Process for the preparation of aluminate binders

Abstract

The present application belongs to the technical field of aluminate binder production, and particularly relates to a preparation method of aluminate binder. Main raw materials of aluminum hydroxide, calcium chloride, calcium oxide and aluminum oxide are used, accurate and fine batching is carried out according to the corresponding chemical composition of the mineral phase composition, and wet grinding is carried out by using a ceramic grinding process, so that the super-micro powder raw material with extremely high fineness and extremely high homogenization degree can be obtained. After the powder is subjected to pressure filtration separation, the powder is subjected to drying treatment, and then the automatic forming equipment is used to press the raw material blank into the tunnel kiln for calcination. After the calcined blank is crushed and ground, the aluminate binder is finally prepared.

Description

Technical Field

[0001] This invention belongs to the field of aluminate binder production technology, specifically relating to a method for preparing aluminate binders. Background Technology

[0002] Aluminate binders are important inorganic materials with excellent physical and chemical properties, such as high melting point, good thermal stability, and excellent corrosion resistance. These properties make aluminate binders widely used in ceramics, glass, metallurgy, and other fields. However, traditional methods for preparing aluminate binders often have some problems, such as complex reaction processes, high energy consumption, and low product purity.

[0003] Patent application CN103922764B, published on August 19, 2015, discloses a binder for monolithic refractory materials and its preparation method. The binder for monolithic refractory materials comprises the following components by mass fraction: 30-70% alumina, 20-60% magnesium oxide, and 5-20% activator. The activator is a mixture of metasilicic acid, polycarboxylic acid, and elemental silicon, wherein the mass fraction of metasilicic acid in the activator mixture is 40-80%, the mass fraction of polycarboxylic acid is 0-40%, and the mass fraction of elemental silicon is 0-50%. However, this preparation method requires the addition of an additional activator, increasing the difficulty of preparation and production costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing aluminate binders. This method utilizes aluminum hydroxide, calcium chloride, calcium oxide, and aluminum oxide as main raw materials, with precise and refined batching according to the chemical composition corresponding to the mineral phases. Wet grinding using ceramic grinding technology yields ultrafine powder raw materials with extremely high fineness and homogenization. After pressure filtration and separation, the powder is dried and then pressed into raw material blanks using automated forming equipment, which are then calcined in a tunnel kiln. The calcined blanks are then crushed and ground to finally obtain the aluminate binder.

[0005] The technical solution adopted in this invention is:

[0006] The method for preparing the aluminate binder includes the following steps:

[0007] (1) Place fine aluminum hydroxide powder in a high-temperature furnace, heat it to 370-420℃, keep it at that temperature for 3-4 hours, then heat it to 1100-1200℃, keep it at that temperature for 3-4 hours, and then cool it down to obtain alumina powder with high porosity.

[0008] (2) Add the high porosity alumina powder obtained in step (1) to the calcium chloride solution, stir under vacuum for 15 minutes, then add calcium oxide powder and alumina powder, add water and wet grind for 15-30 minutes to obtain a mixture;

[0009] (3) The mixed slurry is filtered by pressure, the filtrate and filter cake are collected separately, and the filter cake is dried and pressed into a blank to obtain a blank;

[0010] (4) Dry the blank in step (3) at 50-80℃ for 3-5 hours, then put it into a muffle furnace for heating and firing at 1550-1600℃ for 3-5 hours. After cooling, crush it to obtain aluminate binder.

[0011] The heating rate in step (1) is 2-2.5℃ / hour and the cooling rate is 1-1.5℃ / hour.

[0012] The mass ratio of aluminum hydroxide, calcium chloride, calcium oxide and aluminum oxide is (3-4):(1-2):(2-3):(1-2).

[0013] The particle size of the mixture in step (2) is 0.045-0.065 mm.

[0014] During the vacuum stirring process in step (2), the pressure is 1 kPa.

[0015] The concentration of the calcium chloride solution in step (2) is 15-20 wt%.

[0016] In step (3) of the filter press process, the pressure of the filter press is 80-120MPa.

[0017] The heating rate in step (3) is 2.5-3℃ / hour, and the cooling rate is 0.5-1.5℃ / hour.

