Solid heat storage material based on industrial solid waste and preparation method thereof

Abstract

The invention relates to a solid heat storage material based on industrial solid waste and a preparation method thereof. According to the technical scheme, the preparation method comprises the following steps: mixing alumina fine powder, alumina micro powder, Guangxi mud, silica micro powder, aluminum fluoride, dextrin and silica sol to prepare slurry; putting the copper slag particles with the particle size of 1-3mm, the red mud particles with the particle size of 1-3mm, the copper slag particles with the particle size of less than 1mm, the red mud particles with the particle size of less than 1mm and the slurry into a granulator, granulating, screening to obtain a granulated material, and drying to obtain composite solid waste particles; and uniformly mixing the composite solid waste particles, alumina micro powder, quartz sand fine powder and a polyvinyl alcohol solution with the concentration of 5-10 wt%, carrying out compression molding, drying, carrying out heat treatment at 1000-1300 DEG C for 3-5 h, and naturally cooling to prepare the solid heat storage material based on the industrial solid waste. The solid heat storage material based on the industrial solid waste prepared by the invention has the characteristics of high heat storage capacity, high compression strength, high heat conductivity and high thermal shock resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid heat storage materials. Specifically, it relates to a solid heat storage material based on industrial solid waste and a preparation method thereof. Background Art

[0002] With the development of the economy and society, the rapidly growing industrial solid waste has gradually become an important factor restricting the sustainable development of the economy and society. Among them, copper slag is a by-product generated in the copper smelting process and is a typical representative of industrial solid waste. A large amount of copper slag generated annually due to copper smelting accumulates globally, not only occupying land and causing waste of resources, but also the heavy metal ions such as Cu in the copper slag causing great harm to the soil and water bodies. Red mud is an industrial solid waste generated after extracting alumina, with an annual output exceeding 100 million tons and showing a continuous growth trend. Red mud has strong alkalinity and contains harmful substances such as heavy metals. Conventional treatments of red mud such as stacking or landfill not only occupy land resources, but also have problems of environmental pollution and potential safety hazards.

[0003] Solid heat storage materials use the sensible heat storage principle to complete the storage and release of heat through the temperature change process of the substance itself. The heat storage and release process is relatively simple and the operation is stable, showing broad application prospects in the development and utilization of clean energy such as solar energy and wind energy. To realize the resource utilization and harmless treatment of industrial solid wastes such as copper slag and red mud, the preparation of solid heat storage materials with heat storage function from copper slag and red mud has attracted the attention of those skilled in the art:

[0004] For the patented technology of "A New Type of Heat Storage Brick and Preparation Method (CN202111029688.2)", the heat storage brick prepared mainly from copper slag and steel slag in this technology has a relatively high bulk density and heat storage capacity, but the dense structure makes the thermal shock stability of the heat storage brick low.

[0005] For the patented technology of "A Heat Storage Material and Preparation Method Thereof (CN202011252418.3)", the heat storage material prepared by mixing red mud, fly ash, and slag as the main raw materials with an alkaline activator solution and then forming and curing has high compressive strength and refractoriness, but its low thermal conductivity affects the heat exchange efficiency in the actual application process.

[0006] For the patented technology of "A Method for Preparing a Ceramic Material with Heat Storage Function Using Iron-Containing Industrial Solid Waste (CN202410848664.7)", the heat storage ceramic material prepared using iron-containing solid wastes such as red mud and copper slag in this technology, although having excellent thermal conductivity and high thermal shock stability, has problems of low compressive strength and small heat storage capacity.

[0007] In the patent technology of "A Composite Shell Phase Change Heat Storage Sphere Based on Copper Slag and Its Preparation Method (CN202210841134.0)", although the composite phase change heat storage sphere prepared by using aluminum alloy as the phase change heat storage sphere and copper slag as the outer shell has high heat storage capacity and thermal shock stability, the prepared heat storage sphere has the problem of low compressive strength.

[0008] In summary, the existing solid heat storage materials prepared from industrial solid wastes such as copper slag and red mud have the following technical defects: small heat storage capacity, small compressive strength, low thermal conductivity, and low thermal shock stability. Summary of the Invention

[0009] The present invention aims to overcome the technical defects existing in the prior art. The purpose is to provide a preparation method of a solid heat storage material based on industrial solid wastes. The solid heat storage material based on industrial solid wastes prepared by this method has large heat storage capacity, large compressive strength, high thermal conductivity, and high thermal shock stability.

