Heat storage lava solid particulate matter with good heat stability and preparation method of heat storage lava solid particulate matter

Abstract

The invention discloses a heat storage lava solid particulate matter with good thermal stability and a preparation method thereof, and belongs to the technical field of energy storage materials, the heat storage lava solid particulate matter comprises 68%-73% of SiO2, 2.5%-3.5% of SiC, 11%-14% of Al2O3, 4%-6% of MgO, 2%-3% of Fe2O3, 2%-3% of MnO2, 1.5%-2.5% of TiO2, 2%-3% of ZrO2, 1.5%-2% of La2O3 and 1%-1.5% of ZrSiO4. According to the heat storage lava solid particulate matter with the good heat stability and the preparation method thereof, by means of raw material synergy, process optimization and surface strengthening, the comprehensive advantages of being excellent in high-temperature stability, good in heat storage-heat conduction performance balance, high in mechanical and structural reliability and resistant to corrosion are achieved; the long-term stable service requirement of the high-temperature heat storage system can be met; and the operation and maintenance cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage materials, in particular to a heat-stable heat storage lava solid particle and a preparation method thereof. BACKGROUND

[0002] Under the background of global energy transformation and large-scale application of renewable energy, solid heat storage medium has become the core supporting material in the scene of photothermal power generation, industrial waste heat recovery, regional heating and the like due to its high heat storage density, strong safety and no leakage risk. However, the current solid heat storage medium faces key technical bottlenecks: first, insufficient high-temperature stability; second, unbalanced heat storage-heat conduction performance; third, poor structural reliability, which is difficult to meet the long-term stable demand. SUMMARY

[0003] The purpose of the present application is to provide a heat-stable heat storage lava solid particle and a preparation method thereof. By means of raw material synergy, process optimization and surface strengthening, the comprehensive advantages of high-temperature stability, balanced heat storage-heat conduction performance, strong mechanical and structural reliability and corrosion resistance are realized, which can meet the long-term stable service demand of high-temperature heat storage system and reduce operation and maintenance cost.

[0004] To achieve the above purpose, the present application provides a heat-stable heat storage lava solid particle, which comprises the following raw materials in percentage by weight: 68%-73% SiO2, 2.5%-3.5% SiC, 11%-14% Al2O3, 4%-6% MgO, 2%-3% Fe2O3, 2%-3% MnO2, 1.5%-2.5% TiO2, 2%-3% ZrO2, 1.5%-2% La2O3, 1%-1.5% ZrSiO4.

[0005] Further, the particle size of SiO2 is 75-100 , the purity is ≥98%, the particle size of SiC is 5-8 , the purity is ≥99%, the oxygen content is ≤0.8%, and the specific surface area is 1.5-2.5 ; Al2O3 is D50=5-8 alumina powder, the purity is ≥99%, the specific surface area is 3-5 , and the particle size distribution Span is ≤1.2; MgO is light burned magnesium oxide powder with a particle size of 3-5 , the purity of MgO is ≥95%, and the activity is ≥65%; Fe2O3 is red iron oxide with a particle size of 1-2 , the purity is ≥97%; MnO2 is electrolytic grade powder with a particle size of 2-3 , the purity is ≥98%.​ TiO2 is rutile titanium dioxide powder with a particle size of 1-3 ZrO2 is 3mol% Y2O3 stabilized nano zirconia powder with a particle size of 30-50nm, a tetragonal phase content of ≥95%, and a specific surface area of 20-30 La2O3 is lanthanum oxide powder with a particle size of 2-5 ZrSiO4 is pre-synthetic zirconite composite powder with a particle size of 3-5

[0006] The application also provides a preparation method of the heat-stable heat storage lava solid particle, which comprises the following steps: S1, raw material pretreatment and mixing to obtain a slurry, and centrifugal granulation of the slurry in a centrifugal granulator to form a wet ball blank; S2, drying of the wet ball blank in a hot air circulating drying box to remove water and a binder to obtain a heat storage ball; S3, gradient sintering of the dried ball blank to densify the ball blank; S4, surface strengthening and wrapping of the sintered ball blank to obtain the heat storage lava solid particle.

