High-alumina-silica-ratio material capable of replacing bauxite as well as preparation method and application of high-alumina-silica-ratio material

Abstract

The invention belongs to the technical field of desiliconized fly ash, and particularly relates to a high-alumina-silica-ratio material capable of replacing bauxite as well as a preparation method and application of the high-alumina-silica-ratio material. The preparation method comprises the following steps: S1, crushing coal gangue, and grinding the crushed coal gangue until the particle size is less than 40 meshes to obtain a ground material; s2, mixing the ground material and a catalyst according to a weight ratio of 100: (1-2), roasting, and cooling to obtain activated coal gangue; the catalyst comprises sodium carbonate, calcium oxide and aluminum oxide in a weight ratio of 1: (0.3-0.5): (1.4-1.6); s3, mixing a sodium hydroxide solution, the activated coal gangue and a surfactant, and reacting at 50-90 DEG C for 1-6 hours to obtain desiliconized slurry; and S4, filtering the desiliconized slurry, collecting a solid phase, washing with water, and drying to obtain desiliconized fly ash, namely the high alumina-silica ratio material capable of replacing bauxite. The method is high in desiliconization rate.

Description

Technical Field

[0001] The invention belongs to the technical field of desiliconized fly ash, and in particular relates to a high aluminum-silicon ratio material capable of replacing bauxite, and a preparation method and application thereof. Background Art

[0002] With the development of my country's aluminum industry, large-scale mining of bauxite resources has led to serious waste of bauxite resources in my country. In order to effectively solve the resource problem, the development of low-grade bauxite and the utilization of high-aluminum coal gangue and fly ash have become more and more urgent.

[0003] At present, the main problem in the process of preparing alumina with high-aluminum coal gangue and other minerals instead of bauxite is the low aluminum-silicon ratio. The existing technical solution is to select high-aluminum coal gangue or fly ash for activation and desiliconization to increase the aluminum-silicon ratio. The aluminum-silicon ratio of high-aluminum coal gangue and other minerals after activation and desiliconization is generally 2-4. The cost of using such raw materials to prepare alumina by the Bayer process is relatively high, and the sintering method for preparing alumina has disadvantages such as large amount of red mud and high energy consumption.

[0004] The existing technical solution is to first select low-grade bauxite (A / S=2.5-3.5) and then select bauxite through a series of treatment methods, such as homogenization and crushing-mineral monomer dissociation-fine ore particle preselection-microbubble flotation-selection pulp desliming-concentrate pulp secondary dehydration-tailings pulp secondary dehydration, to increase the aluminum-silicon ratio to 6-9.5 at most. However, the above solution not only has a long process, high cost, and high equipment cost, but also the tailings (A / S=0.9-1.2) cannot be well utilized. The coal gangue currently selected has a low aluminum-silicon ratio, and the aluminum-silicon ratio increases little after desiliconization, which is not suitable as a raw material for preparing alumina by Bayer process dissolution; and the use of low-grade bauxite requires further selection of concentrates to improve the aluminum-silicon ratio, but the process is long, the cost is high, the equipment cost is high, and the tailings (A / S=0.9-1.2) cannot be well utilized.

[0005] Gangue is a kind of waste residue produced during coal mining, mainly composed of minerals in coal seams. Its composition and aluminum-silicon ratio vary depending on the mining area, coal seam type and geological conditions. There are a large number of gangues on the market with an aluminum-silicon ratio of about 1.1 to 1.2 and containing kaolinite and boehmite. They are mainly distributed in Shanxi, Shaanxi, and Inner Mongolia in China, especially in some mining areas in Shanxi. Due to the special geological conditions, gangue contains a higher proportion of kaolinite and boehmite.

