A MgO-Al2O3-ZrO2 refractory brick and its preparation method
By preparing MgO-Al2O3-ZrO2 refractory bricks, the problems of insufficient erosion resistance and high-temperature mechanical properties of chromium-free refractory materials for non-ferrous metal smelting furnaces were solved. This achieved high-efficiency erosion resistance and high-temperature stability of the refractory bricks, improved the service life of the smelting furnace, and reduced costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UNIV OF SCI & TECH BEIJING
- Filing Date
- 2023-12-21
- Publication Date
- 2026-05-26
Abstract
Description
Technical Field
[0001] This invention belongs to the field of refractory materials, specifically relating to a MgO-Al2O3-ZrO2 refractory brick and its preparation method. Background Technology
[0002] Although chromium-containing refractories have excellent performance, the Cr they produce... 6+ There is a risk of carcinogenicity. The application of magnesium aluminum spinel has played a crucial role in the development of new refractory materials during the chromium-free process, with MgO-MgAl2O4 (M-MA) materials being a representative example. M-MA materials possess excellent thermal shock resistance and chemical stability, and are also environmentally friendly and economically efficient, making them one of the most promising chromium-free materials. M-MA materials have been successfully applied in cement rotary kilns; however, their poor high-temperature mechanical properties and corrosion resistance limit their application in iron and steel smelting and non-ferrous metal smelting.
[0003] ZrO2 possesses a unique toughening mechanism. Introducing ZrO2 into M-MA materials can improve the mechanical properties and erosion resistance of MgAl2O4. ZrO2 can react with CaO to form the high-melting-point phase CaZrO3, preventing further slag penetration. Furthermore, adding ZrO2 to MgAl2O4 spinel increases the contact angle between MgAl2O4 and FeO, meaning that the addition of ZrO2 can increase the resistance of MgAl2O4 to FeO erosion.
[0004] The MgO-MgAl2O4-ZrO2 composite material system possesses a unique microstructure, representing an optimized combination of MgO-ZrO2 and MgO-MgAl2O4 materials. It simultaneously offers excellent thermal shock resistance, slag resistance, and high-temperature strength. Therefore, magnesium-aluminum-zirconium refractories hold great potential as an important product in the chromium-free process. However, simply adding the two materials together does not fully realize their respective advantages. To ensure sufficient thermal shock resistance, the MA content cannot be too low, but too high a content will affect erosion resistance. The same applies to the ZrO2 content; too little ZrO2 compromises erosion resistance, while too much is not economically viable.
[0005] The development of a novel MgO-Al2O3-ZrO2 refractory brick for non-ferrous metal smelting furnaces and its preparation method are problems that urgently need to be solved in this invention. Summary of the Invention
[0006] To address the problems of poor erosion resistance and thermal shock stability of refractory bricks used in non-ferrous metal smelting furnaces in the prior art, this invention proposes a MgO-Al2O3-ZrO2 refractory brick and its preparation method.
[0007] The first aspect of the present invention provides a MgO-Al2O3-ZrO2 refractory brick, wherein, based on the total mass of the refractory brick, the refractory brick contains 60-70 wt% brine magnesia particles, 14-26 wt% fine magnesium oxide powder, 1-7 wt% ultrafine magnesium oxide powder, and 3-15 wt% fused zirconium corundum powder.
[0008] As an embodiment of the present invention, based on the total mass of the refractory brick, the refractory brick contains 65-70 wt% brine magnesia particles, 20-26 wt% fine magnesium oxide powder, 3-7 wt% ultrafine magnesium oxide powder, and 8-12 wt% fused zirconium corundum powder.
[0009] As an embodiment of the present invention, the brine magnesia particles have particle sizes of 0-1mm and 1-4mm, the mass ratio of the 0-1mm and 1-4mm brine magnesia particles is (4-6):(5-8), the particle size of the magnesium oxide fine powder is ≤0.088mm, the particle size of the magnesium oxide ultrafine powder is ≤5um, and the particle size of the fused zirconium corundum powder is ≤0.074mm.
[0010] A second aspect of the present invention provides a method for preparing the refractory brick described in the first aspect of the present invention, the method comprising the following steps:
[0011] S1: Based on the total mass of the prepared refractory bricks, 60-70 wt% of brine magnesia particles, 14-26 wt% of magnesia fine powder, 1-7 wt% of magnesia ultrafine powder, 3-15 wt% of fused zirconium corundum powder and a certain proportion of pulp are mixed to obtain the mixed mud.
[0012] S2: The mixed mud is pressed into a blank using a press, and then dried and sintered to obtain the refractory brick.
