Preparation method of high-thermal-conductivity anti-sintering basalt-based solid heat storage particles

Abstract

The invention belongs to the technical field of heat storage materials, and particularly discloses a preparation method of high-thermal-conductivity anti-sintering basalt-based solid heat storage particles, which comprises the following steps: crushing basalt ore, and carrying out wet grinding for 2 hours by using a ball mill; adding basalt particles into a high-speed mixer, spraying a sodium silicate aqueous solution, and stirring; adding crystalline flake graphite; adding nano zirconium dioxide powder into the mixer, and adding a polyvinyl alcohol aqueous solution; and carrying out compression molding by using a four-column hydraulic press to obtain green body particles, putting the green body particles into a roller kiln, and carrying out segmented sintering to obtain solid particles with different particle sizes. According to the preparation method of the high-thermal-conductivity anti-sintering basalt-based solid heat storage particles, the preparation method of gradient particle size ratio, graphite-zirconium dioxide compound modification and low-temperature sintering is adopted, so that the thermal conductivity, the sintering resistance and the mechanical strength of the heat storage particles are synchronously improved on the basis of keeping the advantage of low cost of basalt; the pains in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of thermal storage materials technology, and in particular to a method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles. Background Technology

[0002] In solid particulate energy storage and thermal storage equipment, the performance of the storage particles directly determines the heat exchange efficiency, operational stability, and operating cost of the equipment. Basalt, due to its abundant reserves, low cost, and high-temperature resistance, has become one of the ideal raw materials for thermal storage particles. However, primary basalt particles have two major drawbacks: poor thermal conductivity (only 0.3-0.5 W / (m·K)), resulting in low heat transfer efficiency in thermal storage equipment and a long time required to heat air to the target temperature, failing to meet the requirements for efficient heat exchange; and insufficient resistance to sintering (at equipment operating temperatures of 500-600℃, traditional basalt particles are prone to grain boundary migration, leading to sintering and agglomeration, clogging heat exchange pipelines, and shortening equipment maintenance cycles and service life).

[0003] Among the existing improvement schemes, some technologies use basalt particles of a single size, which cannot optimize the particle packing structure and result in discontinuous heat transfer channels; some technologies add high thermal conductivity metal powders (such as copper powder and aluminum powder) to improve thermal conductivity, but metal powders are expensive and easily oxidized at high temperatures, making it difficult to balance the economy and stability of thermal storage particles; and some technologies use high-temperature melting and sintering (above 1200℃), which can improve particle strength, but will destroy the porous structure inside the raw material, reduce thermal storage capacity, and significantly increase energy consumption.

[0004] To address this, the present invention proposes a method for preparing basalt solid thermal storage particles, which, while retaining the low-cost advantage of basalt, simultaneously improves the thermal conductivity, sintering resistance, and mechanical strength of the thermal storage particles, thus solving the pain points of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing high thermal conductivity and sintering-resistant basalt-based solid thermal storage particles. The prepared thermal storage material particles have no obvious agglomeration, which improves thermal conductivity and sintering resistance, and achieves improved thermal conductivity, enhanced sintering resistance, and controllable cost, making it suitable for the long-term stable operation of solid particulate energy storage and thermal storage equipment.

[0006] To achieve the above objectives, the present invention provides a method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles, comprising the following steps: Step 1: The basalt ore is coarsely crushed to a particle size of 5-10 mm using a crusher, then wet-milled in a ball mill for 2 hours, and classified by a hydraulic classifier to obtain three particle sizes: coarse, medium, and fine. Step 2: Add basalt particles to a high-speed mixer, spray in sodium silicate aqueous solution, and stir; add flake graphite in 3 batches, with an interval of 5 minutes between each batch, and continue stirring for 20-40 minutes to make the graphite uniformly coat the surface of the basalt particles and form a continuous thermally conductive interface layer. Step 3: Add nano-zirconia powder to the mixer, adjust the speed to 500 r / min, and stir at room temperature for 15 min to make the zirconia evenly dispersed in the gaps between the particles; add polyvinyl alcohol aqueous solution as an auxiliary binder, stir for 10 min, and obtain the mixed wet material; Step 4: Dry the mixed wet material with forced air at 60℃ for 4 hours, remove agglomerates by passing it through a 1.5mm sieve, and press it into shape using a four-column hydraulic press to obtain green pellets. Place the green pellets into a roller kiln and sinter them in stages. After sintering, allow them to cool naturally to room temperature to obtain basalt-based solid thermal storage particles. Perform multi-stage sieving on the basalt-based solid thermal storage particles using a vibrating screen to obtain solid particles of varying sizes.