[0010] To achieve the above purpose, the specific steps of the technical solution adopted by the present invention are as follows:

[0011] Step 1: Mix 60 - 80 wt% of bauxite fine powder, 4 - 10 wt% of alumina micro powder, 3 - 7 wt% of Guangxi clay, 2 - 4 wt% of silica micro powder, 1 - 5 wt% of aluminum fluoride, 1 - 3 wt% of dextrin, and 5 - 15 wt% of silica sol to obtain a slurry; then place 15 - 35 wt% of copper slag particles with a particle size of 1 - 3 mm, 15 - 35 wt% of red mud particles with a particle size of 1 - 3 mm, 10 - 20 wt% of copper slag particles with a particle size < 1 mm, 10 - 20 wt% of red mud particles with a particle size < 1 mm, and 10 - 30 wt% of the slurry in a granulator, granulate for 20 - 40 min under the condition of a rotation speed of 30 - 50 r / min, screen to obtain granulated material with a particle size ≥ 0.2 mm, and dry at 80 - 110 °C for 3 - 6 h to obtain composite solid waste particles.

[0012] Step 2: Mix 60 - 80 wt% of the composite solid waste particles, 13 - 17 wt% of alumina micro powder, 5 - 15 wt% of quartz sand fine powder, and 2 - 8 wt% of a polyvinyl alcohol solution with a concentration of 5 - 10 wt% evenly, press and form under the condition of 80 - 100 MPa; dry at 90 - 110 °C for 8 - 12 h, heat-treat at 1000 - 1300 °C for 3 - 5 h, and cool naturally to obtain a solid heat storage material based on industrial solid wastes.

[0013] The chemical composition of the bauxite fine powder: the content of Al2O3 ≥ 75.0 wt%, the content of SiO2 ≤ 10.0 wt%, and the content of Fe2O3 ≤ 2.2 wt%; the particle size of the bauxite fine powder ≤ 75 μm.

[0014] The Al2O3 content of the alumina micropowder in Step 1 is ≥97.0 wt%, and the particle size of the alumina micropowder is ≤5 μm; the alumina micropowder in Step 2 is the same as that in Step 1.

[0015] The chemical composition of the Guangxi clay: the Al2O3 content is 33.0 - 36.0 wt%, the SiO2 content is 45.0 - 50.0 wt%, and the Fe2O3 content is 0.5 - 1.5 wt%; the particle size of the Guangxi clay is ≤75 μm.

[0016] The SiO2 content of the silica fume is ≥97.0 wt%; the particle size of the silica fume is ≤1 μm.

[0017] The AlF3 content of the aluminum fluoride is ≥99.9 wt%.

[0018] The chemical composition of the silica sol: the SiO2 content is ≥25.5 wt%, the Na2O content is ≤0.4 wt%, the pH is 8.5 - 9.5, and the average particle size of the silica sol particles is 8 - 25 nm.

[0019] The chemical composition of the copper slag: the Fe2O3 content is ≥10.0 wt%, the FeO content is ≥40.0 wt%, the SiO2 content is ≥30.0 wt%, and the CuO content is ≥0.50 wt%; the chemical composition of the copper slag particles with a particle size of 1 - 3 mm and the copper slag particles with a particle size of <1 mm is the same.

[0020] The chemical composition of the red mud particles: the Fe2O3 content is ≥40.0 wt%, the Al2O3 content is ≥20.0 wt%, and the SiO2 content is ≥10.0 wt%; the chemical composition of the red mud particles with a particle size of 1 - 3 mm and the red mud particles with a particle size of <1 mm is the same.

[0021] The SiO2 content in the fine quartz sand powder is ≥95 wt%; the particle size of the fine quartz sand powder is ≤75 μm.

[0022] Due to the adoption of the above technical solution, the present invention has the following positive effects compared with the prior art:

[0023] (1) The present invention uses a granulation process to uniformly coat fine bauxite powder and alumina micropowder on the surfaces of red mud and copper slag particles. During the heat treatment process, aluminum fluoride catalyzes the in-situ formation of mullite on the surfaces of red mud and copper slag, effectively inhibiting the oxidation of ferrous oxide and fayalite in red mud and copper slag during high-temperature service, maintaining its characteristic of high specific heat capacity, and enabling the prepared solid heat storage material based on industrial solid waste to have excellent heat storage capacity.

