A method for preparing mullite-cordierite ceramics through co-processing of secondary aluminum ash and lithium smelting slag.

Abstract

This invention provides a method for preparing mullite-cordierite ceramics through the co-processing of secondary aluminum ash and lithium smelting slag. The method includes: performing a first leaching of secondary aluminum ash with acid, then adjusting the pH of the reaction system and performing solid-liquid separation to obtain leached aluminum slag and leachate; mixing the leachate, lithium smelting slag, and a fluxing agent for a second leaching, and performing solid-liquid separation to obtain leached lithium slag; and mixing the leached aluminum slag, leached lithium slag, and a magnesium source for solid-phase sintering to obtain mullite-cordierite ceramic materials. The method provided by this invention utilizes the component characteristics of secondary aluminum ash and lithium smelting slag to effectively remove toxic components and impurity elements, and uses them as raw materials to prepare high-performance ceramic materials with high crystal purity, high strength, and low coefficient of thermal expansion, realizing the resource utilization and high-value utilization of solid waste, and having good economic, social, and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of multi-source solid waste treatment technology, and relates to a method for the co-treatment of secondary aluminum ash and lithium smelting slag, specifically a method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag. Background Technology

[0002] Secondary alumina ash and lithium smelting slag, as waste materials, have high potential for resource utilization. However, their complex composition and toxic substances pose numerous technical challenges to resource treatment. Secondary alumina ash contains highly reactive and harmful components such as aluminum nitride and fluorine / chloride salts. Furthermore, the diverse types, complex contents, and variable occurrence characteristics of impurity elements not only increase the difficulty of separation and treatment but also negatively impact the quality of finished products, posing a challenge to their high-value utilization. However, secondary alumina ash is rich in alumina and contains high-melting-point, high-hardness silica and magnesium aluminum spinel. If these beneficial components could be effectively utilized to replace refractory-grade bauxite in the production of refractory or ceramic materials, it would have enormous commercial potential.

[0003] Lithium smelting slag is a byproduct of lithium extraction from lithium concentrate, primarily composed of aluminosilicates made of silica and alumina. With the rapid development of the new energy industry, the output of lithium smelting slag has increased year by year, while its utilization rate remains low. Lithium smelting slag contains harmful components such as residual acid, fluorine, thallium, and beryllium, posing significant challenges to its safe treatment and resource utilization. Therefore, effectively separating and utilizing these harmful substances from the high-value aluminosilicate components has become an urgent technical problem to be solved.

[0004] Mullite-cordierite ceramic materials are widely used in refractory materials, ceramic kiln furniture, electronic communications, and aerospace fields due to their excellent thermal shock resistance, low coefficient of thermal expansion, high strength, and corrosion resistance. If high-performance ceramic materials could be prepared using secondary alumina ash and lithium smelting slag, it would not only achieve the harmless treatment of waste but also improve resource utilization efficiency. Currently, several schemes have been explored for the resource utilization of secondary alumina ash and lithium smelting slag.

[0005] CN117776698A discloses a method for preparing cordierite ceramics from secondary alumina ash. The method involves removing impurities from the secondary alumina ash through mineralization roasting and acid hydrolysis, followed by mixing it with silicon / magnesium source materials such as talc, kaolin, and silica, and then sintering to prepare cordierite ceramic materials. However, due to the characteristics of the silicon and magnesium components in the secondary alumina ash, the amount added is relatively small, and the two-stage roasting process also suffers from high energy consumption and cost.

[0006] CN118184386A discloses a method for preparing multiphase porous ceramics using aluminum ash slag. The method involves rapidly washing or low-temperature calcining to remove chlorides from secondary aluminum ash to <9%, followed by ball milling and aerobic calcination to obtain porous ceramics dominated by cordierite. However, the aluminum nitride content and distribution in secondary aluminum ash are complex and variable, making it unsuitable as a foaming agent to guarantee the performance of the foamed ceramic products.

