A method for preparing desiliconized coal gangue for electrolytic aluminum

Abstract

This invention discloses a method for preparing desilicationized coal gangue for electrolytic aluminum, relating to the field of solid waste resource utilization technology. The preparation method includes the following steps: mixing coal gangue, γ-Al₂O₃, and α-Al₂O₃ to obtain a mixed powder; calcining the mixed powder to obtain calcined coal gangue; mixing the calcined coal gangue with alkali, an interface modifier, and water, heating the mixture to react, and then filtering, washing, and drying to obtain the desilicationized coal gangue for electrolytic aluminum. Compared with existing alkali extraction methods, this invention can significantly improve the aluminum-silicon ratio of the desilicationized solid waste coal gangue, thereby meeting the requirements of the electrolytic aluminum process for the aluminum-silicon ratio of raw materials. This will help to replace bauxite with solid waste coal gangue for electrolytic aluminum, significantly reducing the current production cost of the electrolytic aluminum industry, while simultaneously realizing the resource utilization of solid waste coal gangue. Furthermore, this invention's method is simple, low-cost, and has good application prospects.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a method for preparing desilicationized coal gangue for electrolytic aluminum. Background Technology

[0002] Aluminum, a commonly used metal, is primarily produced through electrolytic aluminum production, with bauxite being its core raw material. However, bauxite is a non-renewable resource with limited existing reserves, and its depletion due to long-term mining has become a key bottleneck restricting the sustainable development of the electrolytic aluminum industry. Coal gangue, a solid waste generated during coal mining and washing, is a hard, dark gray rock with low carbon content associated with coal seams, mainly composed of Al2O3 and SiO2. Its reserves are extremely abundant and its price is extremely low. Therefore, using solid waste coal gangue as an alumina source to replace bauxite can significantly reduce the production cost of the electrolytic aluminum industry while simultaneously achieving the resource-based reuse of solid waste coal gangue. However, compared to bauxite, coal gangue has a lower aluminum-to-silicon ratio (Al2O3 / SiO2 mass ratio), which is insufficient to meet the requirements of electrolytic aluminum processes. Therefore, it is necessary to increase the aluminum-to-silicon ratio of coal gangue through desilication methods to achieve the substitution of solid waste coal gangue for bauxite. Currently, the main method for desilication of coal gangue is alkaline extraction, which removes SiO2 species from the structure of coal gangue using alkaline substances, thereby increasing the aluminum-silicon ratio of the coal gangue. However, existing alkaline desilication methods for coal gangue often fail to achieve an ideal aluminum-silicon ratio (Al2O3 / SiO2 mass ratio > 3), which cannot meet the requirements of the electrolytic aluminum process for the aluminum-silicon ratio of raw materials.

[0003] Therefore, improving the desilication effect of alkali extraction and obtaining desilicationized coal gangue with a high aluminum-to-silicon ratio is a technical challenge in the field of using solid waste coal gangue to replace bauxite for electrolytic aluminum. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing desilicationized coal gangue for electrolytic aluminum, so as to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] One of the technical solutions of the present invention: a method for preparing desilicationized coal gangue for electrolytic aluminum, comprising the following steps:

[0007] Coal gangue, γ-Al2O3, and α-Al2O3 are mixed to obtain a mixed powder; the mixed powder is calcined to obtain calcined coal gangue; the calcined coal gangue is mixed with alkali, an interface modifier, and water, heated to react, and then filtered, washed, and dried to obtain the desilicationized coal gangue for electrolytic aluminum.