[0007] Preferably, the specific operation of S1 is as follows: S11, adding ZrO2 into deionized water, then adding a composite dispersant to obtain a mixed solution, and performing ultrasonic dispersion on the mixed solution to obtain a suspension; S12, adding the ultrasonically dispersed ZrO2 suspension in S11, SiO2, SiC, Al2O3, MgO, Fe2O3, MnO2, TiO2, La2O3, ZrSiO4, deionized water and a binder into a planetary ball mill to perform ball milling to obtain a uniform slurry; S13, shaping of the slurry in a centrifugal granulator to obtain a wet ball blank.

[0008] Preferably, in S11, the solid-liquid ratio of ZrO2 to deionized water is 1:5, the ultrasonic dispersion power is 200-400W, the frequency is 15-30kHz, the time is 20-40min, the stirring is performed every 10min during the period, the composite dispersant accounts for 0.3% of the total mass of the suspension, the composite dispersant comprises sodium polyacrylate and triethanolamine, the sodium polyacrylate accounts for 0.2% of the total mass of the suspension, and the triethanolamine accounts for 0.1% of the total mass of the suspension; ​​​​​In S12, the deionized water accounts for 12%-14% of the total mass of raw materials, the binder is polyvinyl alcohol, accounts for 1.5%-2% of the total mass of raw materials, the mass concentration of the binder is 8%, the agate ball is used as the grinding medium in the planetary ball mill, the ball-to-material ratio is 3:1, the rotation speed is 250-300 , the ball milling time is 70-80 min, the slurry viscosity is 2000-3000 , the particle size is 50-80 , D50=60 ; In S13, the rotation speed of the centrifugal granulator is 900-1100 , the hot air temperature is 90-100 , the hot air speed is 1.5-2 , the feeding rate is 50-80 , the diameter of the wet ball is 3-5 mm, and the roundness is ≥0.95.

[0009] Preferably, the specific operation of S2 is as follows: S21, the wet ball obtained in S13 is dried in the hot air circulating drying box for the first stage; S22, the ball dried in the first stage in S21 is dried for the second stage to obtain the heat storage ball.

[0010] Preferably, in S21, the drying temperature is 60-80 , the holding time is 2-3 h, and the heating rate is 3-5 ; In S22, the drying temperature is 120-150 , the holding time is 1-2 h, and the heating rate is 3-5 .

[0011] Preferably, the specific operation of S3 is as follows: S31, the heat storage ball obtained in S22 is placed in an air atmosphere high-temperature sintering furnace for primary sintering; S32, the heat storage ball obtained by primary sintering in S31 is sintered for the second stage; S33, the heat storage ball obtained by secondary sintering in S32 is sintered for the third stage; S34, the heat storage ball obtained by tertiary sintering in S33 is sintered for the fourth stage; S35, the heat storage ball obtained by quaternary sintering in S34 is sintered for the fifth stage.

[0012] Preferably, in S31, the primary sintering temperature is increased from room temperature to 600-650 , the heating rate is 3-5 , the holding time is 2-2.5 h, and the furnace pressure is 50 Pa; In S32, the secondary sintering temperature is 1000-1050 , the heating rate is 2-4 , the holding time is 1-2h, and the CO2 concentration in the furnace is kept at 20%-21%; In S33, the tertiary sintering temperature is 1200-1250 , the heating rate is 1-2 , and the holding time is 2-3h; In S34, the quaternary sintering temperature is 1600-1650 , the heating rate is 2-2.5 , and the holding time is 3-3.5h; In S35, the quinary sintering temperature is 800-1000 , the cooling rate is 1-2 , and the holding time for low-temperature annealing treatment is 1-1.5h.

[0013] Preferably, the specific operation of S4 is that the heat storage ball obtained by quinary sintering in S35 is completely immersed in the silica sol, then taken out and naturally drained, and after draining, the heat storage ball is placed in a hot air drying oven for drying, and the heat storage lava solid particulate material is obtained after the heat storage ball after drying is subjected to heat preservation treatment.

[0014] Preferably, in S4, the mass concentration of the silica sol is 30%, the immersion time is 12-15min, the stirring is performed every 5min during the immersion, the natural draining time is 3-5min, the temperature in the hot air drying oven is 150-180 , the drying time is 2-3h, the heat preservation temperature is 600-650 , the heat preservation time is 1h, and the heat storage lava solid particulate material with a dense SiO2 layer with a thickness of 8-10 on the surface is obtained after heat preservation.