[0018] The reaction principle of this preparation method:

[0019] This invention utilizes the decomposition of fine aluminum hydroxide powder at 370–420°C to generate nanoscale pores, forming alumina microcrystals. These microcrystals undergo surface diffusion at 1100–1200°C, creating linkages between them to limit particle rearrangement during the later stages of sintering, resulting in alumina powder with high porosity. A calcium chloride solution is introduced into the high-porosity alumina powder; under vacuum conditions, calcium chloride accumulates at the particle linkages, hindering the merging and growth of nanopores. Furthermore, calcium oxide powder and alumina powder are added to the high-porosity alumina powder to fill the voids between the powder particles, preventing rearrangement of alumina particles during high-temperature sintering and improving the performance of the aluminate binder.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The reaction process is simple, energy consumption is low, and it is easy to realize industrial production;

[0022] (2) By mixing raw materials and wet grinding, the raw materials are fully mixed, one of the raw materials, calcium oxide, is converted into calcium hydroxide, and the other raw material, aluminum oxide, is activated on the particle surface.

[0023] (3) By compounding aluminum hydroxide, calcium chloride, calcium oxide and aluminum oxide and preparing them by pre-calcination and then roasting, the compressive strength of the aluminate binder is greatly improved and the performance of the aluminate binder is enhanced. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments, but these embodiments do not limit the implementation of the present invention.

[0025] Test method:

[0026] Compressive strength: GB201-2000 "Aluminate Cement";

[0027] Flexural strength: GB201-2000 "Aluminate Cement";

[0028] Initial setting time: GB201-2000 "Aluminate Cement";

[0029] Final setting time: GB201-2000 "Aluminate Cement".

[0030] Example 1

[0031] The preparation method of the aluminate binder includes the following steps:

[0032] (1) Place 35g of aluminum hydroxide fine powder in a high-temperature furnace, heat it to 400℃, keep it at that temperature for 3.5 hours, then heat it to 1150℃, keep it at that temperature for 4 hours, and then cool it down to obtain alumina powder with high porosity. The heating rate is 2.25℃ / hour and the cooling rate is 1.25℃ / hour.

[0033] (2) Add the high porosity alumina powder obtained in step (1) to the calcium chloride solution, stir under vacuum for 15 minutes, then add 25g of calcium oxide powder and 15g of alumina powder, add water and wet grind for 25 minutes to obtain a mixture with a particle size of 0.055mm. During the vacuum stirring process, the pressure is 1kPa, the concentration of the calcium chloride solution is 18wt%, and the calcium chloride content in the calcium chloride solution is 15g.

[0034] (3) The mixed slurry is filtered by pressure, the filtrate and filter cake are collected separately, the filter cake is dried and pressed into a blank, wherein the pressure of the filter press is 100MPa;

[0035] (4) The blank in step (3) is dried at 65°C for 4 hours, and then placed in a muffle furnace for heating and firing at 1580°C for 4 hours. After that, it is crushed to obtain an aluminate binder, wherein the heating rate is 2.8°C / hour and the cooling rate is 1°C / hour.

[0036] Example 2

[0037] The preparation method of the aluminate binder includes the following steps:

[0038] (1) Place 30g of aluminum hydroxide fine powder in a high-temperature furnace, heat it to 370℃, keep it at that temperature for 3 hours, then heat it to 1100℃, keep it at that temperature for 3 hours, and then cool it down to obtain alumina powder with high porosity. The heating rate is 2℃ / hour and the cooling rate is 1℃ / hour.

[0039] (2) Add the high porosity alumina powder obtained in step (1) to the calcium chloride solution, stir under vacuum for 15 minutes, then add 10g of calcium oxide powder and 20g of alumina powder, add water and wet grind for 15 minutes to obtain a mixture with a particle size of 0.045mm. During the vacuum stirring process, the pressure is 1kPa, the concentration of the calcium chloride solution is 15wt%, and the calcium chloride content in the calcium chloride solution is 10g.

[0040] (3) The mixed slurry is filtered by pressure, the filtrate and filter cake are collected separately, the filter cake is dried and pressed into a blank, wherein the pressure of the filter press is 80MPa;

[0041] (4) The blank in step (3) is dried at 50°C for 3 hours, and then placed in a muffle furnace for heating and firing at 1550°C for 3 hours. After that, it is crushed to obtain an aluminate binder, wherein the heating rate is 2.5°C / hour and the cooling rate is 0.5°C / hour.

[0042] Example 3

[0043] The preparation method of the aluminate binder includes the following steps:

[0044] (1) Place 40g of aluminum hydroxide fine powder in a high-temperature furnace, heat it to 420℃, keep it at that temperature for 4 hours, then heat it to 1200℃, keep it at that temperature for 4 hours, and then cool it down to obtain alumina powder with high porosity. The heating rate is 2.5℃ / hour and the cooling rate is 1.5℃ / hour.