[0008] Alkali extraction is currently the most commonly used method for desilication of coal gangue. It first requires high-temperature roasting of the coal gangue (to activate the coal gangue through roasting). Roasting causes the Al2O3 in the coal gangue structure to undergo a crystal transformation process from amorphous Al2O3 to γ-Al2O3 to α-Al2O3, generating inert α-Al2O3 to reduce the loss of Al2O3 in the subsequent alkali extraction process. On the other hand, high-temperature roasting transforms the crystalline SiO2 in the coal gangue structure into amorphous SiO2, promoting the removal of SiO2 species in the subsequent alkali extraction process. However, existing alkaline extraction methods have the following problems: 1) Due to the lack of crystal transformation guiding materials, there is a large crystal transformation energy barrier during roasting. The Al2O3 species in the coal gangue structure cannot fully achieve the crystal transformation process from amorphous Al2O3 to γ-Al2O3 to α-Al2O3, which limits the formation of inert α-Al2O3, thus failing to effectively avoid the loss of Al2O3 caused by subsequent alkaline extraction; 2) The high-temperature roasting process removes the surface hydroxyl groups of SiO2 species in the coal gangue structure. Simultaneously, a certain amount of residual carbon remains on the coal gangue surface. These two factors result in a certain degree of hydrophobicity on the roasted coal gangue surface, which affects the contact reaction between the coal gangue and water-soluble alkali, thus hindering the alkaline extraction desilication process. These two problems make it difficult for existing alkaline extraction methods to achieve efficient coal gangue desilication, thus failing to obtain the ideal high aluminum-silicon ratio (Al2O3 / SiO2>3). To address the aforementioned problems, this invention proposes two measures: 1) Introducing solid-phase crystallizing agents (γ-Al2O3 and α-Al2O3) into the roasting system. These solid-phase crystallizing agents, γ-Al2O3 and α-Al2O3, acting as seed crystals, can significantly reduce the crystallization barrier of Al2O3 species in the coal gangue structure through synergistic crystal phase guiding effects, promoting the crystal transformation process of Al2O3 species from amorphous Al2O3 → γ-Al2O3 → α-Al2O3; 2) Introducing an interface regulator (specifically a cationic surfactant) into the alkaline extraction reaction system to improve the contact performance between the hydrophobic roasted coal gangue and the alkaline solution, promoting the extraction and desilication process of the coal gangue by the alkaline solution. Through the above measures, the method of the present invention can significantly improve the aluminum-silicon ratio of desilication coal gangue compared with the existing alkaline extraction method, thereby fully meeting the requirements of the electrolytic aluminum process for the aluminum-silicon ratio of raw materials. This will help to realize the replacement of bauxite with solid waste coal gangue for electrolytic aluminum, significantly reduce the current production cost of the electrolytic aluminum industry, and realize the resource reuse of solid waste coal gangue.

[0009] Furthermore, the crystallinity of the γ-Al2O3 is ≥90%.

[0010] Furthermore, the crystallinity of the α-Al2O3 is ≥90%.

[0011] Furthermore, the mass ratio of the coal gangue (dry basis), γ-Al2O3 and α-Al2O3 is 1:0.005~0.015:0.01~0.03.

[0012] Optionally, after mixing coal gangue, γ-Al2O3 and α-Al2O3, the mixture may also include a grinding step.

[0013] Furthermore, the calcination temperature is 900~1100 ℃, and the time is 10~120 min.

[0014] Furthermore, the alkali is at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0015] Furthermore, the interface modifier is a quaternary ammonium salt type cationic surfactant.

[0016] The desilication system is a strongly alkaline system. Quaternary ammonium salt cationic surfactants can exist stably in a strongly alkaline system and play an interfacial regulation role.

[0017] Preferably, the quaternary ammonium salt cationic surfactant is at least one selected from hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, and dodecyltrimethylammonium chloride.

[0018] More preferably, the quaternary ammonium salt cationic surfactant is hexadecyltrimethylammonium bromide.

[0019] Furthermore, the mass ratio of the roasted coal gangue, alkali, interface modifier and water is 1:0.1~1:0.001~0.01:4~8.

[0020] Furthermore, the heating reaction is carried out at a temperature of 80-95 °C for a duration of 1-3 h.

[0021] Preferably, the heating reaction is carried out under stirring conditions.

