Application of secondary aluminum ash recycling product

Abstract

The invention provides application of a secondary aluminum ash resourceful product, and relates to the technical field of industrial solid waste resourceful treatment. A building material, a refractory material and a water purifying agent are prepared from a secondary aluminum ash recycling product as a raw material, the secondary aluminum ash recycling product is obtained by pelletizing, self-propagating combustion and cooling the raw material, and the raw material comprises the following components in parts by mass: 80-100 parts of secondary aluminum ash and 10-20 parts of fly ash. The indexes such as refractoriness, refractoriness under load, high-temperature compressive strength, high-temperature creep rate, reheating linear change and thermal stability of the high-alumina brick prepared from the secondary aluminum ash recycling product meet the qualified standards, and the normal-temperature compressive strength of the prepared fused cast alumina refractory product for the glass melting furnace can reach 31.55-32.03 MPa; the breaking strength at the normal temperature can reach 7.38-7.46 MPa, the performance is excellent, and good economic benefits and wide application prospects are achieved.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization technology, and in particular to the application of a secondary aluminum ash resource utilization product. Background Technology

[0002] Aluminum ash is a major solid waste generated during aluminum industry production. Depending on the degree of treatment and disposal, it is classified into primary aluminum ash and secondary aluminum ash. Primary aluminum ash mainly originates from the electrolytic aluminum production process and the recycled aluminum melting process. It contains a high level of metallic aluminum and has high recycling value. Secondary aluminum ash is waste generated after the extraction of metallic aluminum from primary aluminum ash or aluminum-containing slag produced during aluminum refining. Its metallic aluminum content is significantly reduced, and while its sources are widespread, its composition is complex. The aluminum nitride contained in secondary aluminum ash readily undergoes hydrolysis when exposed to water or humid air, producing ammonia gas with a pungent odor, causing air pollution. The metallic aluminum it contains reacts with water to produce hydrogen gas, and the aluminum carbide reacts with water to produce methane, both posing a risk of combustion and explosion. Furthermore, secondary aluminum ash contains high levels of alkali metal oxides, fluorides, and chlorides. Long-term accumulation will pollute soil and groundwater, seriously affecting the ecological environment and public health and safety. Due to its significant toxicity and reactivity, it is listed as a hazardous waste.

[0003] Currently, there are two main processes for treating secondary aluminum ash: wet processing and pyrometallurgical processing. Wet processing uses water, acid, and alkali solutions as solvents. Through wet hydrolysis and leaching, the reactivity in the secondary aluminum ash is removed. The leached salts are purified, crystallized, and formulated into aluminum refining agents. The dehydrated filter cake is dried to obtain inert high-alumina material. However, wet processing suffers from low ammonia absorption rates and easy leakage. The cost of producing ammonium salts from the products is too high, and the exhaust gas is difficult to meet emission standards. The entire process can easily generate flammable and explosive gases such as hydrogen and methane, posing safety hazards. Furthermore, the entire process is lengthy, requires significant equipment investment, and is prone to corrosion, resulting in a short service life. The core of pyrometallurgical treatment is to convert aluminum nitride into nitrogen and aluminum oxide through a roasting reaction. A common application is the preparation of calcium aluminate refining slag for steelmaking from secondary aluminum ash. However, current pyrometallurgical treatment generally suffers from problems such as high energy consumption, poor production environment, and relatively difficult flue gas treatment. A few low-temperature pyrometallurgical treatment processes have problems such as maintaining low equipment temperature, resulting in incomplete denitrification rate and difficulty in removing fluorine and chlorine from secondary aluminum ash.

[0004] Therefore, developing a low-energy-consumption, environmentally friendly, and effective secondary aluminum ash resource utilization technology has significant practical importance and application value. Summary of the Invention

[0005] In view of this, the present invention provides an application for the secondary aluminum ash resource recovery product. The preparation method of the secondary aluminum ash resource recovery product provided by the present invention requires no additives, and completes the process using the heat of reaction through an aluminothermic self-propagating reaction, which has the advantages of low energy consumption and low cost. The process produces no waste gas, wastewater, or waste residue emissions, making it environmentally friendly. The final secondary aluminum ash resource recovery product can be widely used in building materials, refractory materials, and water purification agents, showing promising application prospects.

