A method for preparing alumina wear-resistant ceramic balls by taking bauxite as a main raw material and a product thereof

Abstract

The application discloses a method for preparing alumina wear-resistant ceramic balls by taking bauxite as a main raw material, and the ceramic ball is prepared from the following raw materials in parts by weight: bauxite 65-85 parts, active magnesium oxide 3-10 parts, SiC 5-10 parts, clay 10-15 parts, alpha-Al2O3 powder 5-10 parts, talc 0-3 parts, heavy calcium powder 1-4 parts, and barite 2-5 parts. The mixed slurry obtained after the raw material composition is proportioned and ball-milled is subjected to spray granulation, isostatic pressing and molding, and drying, and then is fired by adopting a low-temperature slow-burning and stepwise temperature-lowering system, so that the alumina wear-resistant ceramic balls are obtained. In the application, the bauxite is taken as a matrix, SiC and active magnesium oxide and other materials are added, a reduction reaction is generated in the initial sintering stage, the crystal type transformation process in the ceramic ball is changed, a structure-stable magnesium-iron-aluminum spinel crystal phase is formed, and the toughness of the ceramic ball is improved and the appearance quality of the ceramic ball is improved.

Description

Technical Field

[0001] This invention relates to the field of ceramic grinding media technology, and in particular to a method for preparing alumina ceramic balls using bauxite as the main raw material, and the product thereof. Background Technology

[0002] Alumina wear-resistant ceramic balls are widely used as grinding media in industrial production due to their high strength, high hardness, and wear resistance. Bauxite, in particular, is widely used in the manufacture of alumina wear-resistant ceramic balls because of its abundant availability and low price. However, because bauxite ore contains a relatively high amount of impurities such as Fe2O3 and TiO2, ceramic balls made from this raw material have a brownish-yellow appearance. Furthermore, the sintering process of bauxite produces a large amount of liquid phase, which reduces the wear resistance of the ceramic balls, leading to wear and tear during use and thus lowering the quality of the finished product. Therefore, alumina wear-resistant ceramic balls made primarily from bauxite can only be used in the production of building ceramics and cement.

[0003] To improve the wear resistance and appearance of ceramic balls made from bauxite, existing technologies employ physical or chemical iron removal methods. These methods reduce impurities such as Fe2O3 and TiO2 in the bauxite, thereby increasing the Al2O3 content. However, while this iron removal process is effective for magnetic Fe2O3, it fails to completely remove weakly magnetic mineral phases (such as hematite). To further enhance the wear resistance of the ceramic balls, existing technologies introduce composite crystalline phases by adding various oxides to form an Al2O3-TiO2-CuO-TiC phase. 0.5 N 05 The ZrO2 multiphase system is designed to improve the wear resistance and impact resistance of ceramic balls. However, due to the addition of other crystalline phases, it is difficult for the ceramic balls to generate a sufficient amount of liquid phase for sintering during the sintering process. Therefore, the sintering temperature of the product is relatively high, significantly exceeding the sintering temperature range of similar bauxite ceramic balls. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing alumina wear-resistant ceramic balls using bauxite as the main raw material. Using bauxite as the matrix, active magnesium oxide and SiC are added simultaneously. Through reduction reactions during the firing process and by altering the crystal transformation process within the ceramic balls, a structurally stable magnesium-iron-aluminum spinel phase is formed, thereby improving the toughness and appearance of the ceramic balls. Another objective of this invention is to provide a product obtained using the above-described preparation method.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for preparing alumina wear-resistant ceramic balls using bauxite as the main raw material. The ceramic balls, by weight, consist of 65-85 parts bauxite, 3-10 parts activated magnesium oxide, 5-10 parts SiC, 10-15 parts clay, 5-10 parts α-Al₂O₃ powder, 0-3 parts talc, 1-4 parts heavy calcium carbonate powder, and 2-5 parts barite. The activated magnesium oxide powder is obtained by calcining one or a combination of lightly calcined magnesium powder, magnesium hydroxide, and fused magnesia at 850°C to generate activity. The preparation method includes the following steps:

[0007] (1) After mixing the raw materials, the mixture is ball-milled for 20-35 hours at a mass ratio of raw materials:balls:water = 1:1.5-2.5:0.5-1 to obtain a mixed slurry;

[0008] (2) The mixed slurry is spray granulated, isostatically pressed and dried, and then fired using a low-temperature slow firing-step cooling system. That is, it is heated from room temperature to the decomposition temperature of reducing agent SiC (1000-1200℃) in 7-9 hours, then heated to the firing temperature (1250-1300℃) at a rate of 1℃ / min, held for 30-60 minutes, then cooled naturally to 1050-1100℃, held for 20-40 minutes, then rapidly cooled to 900℃, and finally cooled naturally to room temperature to obtain alumina wear-resistant ceramic balls.