[0022] Furthermore, the desilicationized coal gangue used for electrolytic aluminum has an aluminum-to-silicon ratio >3, and can be used as an alumina source in the electrolytic aluminum process.

[0023] Furthermore, the filtrate obtained after filtration is a sodium silicate solution, which can be used for the synthesis of zeolite molecular sieves or silica, wet desulfurization of flue gas, and as a finished product for sale.

[0024] The present invention discloses the following technical effects:

[0025] Compared with existing alkaline extraction methods, the method of this invention can significantly increase the aluminum-silicon ratio of desilicationed solid waste coal gangue, thereby meeting the requirements of the electrolytic aluminum process for the aluminum-silicon ratio of raw materials. This will help to replace bauxite with solid waste coal gangue in electrolytic aluminum production, significantly reducing the current production costs of the electrolytic aluminum industry, while simultaneously realizing the resource utilization of solid waste coal gangue. Furthermore, the method of this invention is simple, low-cost, and has good application prospects. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The image shows the XRD pattern of the roasted coal gangue prepared in Example 1.

[0028] Figure 2 The image shows the XRD pattern of the roasted coal gangue prepared in Comparative Example 1.

[0029] Figure 3 The image shows the XRD pattern of the roasted coal gangue prepared in Comparative Example 6. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0036] In the following embodiments and comparative examples of the present invention, room temperature refers specifically to 20~30 ℃.

[0037] Unless otherwise specified, all raw materials used in the following examples and comparative examples of this invention are commercially available products. Among them, coal gangue (aluminum-silicon ratio of 0.72) and aluminum ash are industrial grade; γ-Al2O3 (98% crystallinity), α-Al2O3 (98% crystallinity), sodium hydroxide and hexadecyltrimethylammonium bromide (CTAB) are analytical grade reagents.

[0038] The analytical and testing methods involved in the following embodiments, comparative examples, and test examples of this invention are as follows:

[0039] The phase composition of the sample was analyzed and tested using a D / max-2200 PC X-ray diffractometer.

[0040] The aluminum-silicon ratio of the samples was analyzed using a ZSX Primus XRF spectrometer.

[0041] Example 1

[0042] A method for preparing desilicationized coal gangue for electrolytic aluminum production, comprising the following steps:

[0043] (1) Mix and grind 100 g of coal gangue (dry basis), 0.5 g of γ-Al2O3 and 1 g of α-Al2O3 to obtain a mixed powder;

[0044] (2) The mixed powder obtained in step (1) is roasted (900 °C, 120 min) to obtain roasted coal gangue;

[0045] (3) Mix 50 g of roasted coal gangue obtained in step (2), 5 g of sodium hydroxide, 0.5 g of CTAB and 200 g of water, stir and react at 80 °C for 3 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue C1 for electrolytic aluminum.

[0046] Example 2

[0047] A method for preparing desilicationized coal gangue for electrolytic aluminum production, comprising the following steps:

[0048] (1) Mix and grind 100 g of coal gangue (dry basis), 0.7 g of γ-Al2O3 and 1.5 g of α-Al2O3 to obtain a mixed powder;

[0049] (2) The mixed powder obtained in step (1) is roasted (950 °C, 100 min) to obtain roasted coal gangue;

[0050] (3) Mix 50 g of roasted coal gangue obtained in step (2), 15 g of sodium hydroxide, 0.35 g of CTAB and 250 g of water, stir and react at 84 °C for 2.5 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue C2 for electrolytic aluminum.

[0051] Example 3

[0052] A method for preparing desilicationized coal gangue for electrolytic aluminum production, comprising the following steps:

[0053] (1) Mix and grind 100 g of coal gangue (dry basis), 1 g of γ-Al2O3 and 2 g of α-Al2O3 to obtain a mixed powder;

[0054] (2) The mixed powder obtained in step (1) is roasted (1000℃, 70 min) to obtain roasted coal gangue;

[0055] (3) Mix 50 g of roasted coal gangue obtained in step (2), 25 g of sodium hydroxide, 0.25 g of CTAB and 300 g of water, stir and react at 88 °C for 2 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue C3 for electrolytic aluminum.