[0015] Therefore, the heat storage lava solid particulate material with good heat stability and the preparation method thereof have the following beneficial effects: (1) The high-temperature stability is greatly improved: relying on the skeleton support of SiC and the crystal stability of pre-sintered ZrSiO4, and combining with the release of internal stress by low-temperature annealing, the high-temperature volume shrinkage rate of the heat storage particulate material is reduced to 1.2%, the thermal shock resistance is 800 -25 , and the cold-hot cycle life is more than 1200 times, which can meet the long-term service requirement of the heat storage system; (2) The heat storage-heat conduction performance is efficiently balanced: the components (Al2O3, MgO, etc.) cooperatively store heat and the heat conduction path constructed by SiC, and the uniform dispersion of the components realized by the composite dispersant, so that the average specific heat capacity of the medium reaches 1.18 , and the thermal conductivity coefficient reaches 1.85 , and high heat transfer efficiency are considered; (3) The mechanical and structural reliability is significantly enhanced: the gradient sintering process combined with the phase transformation toughening effect of ZrO2 makes the medium density increase to 96.5%, the compressive strength reaches 85 MPa, the surface hardness reaches 620 HV, the filling breakage rate is greatly reduced, and the mechanical impact during transportation and use can be tolerated; (4) Corrosion resistance and service life extension: the surface 9 The dense SiO2 coating layer can effectively isolate the high-temperature oxidizing atmosphere and the heat exchange medium, avoid internal component oxidation or corrosion, further extend the service life of the medium, and reduce the operation and maintenance cost of the heat storage system.

[0016] The technical solutions of the present application will be further described in detail below through examples. DETAILED DESCRIPTION

[0017] The technical solutions of the present application will be further described in detail below through examples.

[0018] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the usual meanings understood by those skilled in the art to which the present application belongs.

[0019] In the present application, unless otherwise specified, other test materials and instruments and equipment are conventional test materials in the art and can be purchased through commercial channels.

[0020] Example 1 The present application provides a heat-stable heat storage lava solid particle, the raw material composition is: 68% SiO2 (particle size 80 , purity 98.5%), 3% SiC (particle size 6 , purity 99.2%, oxygen content 0.6%, specific surface area 2.0 ), 12% Al2O3 (D50=6.5 - alumina powder, purity 99.3%, specific surface area 4 , particle size distribution Span=1.1), 5% MgO (light burned magnesium oxide powder with particle size 4 , MgO purity 96%, activity 68%), 2.5% Fe2O3 (red iron oxide with particle size 1.5 , purity 97.5%), 2.5% MnO2 (electrolytic grade powder with particle size 2.5 , purity 98.5%), 2% TiO2 (particle size 2 ​rutile titanium dioxide powder, purity 99.6%), 2% ZrO2 (3 mol% Y2O3 stabilized nano-zirconia powder with particle size of 40 nm, tetragonal phase content 97%, specific surface area 25 m2 / g, purity 99.3%).

[0021] The preparation method of the heat-stable heat storage lava solid particle material described above comprises the following steps: S1, raw material pretreatment and mixing to obtain slurry, and the slurry is put into a centrifugal granulator for centrifugal granulation and molding: S11, ZrO2 is added to deionized water, the solid-liquid ratio of ZrO2 to deionized water is 1:5, then a mixed dispersant is added to obtain a mixed solution, the mixed dispersant accounts for 0.3% of the total mass of the suspension, including sodium polyacrylate (0.2%) and triethanolamine (0.1%). The mixed solution is ultrasonically dispersed, the power is 300 W, the frequency is 22.5 kHz, the time is 30 min, and stirring is carried out every 10 min during the period, to obtain a suspension.

[0022] S12, the ZrO2 suspension ultrasonically dispersed in S11, SiO2, SiC, Al2O3, MgO, Fe2O3, MnO2, TiO2, La2O3, ZrSiO4, deionized water (13% of the total mass of the raw materials), and a binder (polyvinyl alcohol, 1.75% of the total mass of the raw materials, mass concentration 8%) are added to a planetary ball mill, agate balls are used as grinding media, the ball-to-material ratio is 3:1, the rotation speed is 275 , the ball milling time is 75 min, to obtain a uniform slurry, the slurry viscosity is 2500 , the particle size is 65 , and D50=60 .

[0023] S13, the slurry is put into a centrifugal granulator for molding, the rotation speed of the centrifugal granulator is 1000 , the hot air temperature is 95 , the hot air speed is 1.75 , and the feeding rate is 65 , to obtain wet green balls with a diameter of 4 mm and a roundness of ≥0.95.