[0024] (2) While making full use of the high thermal conductivity characteristics of copper oxide, iron oxide, and ferrous oxide in red mud and copper slag, alumina micropowder is introduced on the surfaces of red mud, copper slag, and the matrix, further improving the thermal conductivity of the solid heat storage material. Therefore, the solid heat storage material based on industrial solid waste prepared has excellent thermal conductivity.

[0025] (3) On the basis of strictly defining the particle size distribution of raw materials, mullite whiskers are formed in-situ on the surfaces of copper slag and red mud particles. The formed mullite whiskers are interlaced with each other in the solid heat storage material, improving the thermal shock stability of the solid heat storage material. Therefore, the thermal shock stability of the solid heat storage material based on industrial solid waste prepared is significantly improved.

[0026] (4) By defining the preparation process and raw material characteristics, while forming mullite phase in-situ on the surfaces of red mud and copper slag particles, mullite is also formed in-situ between alumina micropowder and quartz sand fine powder, thereby forming a stable binding of mullite phase between raw material particles, significantly improving the compressive strength of the solid heat storage material based on industrial solid waste prepared.

[0027] The solid heat storage material based on industrial solid waste prepared by the present invention is detected: the bulk density ≥ 3.20 g / cm 3 ; the thermal conductivity ≥ 5.0 W / (m·K) (room temperature to 1000 °C); the specific heat capacity ≥ 1.52 J / (g·K) (room temperature to 1000 °C); the heat storage density ≥ 1480 J / g (room temperature to 1000 °C); the thermal shock stability ≥ 20 times (1100 °C, air cooling); the compressive strength is 90 - 120 MPa.

[0028] The detection standards for the performance indicators involved in the present invention are: the bulk density is detected in accordance with GB / T 2999-2016; the thermal conductivity is detected in accordance with the standard of GB / T 5990-2021; the specific heat capacity is detected in accordance with GB / T 5990-2021; the thermal shock stability is detected in accordance with GB / T 30873-2014; the compressive strength is detected in accordance with GB / T 5072-2008.

[0029] Therefore, the solid heat storage material based on industrial solid waste prepared by the present invention has the characteristics of large heat storage capacity, large compressive strength, high thermal conductivity, and high thermal shock stability. Specific Embodiments

[0030] The following further describes the present invention in combination with specific embodiments, which is not a limitation to its protection scope.

[0031] A solid heat storage material based on industrial solid waste and its preparation method. The preparation method described in this specific embodiment is:

[0032] Step 1: Mix 60 - 80 wt% of bauxite fine powder, 4 - 10 wt% of alumina micro powder, 3 - 7 wt% of Guangxi clay, 2 - 4 wt% of silica powder, 1 - 5 wt% of aluminum fluoride, 1 - 3 wt% of dextrin, and 5 - 15 wt% of silica sol to obtain a slurry. Then, place 15 - 35 wt% of copper slag particles with a particle size of 1 - 3 mm, 15 - 35 wt% of red mud particles with a particle size of 1 - 3 mm, 10 - 20 wt% of copper slag particles with a particle size < 1 mm, 10 - 20 wt% of red mud particles with a particle size < 1 mm, and 10 - 30 wt% of the slurry into a granulator, granulate for 20 - 40 min at a rotational speed of 30 - 50 r / min, sieve to obtain granulated materials with a particle size ≥ 0.2 mm, and dry at 80 - 110 °C for 3 - 6 h to obtain composite solid waste particles.

[0033] Step 2: Mix 60 - 80 wt% of the composite solid waste particles, 13 - 17 wt% of alumina micro powder, 5 - 15 wt% of fine quartz sand powder, and 2 - 8 wt% of a polyvinyl alcohol solution with a concentration of 5 - 10 wt% evenly, and press and form at 80 - 100 MPa; dry at 90 - 110 °C for 8 - 12 h, heat - treat at 1000 - 1300 °C for 3 - 5 h, and cool naturally to obtain a solid heat storage material based on industrial solid waste.