[0056] Example 4

[0057] A method for preparing desilicationized coal gangue for electrolytic aluminum production, comprising the following steps:

[0058] (1) Mix and grind 100 g of coal gangue (dry basis), 1.3 g of γ-Al2O3 and 2.5 g of α-Al2O3 to obtain a mixed powder;

[0059] (2) The mixed powder obtained in step (1) is roasted (1050 °C, 40 min) to obtain roasted coal gangue;

[0060] (3) Mix 50 g of roasted coal gangue obtained in step (2), 35 g of sodium hydroxide, 0.15 g of CTAB and 350 g of water, stir and react at 92 °C for 1.5 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue C4 for electrolytic aluminum.

[0061] Example 5

[0062] A method for preparing desilicationized coal gangue for electrolytic aluminum production, comprising the following steps:

[0063] (1) Mix and grind 100 g of coal gangue (dry basis), 1.5 g of γ-Al2O3 and 3 g of α-Al2O3 to obtain a mixed powder;

[0064] (2) The mixed powder obtained in step (1) is roasted (1100 °C, 10 min) to obtain roasted coal gangue;

[0065] (3) Mix 50 g of roasted coal gangue obtained in step (2), 50 g of sodium hydroxide, 0.05 g of CTAB and 400 g of water, stir and react at 95 °C for 1 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue C5 for electrolytic aluminum.

[0066] Comparative Example 1

[0067] A method for preparing desilicationized coal gangue, comprising the following steps:

[0068] (1) Grind 100 g of coal gangue (dry basis) and then roast it (900 ℃, 120 min) to obtain roasted coal gangue;

[0069] (2) Mix 50 g of roasted coal gangue obtained in step (1), 5 g of sodium hydroxide and 200 g of water, stir and react at 80°C for 3 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue D1.

[0070] Comparative Example 2

[0071] A method for preparing desilicationized coal gangue, comprising the following steps:

[0072] (1) Grind 100 g of coal gangue (dry basis) and then roast it (1000 ℃, 70 min) to obtain roasted coal gangue;

[0073] (2) Mix 50 g of roasted coal gangue obtained in step (1), 25 g of sodium hydroxide and 300 g of water, stir and react at 88 °C for 2 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue D2.

[0074] Comparative Example 3

[0075] A method for preparing desilicationized coal gangue, comprising the following steps:

[0076] (1) Grind 100 g of coal gangue (dry basis) and then roast it (1100 ℃, 10 min) to obtain roasted coal gangue;

[0077] (2) Mix 50 g of roasted coal gangue obtained in step (1), 50 g of sodium hydroxide and 400 g of water, stir and react at 95 °C for 1 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue D3.

[0078] Comparative Example 4

[0079] A method for preparing desilicationized coal gangue, comprising the following steps:

[0080] (1) Mix and grind 100 g of coal gangue (dry basis), 0.7 g of γ-Al2O3 and 1.5 g of α-Al2O3 to obtain a mixed powder;

[0081] (2) The mixed powder obtained in step (1) is roasted (950 °C, 100 min) to obtain roasted coal gangue;

[0082] (3) Mix 50 g of roasted coal gangue obtained in step (2), 15 g of sodium hydroxide and 250 g of water, stir and react at 84 °C for 2.5 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue D4.

[0083] Comparative Example 5

[0084] A method for preparing desilicationized coal gangue, comprising the following steps:

[0085] (1) Grind 100 g of coal gangue (dry basis) and then roast it (1050 ℃, 40 min) to obtain roasted coal gangue;

[0086] (2) Mix 50 g of roasted coal gangue obtained in step (1), 35 g of sodium hydroxide, 0.15 g of CTAB and 350 g of water, stir and react at 92 °C for 1.5 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue D5.

