Method for preparing mullite-cordierite ceramic by co-processing secondary aluminum ash and lithium smelting slag

Abstract

The invention provides a method for preparing mullite-cordierite ceramic by co-processing secondary aluminum ash and lithium smelting slag, which comprises the following steps: carrying out first leaching on the secondary aluminum ash and acid liquor, then adjusting the pH value of a reaction system, and carrying out solid-liquid separation to obtain leached aluminum slag and leachate; mixing the leachate, the lithium smelting slag and a cosolvent for secondary leaching, and performing solid-liquid separation to obtain leached lithium slag; and mixing the leached aluminum slag, the leached lithium slag and a magnesium source, and carrying out solid-phase sintering to obtain the mullite-cordierite ceramic material. According to the method provided by the invention, toxic components and impurity elements in the secondary aluminum ash and the lithium smelting slag are effectively removed by utilizing component characteristics of the secondary aluminum ash and the lithium smelting slag, and the secondary aluminum ash and the lithium smelting slag are used as raw materials to prepare the high-performance ceramic material with high crystal phase purity, high strength and low thermal expansion coefficient, so that solid waste recycling and high-value utilization are realized, and the method has good economic, social and environmental benefits.

Description

Technical Field

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

[0002] Secondary aluminum ash and lithium smelting slag, as wastes, have high potential for resource utilization, but their complex composition and toxic substances make resource processing face many technical difficulties. Secondary aluminum ash contains highly active harmful components such as aluminum nitride and fluorine / chloride salts. At the same time, the impurity elements are of various types, complex content and variable occurrence characteristics, which not only increases the difficulty of separation and treatment, but also has a negative impact on the quality of the products, making its high-value utilization face challenges. However, secondary aluminum ash is rich in alumina and contains high-melting-point, high-hardness silica and magnesium aluminum spinel. If these beneficial components can be effectively used to replace refractory-grade bauxite to produce refractory or ceramic materials, it will have great commercial potential.

[0003] Lithium smelting slag is a by-product produced during the lithium extraction process of lithium concentrate, mainly composed of aluminosilicates composed of silicon dioxide and aluminum oxide. With the rapid development of the new energy industry, the output of lithium smelting slag has increased year by year, and its utilization rate is low. Lithium smelting slag contains harmful components such as residual acid, fluorine, thallium, and beryllium, which makes its safe treatment and resource utilization face huge challenges. Therefore, how to effectively separate these harmful substances from high-value aluminosilicate components and utilize them has become a technical problem that needs to be solved urgently.

[0004] Mullite-cordierite ceramic materials are widely used in refractory materials, ceramic kiln tools, electronic communications, aerospace and other fields due to their excellent thermal shock resistance, low thermal expansion coefficient, high strength and corrosion resistance. If secondary aluminum ash and lithium smelting slag can be used to prepare high-performance ceramic materials, it can not only achieve harmless treatment of waste, but also improve resource utilization efficiency. At present, there are some plans to try to utilize secondary aluminum ash and lithium smelting slag as resources.

[0005] CN117776698A discloses a method for preparing cordierite ceramics from secondary aluminum ash, wherein the impurities in the secondary aluminum ash are removed by mineralization roasting-acid decomposition, and then the secondary aluminum ash is mixed with silicon / magnesium source materials such as talc, kaolin, and silicon dioxide and sintered to prepare cordierite ceramic materials. However, due to the characteristics of silicon and magnesium components in the secondary aluminum ash, the amount of silicon and magnesium added is relatively small, and the two-stage roasting also has the problem of high energy consumption and cost.

[0006] CN118184386A discloses a method for preparing multiphase porous ceramics using aluminum ash slag, wherein the chloride salt in the secondary aluminum ash is removed to less than 9% by rapid water washing or low-temperature roasting, and the porous ceramics with cordierite as the main component are obtained by aerobic roasting after ball milling. However, the content and occurrence of aluminum nitride in the secondary aluminum ash are complex and changeable, and the performance of the foamed ceramic product cannot be guaranteed by using it as a foaming agent.