[0045] (2) Add the high porosity alumina powder obtained in step (1) to the calcium chloride solution, stir under vacuum for 15 minutes, then add 30g of calcium oxide powder and 20g of alumina powder, add water and wet grind for 30 minutes to obtain a mixture with a particle size of 0.065mm. During the vacuum stirring process, the pressure is 1kPa, the concentration of the calcium chloride solution is 20wt%, and the calcium chloride content in the calcium chloride solution is 20g.

[0046] (3) The mixed slurry is filtered by pressure, the filtrate and filter cake are collected separately, the filter cake is dried and pressed into a blank, wherein the pressure of the filter press is 120MPa;

[0047] (4) The blank in step (3) is dried at 80°C for 5 hours, and then placed in a muffle furnace for heating and firing at 1600°C for 5 hours. After that, it is crushed to obtain an aluminate binder, wherein the heating rate is 3°C / hour and the cooling rate is 1.5°C / hour.

[0048] Example 4

[0049] The preparation method of the aluminate binder includes the following steps:

[0050] (1) Place 32g of aluminum hydroxide fine powder in a high-temperature furnace, heat it to 400℃, keep it at that temperature for 4 hours, then heat it to 1200℃, keep it at that temperature for 4 hours, and then cool it down to obtain alumina powder with high porosity. The heating rate is 2.5℃ / hour and the cooling rate is 1.5℃ / hour.

[0051] (2) Add the high porosity alumina powder obtained in step (1) to the calcium chloride solution, stir under vacuum for 15 minutes, then add 23g of calcium oxide powder and 13g of alumina powder, add water and wet grind for 25 minutes to obtain a mixture with a particle size of 0.065mm. During the vacuum stirring process, the pressure is 1kPa, the concentration of the calcium chloride solution is 20wt%, and the calcium chloride content in the calcium chloride solution is 12g.

[0052] (3) The mixed slurry is filtered by pressure, the filtrate and filter cake are collected separately, the filter cake is dried and pressed into a blank, wherein the pressure of the filter press is 80MPa;

[0053] (4) The blank in step (3) is dried at 50°C for 3 hours, and then placed in a muffle furnace for heating and firing at 1550°C for 4 hours. After that, it is crushed to obtain an aluminate binder, wherein the heating rate is 2.5°C / hour and the cooling rate is 0.5°C / hour.

[0054] Example 5

[0055] The preparation method of the aluminate binder includes the following steps:

[0056] (1) Place 38g of aluminum hydroxide fine powder in a high-temperature furnace, heat it to 420℃, keep it at that temperature for 4 hours, then heat it to 1200℃, keep it at that temperature for 4 hours, and then cool it down to obtain alumina powder with high porosity. The heating rate is 2.5℃ / hour and the cooling rate is 1℃ / hour.

[0057] (2) Add the high porosity alumina powder obtained in step (1) to the calcium chloride solution, stir under vacuum for 15 minutes, then add 27g of calcium oxide powder and 18g of alumina powder, add water and wet grind for 30 minutes to obtain a mixture with a particle size of 0.065mm. During the vacuum stirring process, the pressure is 1kPa, the concentration of the calcium chloride solution is 20wt%, and the calcium chloride content in the calcium chloride solution is 12g.

[0058] (3) The mixed slurry is filtered by pressure, the filtrate and filter cake are collected separately, the filter cake is dried and pressed into a blank, wherein the pressure of the filter press is 120MPa;

[0059] (4) The blank in step (3) is dried at 80°C for 5 hours, and then placed in a muffle furnace for heating and firing at 1580°C for 4 hours. After that, it is crushed to obtain an aluminate binder, wherein the heating rate is 3°C / hour and the cooling rate is 0.5°C / hour.

[0060] Comparative Example 1

[0061] The preparation method of the aluminate binder includes the following steps:

[0062] (1) Add water to 35g of aluminum hydroxide fine powder, 25g of calcium oxide powder, 15g of aluminum oxide powder and 15g of calcium chloride and wet grind them together for 25 minutes to obtain a mixture with a particle size of 0.055mm.

[0063] (2) The mixed slurry is filtered by pressure, the filtrate and filter cake are collected separately, the filter cake is dried and pressed into a blank, wherein the pressure of the filter press is 100MPa;

[0064] (3) The blank in step (2) is dried at 65°C for 4 hours, and then placed in a muffle furnace for heating and firing at 1580°C for 4 hours. After that, it is crushed to obtain an aluminate binder, wherein the heating rate is 2.8°C / hour and the cooling rate is 1°C / hour.

