain the waste titanium slag-meta-kaolin base polymer thermoelectric material.
[0031] Example 2 (1) Mix 45.9 g of water glass with a water content of 64.5% (v / v), 7.9 g of NaOH and 11.5 g of water to prepare an alkaline activator with an alkalinity of 10% and a modulus of 1.4 for later use; (2) Place 30wt.% waste titanium slag powder and 70wt.% metakaolin in a mixer and pre-stir for 120s at 150 rpm to make the raw materials evenly mixed; (3) Mix the well-mixed raw materials with the alkali activator at a water-cement ratio of 0.4 to the total water content in the alkali activator solution, and then place them in a mixer and stir at 150 rpm for 10 min to make a mixed slurry; (4) Pour the prepared mixed slurry into the mold, place the mold in an environment with a temperature of 20℃ and a humidity of ≥60%RH for 1 day, then demold and cure at room temperature to obtain the waste titanium slag-meta-kaolin base polymer thermoelectric material.
[0032] Example 3 (1) Mix 45.9 g of water glass with a water content of 64.5% (v / v), 7.9 g of NaOH and 11.5 g of water to prepare an alkaline activator with an alkalinity of 10% and a modulus of 1.4 for later use; (2) Place 50wt.% waste titanium slag powder and 50wt.% metakaolin in a mixer and pre-stir for 120s at 150 rpm to make the raw materials evenly mixed; (3) Mix the well-mixed raw materials with the alkali activator solution at a water-cement ratio of 0.4, and then mix them with the alkali activator. Place the mixture in a mixer and stir at 150 rpm for 10 min to make a mixed slurry. (4) Pour the prepared mixed slurry into the mold, place the mold in an environment with a temperature of 20℃ and a humidity of ≥60%RH for 1 day, then demold and cure at room temperature to obtain the waste titanium slag-meta-kaolin base polymer thermoelectric material.
[0033] Thermoelectric performance testing: The thermoelectric properties of the waste titanium slag-metakaolin-based geopolymer thermoelectric materials prepared in Examples 1, 2, and 3 were tested. The test items included thermal conductivity, electrical conductivity, Seebeck coefficient, thermoelectric figure of merit, and compressive strength.
[0034] Thermal conductivity: tested using a Hot Disk thermal constant analyzer (TPS2500S), with a heating power of 60 mW; Conductivity: measured by the four-electrode method; Seebeck coefficient: The Seebeck coefficient S is obtained by heating the sample on a heating stage and collecting the temperature and voltage of the cold and hot ends using a data acquisition instrument. The Seebeck coefficient S is then calculated using the Seebeck coefficient formula: S=-ΔV / ΔT. Thermoelectric figure of merit: ZT =S 2 σT / κ. Where ZT denoted as thermoelectric figure of merit, S as Seebeck coefficient, σ as electrical conductivity, κ as thermal conductivity, and T as absolute temperature. Compressive strength: Tested by a pressure testing machine with a compressive load of 2.5 kN / s.
[0035] The performance of the embodiments is shown in Table 2: Table 2
[0036] Note: All the above test items were measured when the sample was 28 days old.
[0037] The thermal conductivity of the embodiments adopted in this invention after 28 days were as follows: Embodiment 1: 0.923 W / m×℃, Embodiment 2: 0.907 W / m×℃, Embodiment 3: 0.834 W / m×℃, and the control group was Embodiment 1.
[0038] The conductivity of the embodiments adopted in this invention after 28 days was as follows: Embodiment 1: 1.74 × 10⁻⁶ -3 S / m, Example 2: 2.15 × 10 -3 S / m, Example 3: 2.52 × 10 -3 S / m, the control group is Example 1.
[0039] The Seebeck coefficients for the 28 days in the embodiments of this invention are as follows: Embodiment 1: 1370 × 10 -3 mV / ℃, Example 2: 1572×10 -3 mV / ℃, Example 3: 1825×10 -3 mV / ℃, with the control group being Experimental Example 1.
[0040] Figure 2 The 28-day Seebeck coefficient diagrams of the waste titanium slag-metakaolin-based geopolymer thermoelectric materials prepared in Examples 1-3 are shown.