[0009] In the above scheme, the chemical composition of the bauxite of the present invention is 65-75 wt% Al2O3, 10-15 wt% SiO2, 2-4.5 wt% Fe2O3, 1.5-2.5 wt% TiO2, 0.5-1 wt% RO+R2O (alkaline earth metal oxides and alkali metal oxides), and 10-12 wt% IL. The particle size of the mixed slurry is D50≤10μm.

[0010] Another objective of this invention is achieved through the following technical solution:

[0011] The product prepared using a method for preparing alumina wear-resistant ceramic balls with bauxite as the main raw material has the following chemical composition: Al₂O₃ 57–64 wt%, SiO₂ 22–26 wt%, Fe₂O₃ 1.5–3.5 wt%, TiO₂ 1.1–2 wt%, CaO 1.1–2.5 wt%, MgO 5.0–8.9 wt%, K₂O + Na₂O 0.2–0.35 wt%, and BaO 1–3.5 wt%. The specific gravity of the alumina wear-resistant ceramic ball product is 3.0–3.3 g / cm³. 3 Equivalent wear < 0.5‰, whiteness 40-55.

[0012] The present invention has the following beneficial effects:

[0013] (1) This invention utilizes the characteristics of low surface energy and high reactivity of active magnesium oxide powder to form a liquid phase at low temperature. At the same time, it interacts with bauxite to change the crystal transformation process and form a spinel crystal phase. While introducing more high fracture energy crystal phases, it ensures that the ceramic balls are densified within a reasonable firing temperature range, thereby improving the toughness of the product.

[0014] (2) This invention utilizes SiC as a reducing agent and controls the sintering process of ceramic balls through low-temperature slow firing and stepped cooling. First, some Fe... 3+ Reduced to Fe 2+ And then further made Fe 2+ By entering the active magnesium aluminum spinel lattice to form stable magnesium iron aluminum spinel, the coloring ions are anchored in the crystal structure, avoiding the occurrence of coloring phenomena, thereby improving the appearance quality of the ceramic ball.

[0015] The present invention will now be described in further detail with reference to embodiments. Detailed Implementation

[0016] Example 1:

[0017] This embodiment describes a method for preparing alumina wear-resistant ceramic balls using bauxite as the main raw material. The raw material composition of the ceramic balls is 700 kg of bauxite, 80 kg of active magnesium oxide (obtained by calcining 117.89 kg of magnesium hydroxide at 850 °C), 60 kg of SiC, 150 kg of clay, 100 kg of α-Al₂O₃ powder, 30 kg of talc, 20 kg of heavy calcium carbonate powder, and 20 kg of barite. The chemical composition of the bauxite is: Al₂O₃ 71.34 wt%, SiO₂ 12.23 wt%, Fe₂O₃ 2.5 wt%, TiO₂ 1.8 wt%, CaO 0.15 wt%, MgO 0.51 wt%, Na₂O 0.08 wt%, and IL 11.39 wt%.

[0018] The preparation method has the following steps:

[0019] (1) After mixing the above raw materials, the mixture is ball-milled for 22 hours at a mass ratio of raw materials:zirconia balls: water = 1:1.5:0.5 to obtain a mixed slurry with a D50 of 6μm;

[0020] (2) After the above mixed slurry is spray granulated, isostatically pressed and dried, it is fired using a low-temperature slow firing-step cooling system. That is, it is heated from room temperature to the decomposition temperature of reducing agent SiC, 1050℃, over 8.5 hours, then heated to 1250℃ at a rate of 1℃ / min, held for 40 minutes, then cooled naturally to 1100℃, held for 22 minutes, then rapidly cooled to 900℃, and finally cooled naturally to room temperature to obtain alumina wear-resistant ceramic balls.

[0021] Example 2:

[0022] This embodiment describes a method for preparing alumina wear-resistant ceramic balls using bauxite as the main raw material. The raw material composition of the ceramic balls is 830 kg of bauxite, 100 kg of active magnesium oxide (obtained by calcining 73.68 kg of magnesium hydroxide and 56.85 kg of lightly calcined magnesium powder at 850 °C), 80 kg of SiC, 130 kg of clay, 80 kg of α-Al₂O₃ powder, 40 kg of heavy calcium carbonate powder, and 30 kg of barite. The chemical composition of the bauxite is: Al₂O₃ 66.3 wt%, SiO₂ 14.31 wt%, Fe₂O₃ 4.3 wt%, TiO₂ 2.4 wt%, CaO 0.3 wt%, MgO 0.33 wt%, K₂O 0.2 wt%, Na₂O 0.08 wt%, and IL 11.78 wt%.

[0023] The preparation method has the following steps:

[0024] (1) After mixing the above raw materials, the mixture is ball-milled for 28 hours at a mass ratio of raw materials:zirconia balls: water = 1:1.8:0.5 to obtain a mixed slurry with a D50 of 8μm;

[0025] (2) After the above mixed slurry is spray granulated, isostatically pressed and dried, it is fired using a low-temperature slow firing-step cooling system. That is, it is heated from room temperature to the decomposition temperature of reducing agent SiC, 1180℃, for 9 hours, then heated to 1300℃ at a rate of 1℃ / min, held for 30 minutes, then cooled naturally to 1050℃, held for 32 minutes, then rapidly cooled to 900℃, and finally cooled naturally to room temperature to obtain alumina wear-resistant ceramic balls.