[0065] Comparative Example 2

[0066] The preparation method of the aluminate binder includes the following steps:

[0067] (1) Place 30g of aluminum hydroxide fine powder in a high-temperature furnace, heat it to 370℃, keep it at that temperature for 3 hours, then heat it to 1100℃, keep it at that temperature for 3 hours, and then cool it down to obtain alumina powder with high porosity. The heating rate is 2℃ / hour and the cooling rate is 1℃ / hour.

[0068] (2) Add 10g of calcium oxide powder and 20g of alumina powder to the high porosity alumina powder obtained in step (1), add water and wet grind for 15 minutes to obtain a mixture with a particle size of 0.045mm.

[0069] (3) The mixed slurry is filtered by pressure, the filtrate and filter cake are collected separately, the filter cake is dried and pressed into a blank, wherein the pressure of the filter press is 80MPa;

[0070] (4) The blank in step (3) is dried at 50°C for 3 hours, and then placed in a muffle furnace for heating and firing at 1550°C for 3 hours. After that, it is crushed to obtain an aluminate binder, wherein the heating rate is 2.5°C / hour and the cooling rate is 0.5°C / hour.

[0071] Comparative Example 3

[0072] The preparation method of the aluminate binder includes the following steps:

[0073] (1) Add 50g of calcium oxide powder and 60g of aluminum oxide powder to a wet mill, add water and wet mill for 30 minutes to obtain a mixture with a particle size of 0.065mm.

[0074] (2) The mixed slurry is filtered by pressure, the filtrate and filter cake are collected separately, the filter cake is dried and pressed into a blank, wherein the pressure of the filter press is 120MPa;

[0075] (3) The blank in step (2) is dried at 80°C for 5 hours, and then placed in a muffle furnace for heating and firing at 1600°C for 5 hours. After that, it is crushed to obtain an aluminate binder, wherein the heating rate is 3°C / hour and the cooling rate is 1.5°C / hour.

[0076] The test data for Examples 1-5 and Comparative Examples 1-3 are shown in Table 1.

[0077] Table 1. Test data for Examples 1-5 and Comparative Examples 1-3

[0078] Pressure resistance / MPa Flexural strength / MPa Initial setting time / min Final setting time / min Example 1 61 10.4 155 210 Example 2 59.8 10.0 160 212 Example 3 59.5 10.1 164 215 Example 4 60 10.1 163 214 Example 5 60.3 10.2 166 218 Comparative Example 1 52.1 9.5 172 225 Comparative Example 2 51.2 9.2 177 228 Comparative Example 3 45.3 8.7 175 226

Claims

1. A method of preparing an aluminate binder, characterized by, The method comprises the following steps: (1) placing aluminum hydroxide powder into a high-temperature furnace, heating to 370-420 DEG C, keeping for 3-4 hours, then heating to 1100-1200 DEG C, keeping for 3-4 hours, then cooling, to obtain high-porosity aluminum oxide powder; (2) adding the high-porosity aluminum oxide powder obtained in step (1) into a calcium chloride solution, vacuum stirring for 15 minutes, then adding calcium oxide powder and aluminum oxide powder, adding water, wet-milling and mixing for 15-30 minutes, to obtain a mixture; (3) performing pressure filtration on the mixture, collecting the filtrate and the filter cake separately, drying the filter cake, and pressing the cake, to obtain a blank; (4) drying the blank in step (3) at 50-80°C for 3-5 hours, and then baking in a muffle furnace, with a baking temperature of 1550-1600°C and a baking time of 3 5 hours, and then crushing after cooling to obtain an aluminate binder; The heating rate in step (1) is 2-2.5 DEG C / hour, and the cooling rate is 1-1.5 DEG C / hour; The concentration of the calcium chloride solution in step (2) is 15-20 wt%; The mass ratio of aluminum hydroxide, calcium chloride, calcium oxide and aluminum oxide is (3-4):(1-2):(2-3):(1-2).

2. The method of preparing aluminate binders according to claim 1, characterized in that, The particle size of the mixture in step (2) is 0.045-0.065 mm.

3. The method of claim 1, wherein the aluminate binder is prepared by the steps of: The pressure during vacuum stirring in step (2) is 1 kPa.

4. The method of claim 1, wherein the aluminate binder is prepared by the steps of: The pressure of the filter press during pressure filtration in step (3) is 80-120 MPa.