[0024] S2, the wet green balls after granulation are placed in a hot air circulating drying oven to remove water and the binder to obtain heat storage balls: ​​​S21, first-stage drying: drying temperature is 70 , holding for 2.5h, and the heating rate is 4 .

[0025] S22, second-stage drying: drying temperature is 135 , holding for 1.5h, and the heating rate is 4 .

[0026] S3, gradient sintering of the dried green pellets to densify the pellets: S31, first-stage sintering: heating from room temperature to 625 , the heating rate is 4 , holding for 2.25h, and the furnace pressure is 50Pa.

[0027] S32, second-stage sintering: heating to 1025 , the heating rate is 3 , holding for 1.5h, and the CO2 concentration in the furnace is kept at 20.5%.

[0028] S33, third-stage sintering: heating to 1225 , the heating rate is 1.5 , holding for 2.5h.

[0029] S34, fourth-stage sintering: heating to 1625 , the heating rate is 2.25 , holding for 3.25h.

[0030] S35, fifth-stage sintering: cooling to 900 , the cooling rate is 1.5 , holding for 1.25h for low-temperature annealing.

[0031] S4, surface strengthening and coating of the sintered green pellets to obtain heat storage lava solid particles: The heat storage pellets are completely immersed in a silica sol (mass concentration 30%) for 13.5min, and stirred every 5min during the process. Then the heat storage pellets are taken out and naturally drained for 3.5min. After draining, the heat storage pellets are placed in a hot air drying oven and dried at a temperature of 165 for 2.5h, and then held at a temperature of 625 for 1h to obtain heat storage lava solid particles coated with a dense SiO2 layer with a thickness of 9 .

[0032] Comparative Example 1 The only difference between this comparative example and Example 1 is that no SiC is added to the raw materials, and the weight percentage of SiO2 is adjusted to 71%, and the rest of the conditions are the same.

[0033] Comparative Example 2 The only difference between this comparative example and Example 1 is that no composite dispersant is used in S11, and ZrO2 is directly mixed with deionized water and then ultrasonically dispersed, and the rest of the conditions are the same.

[0034] Comparative Example 3 The only difference between this comparative example and Example 1 is that S3 omits the low-temperature annealing step of S35 in gradient sintering, and the rest of the conditions are the same.

[0035] Comparative Example 4 The only difference between this comparative example and Example 1 is that no surface strengthening and coating treatment is performed in S4, and the rest of the conditions are the same.

[0036] Comparative Example 5 The only difference between this comparative example and Example 1 is that the raw material directly uses a ZrSiO4 powder with a particle size of 4 μm and a purity of 99.3% without pre-sintering, and the rest of the conditions are the same.

[0037] Performance exploration is performed on the heat storage solid spherical granular samples obtained in Example 1 and Comparative Examples 1-5.

[0038] I. Thermal stability test

[0039] The volume of the sample after being kept at room temperature and 1600 for 2 h is determined by the drainage method, the volume change rate (high-temperature volume shrinkage rate) is calculated, the sample is repeatedly cycled between 800 (high-temperature section) and 25 (low-temperature section), each cycle is kept for 1 h, and the cycle number when the sample cracks or pulverizes is recorded, and the results are shown in Table 1.

[0040] Table 1. High-temperature volume shrinkage rate and cold-heat cycle life of the sample

[0041] As can be seen from Table 1, the high-temperature volume shrinkage rate of Example 1 is much lower than that of Comparative Examples 1-3 and Comparative Example 5. The reason is that: Comparative Example 1 does not add SiC, missing the rigid skeleton formed by SiC in the SiO2 matrix; SiC can inhibit the viscous flow of SiO2 at high temperature, avoiding volume shrinkage due to particle slip of the matrix; and the synergy of SiC and SiO2 in Example 1 directly reduces the volume shrinkage rate by 2.6%.

[0042] Comparative Example 5 uses a ZrSiO4 powder without pre-sintering, which has a particle size of 4 The crystal transformation from ZrSiO4 to ZrO2 and SiO2 occurs in the test, accompanied by 0.8%-1.2% volume expansion, and the matrix structure is loose after expansion, and greater shrinkage occurs after cooling; the ZrSiO4 of Example 1 has a volume change of 0.8% after 1650 The pre-sintering is completed, the crystal form is stable, there is no additional volume change, and the matrix structure is stable together with SiC.