[0007] CN116969703A discloses a method for preparing geopolymerized sulfoaluminate cement using lithium slag and secondary alumina ash. The method uses lithium slag, secondary alumina ash, and phosphogypsum as raw materials to prepare sulfate cement, achieving a maximum uniaxial compressive strength of 45.61 MPa. However, it does not consider the impact of chlorine, calcium, beryllium, thallium, etc., contained in the alumina ash and lithium slag on its stability and durability, and certain environmental risks still exist during use.

[0008] Current technologies still suffer from problems such as high energy consumption, high cost, and incomplete removal of impurities. In particular, the treatment and separation of harmful components in secondary aluminum ash and lithium smelting slag remains a bottleneck. How to effectively separate and utilize the toxic components N, Cl, F, S, and impurity elements Ca, Na, K, etc., in secondary aluminum ash and lithium smelting slag, while fully utilizing their high content of aluminosilicates and spinels to prepare high-value-added functional materials and effectively improve resource utilization, is a pressing problem that needs to be solved by those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to provide a method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag, thereby co-processing secondary aluminum ash and lithium smelting slag to prepare high-performance ceramic materials.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] This invention provides a method for preparing mullite-cordierite ceramics through the co-processing of secondary aluminum ash and lithium smelting slag, the method comprising the following steps:

[0012] (1) The secondary aluminum ash and acid solution are subjected to a first leaching. Then, after adjusting the pH of the reaction system, solid-liquid separation is performed to obtain leached aluminum slag and leaching solution.

[0013] (2) The leachate, lithium smelting slag and flux are mixed for a second leaching, and solid-liquid separation is performed to obtain leached lithium slag;

[0014] (3) The leached aluminum slag, leached lithium slag and magnesium source are mixed and solid-phase sintered to obtain mullite-cordierite ceramic material.

[0015] The method provided by this invention utilizes the fact that both secondary aluminum ash and lithium smelting slag are mainly composed of alumina and silicon dioxide. When used as raw materials to prepare mullite-cordierite ceramics, they can form a good complementary effect, thus preparing high-performance ceramic materials. First, the secondary aluminum ash is acid-dissolved to effectively remove toxic components and impurities such as chlorides, fluorides, sulfides, and aluminum nitrides. Then, the pH of the leachate is adjusted to reduce the aluminum content and reduce aluminum loss, while simultaneously modifying the leachate. The modified leachate is then used to remove impurities from the lithium smelting slag. The modified leachate contains salts such as sodium chloride, potassium chloride, and ammonium chloride. During the leaching process of the lithium smelting slag, it promotes the dissolution of calcium sulfate and simultaneously effectively removes sodium and potassium salts, beryllium, and thallium. The removal of impurities from the aluminum ash and lithium slag is relatively complete. Finally, the impurity-removed aluminum ash, lithium smelting slag, and magnesium source are solid-state sintered to obtain high-performance ceramic materials.

[0016] In this invention, the secondary aluminum ash comprises: 3-8 wt% metallic aluminum, 60-80 wt% aluminum oxide, 1-10 wt% aluminum nitride, 1-10 wt% chloride, 1-5 wt% fluoride, 1-10 wt% silicon dioxide, and 1-10 wt% magnesium oxide.

[0017] The content of metallic aluminum in secondary aluminum ash is 3-8 wt%, for example, it can be 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt% or 8 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] The alumina content in secondary aluminum ash is 60-80 wt%, for example, it can be 60 wt%, 65 wt%, 70 wt%, 75 wt% or 80 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] The aluminum nitride content in secondary aluminum ash is 1-10 wt%, for example, it can be 1 wt%, 3 wt%, 5 wt%, 8 wt% or 10 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] The silica content in secondary aluminum ash is 1-10 wt%, for example, it can be 1 wt%, 3 wt%, 5 wt%, 8 wt% or 10 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] The magnesium oxide content in secondary aluminum ash is 1-10 wt%, for example, it can be 1 wt%, 3 wt%, 5 wt%, 8 wt% or 10 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] In this invention, the lithium smelting slag comprises: 10-30 wt% alumina, 30-70 wt% silicon dioxide, 1-5 wt% iron oxide, 5-10 wt% calcium sulfate, and 1-3 wt% fluoride.