[0034] The chemical composition of the bauxite fine powder: the content of Al2O3 ≥ 75.0 wt%, the content of SiO2 ≤ 10.0 wt%, and the content of Fe2O3 ≤ 2.2 wt%

[0035] The chemical composition of the Guangxi clay: the content of Al2O3 is 33.0 - 36.0 wt%, the content of SiO2 is 45.0 - 50.0 wt%, and the content of Fe2O3 is 0.5 - 1.5 wt%.

[0036] The chemical composition of the silica sol: the content of SiO2 ≥ 25.5 wt%, the content of Na2O ≤ 0.4 wt%, the pH is 8.5 - 9.5, and the average particle size of the silica sol particles is 8 - 25 nm.

[0037] The chemical composition of the copper slag: the content of Fe2O3 ≥ 10.0 wt%, the content of FeO ≥ 40.0 wt%, the content of SiO2 ≥ 30.0 wt%, and the content of CuO ≥ 0.50 wt%.

[0038] The chemical composition of the red mud particles: the content of Fe2O3 ≥ 40.0 wt%, the content of Al2O3 ≥ 20.0 wt%, and the content of SiO2 ≥ 10.0 wt%.

[0039] In this specific embodiment:

[0040] The particle size of the bauxite fine powder ≤ 75 μm;

[0041] The Al2O3 content of the alumina micropowder in Step 1 is ≥ 97.0 wt%, and the particle size of the alumina micropowder is ≤ 5 μm; the alumina micropowder in Step 2 is the same as that in Step 1;

[0042] The particle size of the Guangxi clay is ≤ 75 μm;

[0043] The SiO2 content of the silica micropowder is ≥ 97.0 wt%; the particle size of the silica micropowder is ≤ 1 μm;

[0044] The AlF3 content of the aluminum fluoride is ≥ 99.9 wt%;

[0045] The chemical compositions of the copper slag particles with a particle size of 1 - 3 mm and the copper slag particles with a particle size of < 1 mm are the same;

[0046] The chemical compositions of the red mud particles with a particle size of 1 - 3 mm and the red mud particles with a particle size of < 1 mm are the same;

[0047] The SiO2 content in the fine quartz sand powder is ≥ 95 wt%; the particle size of the fine quartz sand powder is ≤ 75 μm.

[0048] Details are not repeated in the examples.

[0049] Example 1

[0050] A solid heat storage material based on industrial solid waste and its preparation method. The preparation method in this example is as follows:

[0051] Step 1: Mix 60 wt% of bauxite fine powder, 10 wt% of alumina micropowder, 3 wt% of Guangxi clay, 4 wt% of silica micropowder, 5 wt% of aluminum fluoride, 3 wt% of dextrin, and 15 wt% of silica sol to obtain a slurry; then place 35 wt% of copper slag particles with a particle size of 1 - 3 mm, 15 wt% of red mud particles with a particle size of 1 - 3 mm, 10 wt% of copper slag particles with a particle size of < 1 mm, 10 wt% of red mud particles with a particle size of < 1 mm, and 30 wt% of the slurry into a granulator, granulate for 20 min at a rotation speed of 30 r / min, screen, obtain granulated materials with a particle size of ≥ 0.2 mm, and dry at 80 °C for 3 h to obtain composite solid waste particles.

[0052] Step 2: Mix 60 wt% of the composite solid waste particles, 17 wt% of alumina micropowder, 15 wt% of fine quartz sand powder, and 8 wt% of a 5 wt% polyvinyl alcohol solution evenly, press and form at 80 MPa; dry at 90 °C for 8 h, perform heat treatment at 1000 °C for 3 h, and cool naturally to obtain a solid heat storage material based on industrial solid waste.

[0053] The chemical composition of the bauxite fine powder: the content of Al2O3 is 75.0 wt%, the content of SiO2 is 10.0 wt%, and the content of Fe2O3 is 2.2 wt%.

[0054] The chemical composition of the Guangxi clay: the content of Al2O3 is 33.0 wt%, the content of SiO2 is 45.0 wt%, and the content of Fe2O3 is 0.5 wt%.

[0055] The chemical composition of the silica sol: the content of SiO2 is 25.5 wt%, the content of Na2O is 0.4 wt%, the pH is 8.5, and the average particle size of the silica sol particles is 8 nm.