[0043] In Comparative Example 2, ZrO2 is easily aggregated to form large-size particles due to the absence of the composite dispersant, pores are generated around the aggregates, and the overall volume change rate increases due to the shrinkage of the pores at high temperature; the composite dispersant in Example 1 uniformly disperses ZrO2 and fills the small pores, further reducing the shrinkage rate.

[0044] Secondly, the cold and hot cycle life of Example 1 reaches 1200 times, which is significantly longer than Comparative Examples 1-3 and Comparative Example 5, and the advantage is extremely significant. The reason is: The thermal conductivity of SiC is much higher than that of SiO2, which can quickly and uniformly disperse the local thermal stress generated during cold and hot cycles, avoiding the stress concentration caused by the crack initiation; in Comparative Example 1, there is no SiC, and the thermal stress cannot be effectively transmitted, and the sample is prone to crack due to excessive local stress.

[0045] In Comparative Example 3, the low-temperature annealing step is omitted, and internal stress is generated in the sample after sintering due to the difference in heating or cooling rate, and the internal stress is superimposed during cold and hot cycles, accelerating crack propagation; in Example 1, the low-temperature annealing process is used to release the internal stress, and the thermal stress of SiC is dispersed and coordinated, greatly prolonging the cycle life. Low-temperature annealing can completely release residual internal stress, and disperse and coordinate with the thermal stress of SiC, greatly prolonging the cycle life.

[0046] Uniformly dispersed tetragonal ZrO2 will undergo a phase transition from “tetragonal phase-monoclinic phase” under thermal shock, accompanied by a small volume expansion, which can heal small cracks and avoid crack propagation; in Comparative Example 2, ZrO2 is aggregated, and cannot play a role in phase transition toughening, and the cycle life is only 780 times.

[0047] II. Heat storage performance test.

[0048] The differential scanning calorimeter (DSC) is used to test at a temperature range of 25-1000 at a temperature increasing rate of 10 C, the average specific heat capacity is calculated, and the thermal conductivity of the sample is tested at room temperature by the hot-wire method, and the results are shown in Table 2.

[0049] Table 2 Average specific heat capacity and thermal conductivity of the sample

[0050] As can be seen from Table 2, the average specific heat capacity of Example 1 is higher than that of Comparative Examples 1, 2 and 5, indicating that it can store more heat per unit mass. The reason is: Al2O3, MgO in the matrix as the main heat storage component, provide the basic heat storage capacity; Fe2O3, MnO2 as an auxiliary heat storage component, can supplement the heat storage capacity through lattice vibration; Uniformly dispersed ZrO2 can further improve the heat storage capacity through latent heat of phase change; Comparative Example 2 has ZrO2 agglomeration, and the latent heat of phase change cannot be effectively utilized, and the specific heat capacity decreases by 0.1 ; Comparative Example 1 has no SiC support, the porosity of the matrix is slightly high, the density of the heat storage component is reduced, and the specific heat capacity decreases by 0.06 .

[0051] Secondly, the thermal conductivity of Example 1 is significantly higher than that of Comparative Examples 1, 2 and 5, which can quickly realize the storage and release of heat. The reason is: SiC as a high thermal conductivity component, uniformly dispersed in the matrix to form a "thermal conductivity path", directly improving the overall thermal conductivity; Comparative Example 1 has no SiC, and the thermal conductivity is only 1.42 , which is 23.2% lower than that of Example 1; Example 1 has a density of 96.5% through gradient sintering and raw material cooperation, which reduces the hindering of pores to heat transfer; while Comparative Example 5 has micropores due to the absence of pre-sintered ZrSiO4, and Comparative Example 2 has pores due to ZrO2 agglomeration, both of which result in a decrease in thermal conductivity.

[0052] III. Mechanical property test

[0053] A universal testing machine was used to perform axial compression on spherical samples with a diameter of 4 mm, 10 samples were tested for each group, and the average value was taken; a microhardness tester was used to test the surface Vickers hardness (HV) of the sample, the test load was 500g, and the pressure was maintained for 10s; the Archimedes drainage method was used to test the bulk density and theoretical density of the sample, and the density was calculated, and the results are shown in Table 3.