[0006] Therefore, there is an urgent need for a high aluminum-silicon ratio material that can replace bauxite, and a preparation method and application thereof. Summary of the invention

[0007] The purpose of the present invention is to provide a high aluminum-silicon ratio material that can replace bauxite, and a preparation method and application thereof.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A preparation method of a high-aluminum-silicon ratio material that can replace bauxite, comprising the following steps:

[0010] S1. Crush and grind coal gangue to a particle size less than 40 mesh to obtain the ground material;

[0011] S2. Mix the ground material and a catalyst in a weight ratio of 100:(1 - 2), then carry out roasting and cooling to obtain activated coal gangue;

[0012] S3. Mix sodium hydroxide solution, activated coal gangue and a surfactant, and react at 50 - 90 °C for 1 - 6 h to obtain a desilication slurry;

[0013] S4. Filter the desilication slurry, collect the liquid phase, which can be used as a raw material for preparing high-modulus water glass; collect the solid phase, wash it with water, and then dry it to obtain desilicated fly ash, which is the high-aluminum-silicon ratio material that can replace bauxite.

[0014] Further, in the step S1, the original ore aluminum-silicon ratio of the coal gangue is 1.1 - 1.2, and the coal gangue includes kaolinite and boehmite.

[0015] Further, the roasting conditions in the step S2 are: first heat up at a heating rate of 10 - 15 °C / h to 800 - 900 °C and roast for 1 - 2 h, then heat up at a heating rate of 10 - 15 °C / h to 950 - 1050 °C and roast for 2 - 3 h, and finally heat up at a heating rate of 20 - 25 °C / h to 1100 - 1150 °C and roast for 1 - 2 h, and then cool naturally to room temperature.

[0016] There is a part of coal gangue on the market that includes kaolinite phase and boehmite phase, and its original ore aluminum-silicon ratio is 1.1 - 1.2. The existence of the boehmite phase is one of the reasons for the high aluminum content in the coal gangue. In the prior art, the desilication effect of this kind of coal gangue is not ideal, so that this part of the coal gangue cannot be well utilized. The present invention can improve the desilication rate of coal gangue of the type including kaolinite phase and boehmite phase and with an original ore aluminum-silicon ratio of 1.1 - 1.2 by means of gradient roasting. From Figure 1 and 2 it can be seen that through the roasting method of the present invention, the kaolinite phase and boehmite phase after roasting can be maximally disappeared, forming mullite phase, alumina phase and a small amount of anatase, and at the same time, it can be seen that a bread-like peak of amorphous silicon is formed. The reasonable gradient activation temperature and time make the amorphous silica not transform into quartz phase, which also lays a foundation for the subsequent desilication process.

[0017] The catalyst includes sodium carbonate, calcium oxide and aluminum oxide in a weight ratio of 1:(0.3 - 0.5):(1.4 - 1.6).

[0018] The content of silicon dioxide in the liquid phase is a direct indicator for measuring the efficiency of the desilication process. A high content of silicon dioxide indicates that more silicon has been successfully leached into the solution, suggesting that the desilication process is relatively effective. In the present invention, the desilication rate of coal gangue can be improved by adding a catalyst with a specific composition ratio to the ground material. The analysis is that by adjusting the type and dosage of the catalyst, a synergistic effect can be achieved with the specific calcination temperature and time of the present invention. During the calcination process, the catalyst helps to promote the destruction or recrystallization of these mineral structures, thereby increasing the activity of silicon and aluminum and improving the desilication rate. In the absence of a catalyst, impurities in the coal gangue may compete with silicates for adsorption sites, resulting in some silicon being adsorbed by these impurities and unable to dissolve better. The presence of the catalyst can change the surface properties of the minerals and reduce the adsorption capacity of the impurities for silicon. The catalyst can selectively promote the dissolution of silicates while inhibiting the dissolution or adsorption of other impurities.

[0019] Further, in the step S3, the concentration of the sodium hydroxide solution is 100 - 260 g / L.

[0020] Further, in the step S3, the weight ratio of the sodium hydroxide solution, the activated coal gangue, and the surfactant is (4 - 8):1:(0.10 - 0.14).

[0021] Further, the surfactant includes sodium dodecylbenzenesulfonate, polyvinyl alcohol, and coconut oil amide propyl betaine with a weight ratio of 1:(0.2 - 0.4):(1.3 - 1.5).