[0007] CN116969703A discloses a method for preparing geopolymerized sulphoaluminate cement using lithium slag and secondary aluminium ash, wherein lithium slag, secondary aluminium ash and phosphogypsum are used as raw materials to prepare sulphate cement, and the maximum uniaxial compressive strength can reach 45.61 MPa. However, the influence of chlorine, calcium, beryllium and thallium contained in aluminium ash and lithium slag on its stability and durability is not considered, and there are still certain environmental risks during use.

[0008] The existing technology still has 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 is still a bottleneck during the treatment process. How to effectively separate and utilize the toxic components N, Cl, F, S and impurity elements Ca, Na, K in secondary aluminum ash and lithium smelting slag, and at the same time make full use of the high content of aluminosilicate and spinel in them to prepare high value-added functional materials and effectively improve the resource utilization rate is an urgent problem that technicians in this field need to solve. Summary of the invention

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

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

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

[0012] (1) performing a first leaching of the secondary aluminum ash and the acid solution, and then adjusting the pH of the reaction system and performing solid-liquid separation to obtain leached aluminum slag and a leaching solution;

[0013] (2) mixing the leaching solution, lithium smelting slag and a solvent to perform a second leaching, and separating the solid from the liquid to obtain leached lithium slag;

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

[0015] The method provided by the present invention uses secondary aluminum ash and lithium smelting slag as main components with aluminum oxide and silicon oxide, and can form a good complementary effect when preparing mullite-cordierite ceramics as raw materials, so as to prepare high-performance ceramic materials. Firstly, the secondary aluminum ash is acid-dissolved to effectively remove poisonous components and impurity elements such as chloride, fluoride, sulfide and aluminum nitride in the secondary aluminum ash, then, the pH of the leaching solution is adjusted to reduce the aluminum content in the leaching solution, reduce aluminum loss, and complete the modification of the leaching solution at the same time, and then the modified leaching solution is used to remove impurities from the lithium smelting slag. The modified leaching solution contains salts such as sodium chloride, potassium chloride and ammonium chloride. In the leaching process of the lithium smelting slag, the dissolution of calcium sulfate is promoted, and at the same time, components such as sodium potassium salt and beryllium thallium are effectively removed, and the impurities in the aluminum ash and lithium slag are relatively completely removed. Finally, the aluminum ash, lithium smelting slag and magnesium source after impurity removal are solid-phase sintered to obtain the high-performance ceramic material.

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

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

[0018] In the secondary aluminum ash, the content of aluminum oxide is 60-80wt%, for example, it can be 60wt%, 65wt%, 70wt%, 75wt% or 80wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

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

[0020] In the secondary aluminum ash, the content of silicon dioxide is 1-10wt%, for example, it can be 1wt%, 3wt%, 5wt%, 8wt% or 10wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

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

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

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

[0024] In the lithium smelting slag, the content of silicon dioxide is 30-70wt%, for example, it can be 30wt%, 40wt%, 50wt%, 60wt% or 70wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

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

[0026] Preferably, the concentration of the acid solution in step (1) is 30-100 g / L, for example, 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, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the liquid-to-solid ratio of the acid solution to the secondary aluminum ash in step (1) is 3-20 mL / g, for example, 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, and other values ​​not listed within the numerical range are also applicable.

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

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

[0030] Preferably, the end point pH of the pH adjustment in step (1) is 4-6, for example, 4, 4.5, 5, 5.5 or 6, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

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

[0032] Preferably, the co-solvent in step (2) comprises 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 the co-solvent in step (2) is 1-30wt% of the lithium smelting slag, for example, it can be 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%, but is not limited to the listed values, and other values ​​not listed within the numerical 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, 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, and other unlisted values ​​within the numerical range are also applicable.