[0054] Table 3 Compressive strength, surface hardness and density of the sample

[0055] As can be seen from Table 3, the compressive strength of Example 1 is significantly higher than that of Comparative Examples 1, 3, 4 and 5, and the advantage is obvious. The reason is: SiC as a rigid particle can bear part of the compression load and avoid the sliding of the matrix particles; Comparative Example 1 has no SiC, and the matrix is prone to particle dislocation during compression, and the compressive strength is only 62MPa.

[0056] Comparative Example 5 has microcracks in the sintering process due to the crystal form transformation of the unsintered ZrSiO4, which destroys the structural continuity, and the compressive strength is only 78MPa; while the pre-sintered ZrSiO4 of Example 1 has no cracks, and together with SiC forms a rigid support network, which improves the compressive strength.

[0057] And the uniformly dispersed ZrO2 can inhibit the expansion of cracks during compression, while the comparative example 2 is prone to breakage due to the agglomeration of ZrO2, and the pores around the agglomerates become stress concentration points, and the compressive strength is only 70 MPa.

[0058] Secondly, the surface hardness of example 1 is 620 HV, which is higher than that of comparative examples 1, 2 and 5, and can effectively resist surface scratches during loading and use. The reason is that: Example 1 has the highest density, fewer surface pores and higher hardness; comparative example 5 has a density of only 93.5%, more surface micropores and the lowest hardness.

[0059] SiC and ZrO2 are uniformly distributed in the surface layer, which can significantly improve the surface hardness; comparative example 1 has no SiC, and the surface hardness is only 550 HV, which is 11.3% lower than that of example 1.

[0060] Finally, the density of example 1 reaches 96.5%, which is much higher than that of comparative examples 1 and 5, and slightly higher than that of comparative example 2, which is the core guarantee of its mechanical properties and thermal stability. The reason is that: The composite dispersant makes ZrO2 uniformly dispersed and fills the small pores; SiC and pre-sintered ZrSiO4 form a rigid skeleton to prevent structural collapse during sintering; Gradient sintering ensures that the particles are fully sintered without excessive shrinkage or cracking; the absence of any raw material or process will result in a decrease in density, which will further affect the mechanical properties.

[0061] In summary, whether it is thermal stability against high-temperature deformation and thermal shock, or heat storage performance with high heat storage and high thermal conductivity, or mechanical properties with high compressive strength and high hardness, example 1 is significantly better than each comparative example, and fully meets the long-term service requirements of high-temperature heat storage scenarios.

[0062] Therefore, the present application adopts the above-mentioned heat-stable heat storage lava solid particle and its preparation method, which realizes the comprehensive advantages of high-temperature stability, good balance of heat storage-thermal conductivity performance, strong mechanical and structural reliability and corrosion resistance by means of raw material synergy, process optimization and surface strengthening, and can meet the long-term stable service requirements of high-temperature heat storage system and reduce operation and maintenance cost.

[0063] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A heat-stable hot-melt lava solid particulate, characterized by: By weight percentage, the raw materials include: 68%-73% SiO2, 2.5%-3.5% SiC, 11%-14% Al2O3, 4%-6% MgO, 2%-3% Fe2O3, 2%-3% MnO2, 1.5%-2.5% TiO2, 2%-3% ZrO2, 1.5%-2% La2O3, 1%-1.5% ZrSiO4.

2. The method for preparing thermally stable solid particles of thermally stored lava as described in claim 1, characterized in that: The method comprises the following steps: S1, raw material pretreatment and mixing to obtain a slurry, and the slurry is put into a centrifugal granulator to form a wet ball blank by centrifugal granulation; S2, the wet ball blank after granulation is put into a hot air circulating drying box to remove water and binder to obtain a heat storage ball; S3, the dried ball blank is gradient sintered to densify the ball blank; S4, the sintered ball blank is surface strengthened to obtain a heat storage lava solid particle.

3. The method for preparing the hot-stable hot-melt lava solid-state particulate according to claim 2, characterized in that: The specific operation of S1 is as follows: S11, ZrO2 is added to deionized water, and then a composite dispersant is added to obtain a mixed solution, and the mixed solution is ultrasonically dispersed to obtain a suspension; S12, the ZrO2 suspension ultrasonically dispersed in S11, SiO2, SiC, Al2O3, MgO, Fe2O3, MnO2, TiO2, La2O3, ZrSiO4, deionized water, and binder are added to a planetary ball mill for ball milling to obtain a uniform slurry; S13, the slurry is put into a centrifugal granulator for forming to obtain a wet ball blank.