[0007] Preferably, in step 1, the ball mill wet grinding process controls the ball-to-material ratio at 3:1 and the rotation speed at 300 r / min.

[0008] Preferably, in step 1, the coarse particles have a diameter of 0.8-1.2 mm, the medium particles have a diameter of 0.3-0.5 mm, and the fine particles have a diameter of 0.1-0.2 mm, with a mass ratio of coarse, medium, and fine particles of 3:5:2.

[0009] Preferably, in step 2, the high-speed mixer is set to a speed of 800 r / min and a temperature of 60°C, and an aqueous solution of sodium silicate is sprayed in and stirred for 10 min.

[0010] Preferably, in step 2, the flake graphite needs to be pulverized to a particle size of 5-10 μm using an air jet mill before being added, and impurities are removed by passing it through a 2000-mesh sieve.

[0011] Preferably, in step 2, the mass concentration of the sodium silicate aqueous solution is 10%.

[0012] Preferably, in step 3, the nano-sized zirconium dioxide powder with a particle size of 50-100nm is vacuum dried at 80℃ and a vacuum degree of -0.09MPa for 2h to avoid moisture absorption and agglomeration.

[0013] Preferably, in step 3, the mass concentration of the polyvinyl alcohol aqueous solution is 5%.

[0014] Preferably, in step 4, the segmented sintering is as follows: The first stage involves raising the room temperature to 300℃ at a rate of 5℃ / min and holding it at that temperature for 1 hour to remove the binder from the raw materials. The second stage involves raising the temperature from 300℃ to 750℃ at a rate of 3℃ / min and holding it at that temperature for 2 hours to achieve initial densification of the particle surface. The third stage involves raising the temperature from 750℃ to 850-880℃ at a rate of 2℃ / min and holding it at that temperature for 1.5-2 hours to promote the fusion of the graphite and basalt interface.

[0015] Preferably, the following raw materials are added by weight: 90-95 parts basalt particles, 3-8 parts flake graphite, 1-2 parts nano zirconium dioxide, and 0.5-1 parts sodium silicate.

[0016] The advantages and beneficial effects of the above-mentioned method for preparing high thermal conductivity and sintering-resistant basalt-based solid thermal storage particles are as follows: 1. This invention optimizes the particle packing structure through a three-level gradient particle size ratio, reduces gaps and constructs a continuous heat transfer channel, and forms a heat-conducting network with a graphite coating layer. The thermal conductivity of the finished product at room temperature is improved compared with traditional single-particle-size basalt, and the thermal conductivity at 500℃ is ≥1.5W / (m·K), which significantly shortens the air heating time of energy storage and thermal storage equipment.

[0017] 2. This invention disperses nano-zirconia in the interparticle gaps, which can suppress the grain boundary migration of basalt particles at high temperatures. The agglomeration rate is ≤5% after 1000 hours of constant temperature at 600℃, avoiding blockage of equipment heat exchange pipelines and extending the maintenance cycle. At the same time, the low-temperature sintering process (850-880℃) preserves the porous structure inside the particles, taking into account both heat storage capacity and thermal conductivity.

[0018] 3. This invention uses basalt as the main raw material, combined with low-cost flake graphite to replace metal powder, thus reducing raw material costs compared to metal-modified thermal storage particles. The low-temperature sintering process reduces energy consumption compared to high-temperature melting sintering, meeting the needs of large-scale industrial production. The finished particles can be directly applied to existing solid particulate energy storage and thermal storage equipment without requiring structural modifications. It is suitable for various scenarios such as metal processing preheating and industrial waste heat recovery, and has broad application value.

[0019] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0020] The technical solution of the present invention will be further described below through embodiments.