[0022] In the experiment, it was found that adding a surfactant with a specific ratio to the sodium hydroxide solution after gradient calcination of the present invention can improve the batch stability of the preparation method. The analysis is that the gradient calcination of the present invention will endow the coal gangue with a certain structure. Through the method of gradually heating, the mineral structure in the coal gangue is gradually destroyed, making it more porous and loose. This structural change provides more reaction sites for subsequent alkali leaching. Based on this optimized mineral structure, the specific surfactant of the present invention can play a better role. Since the mineral structure becomes more open, the surfactant can more effectively cover and wet these structures, further promoting the penetration and reaction of the alkali solution. The surfactant can reduce the surface tension of the liquid, making it easier for the sodium hydroxide solution to wet and activate the surface of the coal gangue particles. Good wettability ensures that the alkali solution can uniformly cover the coal gangue particles, thereby improving the dissolution efficiency of silicate. At the same time, the surfactant can maintain its functional characteristics within a wide temperature range, reducing batch differences caused by temperature fluctuations. The surfactant can form a thin film on the surface of the coal gangue particles. This film not only reduces the surface tension but also increases the contact area between the alkali solution and the coal gangue particles, promoting the occurrence of interfacial reactions. Gradient calcination ensures the stability of the results of each calcination by precisely controlling the temperature and time at each stage. The surfactant standardizes its addition amount and type. The combination of the two can significantly reduce batch differences caused by fluctuations in operating conditions. Gradient calcination provides a stable mineral structure basis, while the surfactant ensures the uniform distribution and efficient reaction of the alkali solution on this structure. The two work together to ensure that the reaction environment in each experiment is as consistent as possible, thereby improving the batch stability.

[0023] Further, the number of solid-phase water washing times in step S4 is 1 - 5 times.

[0024] Further, in step S4, the solid phase is washed with 1 - 5 times the weight of water.

[0025] The second aspect of the present invention provides a high-aluminum-silicon ratio material that can replace bauxite prepared by the above preparation method.

[0026] The third aspect of the present invention provides the application of the high-aluminum-silicon ratio material that can replace bauxite in the preparation of alumina.

[0027] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0028] 1. The coal gangue selected in the present invention is high-quality coal gangue, with a high aluminum content and aluminum-silicon ratio in the raw ore. The aluminum-silicon ratio of the raw ore is 1.16, and the aluminum-silicon ratio reaches 1.4 - 1.5 after roasting and activation. After one-step desilication, the aluminum-silicon ratio can reach 5 - 7.

[0029] 2. By means of gradient calcination, the present invention can improve the desilication rate of gangue containing kaolinite phase and boehmite and with an original ore aluminum-silicon ratio of 1.1 - 1.2.

[0030] 3. By adding a catalyst with a specific composition ratio to the ground material, the present invention can improve the desilication rate of gangue and the content of sodium silicate in the liquid phase.

[0031] 4. By adding a surfactant with a specific composition ratio to the sodium hydroxide solution and activated gangue, the present invention can improve the batch stability of the preparation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the phase diagram of gangue before calcination.

[0033] Figure 2 It is the phase diagram of gangue after calcination. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0035] Example 1

[0036] This example provides a preparation method of a high aluminum-silicon ratio material that can replace bauxite, including the following steps:

[0037] S1. Crush and grind gangue to a particle size less than 40 mesh to obtain the ground material;

[0038] S2. Mix the ground material and the catalyst with a weight ratio of 100:1.5 and then conduct calcination and cooling to obtain activated gangue; the catalyst includes sodium carbonate, calcium oxide, and aluminum oxide with a weight ratio of 1:0.4:1.5;

[0039] The conditions for calcination are: first, heat up at a heating rate of 12 °C / h to 840 °C and calcine for 1.5 h, then heat up at a heating rate of 12 °C / h to 1000 °C and calcine for 2.5 h, and finally heat up at a heating rate of 22 °C / h to 1120 °C and calcine for 1.5 h, and then cool naturally to room temperature.

[0040] S3. Mix the sodium hydroxide solution with a concentration of 200 g / L, activated gangue, and surfactant with a weight ratio of 6:1:0.12 and react at 60 °C for 3 h to obtain a desilication slurry; the surfactant includes sodium dodecylbenzenesulfonate, polyvinyl alcohol, and cocoamidopropyl betaine with a weight ratio of 1:0.3:1.4.

[0041] S4. Filter the desilication slurry, collect the liquid phase, which can be used as the raw material for preparing high-modulus water glass; collect the solid phase, wash the solid phase twice with 3 times its weight of water, and dry it to obtain desilicated fly ash, which is a high-aluminum-silicon ratio material that can replace bauxite.