[0006] The secondary aluminum ash resource product of the present invention is obtained from raw materials through pelletizing, self-propagating combustion, and cooling. The raw materials, by mass, comprise: 80-100 parts of secondary aluminum ash and 10-20 parts of dust removal ash.

[0007] Preferably, the secondary aluminum ash is low-calorific-value secondary aluminum ash and / or high-calorific-value secondary aluminum ash. More preferably, the secondary aluminum ash is composed of low-calorific-value secondary aluminum ash and high-calorific-value secondary aluminum ash in a mass ratio of (3-7):(3-7).

[0008] Preferably, the secondary aluminum ash is activated before use, specifically by removing iron, crushing, pulverizing and sieving the secondary aluminum ash, and then separating the aluminum and powder until the aluminum content is 1%-5%, thus completing the activation of the secondary aluminum ash.

[0009] This invention provides a method for preparing secondary aluminum ash resource products, specifically including the following steps: After the raw materials are mixed evenly in proportion, they are pelletized. The resulting pellets are then subjected to self-propagating combustion. After combustion is completed, the pellets are cooled to obtain secondary aluminum ash resource products.

[0010] Preferably, the ball material has a length of 40-50 mm, a width of 25-35 mm, a thickness of 15-25 mm, a moisture content of ≤3%, and a compressive strength of ≥10 N.

[0011] Preferably, the self-propagating combustion temperature is 1100℃-1500℃, and the self-propagating combustion time is 6-8 h. More preferably, the self-propagating combustion temperature is 1100℃-1300℃.

[0012] This invention provides a secondary aluminum ash resource product for the preparation of building materials, refractory materials and water purification agents, wherein the secondary aluminum ash resource product is the secondary aluminum ash resource product described in the above technical solution.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention requires no additional additives such as acids, alkalis, or calcium oxide. It only requires controlling the specific ratio of low-calorific-value secondary aluminum ash and high-calorific-value secondary aluminum ash, and adding an appropriate amount of dust removal ash to improve the physical properties of the raw materials. The heat generated by the aluminothermic self-propagating reaction can complete the treatment. The entire process only requires a fan for air supply. The power consumption for treating 1 ton of secondary aluminum ash is about 120 kWh, which is lower in energy consumption and cost than conventional processes, resulting in significant economic benefits.

[0014] This invention has a high conversion rate of aluminum nitride, with a denitrification rate of up to 97.62%, effectively removing the reactivity and toxicity of secondary aluminum ash.

[0015] The process of this invention produces no waste gas, wastewater, or waste residue emissions, making it environmentally friendly. Furthermore, it utilizes a high-temperature integrated filter to separate and capture dust and salt according to different temperature controls, collecting potassium, sodium, and fluoride salts that volatilize at high temperatures in the flue gas for industrial reuse, thereby increasing product added value and maximizing resource utilization.

[0016] This invention activates the secondary aluminum ash in the raw material and optimizes the raw material ratio to maintain the self-propagating combustion temperature of the raw material within a reasonable range of 1100℃-1500℃. This ensures sufficient combustion denitrification, dechlorination, and defluorination effects while avoiding energy waste and operational difficulties caused by high temperatures. The process is highly automated and easy to operate.

[0017] The secondary alumina ash resource obtained by this invention can be widely used in building materials, refractory materials, and water purification agents. Experimental results show that high-alumina bricks prepared using the product of this invention meet the qualified standards in terms of refractoriness, load softening temperature, high-temperature compressive strength, high-temperature creep rate, reheat linear change, and thermal stability. The fused cast alumina refractory products used in glass melting furnaces can achieve a room-temperature compressive strength of 31.55-32.03 MPa and a room-temperature flexural strength of 7.38-7.46 MPa, demonstrating excellent performance, good economic benefits, and broad application prospects. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 This is the result of the denitrification rate test. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention provides a secondary aluminum ash resource product, which is obtained from raw materials through pelletizing, self-propagating combustion, and cooling. The raw materials, by mass, comprise: 80-100 parts of secondary aluminum ash and 10-20 parts of dust removal ash.