[0056] The chemical composition of the copper slag: the content of Fe2O3 is 10.0 wt%, the content of FeO is 40.0 wt%, the content of SiO2 is 30.0 wt%, and the content of CuO is 0.50 wt%.

[0057] The chemical composition of the red mud particles: the content of Fe2O3 is 40.0 wt%, the content of Al2O3 is 20.0 wt%, and the content of SiO2 is 10.0 wt%.

[0058] The solid heat storage material based on industrial solid waste prepared in this example was tested: the bulk density is 3.31 g / cm 3 ; the thermal conductivity is 5.8 W / (m·K) (room temperature to 1000 °C); the specific heat capacity is 1.60 J / (g·K) (room temperature to 1000 °C); the heat storage density is 1562 J / g (room temperature to 1000 °C); the thermal shock stability is 24 times (1100 °C, air-cooled); the compressive strength is 90 MPa.

[0059] Example 2

[0060] A solid heat storage material based on industrial solid waste and its preparation method. The preparation method described in this example is:

[0061] Step 1: Mix 70 wt% of bauxite fine powder, 8 wt% of alumina micro powder, 4 wt% of Guangxi clay, 3 wt% of silicon micro powder, 3 wt% of aluminum fluoride, 2 wt% of dextrin and 10 wt% of silica sol to obtain a slurry; then place 30 wt% of copper slag particles with a particle size of 1 - 3 mm, 20 wt% of red mud particles with a particle size of 1 - 3 mm, 13 wt% of copper slag particles with a particle size < 1 mm, 13 wt% of red mud particles with a particle size < 1 mm and 24 wt% of the slurry in a granulator, granulate for 30 min at a rotation speed of 40 r / min, screen to obtain granulated material with a particle size ≥ 0.2 mm, and dry at 90 °C for 4 h to obtain composite solid waste particles.

[0062] Step 2: Mix 70 wt% of composite solid waste particles, 15 wt% of alumina micro-powder, 9 wt% of fine quartz sand powder, and 6 wt% of a 7 wt% polyvinyl alcohol solution evenly, and press them into shape under the condition of 90 MPa; dry them at 100 °C for 9 h, heat-treat them at 1100 °C for 4 h, and cool them naturally to obtain a solid heat storage material based on industrial solid waste.

[0063] The chemical composition of the bauxite fine powder: the content of Al2O3 is 76.8 wt%, the content of SiO2 is 9.4 wt%, and the content of Fe2O3 is 2.0 wt%.

[0064] The chemical composition of the Guangxi clay: the content of Al2O3 is 34.4 wt%, the content of SiO2 is 46.2 wt%, and the content of Fe2O3 is 0.8 wt%.

[0065] The chemical composition of the silica sol: the content of SiO2 is 26.8 wt%, the content of Na2O is 0.3 wt%, the pH is 8.8, and the average particle size of the silica sol particles is 12 nm.

[0066] The chemical composition of the copper slag: the content of Fe2O3 is 10.5 wt%, the content of FeO is 41.4 wt%, the content of SiO2 is 31.2 wt%, and the content of CuO is 0.55 wt%.

[0067] The chemical composition of the red mud particles: the content of Fe2O3 is 40.5 wt%, the content of Al2O3 is 20.7 wt%, and the content of SiO2 is 10.6 wt%.

[0068] The solid heat storage material based on industrial solid waste prepared in this example was tested: the bulk density is 3.29 g / cm 3 ; the thermal conductivity is 5.5 W / (m·K) (room temperature to 1000 °C); the specific heat capacity is 1.57 J / (g·K) (room temperature to 1000 °C); the heat storage density is 1531 J / g (room temperature to 1000 °C); the thermal shock stability is 23 times (1100 °C, air cooling); the compressive strength is 98 MPa.

[0069] Example 3

[0070] A solid heat storage material based on industrial solid waste and its preparation method. The preparation method described in this example is:

[0071] Step 1: Mix 75 wt% of fine bauxite powder, 6 wt% of alumina micropowder, 5 wt% of Guangxi clay, 3 wt% of silica micropowder, 2 wt% of aluminum fluoride, 2 wt% of dextrin and 7 wt% of silica sol to prepare a slurry; then place 25 wt% of copper slag particles with a particle size of 1 - 3 mm, 25 wt% of red mud particles with a particle size of 1 - 3 mm, 17 wt% of copper slag particles with a particle size < 1 mm, 17 wt% of red mud particles with a particle size < 1 mm and 16 wt% of the slurry in a granulator, granulate for 30 min at a rotational speed of 40 r / min, screen to obtain granulated material with a particle size ≥ 0.2 mm, and dry at 100 °C for 5 h to prepare composite solid waste particles.