[0023] In lithium smelting slag, the alumina content is 10-30 wt%, for example, it can be 10 wt%, 15 wt%, 20 wt%, 25 wt% or 30 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] The silica content in lithium smelting slag is 30-70 wt%, for example, it can be 30 wt%, 40 wt%, 50 wt%, 60 wt% or 70 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the acid solution in step (1) includes a hydrochloric acid solution.

[0026] Preferably, the concentration of the acid solution in step (1) is 30-100 g / L, for example, it can be 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L or 100 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the liquid-solid ratio of the acid solution to the secondary aluminum ash in step (1) is 3-20 mL / g, for example, it can be 3 mL / g, 5 mL / g, 8 mL / g, 10 mL / g, 12 mL / g, 15 mL / g, 18 mL / g or 20 mL / g, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the temperature of the first leaching in step (1) is 50-90°C, for example, it can be 50°C, 60°C, 70°C, 80°C or 90°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the first leaching time in step (1) is 40-120 min, for example, it can be 40 min, 50 min, 60 min, 80 min, 100 min or 120 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, the endpoint pH of pH adjustment in step (1) is 4-6, for example, it can be 4, 4.5, 5, 5.5 or 6, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the pH adjuster used in step (1) includes one or a combination of at least two of ammonia, ammonia water, or potassium hydroxide. Typical but non-limiting combinations include a combination of ammonia and ammonia water, a combination of ammonia water and potassium hydroxide, a combination of ammonia and potassium hydroxide, or a combination of ammonia, ammonia water, and potassium hydroxide.

[0032] Preferably, the co-solvent in step (2) includes one or a combination of at least two of hydrochloric acid, ethanol, or acetic acid. Typical but non-limiting combinations include a combination of hydrochloric acid and ethanol, a combination of ethanol and acetic acid, a combination of hydrochloric acid and acetic acid, or a combination of hydrochloric acid, ethanol, and acetic acid.

[0033] Preferably, the amount of fluxing agent used in step (2) is 1-30 wt% of lithium smelting slag, for example, it can be 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt% or 30 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the liquid-to-solid ratio of the second leaching in step (2) is 5-100 mL / g, for example, it can be 5 mL / g, 10 mL / g, 30 mL / g, 50 mL / g, 80 mL / g or 100 mL / g, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the temperature of the second leaching in step (2) is 30-90°C, for example, it can be 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or 90°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the magnesium source in step (3) includes any one or a combination of at least two of magnesium oxide, magnesium hydroxide, or magnesium aluminum spinel. Typical but non-limiting combinations include a combination of magnesium oxide and magnesium hydroxide, a combination of magnesium hydroxide and magnesium aluminum spinel, a combination of magnesium oxide and magnesium aluminum spinel, or a combination of magnesium oxide, magnesium hydroxide, and magnesium aluminum spinel.

[0037] In this invention, the leached aluminum slag, leached lithium slag, and magnesium source are mixed according to the elemental stoichiometric ratio of the mullite-cordierite design formula.

[0038] Preferably, the solid-state sintering temperature in step (3) is 1250-1500℃, for example, it can be 1250℃, 1300℃, 1350℃, 1400℃, 1450℃ or 1500℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, the solid-state sintering time in step (3) is 60-120 min, for example, it can be 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] As a preferred embodiment of the method provided by the present invention, the method includes the following steps:

[0041] (1) The secondary aluminum ash is leached with hydrochloric acid solution. The concentration of hydrochloric acid solution is 30-100 g / L, the liquid-solid ratio of hydrochloric acid solution to secondary aluminum ash is 3-20 mL / g, the leaching temperature is 50-90℃, the leaching time is 40-120 min, and after leaching, the pH of the reaction system is adjusted to 4-6 with a regulator. Then, solid-liquid separation is carried out. The regulator includes one or a combination of at least two of ammonia gas, ammonia water or potassium hydroxide to obtain leached aluminum slag and leaching solution.

[0042] (2) The leaching solution, lithium smelting slag and co-solvent are mixed and leached. The co-solvent includes one or a combination of at least two of hydrochloric acid, ethanol or acetic acid. The amount of co-solvent is 1-30 wt% of lithium smelting slag. The liquid-to-solid ratio of leaching is 5-100 mL / g. The leaching temperature is 30-90℃. After leaching, solid and liquid are separated to obtain leached lithium slag.