[0022] The secondary aluminum ash of the present invention is preferably low-calorific-value secondary aluminum ash and / or high-calorific-value secondary aluminum ash. In some preferred embodiments of the present invention, the secondary aluminum ash is composed of low-calorific-value secondary aluminum ash and high-calorific-value secondary aluminum ash in a mass ratio of (3-7):(3-7).

[0023] This invention utilizes a mixture of low-calorific-value and high-calorific-value secondary aluminum ash in a specific ratio as raw material to prepare secondary aluminum ash resource products. This achieves a balance between heat and reaction stability, making it an important means of balancing product quality and process energy efficiency. Low-calorific-value aluminum ash has a low calorific value, resulting in limited heat generation during the aluminothermic reaction. If its proportion is too high, the reaction cannot sustain self-propagating combustion, affecting the treatment effect. High-calorific-value aluminum ash, on the other hand, has a high calorific value, providing sufficient heat to sustain the reaction. However, if its proportion is too high, the reaction process becomes difficult to control, making it impossible to maintain uniformity in the combustion process, thus failing to obtain the desired quality resource products. Therefore, this invention adjusts the reactivity of the secondary aluminum ash raw materials by controlling the ratio of low-calorific-value and high-calorific-value secondary aluminum ash. By considering their combined calorific value characteristics, self-propagating combustion is ensured to proceed stably within an ideal heat range. This also avoids resource waste caused by a high content of high-calorific-value aluminum ash or increased energy consumption caused by a high content of low-calorific-value aluminum ash, ensuring that energy consumption during the treatment process remains at a low level. Furthermore, the performance of the secondary aluminum ash resource products of this invention is closely related to the chemical composition of the raw materials; low-calorific-value aluminum ash and high-calorific-value aluminum ash have significant differences in composition. Mixing them in a reasonable proportion can ensure a balanced composition in the final product, meeting the performance requirements for subsequent use as building materials, refractory materials, and water purification agents.

[0024] High-calorific-value secondary aluminum ash contains high levels of aluminum nitride and metallic aluminum. When their proportion in the mixed raw materials is too high, localized temperature spikes occur during self-propagating combustion, with instantaneous high temperatures exceeding 1600℃. This leads to rapid sintering on the surface of the raw materials, forming a dense alumina shell that hinders the contact between the internal aluminum nitride and oxygen, thus inhibiting the continued denitrification reaction. Simultaneously, the excessively high combustion rate causes the reaction front to advance too quickly, preventing the aluminum nitride inside the raw materials from fully oxidizing and decomposing before being solidified and sealed at high temperatures, resulting in incomplete denitrification. Furthermore, localized overheating can cause some aluminum nitride to undergo disproportionation reactions, generating a stable aluminum oxynitride intermediate phase. This intermediate phase is difficult to further decompose during subsequent cooling and ultimately remains in the product, reducing the denitrification rate. Therefore, controlling the proportion of high-calorific-value secondary aluminum ash within a reasonable range can maintain the combustion temperature within an appropriate range, ensuring a moderate combustion rate and uniform reaction front advancement, allowing sufficient time for aluminum nitride to contact oxygen and completely convert into alumina and nitrogen.

[0025] This invention allows for the adjustment of the proportion of low-calorific-value and high-calorific-value aluminum ash within a specific range according to the actual needs of the raw materials, so as to ensure the stability of the process and the quality of the product, and to make the product have good comprehensive performance, which can meet the production needs of most building materials, refractory materials and water purification agents.

[0026] The secondary aluminum ash described in this invention undergoes activation treatment before use. Specifically, the secondary aluminum ash is de-ironized, crushed, pulverized, and then sieved. The aluminum and powder are then separated until the aluminum content is 1%-5%, thus completing the activation of the secondary aluminum ash.

[0027] In some specific embodiments of the present invention, the secondary aluminum ash is removed from iron, crushed, and pulverized before being passed through a 120-150 mesh sieve.

[0028] The raw materials of this invention also include dust collector ash, which falls under the category of hazardous waste. This ash has small particle size, high salt content, and high specific surface area and calorific value. In the aluminum ash treatment process, the dust collector ash is used to improve the properties of the product.