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

[0036] Preferably, the magnesium source in step (3) comprises any one of magnesium oxide, magnesium hydroxide or magnesium aluminum spinel, or a combination of at least two of them. 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 the present invention, the leached aluminum slag, the leached lithium slag and the magnesium source are mixed according to the stoichiometric ratio of elements in the mullite-cordierite design formula.

[0038] Preferably, the temperature of the solid phase sintering in step (3) is 1250-1500°C, for example, it can be 1250°C, 1300°C, 1350°C, 1400°C, 1450°C or 1500°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

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

[0040] As a preferred technical solution of the method provided by the present invention, the method comprises the following steps:

[0041] (1) leaching the secondary aluminum ash with a hydrochloric acid solution, wherein the concentration of the hydrochloric acid solution is 30-100 g / L, the liquid-to-solid ratio of the hydrochloric acid solution to the secondary aluminum ash is 3-20 mL / g, the leaching temperature is 50-90° C., the leaching time is 40-120 min, and after the leaching is completed, the pH of the reaction system is adjusted to 4-6 with a regulator, and then solid-liquid separation is performed, wherein 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 a leachate;

[0042] (2) mixing the leaching solution, lithium smelting slag and a solvent for leaching, wherein the solvent comprises one or a combination of at least two of hydrochloric acid, ethanol or acetic acid, the amount of the solvent is 1-30wt% of the lithium smelting slag, the liquid-solid ratio of the leaching is 5-100mL / g, the leaching temperature is 30-90°C, and after the leaching is completed, solid-liquid separation is performed to obtain leached lithium slag;

[0043] (3) The leached aluminum slag, the leached lithium slag and the magnesium source are mixed and solid-phase sintered at a temperature of 1250-1500° C. for 60-120 min to obtain a 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, which are abundant in source and low in cost. The complementary effect of the component characteristics of the two solid wastes is utilized to effectively remove the toxic components N, Cl, F, S and impurity elements Ca, Na, K, etc.

[0046] (2) The preparation method of the present invention has a simple process and low energy consumption, and can prepare high-performance mullite-cordierite ceramic materials with low thermal expansion coefficient, high strength and strong corrosion resistance. At the same time, it can realize the large-scale consumption and high-value utilization of secondary aluminum ash and lithium smelting slag, and has good economic, social and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a process flow chart 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 It is the XRD spectrum of the mullite-cordierite ceramic prepared in Example 1. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

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

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

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

[0053] Example 1

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

[0055] (1) leaching the secondary aluminum ash in a hydrochloric acid solution with a concentration of 50 g / L, a leaching liquid-solid ratio of 4 mL / g, a leaching temperature of 90° C., and a leaching time of 60 min. After the leaching is completed, adjusting the pH of the leaching system to 5 by using ammonia water and potassium hydroxide, and the mass ratio of ammonia water to potassium hydroxide is 3:1, and then filtering to obtain leached aluminum slag and a leachate;

[0056] (2) adding lithium smelting slag and hydrochloric acid to the obtained leachate for leaching, wherein the amount of hydrochloric acid added is 10wt% of the lithium smelting slag, the leaching liquid-solid ratio is 10mL / g, the leaching temperature is 80°C, and filtering to obtain leached lithium slag;

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

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

[0059] Example 2

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

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

[0062] (2) adding lithium smelting slag and hydrochloric acid to the obtained leachate for leaching, wherein the amount of hydrochloric acid added is 7wt% of the lithium smelting slag, the leachate-solid ratio is 12mL / g, the leaching temperature is 60°C, and filtering to obtain leached lithium slag;

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

[0064] Example 3

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

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

[0067] (2) adding lithium smelting slag and acetic acid to the obtained leachate for leaching, wherein the amount of acetic acid added is 12wt% of the lithium smelting slag, the leachate-solid ratio is 20mL / g, the leaching temperature is 70°C, and filtering to obtain leached lithium slag;

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

[0069] Example 4

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

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

[0072] (2) adding lithium smelting slag and ethanol to the obtained leachate for leaching, wherein the amount of ethanol added is 10wt% of the lithium smelting slag, the leaching liquid-solid ratio is 20mL / g, the leaching temperature is 40°C, and filtering to obtain leached lithium slag;