[0042] Example 2

[0043] This example provides a preparation method of a high-aluminum-silicon ratio material that can replace bauxite, including the following steps:

[0044] S1. Crush and grind the coal gangue to a particle size less than 40 mesh to obtain the ground material;

[0045] S2. Mix the ground material and the catalyst in a weight ratio of 100:2, then carry out roasting and cooling to obtain activated coal gangue; the catalyst includes sodium carbonate, calcium oxide, and aluminum oxide in a weight ratio of 1:0.3:1.4;

[0046] The roasting conditions are as follows: first, heat up to 900 °C at a heating rate of 10 °C / h and roast for 2 h, then heat up to 1050 °C at a heating rate of 10 °C / h and roast for 2 h, and finally heat up to 1100 °C at a heating rate of 25 °C / h and roast for 2 h, and then cool naturally to room temperature.

[0047] S3. Mix the sodium hydroxide solution with a concentration of 260 g / L, the activated coal gangue, and the surfactant in a weight ratio of 8:1:0.10, and react at 50 °C for 6 h to obtain a desilication slurry; the surfactant includes sodium dodecylbenzene sulfonate, polyvinyl alcohol, and cocamidopropyl betaine in a weight ratio of 1:0.2:1.5.

[0048] S4. Filter the desilication slurry, collect the liquid phase, which can be used as the raw material for preparing high-modulus water glass; collect the solid phase, wash the solid phase three times with 5 times its weight of water, and dry it to obtain desilicated fly ash, which is a high-aluminum-silicon ratio material that can replace bauxite.

[0049] Comparative Example 1

[0050] The difference between this comparative example and Example 1 is: S2. Roast the ground material and cool it to obtain activated coal gangue.

[0051] Comparative Example 2

[0052] The difference between this comparative example and Example 1 is: the catalyst includes sodium carbonate, calcium oxide, and aluminum oxide in a weight ratio of 1:1:1.

[0053] Comparative Example 3

[0054] The difference between this comparative example and Example 1 is as follows: The method of Example 1 in Chinese Patent 202011249899.2, a method for improving the desilication rate of coal gangue by aluminum ash catalysis, was used.

[0055] Comparative Example 4

[0056] The difference between this comparative example and Example 1 is as follows: The roasting conditions were as follows: heating up to 1100 °C at a heating rate of 15 °C / h, roasting for 5.2 h, and then naturally cooling to room temperature.

[0057] Comparative Example 5

[0058] The difference between this comparative example and Example 1 is as follows: The roasting conditions were as follows: first heating up to 980 °C at a heating rate of 22 °C / h and roasting for 1.4 h, then heating up to 1060 °C at a heating rate of 22 °C / h and roasting for 1.4 h, and finally heating up to 1250 °C at a heating rate of 12 °C / h and roasting for 2.4 h, and then naturally cooling to room temperature.

[0059] Comparative Example 6

[0060] The difference between this comparative example and Example 1 is as follows: A sodium hydroxide solution with a concentration of 200 g / L and activated coal gangue with a weight ratio of 6:1 were mixed and reacted at 60 °C for 3 h to obtain a desilication slurry.

[0061] Comparative Example 7

[0062] The difference between this comparative example and Example 1 is as follows: The surfactant includes sodium dodecylbenzenesulfonate, polyvinyl alcohol, and cocoamidopropyl betaine with a weight ratio of 1:1:1.

[0063] Performance Test

[0064] High-aluminum-silica-ratio materials that can replace bauxite and solutions containing sodium silicate were prepared using the preparation methods of Examples 1-2 and Comparative Examples 1-7, respectively. The samples were coal gangue purchased from three different manufacturers in Inner Mongolia, namely Sample 1 (original ore aluminum-silica ratio of 1.15), Sample 2 (original ore aluminum-silica ratio of 1.1), and Sample 3 (original ore aluminum-silica ratio of 1.2). All three samples included kaolinite and boehmite.

[0065] The results are shown in Tables 1-2, where A / S is the aluminum-silica ratio, and the contents in the solid-phase composition table are all mass percentages.