[0029] Dust collector ash plays multiple synergistic roles in the self-propagating combustion process. First, the dust collector ash contains a certain amount of aluminum nitride and metallic aluminum, which can provide additional heat for the combustion reaction, helping to maintain a stable self-propagating combustion state. Second, the dust collector ash particles are small and have a large specific surface area. When uniformly dispersed in the pellets, they can form a continuous reaction channel network, promoting the diffusion and transport of oxygen into the pellets, improving the oxidation reaction efficiency, and thus significantly increasing the denitrification rate. Third, the alkali metal salts in the dust collector ash volatilize at high temperatures, forming a microporous structure between the particles, further improving the permeability of the pellets, which is conducive to the timely discharge of nitrogen generated during combustion and avoids the inhibitory effect of gas retention on the reaction. In addition, the alumina component in the dust collector ash forms a good bonding interface with the secondary aluminum ash matrix during high-temperature sintering, improving the density and structural uniformity of the final product, making it exhibit better mechanical properties and thermal stability in the subsequent preparation of refractory materials. When using fly ash from waste incineration to replace dust collector ash, its chemical composition is poorly compatible with the aluminum ash system and contains a large amount of heavy metals and harmful impurities. Not only can it not play the above-mentioned synergistic role, but it will also generate harmful gases at high temperatures and affect the purity of the product, resulting in a significant decrease in denitrification effect.

[0030] This invention provides a method for preparing secondary aluminum ash resource products, specifically including the following steps: After the raw materials are mixed evenly in proportion, they are pelletized. The resulting pellets are then subjected to self-propagating combustion. After combustion is completed, the pellets are cooled to obtain secondary aluminum ash resource products.

[0031] The ball material of this invention has a length of 40-50 mm, a width of 25-35 mm, a thickness of 15-25 mm, a moisture content of ≤3%, and a compressive strength of ≥10 N.

[0032] The self-propagating combustion temperature of this invention is 1100℃-1500℃. In some preferred embodiments of this invention, the self-propagating combustion temperature is 1100℃-1300℃. This invention maintains the self-propagating combustion temperature of the raw material at 1100℃-1500℃ by activating the secondary aluminum ash and adjusting the raw material ratio, thereby ensuring complete combustion and denitrification of the raw material and removing the reactivity and combustibility of the secondary aluminum ash.

[0033] In some specific embodiments of the present invention, the self-propagating combustion process is carried out in a self-propagating reactor, which is also equipped with a high-temperature integrated filter, and Roots blowers are installed at the bottom and sides of the furnace. Raw materials are fed into the furnace via an automatic conveying device. The oxygen-enriched side-blowing technology of the self-propagating combustion process ensures that the raw materials are fully combusted at a specific temperature and release sufficient heat, maintaining the temperature of the regenerator furnace between 1100℃ and 1500℃ for 6-8 hours to fully remove nitrogen, chlorine, and fluorine, thereby removing the reactivity and toxicity of secondary aluminum ash and obtaining high-quality resource-based products. During the combustion process, potassium, sodium, and fluoride salts in the flue gas volatilize at high temperatures. The high-temperature integrated filter can separate and capture dust according to different temperature controls, allowing gaseous salts to condense and be captured and recovered for use as industrial salt. The Roots blowers play a role in providing oxygen support, regulating the reaction temperature, promoting airflow circulation, removing waste gas and heat, improving filter efficiency, and promoting gas cooling and purification during the reaction process.

[0034] After the material has completed its reaction in the furnace, it is cooled and graded to finally obtain qualified secondary aluminum ash resource products, which can be used as raw materials in the fields of building materials, refractory materials and water purification agents.

[0035] To further illustrate the present invention, the following embodiments will be described in detail.

[0036] The composition of the dust used in the embodiments and comparative examples of this invention is as follows: Dust collector ash: AlN 6.605wt.%, SiO2 2.529wt.%, Cl 1.485wt.%, MgO 0.937wt.%, SO3 0.830wt.%, CaO 0.657wt.%, Fe2O3 0.557wt.%, K2O 0.366wt.%, MnO 0.173wt.%, CuO 0.028wt.%, balance Al2O3.