[0013] As an embodiment of the present invention, in step S1, based on the total mass of the prepared refractory bricks, 65-70 wt% of brine magnesia particles, 20-26 wt% of magnesia fine powder, 3-7 wt% of magnesia ultrafine powder, 8-12 wt% of fused zirconium corundum powder and a certain proportion of pulp are mixed.
[0014] In one embodiment of the present invention, in step S1, the pulp is derived from pulp waste liquor;
[0015] Based on the total mass of the brine magnesia particles, magnesium oxide fine powder, magnesium oxide ultrafine powder, and fused zirconium corundum powder, the amount of pulp added is 2-5 wt%.
[0016] In one embodiment of the present invention, in step S2, the pressing pressure is 100-400 MPa.
[0017] As one embodiment of the present invention, the drying temperature is 60-200℃ and the time is 18-36h.
[0018] As an embodiment of the present invention, the sintering temperature is 1600℃-1780℃ and the time is 1-8h.
[0019] The third aspect of the present invention provides the application of the refractory bricks described in the first aspect of the present invention or the refractory bricks prepared by the method described in the second aspect of the present invention in non-ferrous metal smelting furnaces or iron and steel smelting furnaces.
[0020] This invention addresses the problems of poor erosion resistance and unsatisfactory high-temperature mechanical properties of existing chromium-free refractory materials used in non-ferrous metal smelting furnaces. Under the influence of FeO-SiO2 slag, traditional M-MA materials undergo a chemical reaction with the slag, leading to structural damage and significantly reduced performance. This invention uses brine magnesia, fine magnesium oxide powder, and fused zirconium corundum powder as raw materials to prepare a MgO-Al2O3-ZrO2 composite green body. After drying, it is held at 1600℃-1780℃ to form a ternary metastable MAZ phase, which decomposes into a uniformly finely dispersed M-MA-Z ternary eutectic during slow cooling. This yields a novel MgO-Al2O3-ZrO2 refractory brick for non-ferrous metal smelting furnaces with highly dispersed ZrO2 and MgAl2O4. Compared with traditional MgO-Al2O3-ZrO2 refractory bricks and M-MA materials, the novel MgO-Al2O3-ZrO2 refractory brick exhibits superior erosion resistance and high-temperature mechanical properties. It is more suitable for application in the non-ferrous metal smelting industry, and can greatly extend the service life of non-ferrous metal smelting furnaces. Specifically, it performs as follows:
[0021] (1) In the non-ferrous metal smelting process, in existing M-MA materials and traditional MgO-Al2O3-ZrO2 refractory bricks, MgO and MgAl2O4 easily react with FeO and SiO2 in the slag to form erosion products that differ significantly from the brick structure, thus damaging the brick structure. In this invention, MA and ZrO2 are introduced in the form of zirconium corundum to achieve high dispersion of the two. A sintering temperature of 1690℃ and reasonable control of the cooling rate are used to synthesize the MAZ ternary eutectic structure, further homogenizing and finely dispersing the two. The highly homogenized and finely dispersed MA and ZrO2 can effectively prevent slag erosion;
[0022] (2) Existing M-MA materials are prone to the formation of low-melting-point compounds such as CaO-Al2O3 and CaO-SiO2 during high-temperature service, which greatly affects the high-temperature mechanical properties of the materials. The introduction of ZrO2 can react with CaO to form CaZrO3, which promotes the densification of the brick body and also inhibits the formation of these low-melting-point compounds. For traditional MgO-Al2O3-ZrO2 refractory bricks, the presence of ZrO2 can achieve the same effect as the present invention, but due to the insufficient dispersion of ZrO2, a high addition amount is required, which in turn leads to increased costs. Therefore, the present invention ensures good performance while also having good economic benefits. Detailed Implementation
[0023] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific embodiments.
[0024] Example 1
[0025] A mixture of 66 wt% brine magnesia, 26 wt% fine magnesia powder, 5 wt% ultrafine magnesia powder, and 3 wt% fused zirconium corundum powder was prepared. 3.76 wt% pulp was added as a binder to the mixture. The mixture was thoroughly kneaded, pressed into a green body, and dried at 200℃ for 24 hours. This yielded a MgO-Al2O3-ZrO2 composite green body. The pressed brick was then dried in a drying oven for 24 hours, followed by firing at 1690℃ for 8 hours to obtain a novel MgO-Al2O3-ZrO2 refractory brick.