[0021] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0022] The following examples are not intended to limit the invention, but are only for illustration. Unless otherwise specified, the experimental methods used in the following examples are generally performed under conventional conditions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0023] Example 1 92 parts of basalt particles (coarse particles 0.8-1.2mm: medium particles 0.3-0.5mm: fine particles 0.1-0.2mm = 3:5:2), 6 parts of flake graphite, 1.5 parts of nano-zirconia, and 0.5 parts of sodium silicate.

[0024] A method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles includes the following steps: Step 1: The basalt ore is fed into a jaw crusher for coarse crushing to 5-10mm, and then wet-ground in a ball mill with a ball-to-material ratio of 3:1, a rotation speed of 300r / min, and a grinding time of 2h. The ore is then classified using a hydraulic classifier to obtain three particle sizes: coarse particles (0.8-1.2mm), medium particles (0.3-0.5mm), and fine particles (0.1-0.2mm), with a mass ratio of 3:5:2.

[0025] Flake graphite was pulverized to a particle size of 5-10 μm using an air jet mill and then passed through a 2000-mesh sieve to remove impurities. Nano-sized zirconium dioxide powder (particle size 50-100 nm) was vacuum dried at 80 °C and a vacuum degree of -0.09 MPa for 2 h to prevent moisture absorption and clumping.

[0026] Step 2: Add basalt particles to a high-speed mixer, set the speed to 800 r / min and the temperature to 60℃, spray in a 10% sodium silicate aqueous solution, and stir for 10 min; add flake graphite in 3 batches, with an interval of 5 min between each batch, and continue stirring for 20 min to make the graphite uniformly coat the surface of the basalt particles and form a continuous thermally conductive interface layer.

[0027] Step 3: Add the treated nano-zirconia powder to the mixer, adjust the speed to 500 r / min, and stir at room temperature for 15 min to make the zirconia uniformly dispersed in the gaps between the particles; add 5% mass concentration of polyvinyl alcohol aqueous solution as an auxiliary binder, stir for 10 min, and obtain the mixed wet material.

[0028] Step 4: Dry the mixed wet material at 60℃ for 4 hours with forced air, remove agglomerates by passing it through a 1.5mm sieve, and press it into shape using a four-column hydraulic press. Select a 5mm diameter circular mold, set the pressing pressure to 22MPa and the holding time to 30s to obtain green pellets. Place the green pellets into a roller kiln and sinter them in stages. After sintering, allow them to cool naturally to room temperature to obtain basalt-based solid thermal storage particles. Use a vibrating screen to perform multi-stage sieving of the basalt-based solid thermal storage particles to obtain solid particles of different sizes.

[0029] Segmented sintering is: The first stage involves raising the room temperature to 300℃ at a rate of 5℃ / min and holding it at that temperature for 1 hour to remove the binder from the raw materials.

[0030] In the second stage, the temperature is increased from 300℃ to 750℃ at a rate of 3℃ / min, and the temperature is maintained for 2 hours to achieve initial densification of the particle surface.

[0031] The third stage involves raising the temperature from 750℃ to 850℃ at a rate of 2℃ / min and holding it at that temperature for 1.5 hours to promote the fusion of the graphite and basalt interface.

[0032] Example 2 90 parts of basalt particles (coarse particles 0.8-1.2mm: medium particles 0.3-0.5mm: fine particles 0.1-0.2mm = 3:5:2), 8 parts of flake graphite, 1.5 parts of nano-zirconia, and 0.5 parts of sodium silicate.

[0033] A method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles includes the following steps: Step 1: The basalt ore is fed into a jaw crusher for coarse crushing to 5-10mm, and then wet-ground in a ball mill with a ball-to-material ratio of 3:1, a rotation speed of 300r / min, and a grinding time of 2h. The ore is then classified using a hydraulic classifier to obtain three particle sizes: coarse particles (0.8-1.2mm), medium particles (0.3-0.5mm), and fine particles (0.1-0.2mm), with a mass ratio of 3:5:2.

[0034] Flake graphite was pulverized to a particle size of 5-10 μm using an air jet mill and then passed through a 2000-mesh sieve to remove impurities. Nano-sized zirconium dioxide powder (particle size 50-100 nm) was vacuum dried at 80 °C and a vacuum degree of -0.09 MPa for 2 h to prevent moisture absorption and clumping.