[0072] Step 2: Mix 75 wt% of the composite solid waste particles, 14 wt% of alumina micropowder, 7 wt% of fine quartz sand powder, and 4 wt% of a polyvinyl alcohol solution with a concentration of 8 wt% evenly, press and mold at 95 MPa; dry at 100 °C for 10 h, heat-treat at 1200 °C for 4 h, and cool naturally to prepare a solid heat storage material based on industrial solid waste.

[0073] The chemical composition of the fine bauxite powder: The content of Al2O3 is 78.9 wt%, the content of SiO2 is 8.9 wt%, and the content of Fe2O3 is 1.6 wt%.

[0074] The chemical composition of the Guangxi clay: The content of Al2O3 is 35.1 wt%, the content of SiO2 is 48.4 wt%, and the content of Fe2O3 is 1.2 wt%.

[0075] The chemical composition of the silica sol: The content of SiO2 is 28.2 wt%, the content of Na2O is 0.3 wt%, the pH is 9.2, and the average particle size of the silica sol particles is 22 nm.

[0076] The chemical composition of the copper slag: The content of Fe2O3 is 11.0 wt%, the content of FeO is 42.8 wt%, the content of SiO2 is 32.1 wt%, and the content of CuO is 0.58 wt%.

[0077] The chemical composition of the red mud particles: The content of Fe2O3 is 40.9 wt%, the content of Al2O3 is 20.9 wt%, and the content of SiO2 is 11.1 wt%.

[0078] The solid heat storage material based on industrial solid waste prepared in this example was tested: The bulk density is 3.26 g / cm 3 ; The thermal conductivity is 5.3 W / (m·K) (room temperature - 1000 °C); The specific heat capacity is 1.54 J / (g·K) (room temperature - 1000 °C); The heat storage density is 1501 J / g (room temperature - 1000 °C); The thermal shock stability is 22 times (1100 °C, air cooling); The compressive strength is 107 MPa.

[0079] Example 4

[0080] A solid heat storage material based on industrial solid waste and its preparation method. The preparation method described in this example is as follows:

[0081] Step 1: Mix 80 wt% of bauxite fine powder, 4 wt% of alumina fine powder, 7 wt% of Guangxi clay, 2 wt% of silica fine powder, 1 wt% of aluminum fluoride, 1 wt% of dextrin, and 5 wt% of silica sol to obtain a slurry; then place 15 wt% of copper slag particles with a particle size of 1 - 3 mm, 35 wt% of red mud particles with a particle size of 1 - 3 mm, 20 wt% of copper slag particles with a particle size < 1 mm, 20 wt% of red mud particles with a particle size < 1 mm, and 10 wt% of the slurry in a granulator, granulate at a rotation speed of 50 r / min for 40 min, screen to obtain granulated materials with a particle size ≥ 0.2 mm, and dry at 110 °C for 6 h to obtain composite solid waste particles.

[0082] Step 2: Mix 80 wt% of the composite solid waste particles, 13 wt% of alumina fine powder, 5 wt% of quartz sand fine powder, and 2 wt% of a 10 wt% polyvinyl alcohol solution evenly, press and form at 100 MPa; dry at 110 °C for 12 h, heat-treat at 1300 °C for 5 h, and cool naturally to obtain a solid heat storage material based on industrial solid waste.

[0083] The chemical composition of the bauxite fine powder: The content of Al2O3 is 79.6 wt%, the content of SiO2 is 8.2 wt%, and the content of Fe2O3 is 1.3 wt%.

[0084] The chemical composition of the Guangxi clay: The content of Al2O3 is 36.0 wt%, the content of SiO2 is 50.0 wt%, and the content of Fe2O3 is 1.5 wt%.

[0085] The chemical composition of the silica sol: The content of SiO2 is 30.5 wt%, the content of Na2O is 0.2 wt%, the pH is 9.5, and the average particle size of the silica sol particles is 25 nm.