[0087] Comparative Example 6

[0088] A method for preparing desilicationized coal gangue (referring to the method disclosed in patent CN112390264B) includes the following steps:

[0089] (1) Mix coal gangue and aluminum ash at a mass ratio of aluminum ash to coal gangue (dry basis) of 1:100 to obtain a mixture.

[0090] (2) The mixture was roasted at 1050 °C for 40 min to obtain roasted coal gangue;

[0091] (3) The roasted coal gangue was desiliconized under the conditions of sodium hydroxide concentration of 90 g / L, solid-liquid ratio of 350 g / L, desiliconization temperature of 85℃ and desiliconization time of 60 min. Then it was filtered, washed and dried to obtain filtrate and desiliconized coal gangue D6.

[0092] Comparative Example 7

[0093] A method for preparing desilicationized coal gangue, comprising the following steps:

[0094] (1) Mix and grind 100 g of coal gangue (dry basis) and 1.5 g of γ-Al2O3 to obtain a mixed powder;

[0095] (2) The mixed powder obtained in step (1) is roasted (900 °C, 120 min) to obtain roasted coal gangue;

[0096] (3) Mix 50 g of roasted coal gangue obtained in step (2), 5 g of sodium hydroxide, 0.5 g of CTAB and 200 g of water, stir and react at 80 °C for 3 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue D7.

[0097] Comparative Example 8

[0098] A method for preparing desilicationized coal gangue, comprising the following steps:

[0099] (1) Mix and grind 100 g of coal gangue (dry basis) and 1.5 g of α-Al2O3 to obtain a mixed powder;

[0100] (2) The mixed powder obtained in step (1) is roasted (900 °C, 120 min) to obtain roasted coal gangue;

[0101] (3) Mix 50 g of roasted coal gangue obtained in step (2), 5 g of sodium hydroxide, 0.5 g of CTAB and 200 g of water, stir and react at 80 °C for 3 h, then filter, wash and dry to obtain filtrate and desilicationized coal gangue D8.

[0102] Test Example 1

[0103] Phase analysis:

[0104] Figure 1 The image shows the XRD pattern of the roasted coal gangue prepared in Example 1.

[0105] Figure 2 The image shows the XRD pattern of the roasted coal gangue prepared in Comparative Example 1.

[0106] Figure 3 The image shows the XRD pattern of the roasted coal gangue prepared in Comparative Example 6.

[0107] Depend on Figures 1-3 It can be seen that the roasted coal gangue samples prepared in Examples 1, 1, and 6 all exhibit characteristic diffraction peaks belonging to α-Al2O3 crystals, indicating that the alumina species in the coal gangue structure underwent a crystal transformation process during the roasting and activation process, generating inert α-Al2O3. Compared with Comparative Examples 1 and 6, the peak intensity of the characteristic diffraction peak of α-Al2O3 crystals in the roasted coal gangue sample prepared in Example 1 of this invention is much higher than that of the former two, indicating that the use of crystal guides γ-Al2O3 and α-Al2O3 in the method of this invention greatly promotes the crystal transformation process of alumina species in the coal gangue structure, significantly generating more inert α-Al2O3 crystal phase, thereby significantly reducing the loss of alumina during the subsequent alkaline desilication process.

[0108] Test Example 2

[0109] Aluminum-to-silicon ratio test:

[0110] The aluminum-silicon ratio of the desilicationized coal gangue finally obtained in each embodiment and comparative example was tested, and the results are shown in Table 1.

[0111] Table 1. Aluminum-to-silicon ratio of desilicationized coal gangue prepared in each embodiment and comparative example.