[0037] Unless otherwise specified, all experiments were repeated three times. Analysis of variance (ANOVA) and Duncan's multiple comparison analysis were performed using SPSS 21.0. Results are expressed as mean ± standard deviation, and p < 0.05 was considered statistically significant.

[0038] Example 1: A method for preparing a secondary aluminum ash resource product, comprising the following steps: S1. Remove iron from low-calorific-value secondary aluminum ash and high-calorific-value secondary aluminum ash, crush and pulverize them respectively, and then pass them through a 150-mesh sieve to complete the activation of secondary aluminum ash. S2. Weigh 80 parts by weight of activated secondary aluminum ash (low calorific value secondary aluminum ash: high calorific value secondary aluminum ash = 7:3, calorific value 854 kcal / kg) and 20 parts by weight of dust removal ash, mix them evenly and send them to a high-pressure briquetting machine through a screw conveyor to form briquettes, and obtain briquettes with a length of 45±2 mm, a width of 30±2 mm, a thickness of 20±2 mm, an average moisture content of 3%, and a compressive strength of 10 N. S3. The ball material is fed to the top of the furnace by the feeding belt. The material layer is formed in the furnace by the material layer. The initial ignition requires a small amount of coal and wood to ignite the local material layer. The oxygen-rich environment is maintained by the continuous ventilation and oxygen supply of the Roots blowers at the bottom and sides of the furnace, so that the material burns violently. The heat generated spreads from the ignition area outward through heat conduction until the self-propagating combustion reaction is complete. The self-propagating combustion temperature is 1200℃ and the duration is 7 hours. S4. After combustion is completed and cooled, secondary aluminum ash resource products are obtained.

[0039] Example 2 Same as Example 1, except that the raw material composition is as follows: 90 parts by weight of secondary aluminum ash (low calorific value secondary aluminum ash: high calorific value secondary aluminum ash = 3:7, calorific value is 1297 kcal / kg), and 10 parts by weight of dust removal ash.

[0040] Comparative Example 1 Same as Example 1, except that no dust was added.

[0041] Comparative Example 2 Same as Example 1, except that the dust removal ash is replaced with an equal amount of waste incineration fly ash.

[0042] Comparative Example 3 Same as Example 1, except that: the ratio of low calorific value secondary aluminum ash to high calorific value secondary aluminum ash is 1:9.

[0043] Comparative Example 4 Same as Example 1, except that: the ratio of low calorific value secondary aluminum ash to high calorific value secondary aluminum ash is 9:1.

[0044] This comparative example was not further studied because the content of low-calorific-value secondary aluminum ash was too high, making it impossible to achieve a complete self-propagating combustion reaction and obtain resource-based products that could be used for subsequent product preparation.

[0045] The denitrification rates of the raw materials in Examples 1-2 and Comparative Examples 1-3 were measured, and the results are shown in Table 1.

[0046] Table 1

[0047] Note: Different lowercase letters in the same column in the table indicate a significant difference between the two (P < 0.05).

[0048] As can be seen from the denitrification rate test results in Table 1, there are significant differences in denitrification effect between the embodiments of the present invention and the comparative examples. The denitrification rate of Example 1 reached 96.17±0.37%, and the denitrification rate of Example 2 was even higher at 97.62±0.62%, both exhibiting excellent denitrification performance. In contrast, the denitrification rates of Comparative Examples 1, 2, and 3 were 93.06±0.54%, 92.98±0.78%, and 92.45±0.45%, respectively, all significantly lower than those of the embodiments. Duncan's multiple comparison analysis showed that the denitrification rate of Example 2 was significantly higher than that of Example 1 (P<0.05), while there was no significant difference among the three comparative examples, but all were significantly lower than those of the two embodiments. This result fully demonstrates that the present invention, by optimizing the combination formulation of secondary aluminum ash (a specific ratio of low-calorific-value and high-calorific-value aluminum ash) and dust collector ash, can effectively improve the denitrification efficiency of the aluminothermic self-propagating reaction. Example 2 showed a 1.5 percentage point increase in denitrification rate compared to Example 1. This is related to the 3:7 mass ratio of low-calorific-value secondary aluminum ash to high-calorific-value secondary aluminum ash used. This ratio resulted in a calorific value of 1297 kcal / kg for the mixture, higher than the 854 kcal / kg in Example 1, providing sufficient heat support for a more complete combustion reaction. Comparative Example 1 did not add dust collector ash, Comparative Example 2 used waste incineration fly ash instead of dust collector ash, and Comparative Example 3 used an extreme low-calorific-value to high-calorific-value aluminum ash ratio (1:9). All these schemes resulted in a 3-5 percentage point decrease in denitrification rate, indicating that the addition of dust collector ash and a reasonable aluminum ash ratio are crucial for maintaining efficient denitrification.