[0026] The obtained novel MgO-Al2O3-ZrO2 refractory brick was tested and found to have an apparent porosity of 14.4% and a bulk density of 3 g / cm³. 3 Its compressive strength at room temperature is 145.6 MPa, and its flexural strength at high temperature is 16.43 MPa.
[0027] Example 2
[0028] A mixture of 66 wt% brine magnesia, 23 wt% fine magnesia powder, 5 wt% ultrafine magnesia powder, and 6 wt% fused zirconium corundum powder was prepared. 3.76 wt% pulp was added as a binder to the mixture. The mixture was thoroughly kneaded, pressed into a green body, and dried at 200℃ for 24 hours to obtain a MgO-Al2O3-ZrO2 composite green body. The pressed brick was then dried in a drying oven for 24 hours, and then fired at 1670℃ for 8 hours to obtain a novel MgO-Al2O3-ZrO2 refractory brick.
[0029] The obtained novel MgO-Al2O3-ZrO2 refractory brick was tested and found to have an apparent porosity of 14.5% and a bulk density of 3 g / cm³. 3Its compressive strength at room temperature is 117.33 MPa, and its flexural strength at high temperature is 12.6 MPa.
[0030] Example 3
[0031] A mixture of 66 wt% brine magnesia, 20 wt% fine magnesia powder, 5 wt% ultrafine magnesia powder, and 9 wt% fused zirconium corundum powder was prepared. 3.76 wt% pulp was added as a binder to the mixture. The mixture was thoroughly kneaded, pressed into a green body, and dried at 200℃ for 24 hours. This yielded a MgO-Al2O3-ZrO2 composite green body. The pressed brick was then dried in a drying oven for 24 hours, followed by firing at 1690℃ for 8 hours to obtain a novel MgO-Al2O3-ZrO2 refractory brick.
[0032] The obtained novel MgO-Al2O3-ZrO2 refractory brick was tested and found to have an apparent porosity of 16.5% and a bulk density of 2.95 g / cm³. 3 Its compressive strength at room temperature is 68 MPa, and its flexural strength at high temperature is 12.33 MPa.
[0033] Example 4
[0034] A mixture of 66 wt% brine magnesia, 17 wt% fine magnesia powder, 5 wt% ultrafine magnesia powder, and 12 wt% fused zirconium corundum powder was prepared. 3.76 wt% pulp was added as a binder to the mixture. The mixture was thoroughly kneaded, pressed into a green body, and dried at 200℃ for 24 hours. This yielded a MgO-Al2O3-ZrO2 composite green body. The pressed brick was then dried in a drying oven for 24 hours, followed by firing at 1640℃ for 8 hours to obtain a novel MgO-Al2O3-ZrO2 refractory brick.
[0035] The obtained novel MgO-Al2O3-ZrO2 refractory brick was tested and found to have an apparent porosity of 19% and a bulk density of 2.86 g / cm³. 3 Its compressive strength at room temperature is 35.4 MPa, and its flexural strength at high temperature is 4.6 MPa.
[0036] Example 5
[0037] A mixture of 66 wt% brine magnesia, 14 wt% fine magnesia powder, 5 wt% ultrafine magnesia powder, and 15 wt% fused zirconium corundum powder was prepared. 3.76 wt% pulp was added as a binder to the mixture. The mixture was thoroughly kneaded, pressed into a green body, and dried at 200℃ for 24 hours to obtain a MgO-Al2O3-ZrO2 composite green body. The pressed brick was then dried in a drying oven for 24 hours, and then fired at 1670℃ for 8 hours to obtain a novel MgO-Al2O3-ZrO2 refractory brick.
[0038] The obtained novel MgO-Al2O3-ZrO2 refractory brick was tested and found to have an apparent porosity of 18.3% and a bulk density of 2.9 g / cm³. 3 Its compressive strength at room temperature is 31.4 MPa, and its flexural strength at high temperature is 20.73 MPa.
[0039] Example 6
[0040] 65 wt% brine magnesia, 21 wt% fine magnesia powder, 6 wt% ultrafine magnesia powder, and 8 wt% fused zirconium corundum powder were mixed. 3.76 wt% pulp was added as a binder to the above mixture. The mixture was thoroughly kneaded, pressed into a green body, and dried at 200℃ for 24 hours to obtain a MgO-Al2O3-ZrO2 composite green body. The pressed brick body was then dried in a drying oven for 24 hours, and then fired at 1720℃ for 8 hours to obtain a novel MgO-Al2O3-ZrO2 refractory brick.
[0041] The obtained novel MgO-Al2O3-ZrO2 refractory brick was tested and found to have an apparent porosity of 14.2% and a bulk density of 3.02 g / cm³. 3 Its compressive strength at room temperature is 82.4 MPa, and its flexural strength at high temperature is 20.33 MPa.