[0086] The chemical composition of the copper slag: The content of Fe2O3 is 11.4 wt%, the content of FeO is 43.7 wt%, the content of SiO2 is 32.8 wt%, and the content of CuO is 0.60 wt%.

[0087] The chemical composition of the red mud particles: The content of Fe2O3 is 41.2 wt%, the content of Al2O3 is 22.3 wt%, and the content of SiO2 is 11.9 wt%.

[0088] The solid heat storage material based on industrial solid waste prepared in this example is detected: The bulk density is 3.21 g / cm3 ; The thermal conductivity is 5.0 W / (m·K) (room temperature to 1000 °C); the specific heat capacity is 1.52 J / (g·K) (room temperature to 1000 °C); the heat storage density is 1482 J / g (room temperature to 1000 °C); the thermal shock stability is 20 times (1100 °C, air cooling); the compressive strength is 120 MPa.

[0089] The following are the positive effects of this specific embodiment compared with the prior art:

[0090] (1) In this specific embodiment, the granulation process is used to uniformly coat the surface of red mud and copper slag particles with fine bauxite powder and alumina micropowder. During the heat treatment process, aluminum fluoride catalyzes the in-situ formation of mullite on the surface of red mud and copper slag, effectively inhibiting the oxidation of ferrous oxide and fayalite in red mud and copper slag during high-temperature service, maintaining its high specific heat capacity characteristic, and enabling the prepared solid heat storage material based on industrial solid waste to have excellent heat storage capacity.

[0091] (2) While making full use of the high thermal conductivity characteristics of copper oxide, iron oxide and ferrous oxide in red mud and copper slag, alumina micropowder is introduced on the surface of red mud and copper slag and in the matrix, further improving the thermal conductivity of the solid heat storage material. Therefore, the prepared solid heat storage material based on industrial solid waste has excellent thermal conductivity.

[0092] (3) On the basis of strictly limiting the particle size distribution of raw materials, mullite whiskers are formed in-situ on the surface of copper slag and red mud particles. The formed mullite whiskers intersect with each other in the solid heat storage material, improving the thermal shock stability of the solid heat storage material. Therefore, the thermal shock stability of the prepared solid heat storage material based on industrial solid waste is significantly improved.

[0093] (4) Through the limitation of the preparation process and raw material characteristics, while forming mullite phase in-situ on the surface of red mud and copper slag particles, mullite is also formed in-situ between alumina micropowder and fine quartz sand powder, thereby forming a stable mullite phase bond between raw material particles, significantly improving the compressive strength of the prepared solid heat storage material based on industrial solid waste.

[0094] The solid heat storage material based on industrial solid waste prepared by this specific embodiment is tested: the bulk density ≥ 3.20 g / cm 3 ; The thermal conductivity ≥ 5.0 W / (m·K) (room temperature to 1000 °C); the specific heat capacity ≥ 1.52 J / (g·K) (room temperature to 1000 °C); the heat storage density ≥ 1480 J / g (room temperature to 1000 °C); the thermal shock stability ≥ 20 times (1100 °C, air cooling); the compressive strength is 90 - 120 MPa.

[0095] The detection standards for the performance indicators involved in this specific embodiment are as follows: the bulk density is detected in accordance with GB / T 2999-2016; the thermal conductivity is detected in accordance with the standard of GB / T 5990-2021; the specific heat capacity is detected in accordance with GB / T 5990-2021; the thermal shock stability is detected in accordance with GB / T 30873-2014; and the compressive strength is detected in accordance with GB / T 5072-2008.

[0096] Therefore, the solid heat storage material based on industrial solid waste prepared in this specific embodiment has the characteristics of large heat storage capacity, large compressive strength, high thermal conductivity, and high thermal shock stability.