[0049] Test Example 1 The products obtained in Examples 1-2 and Comparative Examples 1-3 were used to prepare high-alumina bricks. The preparation method was the same as that in Example 1 of CN110304908 A, except that the products obtained in the examples and comparative examples of this invention were used instead of alumina powder. The specific method is as follows: S1. Raw material selection: Select high-quality raw materials; S2. Crushing: The raw materials from the first step are crushed separately. S3. Screening: The crushed raw materials are passed through a 180-mesh sieve to obtain iron sheet powder, mullite powder, and alumina powder. The screened iron sheet is then passed through a 3 mm sieve, and the remaining iron sheet is passed through a 5 mm sieve to obtain iron sheet with a particle size of 3-5 mm. Similarly, mullite particles with a particle size of 1-3 mm and high-alumina material with a particle size of 0.5-1 mm are obtained. S4. Ingredients: Mix 8 parts of sheet metal, 30 parts of mullite granules, 22 parts of high-alumina material, 21 parts of sheet metal powder, 7 parts of mullite powder, 5 parts of secondary aluminum ash resource utilization product, and 7 parts of Guangxi white clay. First, add the sheet metal, mullite, and high-alumina material and stir. Then, add 3 parts of water, sheet metal powder, mullite powder, and secondary aluminum ash resource utilization product, and continue stirring until uniform. S5. Molding: The mixed raw materials are pressed into shape using a 400-ton press six times. S6. Drying: Dry the shaped semi-finished product at 110℃ for 20 hours; S7. Semi-finished product inspection: Remove non-compliant semi-finished products. S8. Firing: With the ambient temperature controlled at around 30℃, the qualified semi-finished product is heated to 1490℃ at a rate of 5℃ / minute, and then kept at that temperature for 8 hours to obtain the finished product.

[0050] The properties of the obtained high-alumina bricks were tested, and the specific indicators were as follows: Refractoriness (°C): ≥1790; Softening temperature under load (°C) 0.2 MPa × 0.6%: ≥1510; Bulk density (g / cm³) 3 ): ≥2.48; Apparent porosity (%): ≤20; High temperature compressive strength (MPa): ≥55.06; High-temperature creep rate % (0.2 MPa, 1280℃, 2 h) ≤: 0.7; Reheat line change, 1500℃×2 h%: ±0.3; Thermal stability (1100℃ water cooling) ≥15.

[0051] The performance test results of each high-alumina brick are shown in Table 2.

[0052] Table 2 Performance test results of high alumina bricks

[0053] Residual aluminum nitride has multiple negative impacts on the performance of refractory materials. When the denitrification rate is below 95%, the residual aluminum nitride in the product will continue to react with water vapor and oxygen in the air in subsequent high-temperature service environments, generating ammonia and alumina. This process is accompanied by volume expansion, generating significant internal stress within the material, leading to the initiation and propagation of microcracks, thereby significantly reducing the material's high-temperature compressive strength and creep resistance. Simultaneously, the ammonia produced by aluminum nitride hydrolysis forms pores and channels within the material, disrupting its dense structure, increasing apparent porosity, and decreasing thermal stability. Furthermore, incompletely converted aluminum nitride can undergo solid-phase reactions with other components in the material at high temperatures, generating low-melting-point phases, resulting in a decrease in the load softening temperature and excessive reheat linear variation.