[0026] Example 3:

[0027] This embodiment describes a method for preparing alumina wear-resistant ceramic balls using bauxite as the main raw material. The raw material composition of the ceramic balls is as follows: 660 kg of bauxite, 40 kg of active magnesium oxide (obtained by calcining 14.74 kg of magnesium hydroxide, 22.47 kg of lightly calcined magnesium powder, and 10.5 kg of fused magnesia at 850°C), 50 kg of SiC, 120 kg of clay, 50 kg of α-Al₂O₃ powder, 25 kg of talc, 30 kg of heavy calcium carbonate powder, and 50 kg of barite. The chemical composition of the bauxite is: Al₂O₃ 73.58 wt%, SiO₂ 10.31 wt%, Fe₂O₃ 2 wt%, TiO₂ 2.1 wt%, MgO 0.3 wt%, K₂O 0.2 wt%, and IL 11.51 wt%.

[0028] The preparation method has the following steps:

[0029] (1) After mixing the above raw materials, the mixture is ball-milled for 30 hours at a mass ratio of raw materials:zirconia balls: water = 1:2.4:1 to obtain a mixed slurry with a D50 of 5μm;

[0030] (2) After the above mixed slurry is spray granulated, isostatically pressed and dried, it is fired using a low-temperature slow firing-step cooling system. That is, it is heated from room temperature to the decomposition temperature of reducing agent SiC, 1200℃, over 7 hours, and then heated to 1300℃ at a rate of 1℃ / min. After holding at this temperature for 50 minutes, it is naturally cooled to 1080℃, held at this temperature for 26 minutes, and then rapidly cooled to 900℃. Finally, it is naturally cooled to room temperature to obtain alumina wear-resistant ceramic balls.

[0031] The chemical composition of the alumina wear-resistant ceramic balls in this invention is shown in Table 1, and their technical specifications are shown in Table 2.

[0032] Table 1 Chemical composition of alumina wear-resistant ceramic balls in embodiments of the present invention

[0033]

[0034] Table 2 Technical Specifications of Alumina Wear-Resistant Ceramic Balls in Embodiments of the Invention

[0035]

Claims

1. A method for preparing alumina wear-resistant ceramic balls using bauxite as the main raw material, characterized in that: The ceramic spheres are composed of the following raw materials by weight: 65-85 parts bauxite, 3-10 parts activated magnesium oxide, 5-10 parts SiC, 10-15 parts clay, 5-10 parts α-Al₂O₃ powder, 0-3 parts talc, 1-4 parts heavy calcium carbonate powder, and 2-5 parts barite; the activated magnesium oxide powder is obtained by calcining one or a combination of lightly calcined magnesium powder, magnesium hydroxide, and fused magnesia at 850°C to generate activity; the preparation method includes the following steps: (1) After mixing the raw materials, the mixture is ball-milled for 20-35 hours at a mass ratio of raw materials:balls:water = 1:1.5-2.5:0.5-1 to obtain a mixed slurry; (2) The mixed slurry is spray granulated, isostatically pressed and dried, and then fired using a low-temperature slow firing-step cooling system. That is, it is heated from room temperature to the decomposition temperature of reducing agent SiC (1000-1200℃) in 7-9 hours, then heated to the firing temperature (1250-1300℃) at a rate of 1℃ / min, held for 30-60 minutes, then cooled naturally to 1050-1100℃, held for 20-40 minutes, then rapidly cooled to 900℃, and finally cooled naturally to room temperature to obtain alumina wear-resistant ceramic balls.

2. The method for preparing alumina wear-resistant ceramic balls using bauxite as the main raw material according to claim 1, characterized in that: The chemical composition of the bauxite is 65-75 wt% Al2O3, 10-15 wt% SiO2, 2-4.5 wt% Fe2O3, 1.5-2.5 wt% TiO2, 0.5-1 wt% RO+R2O, and 10-12 wt% IL.

3. The method for preparing alumina wear-resistant ceramic balls using bauxite as the main raw material according to claim 1, characterized in that: The particle size of the mixed slurry is D50≤10μm.

4. The product obtained by the method for preparing alumina wear-resistant ceramic balls using bauxite as the main raw material as described in any one of claims 1-3, characterized in that: The chemical composition of the alumina wear-resistant ceramic balls is as follows: Al2O3 57-64 wt%, SiO2 22-26 wt%, Fe2O3 1.5-3.5 wt%, TiO2 1.1-2 wt%, CaO 1.1-2.5 wt%, MgO 5.0-8.9 wt%, K2O+Na2O 0.2-0.35 wt%, and BaO 1-3.5 wt%.

5. The product according to claim 4, characterized in that: The specific gravity of the alumina wear-resistant ceramic balls is 3.0–3.3 g / cm³. 3 Equivalent wear < 0.5‰, whiteness 40-55.

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