[0035] Step 2: Add basalt particles to a high-speed mixer, set the speed to 800 r / min and the temperature to 60℃, spray in a 10% sodium silicate aqueous solution, and stir for 10 min; add flake graphite in 3 batches, with an interval of 5 min between each batch, and continue stirring for 40 min to make the graphite uniformly coat the surface of the basalt particles and form a continuous thermally conductive interface layer.

[0036] Step 3: Add the treated nano-zirconia powder to the mixer, adjust the speed to 500 r / min, and stir at room temperature for 15 min to make the zirconia uniformly dispersed in the gaps between the particles; add 5% mass concentration of polyvinyl alcohol aqueous solution as an auxiliary binder, stir for 10 min, and obtain the mixed wet material.

[0037] Step 4: Dry the mixed wet material with forced air at 60℃ for 4 hours, remove agglomerates by passing it through a 1.5mm sieve, and press it into shape using a four-column hydraulic press. Select a circular mold with a diameter of 5mm, set the pressing pressure to 24MPa and the holding time to 30s to obtain green pellets. Place the green pellets into a roller kiln and sinter them in stages. After sintering, allow them to cool naturally to room temperature to obtain basalt-based solid thermal storage particles. Use a vibrating screen to perform multi-stage sieving of the basalt-based solid thermal storage particles to obtain solid particles of different sizes.

[0038] Segmented sintering is: The first stage involves raising the room temperature to 300℃ at a rate of 5℃ / min and holding it at that temperature for 1 hour to remove the binder from the raw materials.

[0039] In the second stage, the temperature is increased from 300℃ to 750℃ at a rate of 3℃ / min, and the temperature is maintained for 2 hours to achieve initial densification of the particle surface.

[0040] The third stage involves raising the temperature from 750℃ to 850℃ at a rate of 2℃ / min and holding it at that temperature for 1.5 hours to promote the fusion of the graphite and basalt interface.

[0041] Example 3 95 parts of basalt particles (coarse particles 0.8-1.2mm: medium particles 0.3-0.5mm: fine particles 0.1-0.2mm = 3:5:2), 5 parts of flake graphite, 2 parts of nano-zirconia, and 1 part of sodium silicate.

[0042] A method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles includes the following steps: Step 1: The basalt ore is fed into a jaw crusher for coarse crushing to 5-10mm, and then wet-ground in a ball mill with a ball-to-material ratio of 3:1, a rotation speed of 300r / min, and a grinding time of 2h. The ore is then classified using a hydraulic classifier to obtain three particle sizes: coarse particles (0.8-1.2mm), medium particles (0.3-0.5mm), and fine particles (0.1-0.2mm), with a mass ratio of 3:5:2.

[0043] Flake graphite was pulverized to a particle size of 5-10 μm using an air jet mill and then passed through a 2000-mesh sieve to remove impurities. Nano-sized zirconium dioxide powder (particle size 50-100 nm) was vacuum dried at 80 °C and a vacuum degree of -0.09 MPa for 2 h to prevent moisture absorption and clumping.

[0044] Step 2: Add basalt particles to a high-speed mixer, set the speed to 800 r / min and the temperature to 60℃, spray in a 10% sodium silicate aqueous solution, and stir for 10 min; add flake graphite in 3 batches, with an interval of 5 min between each batch, and continue stirring for 20 min to make the graphite uniformly coat the surface of the basalt particles and form a continuous thermally conductive interface layer.

[0045] Step 3: Add the treated nano-zirconia powder to the mixer, adjust the speed to 500 r / min, and stir at room temperature for 15 min to make the zirconia uniformly dispersed in the gaps between the particles; add 5% mass concentration of polyvinyl alcohol aqueous solution as an auxiliary binder, stir for 10 min, and obtain the mixed wet material.