[0066] Table 1 Solid-phase determination results

[0067]

[0068]

[0069] Table 2 Silicon dioxide content in the liquid phase

[0070]

[0071]

[0072] It can be seen from the results that the alumina-silica ratio after desilication in the solid phase in Examples 1-2 can reach 5-7, and the silicon content in the liquid phase is high.

[0073] In Comparative Example 1, no catalyst was added, and both the desilication rate of coal gangue and the content of sodium silicate in the liquid phase decreased.

[0074] In Comparative Example 2, the catalyst ratio was different, and both the desilication rate of coal gangue and the content of sodium silicate in the liquid phase decreased.

[0075] In Comparative Example 3, the method of the prior art was used for treatment, and both the desilication rate of coal gangue and the content of sodium silicate in the liquid phase decreased, indicating that the catalyst used in Comparative Example 3 had poor treatment effect on coal gangue with an original ore alumina-silica ratio of 1.1-1.2 and including kaolinite and boehmite.

[0076] In Comparative Examples 4 and 5, the calcination conditions were different, the desilication rate of coal gangue decreased, and the alumina-silica ratio decreased.

[0077] In Comparative Example 6, no surfactant was added, and the batch stability decreased.

[0078] In Comparative Example 7, the surfactant ratio was different, and the batch stability decreased, indicating that only by using the surfactant with the ratio of the present invention can the stability effect of desilication be maintained.

[0079] The above are the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a high aluminum-silicon ratio material that can replace bauxite, characterized in that: The following steps are involved: S1. Crushing and grinding the coal gangue to a particle size less than 40 meshes to obtain a ground material; S2, mixing the ground material and the catalyst in a weight ratio of 100:(1-2), roasting, cooling, and obtaining activated coal gangue; the catalyst comprises sodium carbonate, calcium oxide, and aluminum oxide in a weight ratio of 1:(0.3-0.5):(1.4-1.6); S3, mixing sodium hydroxide solution, activated coal gangue and surfactant, reacting at 50-90° C. for 1-6 hours to obtain a desiliconized slurry; S4. Filter the desiliconized slurry and collect the liquid phase; collect the solid phase, wash it with water, and dry it to obtain desiliconized fly ash, which is a high aluminum-silicon ratio material that can replace bauxite.

2. The method for preparing a high aluminum-silicon ratio material that can replace bauxite according to claim 1, characterized in that: In the step S1, the original aluminum-silicon ratio of the coal gangue is 1.1-1.2, and the coal gangue includes kaolinite and boehmite.

3. The method for preparing a high aluminum-silicon ratio material that can replace bauxite according to claim 1, characterized in that: The calcination conditions in step S2 are: firstly, heating to 800-900°C at a heating rate of 10-15°C / h and calcining for 1-2h, then heating to 950-1050°C at a heating rate of 10-15°C / h and calcining for 2-3h, and finally heating to 1100-1150°C at a heating rate of 20-25°C / h and calcining for 1-2h, and then naturally cooling to room temperature.

4. The method for preparing a high aluminum-silicon ratio material that can replace bauxite according to claim 1, characterized in that: The concentration of the sodium hydroxide solution in step S3 is 100-260 g / L.

5. The method for preparing a high aluminum-silicon ratio material capable of replacing bauxite according to claim 1, characterized in that: In step S3, the weight ratio of the sodium hydroxide solution, activated coal gangue and surfactant is (4-8):1:(0.10-0.14).

6. The method for preparing a high aluminum-silicon ratio material capable of replacing bauxite according to claim 5, characterized in that: The surfactant comprises sodium dodecylbenzene sulfonate, polyvinyl alcohol and cocamidopropyl betaine in a weight ratio of 1: (0.2-0.4): (1.3-1.5).

7. The method for preparing a high aluminum-silicon ratio material capable of replacing bauxite according to claim 1, characterized in that: The solid phase is washed with water 1 to 5 times in step S4.

8. The method for preparing a high aluminum-silicon ratio material capable of replacing bauxite according to claim 1, characterized in that: In the step S4, the solid phase is washed with 1-5 times the weight of water.

9. A high aluminum-silicon ratio material that can replace bauxite and is obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the high aluminum-silicon ratio material capable of replacing bauxite as claimed in claim 9 in the preparation of alumina.

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