[0042] Comparative Example 1
[0043] 69 wt% brine magnesia, 21 wt% fine magnesia powder, and 10 wt% zirconium oxide powder were mixed. 3.76 wt% pulp was added as a binder to the mixture. The mixture was thoroughly kneaded, pressed into a green body, and dried at 200℃ for 24 hours. This yielded an MgO-ZrO2 composite green body. The pressed brick was then dried in a drying oven for 24 hours, and finally fired at 1550℃ for 6 hours to obtain MgO-ZrO2 refractory bricks.
[0044] The obtained MgO-ZrO2 refractory bricks were tested and found to have an apparent porosity of 19.6% and a bulk density of 2.82 g / cm³. 3 Its compressive strength at room temperature is 29.3 MPa, and its flexural strength at high temperature is 5.6 MPa.
[0045] Comparative Example 2
[0046] 72 wt% brine magnesia, 12 wt% fine magnesia powder, and 16 wt% fused zirconium corundum powder were mixed. 3.76 wt% pulp was added as a binder to the mixture. The mixture was thoroughly mixed, pressed into a green body, and dried at 200℃ for 24 hours to obtain a MgO-Al2O3-ZrO2 composite green body. The pressed brick body was then dried in a drying oven for 24 hours, and then fired at 1630℃ for 8 hours to obtain a novel MgO-Al2O3-ZrO2 refractory brick.
[0047] The obtained novel MgO-Al2O3-ZrO2 refractory brick was tested and found to have an apparent porosity of 19.8% and a bulk density of 2.81 g / cm³. 3 The compressive strength at room temperature is 29.3 MPa, and the flexural strength at high temperature is 4.31 MPa.
[0048] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A MgO-Al2O3-ZrO2 refractory brick, characterized in that, Based on the total mass of the refractory brick, the refractory brick contains 60-70 wt% brine magnesia particles, 14-26 wt% fine magnesium oxide powder, 1-7 wt% ultrafine magnesium oxide powder, and 3-15 wt% fused zirconium corundum powder. The brine magnesia particles have particle sizes of 0-1 mm and 1-4 mm, and the mass ratio of the 0-1 mm and 1-4 mm brine magnesia particles is (4-6):(5-8). The particle size of the magnesium oxide fine powder is ≤0.088 mm, the particle size of the magnesium oxide ultrafine powder is ≤5 μm, and the particle size of the fused zirconium corundum powder is ≤0.074 mm.
2. The refractory brick according to claim 1, characterized in that, Based on the total mass of the refractory brick, the refractory brick contains 65-70 wt% brine magnesia particles, 20-26 wt% fine magnesium oxide powder, 3-7 wt% ultrafine magnesium oxide powder, and 8-12 wt% fused zirconium corundum powder.
3. A method for preparing the refractory brick according to claim 1, characterized in that, The method includes the following steps: S1: Based on the total mass of the prepared refractory bricks, 60-70wt% of brine magnesia particles, 14-26wt% of magnesia fine powder, 1-7wt% of magnesia ultrafine powder, 3-15wt% of fused zirconium corundum powder and a certain proportion of pulp are mixed to obtain the mixed mud. S2: The mixed mud is pressed into a blank using a press, and then dried and sintered to obtain the refractory brick.
4. The method according to claim 3, characterized in that, In step S1, based on the total mass of the prepared refractory bricks, 65-70 wt% of brine magnesia particles, 20-26 wt% of fine magnesium oxide powder, 3-7 wt% of ultrafine magnesium oxide powder, 8-12 wt% of fused zirconium corundum powder, and a certain proportion of pulp are mixed together.
5. The method according to claim 3, characterized in that, In step S1, the pulp comes from pulp waste liquor; Based on the total mass of the brine magnesia particles, magnesium oxide fine powder, magnesium oxide ultrafine powder and fused zirconium corundum powder, the amount of pulp added is 2-5 wt%.
6. The method according to claim 3, characterized in that, In step S2, the pressing pressure is 100-400 MPa.
7. The method according to claim 3, characterized in that, In step S2, the drying temperature is 60-200℃ and the time is 18-36h.
8. The method according to claim 3, characterized in that, In step S2, the sintering temperature is 1600-1780℃ and the time is 1-8h.
9. The application of the refractory bricks according to any one of claims 1 to 2 or the refractory bricks prepared by the method according to any one of claims 3 to 8 in non-ferrous metal smelting furnaces or iron and steel smelting furnaces.