[0112]

[0113] As shown in Table 1, compared with the desilication coal gangue samples (D1~D3) prepared by the existing alkaline extraction method, the desilication coal gangue samples (C1~C5) prepared by the method of the present invention have significantly higher aluminum-silicon ratios, all exceeding 3, which fully meets the requirements of the electrolytic aluminum process for the aluminum-silicon ratio of raw materials. Compared with the samples obtained by using only the crystal guide agent (D4) and only the interface modifier (D5), the desilication coal gangue samples (C1~C5) prepared by the method of the present invention have significantly higher aluminum-silicon ratios, indicating that there is a significant "synergistic effect" between the crystal guide agent and the interface modifier in the method of the present invention. Simultaneous use is necessary to achieve the best desilication effect. In addition, a patent (CN112390264B) reported that introducing "aluminum ash" during the alkaline extraction and desilication process of coal gangue can increase the aluminum-silicon ratio of desilicationized coal gangue. Therefore, "aluminum ash" was used instead of the crystal guiding agent in the method of this invention to prepare a comparative sample (D6) of desilicationized coal gangue using the method disclosed in the patent (CN112390264B). It can be seen that compared with sample D6, the aluminum-silicon ratio of the desilicationized coal gangue samples (C1~C5) prepared by the method of this invention is significantly higher, indicating that the method of this invention has a more superior desilication effect on coal gangue. Furthermore, the aluminum-silicon ratio of desilication coal gangue sample D7, prepared using crystal guide agent γ-Al2O3 alone, and desilication coal gangue sample D8, prepared using crystal guide agent α-Al2O3 alone, was significantly lower than that of the desilication coal gangue samples (C1~C5) prepared by the method of the present invention. This indicates that there is a significant synergistic effect between crystal guide agents γ-Al2O3 and α-Al2O3 in the method of the present invention, and only by using them simultaneously can the best desilication and aluminum retention effect be achieved.

[0114] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for the preparation of desiliconized coal gangue for electrolytic aluminum production, characterized by, The method comprises the following steps: The coal gangue, gamma-Al2O3 and alpha-Al2O3 are mixed to obtain a mixed powder; the mixed powder is calcined to obtain calcined coal gangue; the calcined coal gangue is mixed with alkali, an interface regulator and water, heated and reacted, and then filtered, washed and dried to obtain the desiliconized coal gangue for electrolytic aluminum; The interface regulator is a quaternary ammonium salt type cationic surfactant.

2. The method for preparing desilicationized coal gangue for electrolytic aluminum as described in claim 1, characterized in that, The crystallinity of the gamma-Al2O3 is greater than or equal to 90%.

3. The method for preparing desilicationized coal gangue for electrolytic aluminum as described in claim 1, characterized in that, The crystallinity of the alpha-Al2O3 is greater than or equal to 90%.

4. The method for preparing desilicationized coal gangue for electrolytic aluminum as described in claim 1, characterized in that, The mass ratio of the coal gangue, gamma-Al2O3 and alpha-Al2O3 is 1:0.005-0.015:0.01-0.

03.

5. The method for preparing desilicationized coal gangue for electrolytic aluminum as described in claim 1, characterized in that, The calcination temperature is 900-1100 DEG C, and the time is 10-120 min.

6. The method for preparing desilicationized coal gangue for electrolytic aluminum as described in claim 1, characterized in that, The alkali is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.

7. The method for preparing desilicationized coal gangue for electrolytic aluminum as described in claim 1, characterized in that, The quaternary ammonium salt type cationic surfactant is at least one of cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, cetyltrimethylammonium chloride, tetradecyltrimethylammonium chloride and dodecyltrimethylammonium chloride.

8. The method for preparing desilicationized coal gangue for electrolytic aluminum as described in claim 1, characterized in that, The mass ratio of the calcined coal gangue, alkali, interface regulator and water is 1:0.1-1:0.001-0.01:4-8.

9. The method for preparing desilicationized coal gangue for electrolytic aluminum as described in claim 1, characterized in that, The heating reaction temperature is 80-95 DEG C, and the time is 1-3 h.

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