[0046] Step 4: Dry the mixed wet material at 60℃ for 4 hours with forced air, remove agglomerates by passing it through a 1.5mm sieve, and press it into shape using a four-column hydraulic press. Select a 5mm diameter circular mold, set the pressing pressure to 22MPa and the holding time to 30s to obtain green pellets. Place the green pellets into a roller kiln and sinter them in stages. After sintering, allow them to cool naturally to room temperature to obtain basalt-based solid thermal storage particles. Use a vibrating screen to perform multi-stage sieving of the basalt-based solid thermal storage particles to obtain solid particles of different sizes.

[0047] Segmented sintering is: The first stage involves raising the room temperature to 300℃ at a rate of 5℃ / min and holding it at that temperature for 1 hour to remove the binder from the raw materials.

[0048] In the second stage, the temperature is increased from 300℃ to 750℃ at a rate of 3℃ / min, and the temperature is maintained for 2 hours to achieve initial densification of the particle surface.

[0049] The third stage involves raising the temperature from 750℃ to 880℃ at a rate of 2℃ / min and holding it at that temperature for 2 hours to promote the fusion of the graphite and basalt interface.

[0050] Comparative Example 1 98 parts of basalt particles (single particle size 0.3-0.5 mm) and 1.5 parts of sodium silicate.

[0051] A method for preparing basalt-based solid thermal energy storage particles includes the following steps: Step 1: Crush the basalt ore into a crusher to a particle size of 0.3-0.5 mm, and then wet grind it in a ball mill, controlling the ball-to-material ratio at 3:1, the rotation speed at 300 r / min, and the grinding time at 2 h. Step 2: Add the basalt particles to a high-speed mixer, set the rotation speed at 800 r / min and the temperature at 60 °C, spray in a 10% sodium silicate aqueous solution, and stir for 10 min.

[0052] Step 3: Dry the mixture at 60℃ for 4 hours with forced air, remove agglomerates by passing it through a 1.5mm sieve, and press it into shape using a four-column hydraulic press. Select a 5mm diameter circular mold, set the pressing pressure to 22MPa and the holding time to 30s to obtain green pellets. Place the green pellets into a roller kiln and sinter them in stages. After sintering, allow them to cool naturally to room temperature to obtain basalt-based solid thermal storage particles. Perform multi-stage sieving on the basalt-based solid thermal storage particles using a vibrating screen to obtain solid particles of different sizes.

[0053] Segmented sintering is: The first stage involves raising the room temperature to 300℃ at a rate of 5℃ / min and holding it at that temperature for 1 hour to remove the binder from the raw materials.

[0054] In the second stage, the temperature is increased from 300℃ to 750℃ at a rate of 3℃ / min, and the temperature is maintained for 2 hours to achieve initial densification of the particle surface.

[0055] The third stage involves raising the temperature from 750℃ to 850℃ at a rate of 2℃ / min and holding it at that temperature for 1.5 hours to promote the fusion of the graphite and basalt interface.

[0056] Comparative Example 2 95 parts of basalt ore (coarse particles 0.8-1.2mm: medium particles 0.3-0.5mm: fine particles 0.1-0.2mm = 3:5:2), 5 parts of flake graphite, and 0.5 parts of sodium silicate.

[0057] A method for preparing basalt-based solid thermal energy storage particles includes the following steps: Step 1: The basalt ore is fed into a crusher and coarsely crushed to 5-10mm, then wet-ground in a ball mill with a ball-to-material ratio of 3:1, a rotation speed of 300r / min, and a grinding time of 2h. The basalt ore is then classified using a hydraulic classifier to obtain three particle sizes: coarse particles (0.8-1.2mm), medium particles (0.3-0.5mm), and fine particles (0.1-0.2mm), with a mass ratio of 3:5:2.

[0058] Flake graphite is pulverized to a particle size of 5-10 μm using an air jet mill and then passed through a 2000-mesh sieve to remove impurities.

[0059] Step 2: Add basalt particles to a high-speed mixer, set the speed to 800 r / min and the temperature to 60℃, spray in a 10% sodium silicate aqueous solution, and stir for 10 min; add flake graphite in 3 batches, with an interval of 5 min between each batch, and continue stirring for 20 min to make the graphite uniformly coat the surface of the basalt particles and form a continuous thermally conductive interface layer.