[0043] (3) The leached aluminum slag, leached lithium slag and magnesium source are mixed and solid-state sintering is carried out. The solid-state sintering temperature is 1250-1500℃ and the solid-state sintering time is 60-120min to obtain mullite-cordierite ceramic material.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The method provided by the present invention uses secondary aluminum ash and lithium smelting slag as raw materials. The raw materials are abundant and inexpensive. By utilizing the complementary effect of the component characteristics of the two solid wastes, the toxic components N, Cl, F, S and impurity elements Ca, Na, K and other components are effectively removed.

[0046] (2) The preparation method of the present invention is simple and energy-efficient, and produces high-performance mullite-cordierite ceramic materials with low thermal expansion coefficient, high strength and strong corrosion resistance. At the same time, it realizes the large-scale disposal and high-value utilization of secondary aluminum ash and lithium smelting slag, which has good economic, social and environmental benefits. Attached Figure Description

[0047] Figure 1 This is a process flow diagram of the method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag provided in Example 1.

[0048] Figure 2 This is the XRD pattern of the mullite-cordierite ceramic prepared in Example 1. Detailed Implementation

[0049] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0050] To clearly illustrate the technical solution of the present invention, in a specific embodiment, the composition of the secondary aluminum ash used includes: 5.4 wt% metallic aluminum, 67.6 wt% aluminum oxide, 5.2 wt% aluminum nitride, 3.4 wt% chloride, 2.1 wt% fluoride, 6.8 wt% silicon dioxide, 5.3 wt% magnesium oxide, and 4.2 wt% other impurities.

[0051] The composition of the lithium smelting slag used includes: 17.2 wt% alumina, 47.6 wt% silicon dioxide, 3.9 wt% iron oxide, 24.8 wt% calcium sulfate, 1.3 wt% fluoride, and 5.2 wt% other impurities.

[0052] To clearly illustrate the technical solution of the present invention, in a specific embodiment, in step (3), the leached aluminum slag, leached lithium slag and magnesium source are mixed according to the elemental stoichiometric ratio of the cordierite-mullite design formula.

[0053] Example 1

[0054] This embodiment provides a method such as Figure 1 The method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag, as shown, includes the following steps:

[0055] (1) The secondary aluminum ash was leached in a hydrochloric acid solution with a concentration of 50 g / L. The leaching liquid-to-solid ratio was 4 mL / g, the leaching temperature was 90℃, and the leaching time was 60 min. After leaching, the pH of the leaching system was adjusted to 5 by ammonia and potassium hydroxide. The mass ratio of ammonia to potassium hydroxide was 3:1. Then the system was filtered to obtain leached aluminum slag and leaching solution.

[0056] (2) Lithium smelting slag and hydrochloric acid were added to the obtained leachate for leaching. The amount of hydrochloric acid added was 10 wt% of the lithium smelting slag, the solid ratio of the leachate was 10 mL / g, the leaching temperature was 80℃, and the leached lithium slag was obtained by filtration.

[0057] (3) The obtained leached aluminum slag, leached lithium slag and magnesium aluminum spinel are uniformly mixed according to the elemental stoichiometric ratio of 60wt% cordierite and 40wt% mullite in the composition of mullite-cordierite ceramic, and calcined at 1400℃ for 100min to obtain mullite-cordierite ceramic.

[0058] The XRD pattern of the mullite-cordierite ceramic prepared in this embodiment is as follows: Figure 2 As shown, the spectrum indicates that the obtained product is a mullite-cordierite ceramic material with very high crystal phase purity.

[0059] Example 2

[0060] This embodiment provides a method for preparing mullite-cordierite ceramics through the co-processing of secondary aluminum ash and lithium smelting slag, the method comprising the following steps:

[0061] (1) The secondary aluminum ash was leached in a hydrochloric acid solution with a concentration of 30 g / L. The leaching liquid-to-solid ratio was 5 mL / g, the leaching temperature was 60℃, and the leaching time was 120 min. After the leaching was completed, the pH of the leaching system was adjusted to 4 by ammonia gas, and then filtered to obtain leached aluminum slag and leaching liquid.