[0054] Although Comparative Example 3 had the lowest denitrification rate, its formulation, which used a higher proportion of high-calorific-value aluminum ash, resulted in a relatively complete alumina protective layer forming on the product surface during high-temperature sintering. While it passed conventional refractoriness tests, it still failed to meet standards for indicators related to long-term high-temperature service, such as high-temperature creep rate and thermal stability. This is because the residual aluminum nitride inside gradually reacts and releases stress under continuous high temperatures, leading to material performance degradation. This invention, by increasing the denitrification rate to over 96% (significantly improving performance), reduces the residual aluminum nitride content in the product to an extremely low level, fundamentally eliminating the aforementioned hidden dangers and ensuring that the prepared refractory material meets the qualified standards in all performance indicators.

[0055] Test Example 1 examined the performance of high-alumina bricks prepared with different formulations on eight key performance indicators, including refractoriness, load softening temperature, bulk density, apparent porosity, high-temperature compressive strength, high-temperature creep rate, reheat linear change, and thermal stability. The results showed that the high-alumina bricks prepared using the secondary alumina ash resource products of Examples 1 and 2 met the qualification standards in all eight indicators, fully demonstrating the excellent performance of the product of this invention as a refractory material raw material. In contrast, the performance of the high-alumina bricks prepared in the comparative examples was significantly insufficient. The high-alumina bricks of Comparative Examples 1 and 2 failed to meet the standards in six indicators, including refractoriness, load softening temperature, high-temperature compressive strength, high-temperature creep rate, reheat linear change, and thermal stability, only meeting the standards in two basic physical indicators: bulk density and apparent porosity. Comparative Example 3 fared slightly better, meeting the qualification standard for refractoriness, but still failing in the remaining seven indicators. This series of data shows that the addition of dust collector ash and the proper ratio of low-calorific-value and high-calorific-value secondary alumina ash not only affect the denitrification efficiency but also the microstructure and macroscopic properties of the final product. The comparative product, due to insufficient denitrification and unbalanced composition, resulted in significant deterioration of the mechanical properties, creep resistance, and thermal stability of the prepared high-alumina bricks under high-temperature operating conditions, failing to meet practical application requirements.

[0056] Test Example 2 The products obtained in Examples 1-2 and Comparative Examples 1-3 were used to prepare cast alumina refractory products for glass melting furnaces. The preparation method was the same as that in Example 1 of CN 112110716 A, except that the alumina was replaced with an equal amount of the products obtained in Examples 1-2 and Comparative Examples 1-3. The specific method is as follows: S1. Mixing: Weigh 32 kg of secondary aluminum ash resource product, add 26.3 kg of zircon sand, 10 kg of desilicationized zirconium, 1 kg of soda ash, 2.5 kg of calcium silicate and 1.2 kg of ferric oxide, mix evenly, crush with a pulverizer, and sieve with a 700 μm sieve. Particles larger than 700 μm are further crushed until they are no larger than 700 μm to obtain the mixture. S2 Melting: The mixture is transferred to an electric arc furnace and heated to 2000℃ using a graphite electrode. It is melted for 130 min to obtain a molten liquid. The outlet of the oxygen lance is inserted 40 cm below the surface of the molten liquid. Oxygen is purged into the molten liquid for a first oxygen blowing treatment for 8 min. The oxygen pressure is 0.4 MPa and the oxygen flow rate is 450 L / h. After stopping the oxygen blowing, the mixture is refined at 2000℃ for another 18 min. Then, oxygen is purged into the molten liquid for a second oxygen blowing treatment for 8 min to obtain the casting liquid. S3 casting: Take 1.8 kg of yttrium oxide and 3 kg of tetragonal nano-zirconia, mix them evenly, and put them into a sand mold placed in an insulated box. Pour the casting liquid into the mold and cool it to 60℃ over 10 days to obtain a size of 80 cm. 40 cm Refractory products for casting alumina for glass melting furnaces with a diameter of 10cm.

[0057] The test results of cast alumina refractory products used in various glass melting furnaces are shown in Table 3.

[0058] Table 3. Performance Test Results of Cast Alumina Refractory Products for Glass Melting Furnaces

[0059] Note: Different lowercase letters in the same column in the table indicate a significant difference between the two (P < 0.05).