4. The method for preparing the hot-stable hot-melt lava solid-state particulate according to claim 3, characterized in that: In S11, the solid-liquid ratio of ZrO2 to deionized water is 1:5, the ultrasonic dispersion power is 200-400W, the frequency is 15-30kHz, the time is 20-40min, and the suspension is stirred every 10min during the period, the composite dispersant accounts for 0.3% of the total mass of the suspension, the composite dispersant includes sodium polyacrylate and triethanolamine, wherein the sodium polyacrylate accounts for 0.2% of the total mass of the suspension, and the triethanolamine accounts for 0.1% of the total mass of the suspension; In S12, the deionized water accounts for 12%-14% of the total mass of raw materials, the binder is polyvinyl alcohol, and accounts for 1.5%-2% of the total mass of raw materials, the mass concentration of the binder is 8%, the agate ball is used as the grinding medium in the planetary ball mill, the ball-to-material ratio is 3:1, the rotation speed is 250-300 rpm, the ball milling time is 70-80 min, the slurry viscosity is 2000-3000 mPa·s, the particle size is 50-80 μm, and D50=60 μm. In S13, the centrifugal granulator rotates at 900-1100 rpm , the hot air temperature is 90-100 , the hot air speed is 1.5-2 , the feeding rate is 50-80 , the diameter of the wet ball is 3-5 mm, and the roundness is ≥0.

95.

5. The method of claim 2, wherein the method is characterized by: The specific operation of S2 is as follows: S21, the wet ball blank obtained in S13 is dried in a hot air circulating drying box for a first stage of drying; S22, the ball blank after the first stage of drying in S21 is dried for a second stage to obtain a heat storage ball.

6. The method for preparing the hot-stable hot-melt lava solid-state particulate according to claim 5, characterized in that: In S21, the drying temperature is 60-80 , the holding time is 2-3h, and the heating rate is 3-5 ; In S22, the drying temperature is 120-150 , the holding time is 1-2 h, and the heating rate is 3-5 .

7. The method according to claim 2, wherein the method is characterized by: The specific operation of S3 is as follows: S31, the heat storage ball obtained in S22 is placed in an air atmosphere high temperature sintering furnace for primary sintering; S32, the heat storage ball obtained by primary sintering in S31 is sintered for a second stage; S33, the heat storage ball obtained by secondary sintering in S32 is sintered for a third stage; S34, the heat storage ball obtained by tertiary sintering in S33 is sintered for a fourth stage; S35, the heat storage ball obtained by quaternary sintering in S34 is sintered for a fifth stage.

8. The method of claim 7, wherein the method is characterized by: In S31, the primary sintering temperature is raised from room temperature to 600-650 at a rate of 3-5 , and the temperature is maintained for 2-2.5 h at a furnace pressure of 50 Pa. In S32, the secondary sintering temperature is 1000-1050 , the heating rate is 2-4 , the holding time is 1-2h, and the CO2 concentration in the furnace is kept at 20%-21%. In S33, the temperature of the third sintering is 1200-1250 , the heating rate is 1-2 , and the holding time is 2-3h. In S34, the sintering temperature is 1600-1650 , the heating rate is 2-2.5 , and the holding time is 3-3.5h. In S35, the sintering temperature is 800-1000 , the cooling rate is 1-2 , and the holding time is 1-1.5 h for low-temperature annealing.

9. The method of claim 2, wherein the method is characterized by: The specific operation of S4 is as follows: the heat storage ball obtained by quinary sintering in S35 is completely immersed in a silica sol, then taken out and naturally drained, and after draining, the heat storage ball is placed in a hot air drying box for drying, and the dried heat storage ball is subjected to heat preservation treatment to obtain a heat storage lava solid particle.

10. The method of claim 9, wherein the method is characterized by: In S4, the mass concentration of the silica sol is 30%, the immersion time is 12-15 min, the stirring is performed every 5 min during the immersion, the natural draining time is 3-5 min, the temperature in the hot air drying oven is 150-180 , the drying time is 2-3 h, the holding temperature is 600-650 , the holding time is 1 h, and the heat storage lava solid particles with a dense SiO2 layer of 8-10 μm in thickness on the surface are obtained after the holding.

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