[0060] Step 3: Dry the mixture at 60℃ for 4 hours with forced air, remove agglomerates by passing it through a 1.5mm sieve, and press it into shape using a four-column hydraulic press. Select a 5mm diameter circular mold, set the pressing pressure to 22MPa and the holding time to 30s to obtain green pellets. Place the green pellets into a roller kiln and sinter them in stages. After sintering, allow them to cool naturally to room temperature to obtain basalt-based solid thermal storage particles. Perform multi-stage sieving on the basalt-based solid thermal storage particles using a vibrating screen to obtain solid particles of different sizes.

[0061] Segmented sintering is: The first stage involves raising the room temperature to 300℃ at a rate of 5℃ / min and holding it at that temperature for 1 hour to remove the binder from the raw materials.

[0062] In the second stage, the temperature is increased from 300℃ to 750℃ at a rate of 3℃ / min, and the temperature is maintained for 2 hours to achieve initial densification of the particle surface.

[0063] The third stage involves raising the temperature from 750℃ to 850℃ at a rate of 2℃ / min and holding it at that temperature for 1.5 hours to promote the fusion of the graphite and basalt interface.

[0064] Comparative Example 3 Unlike Comparative Example 1, segmented sintering was not performed. Instead, the green pellets were placed in a roller kiln for melt sintering at a temperature of 1250°C for 2 hours. After sintering, the pellets were allowed to cool naturally to room temperature. The rest of the process was the same as in Example 1.

[0065] The performance of the basalt-based solid thermal storage particles prepared by the methods of Examples 1-3 and Comparative Examples 1-3 was tested.

[0066] Thermal conductivity: Tested using the hot wire method, the thermal conductivity of the finished product must be ≥1.2W / (m·K) (at room temperature) and ≥1.5W / (m·K) at 500℃.

[0067] Sintering resistance: After being placed in a constant temperature chamber at 600℃ for 1000 hours, the particle agglomeration rate was tested and required to be ≤5%.

[0068] Compressive strength: Tested using a pressure testing machine, the compressive strength of a single particle is ≥15MPa to prevent breakage during use.

[0069] The test results are as follows: Example 1: Thermal conductivity at room temperature 1.32 W / (m·K), thermal conductivity at 500℃ 1.65 W / (m·K), agglomeration rate at 600℃ / 1000h 3.2%, single particle compressive strength 16.8 MPa, specific heat capacity at 500℃ 0.85 kJ / (kg·K).

[0070] Example 2: Thermal conductivity at room temperature 1.68 W / (m·K), thermal conductivity at 500℃ 2.03 W / (m·K), agglomeration rate at 600℃ / 1000h 4.5%, single particle compressive strength 14.2 MPa, specific heat capacity at 500℃ 0.82 kJ / (kg·K).

[0071] Example 3: Thermal conductivity at room temperature 1.21 W / (m·K), thermal conductivity at 500℃ 1.52 W / (m·K), agglomeration rate at 600℃ / 1000h 1.8%, single particle compressive strength 18.5 MPa, specific heat capacity at 500℃ 0.87 kJ / (kg·K).

[0072] Comparative Example 1: Thermal conductivity at room temperature is 0.45 W / (m·K), and agglomeration rate at 600℃ / 1000h is 22.7%. Comparative Example 1 does not involve the gradient particle size of basalt or the addition of flake graphite and nano-zirconia. Its thermal conductivity is reduced and its agglomeration rate is increased, proving that the gradient particle size ratio and composite modification are the core basis for improving performance.

[0073] Comparative Example 2: Agglomeration rate of 15.3% at 600℃ / 1000h. No nano-zirconia powder was added in Comparative Example 2. Its agglomeration rate was higher than that of Examples 1-3 but lower than that of Comparative Example 1, which proves that nano-zirconia is a key auxiliary material for inhibiting high-temperature agglomeration.

[0074] Comparative Example 3: Thermal conductivity at room temperature is 0.75 W / (m·K), thermal conductivity at 500℃ is 1.08 W / (m·K), agglomeration rate at 600℃ / 1000h is 12.4%, and sintering temperature at 850℃ is much lower than the melting temperature of basalt. This reduces energy consumption while preserving the porous structure inside the particles, thus balancing heat storage capacity and thermal conductivity.