[0060] Test Example 2 further verified the application performance of the product of the present invention by preparing cast alumina refractory products for glass melting furnaces. As can be seen from the data in Table 3, in terms of room temperature compressive strength, the products prepared in Example 1 and Example 2 reached 31.55±0.55 MPa and 32.03±0.57 MPa, respectively, with no significant difference between them (both marked as a), but both were significantly higher than all comparative examples. The room temperature compressive strengths of Comparative Examples 1, 2, and 3 were 27.76±0.24 MPa, 28.08±0.42 MPa, and 30.29±0.29 MPa, respectively, which were reduced by approximately 12.0%, 12.3%, and 5.4% compared to the examples. Among them, the compressive strength of Comparative Examples 1 and 2 showed no significant difference (both marked as c), and although Comparative Example 3 was slightly higher than the former two (marked as b), it was still significantly lower than the examples. Regarding room temperature flexural strength, Examples 1 and 2 achieved 7.38±0.38 MPa and 7.46±0.46 MPa, respectively, which were also significantly better than the comparative examples. The room temperature flexural strengths of Comparative Examples 1, 2, and 3 were 6.79±0.21 MPa, 6.64±0.36 MPa, and 6.94±0.56 MPa, respectively, representing a decrease of approximately 8-11% compared to the examples. It is noteworthy that the differences in flexural strength among the comparative examples were relatively small, with some comparative examples showing no significant differences.

[0061] The analysis of the three sets of test data leads to the following conclusions: This invention, through precise control of the proportion of secondary alumina ash and the addition of dust removal ash, successfully achieved a denitrification rate exceeding 96%, directly translating into performance advantages in the final product. In the field of refractory materials applications, the high-alumina bricks and cast alumina refractory products prepared using the product of this invention exhibit excellent comprehensive performance, with all key indicators meeting or exceeding industry standards. In contrast, the comparative example, due to an unreasonable formulation design, although achieving an overall denitrification rate of over 92%, this 3-5 percentage point difference was significantly amplified in practical applications, leading to marked deterioration in the high-temperature mechanical properties, thermal stability, and structural integrity of the products. Statistical analysis shows that the performance difference between the examples and the comparative example is significant (P<0.05), fully demonstrating that the technical solution of this invention provides an efficient, economical, and environmentally friendly technical route for the resource utilization of secondary alumina ash.

[0062] Test Example 3 Aluminum ash from different sources was collected, and the contents of Al and AlN were determined. Its calorific value was also tested. The results are shown in Table 4.

[0063] Note: A calorific value greater than 1200 kcal / kg is considered high calorific value, and a calorific value less than 1200 kcal / kg is considered low calorific value.

[0064] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. The application of a secondary aluminum ash resource product in the preparation of building materials, refractory materials, and water purification agents, characterized in that, The secondary aluminum ash resource product is obtained from raw materials through pelletizing, self-propagating combustion, and cooling. The raw materials, by mass, include: 80-100 parts of secondary aluminum ash and 10-20 parts of dust removal ash.

2. The application according to claim 1, characterized in that, The secondary aluminum ash is low-calorific-value secondary aluminum ash and / or high-calorific-value secondary aluminum ash.

3. The application according to claim 2, characterized in that, The secondary aluminum ash is composed of low-calorific-value secondary aluminum ash and high-calorific-value secondary aluminum ash in a mass ratio of (3-7):(3-7).

4. The application according to claim 1, characterized in that, The secondary aluminum ash is activated before use.

5. The application according to claim 1, characterized in that, The raw materials also include 5 parts by weight of a fluorine-fixing agent.

6. The application according to claim 1, characterized in that, The preparation method of the secondary aluminum ash resource product includes the following steps: After the raw materials are mixed evenly in proportion, they are pelletized. The resulting pellets are then subjected to self-propagating combustion. After combustion is completed, the pellets are cooled to obtain secondary aluminum ash resource products.

7. The application according to claim 6, characterized in that, The ball material has a length of 40-50 mm, a width of 25-35 mm, a thickness of 15-25 mm, a moisture content of ≤3%, and a compressive strength of ≥10 N.

8. The application according to claim 6, characterized in that, The self-propagating combustion temperature is 1100℃-1500℃, and the self-propagating combustion time is 6-8 h.

9. The application according to claim 8, characterized in that, The self-propagating combustion temperature is 1100℃-1300℃.

Images