[0041] The 28-day thermoelectric figure of merit adopted in this invention are as follows: Example 1: 5.88 × 10⁻⁶ -5 Example 2: 1.62 × 10 -4 Example 3: 2.67 × 10 -4 The control group was Example 1.
[0042] Figure 3 The 28-day thermoelectric figure of merit of the waste titanium slag-metakaolin-based geopolymer thermoelectric materials prepared in Examples 1-3 is shown.
[0043] The 28-day compressive strengths of the embodiments adopted in this invention are as follows: Embodiment 1: 76.5 MPa, Embodiment 2: 69.8 MPa, Embodiment 3: 65.3 MPa, and the control group is Embodiment 1.
[0044] Figure 4 The 28-day compressive strength diagrams of the waste titanium slag-metakaolin-based geopolymer thermoelectric materials prepared in Examples 1-3 are shown.
[0045] As described above, the present invention can be implemented well.
[0046] The embodiments of the present invention are not limited to the above embodiments. The above description is only a partial embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes, substitutions, combinations, simplifications, etc. made without departing from the essence and principle of the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.
Claims
1. A method for preparing a waste titanium slag-metakaolin-based polymer thermoelectric material, characterized in that, Includes the following steps: (1) Place the waste titanium slag powder and metakaolin in a mixer and pre-mix them to make the raw materials evenly mixed; (2) After mixing the well-mixed raw materials with the alkali activator, place them in a mixer and stir to make a mixed slurry; (3) Pour the prepared mixed slurry into the mold, cure it, then demold it and cure it at room temperature to obtain the waste titanium slag-metakaolin base polymer thermoelectric material.
2. The preparation method of a waste titanium slag-metakaolin-based geopolymer thermoelectric material according to claim 1, characterized in that, In step (1), the raw material composition of the waste titanium slag powder and metakaolin is as follows by mass parts: 0-50 parts of waste titanium slag powder and 50-100 parts of metakaolin.
3. The preparation method of a waste titanium slag-metakaolin-based geopolymer thermoelectric material according to claim 1, characterized in that, In step (1), the waste titanium slag powder is obtained by ball milling waste titanium slag. Waste titanium slag includes industrial solid waste generated during the production of titanium dioxide or the smelting of ilmenite. The weight percentage of water in the waste titanium slag is less than 1.0%. The TiO2 content in the composition of the waste titanium slag does not exceed 30%, and the activity index of the waste titanium slag is greater than 60%.
4. The preparation method of a waste titanium slag-metakaolin-based geopolymer thermoelectric material according to claim 1, characterized in that, In step (1), the particle size range of the waste titanium slag powder is 7-15 μm.
5. The preparation method of a waste titanium slag-metakaolin-based geopolymer thermoelectric material according to claim 1, characterized in that, In step (1), the particle size of the metakaolin is 2-10 μm; the content of SiO2 and Al2O3 in the metakaolin composition is greater than 30%.
6. The preparation method of a waste titanium slag-metakaolin-based geopolymer thermoelectric material according to claim 1, characterized in that, In step (2), the alkaline activator solution is prepared with an alkalinity of 10% and a modulus of 1.
4.
7. The preparation method of a waste titanium slag-metakaolin-based geopolymer thermoelectric material according to claim 1, characterized in that, In step (2), the alkaline activator solution is one or more of the following: water glass + sodium hydroxide, water glass + sodium carbonate, and water glass + sodium hydroxide + sodium carbonate.
8. The preparation method of a waste titanium slag-metakaolin-based geopolymer thermoelectric material according to claim 1, characterized in that, In step (2), the water-cement ratio of the total water content in the uniformly mixed raw materials and alkali activator solution is 0.
4.
9. The preparation method of a waste titanium slag-metakaolin-based geopolymer thermoelectric material according to claim 1, characterized in that, In steps (1) and (2), the speed of the mixer is 100-200 rpm.
10. The waste titanium slag-metakaolin-based polymer thermoelectric material prepared by the preparation method of the waste titanium slag-metakaolin-based polymer thermoelectric material according to any one of claims 1 to 9.