[0062] (2) Lithium smelting slag and hydrochloric acid were added to the obtained leachate for leaching. The amount of hydrochloric acid added was 7 wt% of the lithium smelting slag, the solid ratio of the leachate was 12 mL / g, the leaching temperature was 60℃, and the leached lithium slag was obtained by filtration.

[0063] (3) The obtained leached aluminum slag, leached lithium slag and magnesium aluminum spinel are uniformly mixed according to the elemental stoichiometric ratio of 60wt% cordierite and 40wt% mullite in the composition of mullite-cordierite ceramic, and calcined at 1440℃ for 120min to obtain mullite-cordierite ceramic.

[0064] Example 3

[0065] This embodiment provides a method for preparing mullite-cordierite ceramics through the co-processing of secondary aluminum ash and lithium smelting slag, the method comprising the following steps:

[0066] (1) The secondary aluminum ash was leached in a hydrochloric acid solution with a concentration of 60 g / L. The leaching liquid-to-solid ratio was 8 mL / g, the leaching temperature was 70℃, and the leaching time was 85 min. After the leaching was completed, the pH of the leaching system was adjusted to 4 by potassium hydroxide, and then filtered to obtain leached aluminum slag and leaching solution.

[0067] (2) Lithium smelting slag and acetic acid were added to the obtained leachate for leaching. The amount of acetic acid added was 12wt% of the lithium smelting slag, the solid ratio of the leachate was 20mL / g, the leaching temperature was 70℃, and the leached lithium slag was obtained by filtration.

[0068] (3) The obtained leached aluminum slag, leached lithium slag and magnesium aluminum spinel are uniformly mixed according to the elemental stoichiometric ratio of 60wt% cordierite and 40wt% mullite in the composition of mullite-cordierite ceramic, and calcined at 1380℃ for 80min to obtain mullite-cordierite ceramic.

[0069] Example 4

[0070] This embodiment provides a method for preparing mullite-cordierite ceramics through the co-processing of secondary aluminum ash and lithium smelting slag, the method comprising the following steps:

[0071] (1) The secondary aluminum ash was leached in a hydrochloric acid solution with a concentration of 90 g / L. The leaching liquid-to-solid ratio was 3 mL / g, the leaching temperature was 55℃, and the leaching time was 40 min. After the leaching was completed, the pH of the leaching system was adjusted to 4 by ammonia water, and then filtered to obtain leached aluminum slag and leaching solution.

[0072] (2) Lithium smelting slag and ethanol were added to the obtained leachate for leaching. The amount of ethanol added was 10 wt% of the lithium smelting slag, the solid ratio of the leachate was 20 mL / g, the leaching temperature was 40 °C, and the leached lithium slag was obtained by filtration.

[0073] (3) The obtained leached aluminum slag, leached lithium slag and magnesium aluminum spinel are uniformly mixed according to the elemental stoichiometric ratio of 80wt% cordierite and 20wt% mullite in the composition of mullite-cordierite ceramic, and calcined at 1350℃ for 90min to obtain mullite-cordierite ceramic.

[0074] Example 5

[0075] This embodiment provides a method for preparing mullite-cordierite ceramics through the co-processing of secondary aluminum ash and lithium smelting slag, the method comprising the following steps:

[0076] (1) The secondary aluminum ash was leached in a hydrochloric acid solution with a concentration of 100 g / L. The leaching liquid-to-solid ratio was 20 mL / g, the leaching temperature was 50 °C, and the leaching time was 60 min. After leaching, the pH of the leaching system was adjusted to 6 by ammonia and potassium hydroxide. The mass ratio of ammonia to potassium hydroxide was 3:1. Then the system was filtered to obtain leached aluminum slag and leaching solution.

[0077] (2) Lithium smelting slag and hydrochloric acid were added to the obtained leachate for leaching. The amount of hydrochloric acid added was 30 wt% of the lithium smelting slag, the solid ratio of the leachate was 100 mL / g, the leaching temperature was 90 °C, and the leached lithium slag was obtained by filtration.