[0075] Therefore, this invention adopts the above-mentioned method for preparing high thermal conductivity and sintering resistant basalt-based solid thermal storage particles. It uses a gradient particle size distribution, graphite-zirconia composite modification, and low-temperature sintering to prepare the particles. While retaining the low-cost advantage of basalt, it simultaneously improves the thermal conductivity, sintering resistance, and mechanical strength of the thermal storage particles, thus solving the pain points of the existing technology.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles, characterized in that, Includes the following steps: Step 1: The basalt ore is coarsely crushed to a particle size of 5-10 mm using a crusher, then wet-milled in a ball mill for 2 hours, and classified by a hydraulic classifier to obtain three particle sizes: coarse, medium, and fine. Step 2: Add basalt particles to a high-speed mixer, spray in sodium silicate aqueous solution, and stir; add flake graphite in 3 batches, with an interval of 5 minutes between each batch, and continue stirring for 20-40 minutes to make the graphite uniformly coat the surface of the basalt particles and form a continuous thermally conductive interface layer. Step 3: Add nano-zirconia powder to the mixer, adjust the speed to 500 r / min, and stir at room temperature for 15 min to make the zirconia evenly dispersed in the gaps between the particles; add polyvinyl alcohol aqueous solution as an auxiliary binder, stir for 10 min, and obtain the mixed wet material; Step 4: Dry the mixed wet material with forced air at 60℃ for 4 hours, remove agglomerates by passing it through a 1.5mm sieve, and press it into shape using a four-column hydraulic press to obtain green pellets. Place the green pellets into a roller kiln and sinter them in stages. After sintering, allow them to cool naturally to room temperature to obtain basalt-based solid thermal storage particles. Perform multi-stage sieving on the basalt-based solid thermal storage particles using a vibrating screen to obtain solid particles of varying sizes.

2. The method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles according to claim 1, characterized in that: In step 1, the ball mill wet grinding process controls the ball-to-material ratio at 3:1 and the rotation speed at 300 r / min.

3. The method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles according to claim 1, characterized in that: In step 1, the coarse particles have a diameter of 0.8-1.2 mm, the medium particles have a diameter of 0.3-0.5 mm, and the fine particles have a diameter of 0.1-0.2 mm. The mass ratio of coarse, medium, and fine particles is 3:5:

2.

4. The method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles according to claim 1, characterized in that: In step 2, the high-speed mixer is set to a speed of 800 r / min and a temperature of 60℃, and an aqueous solution of sodium silicate is sprayed in and stirred for 10 min.

5. The method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles according to claim 1, characterized in that: In step 2, before adding the flake graphite, the flake graphite needs to be pulverized to a particle size of 5-10μm using an air jet mill and then passed through a 2000-mesh sieve to remove impurities.

6. The method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles according to claim 1, characterized in that: In step 2, the mass concentration of the sodium silicate aqueous solution is 10%.

7. The method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles according to claim 1, characterized in that: In step 3, nano-sized zirconium dioxide powder with a particle size of 50-100 nm is vacuum dried at 80 °C and a vacuum degree of -0.09 MPa for 2 hours to avoid moisture absorption and agglomeration.

8. The method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles according to claim 1, characterized in that: In step 3, the mass concentration of the polyvinyl alcohol aqueous solution is 5%.

9. The method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles according to claim 1, characterized in that, In step 4, the segmented sintering is as follows: The first stage involves raising the room temperature to 300℃ at a rate of 5℃ / min and holding it at that temperature for 1 hour to remove the binder from the raw materials. The second stage involves raising the temperature from 300℃ to 750℃ at a rate of 3℃ / min and holding it at that temperature for 2 hours to achieve initial densification of the particle surface. The third stage involves raising the temperature from 750℃ to 850-880℃ at a rate of 2℃ / min and holding it at that temperature for 1.5-2 hours to promote the fusion of the graphite and basalt interface.

10. The method for preparing high thermal conductivity, sintering-resistant basalt-based solid thermal storage particles according to claim 1, characterized in that, Add the following raw materials by weight: 90-95 parts basalt particles, 3-8 parts flake graphite, 1-2 parts nano zirconium dioxide, and 0.5-1 parts sodium silicate.