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

[0074] Example 5

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

[0076] (1) leaching the secondary aluminum ash in a hydrochloric acid solution with a concentration of 100 g / L, with a leaching liquid-solid ratio of 20 mL / g, a leaching temperature of 50° C., and a leaching time of 60 min. After the leaching is completed, adjusting the pH of the leaching system to 6 by using ammonia water and potassium hydroxide, with a mass ratio of ammonia water to potassium hydroxide of 3:1, and then filtering to obtain leached aluminum slag and a leachate;

[0077] (2) adding lithium smelting slag and hydrochloric acid to the obtained leachate for leaching, wherein the amount of hydrochloric acid added is 30wt% of the lithium smelting slag, the leaching liquid-solid ratio is 100mL / g, the leaching temperature is 90°C, and filtering to obtain leached lithium slag;

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

[0079] Example 6

[0080] The present embodiment provides a method for preparing mullite-cordierite ceramics by co-treatment of secondary aluminum ash and lithium smelting slag. Compared with Example 1, the pH regulator in step (1) is replaced by calcium hydroxide from ammonia water and potassium hydroxide, and the rest is the same as Example 1.

[0081] Example 7

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

[0083] Comparative Example 1

[0084] This comparative example provides a method for preparing mullite-cordierite ceramics by co-treatment of secondary aluminum ash and lithium smelting slag. Compared with Example 1, in step (2), an equal volume of the leaching liquid leached from the lithium smelting slag is replaced by water, and the rest is the same as 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 to be 1100°C, and the rest is the same as 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 to be 1600°C, and the rest is the same as Example 1.

[0089] Comparative Example 4

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

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

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

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

[0094] The thermal expansion coefficient of the material is tested according to standard GB / T 7320-2008.

[0095] The flexural strength of the material is tested according to standard GB / T 6569-86.

[0096] Table 1

[0097]

[0098] As can be seen from Table 1, the method provided by the present invention uses secondary aluminum ash and lithium smelting slag to prepare mullite-cordierite ceramic materials, which can achieve high-value resource utilization of secondary aluminum ash and lithium smelting slag. The mullite-cordierite material obtained by using the preferred process parameters of the present invention has the advantages of low thermal expansion coefficient, high strength and strong corrosion resistance.

[0099] Compared with Example 1, in Example 6, although calcium hydroxide plays a role in adjusting the pH, it will combine with the fluoride ions in the leachate to form CaF2 which remains in the leached aluminum slag, resulting in the formation of a large amount of calcium-containing mineral phases in the subsequent solid-phase sintering, a decrease in the cordierite content, and a decrease in the flexural strength; in Example 7, sulfuric acid is used as a co-solvent, and its solubility is poor, resulting in excessive calcium sulfate residue. Similarly, a large amount of calcium-containing mineral phases are formed during the sintering process, and the cordierite content is reduced, thereby causing a decrease in product performance.

[0100] In Comparative Example 1, water is used as the leaching liquid, and it is difficult to leach calcium sulfate in the lithium smelting slag, resulting in the generation of a large amount of calcium-containing mineral phases, and the mullite-cordierite phase is significantly reduced, making it difficult to form qualified products. It can be seen that the leaching liquid of the secondary aluminum ash and the co-solvent work synergistically to efficiently remove impurities in the lithium smelting slag, ensuring that high-performance ceramic materials are finally obtained; in Comparative Examples 2 and 3, the sintering temperature is too low, and no mullite-cordierite phase is generated, and the sintering temperature is too high, resulting in a large amount of glass phase; in Comparative Example 4, water is used as the secondary aluminum ash leaching solvent, and aluminum nitride and fluoride salts are not completely removed, and impurity mineral phases and stress points are formed during the sintering process, resulting in a significant decrease in flexural strength and a sharp increase in the thermal expansion coefficient.