[0078] (3) The obtained leached aluminum slag, leached lithium slag and magnesium aluminum spinel are uniformly mixed according to the elemental stoichiometric ratio of 80wt% cordierite and 20wt% mullite in the composition of mullite-cordierite ceramic, and calcined at 1500℃ for 60min to obtain mullite-cordierite ceramic.

[0079] Example 6

[0080] This embodiment provides a method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag. Compared with Example 1, the pH adjuster in step (1) is replaced by calcium hydroxide instead of ammonia and potassium hydroxide. All other steps are the same as in Example 1.

[0081] Example 7

[0082] This embodiment provides a method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag. Compared with Example 1, the co-solvent in step (2) is replaced by sulfuric acid in equal mass with hydrochloric acid, and the rest is the same as in Example 1.

[0083] Comparative Example 1

[0084] This comparative example provides a method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag. Compared with Example 1, in step (2), the same volume of the leachate from the lithium smelting slag is replaced with water, and the rest is the same as in Example 1.

[0085] Comparative Example 2

[0086] This embodiment provides a method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag. Compared with Example 1, the solid phase sintering temperature in step (3) is controlled at 1100℃, and the rest are the same as in Example 1.

[0087] Comparative Example 3

[0088] This embodiment provides a method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag. Compared with Example 1, the solid-phase sintering temperature in step (3) is controlled at 1600℃, and the rest are the same as in Example 1.

[0089] Comparative Example 4

[0090] This comparative example provides a method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag. Compared with Example 1, the hydrochloric acid in step (1) is replaced with water in equal volume, and the rest is the same as in Example 1.

[0091] The materials prepared in the examples and comparative examples were subjected to composition determination and performance testing, and the test results are listed in Table 1.

[0092] The composition of the material was determined by X-ray diffraction.

[0093] The bulk density and apparent porosity of the material were tested in accordance with standard GB / T 2997-2000.

[0094] The coefficient of thermal expansion of the material was tested in accordance with standard GB / T 7320-2008.

[0095] The flexural strength of the material was tested in accordance with standard GB / T 6569-86.

[0096] Table 1

[0097]

[0098] As shown in Table 1, the method provided by this invention uses secondary aluminum ash and lithium smelting slag to prepare mullite-cordierite ceramic materials, enabling high-value resource utilization of these materials. The mullite-cordierite materials obtained using the preferred process parameters of this invention have advantages such as low thermal expansion coefficient, high strength, and strong corrosion resistance.

[0099] Compared to Example 1, in Example 6, although calcium hydroxide played a role in adjusting the pH, it combined with fluoride ions in the leachate to form CaF2, which remained in the leached aluminum slag. This resulted in the formation of a large amount of calcium-containing mineral phase during subsequent solid-phase sintering, reducing the cordierite content and decreasing the flexural strength. In Example 7, sulfuric acid, as a co-solvent, had a poor solubilizing effect, leading to excessive calcium sulfate residue. Similarly, this resulted in the formation of a large amount of calcium-containing mineral phase during sintering, reducing the cordierite content and thus lowering the product performance.

[0100] In Comparative Example 1, water was used as the leaching solution, which made it difficult to leach calcium sulfate from the lithium smelting slag, resulting in the formation of a large amount of calcium-containing mineral phases and a significant reduction in the mullite-cordierite phase, making it difficult to form a qualified product. It can be seen that the leaching solution of the secondary aluminum ash and the fluxing agent work together to efficiently remove impurities from the lithium smelting slag, ensuring that high-performance ceramic materials are finally obtained. In Comparative Examples 2 and 3, the sintering temperature was too low, and no mullite-cordierite phase was formed. The sintering temperature was too high, resulting in the formation of a large amount of glass phase. In Comparative Example 4, water was used as the leaching solvent for the secondary aluminum ash, and the aluminum nitride and fluoride salts were not completely removed. Impurity mineral phases and stress points were formed during the sintering process, resulting in a significant reduction in flexural strength and a sharp increase in the coefficient of thermal expansion.