Claims

1. A preparation method of a solid heat storage material based on industrial solid waste, characterized in that, The preparation method is as follows: Step 1: Mix 60 - 80 wt% of bauxite fine powder, 4 - 10 wt% of alumina micro - powder, 3 - 7 wt% of Guangxi clay, 2 - 4 wt% of silica powder, 1 - 5 wt% of aluminum fluoride, 1 - 3 wt% of dextrin, and 5 - 15 wt% of silica sol to obtain a slurry; then place 15 - 35 wt% of copper slag particles with a particle size of 1 - 3 mm, 15 - 35 wt% of red mud particles with a particle size of 1 - 3 mm, 10 - 20 wt% of copper slag particles with a particle size < 1 mm, 10 - 20 wt% of red mud particles with a particle size < 1 mm, and 10 - 30 wt% of the slurry in a granulator, granulate for 20 - 40 min under the condition of a rotation speed of 30 - 50 r / min, screen to obtain granulated materials with a particle size ≥ 0.2 mm, and dry at 80 - 110 °C for 3 - 6 h to obtain composite solid waste particles; Step 2: Mix 60 - 80 wt% of the composite solid waste particles, 13 - 17 wt% of alumina micro - powder, 5 - 15 wt% of fine quartz sand powder, and 2 - 8 wt% of a polyvinyl alcohol solution with a concentration of 5 - 10 wt% evenly, press - mold under the condition of 80 - 100 MPa; dry at 90 - 110 °C for 8 - 12 h, perform heat treatment at 1000 - 1300 °C for 3 - 5 h, and cool naturally to obtain a solid heat storage material based on industrial solid waste.

2. The preparation method of the solid heat storage material based on industrial solid waste according to claim 1, characterized in that, The chemical composition of the bauxite fine powder: The content of Al2O3 ≥ 75.0 wt%, the content of SiO2 ≤ 10.0 wt%, and the content of Fe2O3 ≤ 2.2 wt%; the particle size of the bauxite fine powder ≤ 75 μm.

3. The preparation method of the solid heat storage material based on industrial solid waste according to claim 1, characterized in that, The content of Al2O3 in the alumina micro - powder in Step 1 ≥ 97.0 wt%, the particle size of the alumina micro - powder ≤ 5 μm; the alumina micro - powder in Step 2 is the same as that in Step 1.

4. The preparation method of the solid heat storage material based on industrial solid waste according to claim 1, wherein The chemical composition of the Guangxi clay: The content of Al2O3 is 33.0 - 36.0 wt%, the content of SiO2 is 45.0 - 50.0 wt%, and the content of Fe2O3 is 0.5 - 1.5 wt%; the particle size of the Guangxi clay ≤ 75 μm.

5. The preparation method of the solid heat storage material based on industrial solid waste according to claim 1, wherein, The content of SiO2 in the silica powder ≥ 97.0 wt%; the particle size of the silica powder ≤ 1 μm.

6. The preparation method of the solid heat storage material based on industrial solid waste according to claim 1, characterized in that, The content of AlF3 in the aluminum fluoride ≥ 99.9 wt%.

7. The preparation method of the solid heat storage material based on industrial solid waste according to claim 1, wherein, The chemical composition of the silica sol: The content of SiO2 ≥ 25.5 wt%, the content of Na2O ≤ 0.4 wt%, the pH is 8.5 - 9.5, and the average particle size of the silica sol particles is 8 - 25 nm.

8. The preparation method of the solid heat storage material based on industrial solid waste according to claim 1, wherein, The chemical composition of the copper slag: The content of Fe2O3 ≥ 10.0 wt%, the content of FeO ≥ 40.0 wt%, the content of SiO2 ≥ 30.0 wt%, and the content of CuO ≥ 0.50 wt%; the chemical compositions of the copper slag particles with a particle size of 1 - 3 mm and the copper slag particles with a particle size < 1 mm are the same.

9. The preparation method of the solid heat storage material based on industrial solid waste according to claim 1, wherein The chemical composition of the red mud particles: The content of Fe2O3 ≥ 40.0 wt%, the content of Al2O3 ≥ 20.0 wt%, and the content of SiO2 ≥ 10.0 wt%; the chemical compositions of the red mud particles with a particle size of 1 - 3 mm and the red mud particles with a particle size < 1 mm are the same.

10. The preparation method of the solid heat storage material based on industrial solid waste according to claim 1, characterized in that, The content of SiO2 in the fine quartz sand powder ≥ 95 wt%; the particle size of the fine quartz sand powder ≤ 75 μm.

11. A solid heat storage material based on industrial solid waste, characterized in that, The solid heat storage material based on industrial solid waste is the solid heat storage material based on industrial solid waste prepared according to the preparation method of the solid heat storage material based on industrial solid waste described in any one of claims 1 to 10.