[0101] In summary, the method provided by the present invention utilizes the component characteristics of secondary aluminum ash and lithium smelting slag, and realizes the short-process removal of poisonous components and impurity elements in secondary aluminum ash and lithium smelting slag through the synergistic effect of dilute acid dissolution-pH adjustment-acid leaching; the secondary aluminum ash and lithium smelting slag are recycled to prepare mullite-cordierite ceramic materials. The prepared ceramic materials have the advantages of low thermal expansion coefficient, high strength, strong corrosion resistance, etc., which help to improve the resource utilization rate of secondary aluminum ash and lithium smelting slag, and have good economic, social and environmental benefits.

[0102] The applicant declares that the above is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing mullite-cordierite ceramics by co-processing secondary aluminum ash and lithium smelting slag, characterized in that: The method comprises the following steps: (1) performing a first leaching of the secondary aluminum ash and the acid solution, and then adjusting the pH of the reaction system and performing solid-liquid separation to obtain leached aluminum slag and a leaching solution; (2) mixing the leaching solution, lithium smelting slag and a solvent to perform a second leaching, and separating the solid from the liquid to obtain leached lithium slag; (3) The leached aluminum slag, the leached lithium slag and the magnesium source are mixed and solid-phase sintered to obtain a mullite-cordierite ceramic material.

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

3. The method according to claim 1 or 2, characterized in that: The liquid-to-solid ratio of the acid solution to the secondary aluminum ash in step (1) is 3-20 mL / g.

4. The method according to any one of claims 1 to 3, characterized in that: Step (1) The temperature of the first leaching is 50-90° C.; Preferably, the first leaching time in step (1) is 40-120 min.

5. The method according to any one of claims 1 to 4, characterized in that: The end point pH of the pH adjustment in step (1) is 4-6; Preferably, the regulator used for adjusting the pH in step (1) comprises one or a combination of at least two of ammonia gas, ammonia water or potassium hydroxide.

6. The method according to any one of claims 1 to 5, characterized in that: The co-solvent in step (2) comprises one or a combination of at least two of hydrochloric acid, ethanol or acetic acid; Preferably, the amount of the co-solvent in step (2) is 1-30wt% of the lithium smelting slag.

7. The method according to any one of claims 1 to 6, characterized in that: Step (2) the liquid-to-solid ratio of the second leaching is 5-100 mL / g; Preferably, the temperature of the second leaching in step (2) is 30-90°C.

8. The method according to any one of claims 1 to 7, characterized in that: The magnesium source in step (3) includes any one of magnesium oxide, magnesium hydroxide or magnesium aluminum spinel, or a combination of at least two of them.

9. The method according to any one of claims 1 to 8, characterized in that: The temperature of the solid phase sintering in step (3) is 1250-1500° C. Preferably, the solid phase sintering time in step (3) is 60-120 min.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) leaching the secondary aluminum ash with a hydrochloric acid solution, wherein the concentration of the hydrochloric acid solution is 30-100 g / L, the liquid-to-solid ratio of the hydrochloric acid solution to the secondary aluminum ash is 3-20 mL / g, the leaching temperature is 50-90° C., the leaching time is 40-120 min, and after the leaching is completed, the pH of the reaction system is adjusted to 4-6 with a regulator, and then solid-liquid separation is performed, wherein 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 a leachate; (2) mixing the leaching solution, lithium smelting slag and a solvent for leaching, wherein the solvent comprises one or a combination of at least two of hydrochloric acid, ethanol or acetic acid, the amount of the solvent is 1-30wt% of the lithium smelting slag, the liquid-solid ratio of the leaching is 5-100mL / g, the leaching temperature is 30-90°C, and after the leaching is completed, solid-liquid separation is performed to obtain leached lithium slag; (3) The leached aluminum slag, the leached lithium slag and the magnesium source are mixed and solid-phase sintered at a temperature of 1250-1500° C. for 60-120 min to obtain a mullite-cordierite ceramic material.

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