[0101] In summary, the method provided by this invention utilizes the component characteristics of secondary aluminum ash and lithium smelting slag to achieve a short-process removal of toxic components and impurity elements from secondary aluminum ash and lithium smelting slag through the synergistic effect of dilute acid leaching, pH adjustment, and acidic leaching. Furthermore, the method utilizes the secondary aluminum ash and lithium smelting slag to prepare mullite-cordierite ceramic materials. The prepared ceramic materials have advantages such as low coefficient of thermal expansion, high strength, and strong corrosion resistance, which helps to improve the resource utilization rate of secondary aluminum ash and lithium smelting slag, and has good economic, social, and environmental benefits.

[0102] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing mullite-cordierite ceramics through the co-processing of secondary aluminum ash and lithium smelting slag, characterized in that, The method includes the following steps: (1) The secondary aluminum ash is leached with hydrochloric acid solution for the first time, and then the pH of the reaction system is adjusted and solid-liquid separation is carried out. The final pH of the pH adjustment is 4-6, and leached aluminum slag and leaching solution are obtained. (2) The leachate, lithium smelting slag and co-solvent are mixed for a second leaching, wherein the co-solvent includes ethanol and / or acetic acid, and the solid-liquid separation is performed to obtain leached lithium slag; (3) The leached aluminum slag, leached lithium slag and magnesium source are mixed and solid-phase sintered to obtain mullite-cordierite ceramic material.

2. The method according to claim 1, characterized in that, The concentration of the hydrochloric acid solution in step (1) is 30-100 g / L.

3. The method according to claim 1, characterized in that, The liquid-to-solid ratio of the hydrochloric acid solution to the secondary aluminum ash in step (1) is 3-20 mL / g.

4. The method according to claim 1, characterized in that, Step (1) The temperature of the first leaching is 50-90℃.

5. The method according to claim 1, characterized in that, Step (1) The first leaching time is 40-120 min.

6. The method according to claim 1, characterized in that, The pH adjuster used in step (1) includes one or a combination of at least two of ammonia, ammonia water, or potassium hydroxide.

7. The method according to claim 1, characterized in that, The amount of flux used in step (2) is 1-30 wt% of the lithium smelting slag.

8. The method according to claim 1, characterized in that, In step (2), the liquid-to-solid ratio of the second leaching is 5-100 mL / g.

9. The method according to claim 1, characterized in that, Step (2) The temperature of the second leaching is 30-90℃.

10. The method according to claim 1, characterized in that, The magnesium source in step (3) includes any one or a combination of at least two of magnesium oxide, magnesium hydroxide, or magnesium aluminum spinel.

11. The method according to claim 1, characterized in that, The solid-state sintering temperature in step (3) is 1250-1500℃.

12. The method according to claim 1, characterized in that, The solid-state sintering time in step (3) is 60-120 min.

13. The method according to claim 1, characterized in that, The method includes the following steps: (1) The secondary aluminum ash is leached with hydrochloric acid solution. The concentration of hydrochloric acid solution is 30-100 g / L, the liquid-solid ratio of hydrochloric acid solution to secondary aluminum ash is 3-20 mL / g, the leaching temperature is 50-90℃, the leaching time is 40-120 min, and after leaching, the pH of the reaction system is adjusted to 4-6 with a regulator. Then, solid-liquid separation is carried out. The regulator includes one or a combination of at least two of ammonia gas, ammonia water or potassium hydroxide to obtain leached aluminum slag and leaching solution. (2) The leaching solution, lithium smelting slag and co-solvent are mixed and leached. The co-solvent includes ethanol and / or acetic acid. The amount of co-solvent is 1-30 wt% of lithium smelting slag. The liquid-to-solid ratio of leaching is 5-100 mL / g. The leaching temperature is 30-90℃. After leaching, solid and liquid are separated to obtain leached lithium slag. (3) The leached aluminum slag, leached lithium slag and magnesium source are mixed and solid-phase sintered. The solid-phase sintering temperature is 1250-1500℃ and the solid-phase sintering time is 60-120min to obtain mullite-cordierite ceramic material.

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