Chromium-free long-life magnesium-aluminum-zirconium composite refractory brick and preparation method thereof

Abstract

The invention relates to a chromium-free long-life magnesium-aluminum-zirconium composite refractory brick, and relates to the technical field of refractory materials. The raw materials comprise, by mass, 75-85% of aggregate, 15-25% of matrix fine powder and an additive, and the aggregate comprises, by mass, 40-60% of fused magnesite particles, 10-25% of tabular alumina particles and 5-15% of pre-synthesized magnesium aluminate spinel particles; the matrix fine powder is prepared from 5%-10% of fused magnesia fine powder, 3%-8% of active alpha-Al2O3 micro powder, 2%-6% of zirconium dioxide micro powder and 1%-3% of metal aluminum powder; the additive is thermosetting phenolic resin; and sintering at the temperature of 1550-1650 DEG C in a heat preservation manner. The composite refractory brick does not contain chromium, is environment-friendly, is particularly suitable for harsh working condition parts such as furnace mouths, spray guns, siphon mouths, slag line areas and the like of copper, lead, zinc and other nonferrous smelting furnaces, and can obviously prolong the service life and reduce the production cost.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a chromium-free, long-life magnesium-aluminum-zirconium composite refractory brick and its preparation method. The chromium-free, long-life magnesium-aluminum-zirconium composite refractory brick of this invention, as a furnace lining material, contains no chromium, is environmentally friendly, and is particularly suitable for harsh operating conditions in furnaces and kilns for non-ferrous metal smelting such as copper, lead, and zinc, including furnace openings, lances, siphon inlets, and slag line areas, significantly improving its service life. Background Technology

[0002] Non-ferrous metal pyrometallurgy (such as the smelting and refining processes of copper, lead, and zinc) is a crucial foundational industry of the national economy. Its core equipment—metallurgical furnaces (such as anode furnaces, flash furnaces, and fuming furnaces)—contains extremely harsh internal environments. The furnace lining refractory materials are subjected to prolonged exposure to high temperatures (typically exceeding 1300℃), highly corrosive melts (metals, matte, slag, etc.), drastic temperature fluctuations, and the combined effects of alternating oxidizing and reducing atmospheres. Therefore, refractory materials are required to possess excellent resistance to slag erosion, high-temperature molten metal scouring, and metal molten metal penetration, while also exhibiting sufficient thermal shock stability.

[0003] Traditionally, to meet the stringent requirements for high-temperature strength, erosion resistance, and thermal shock resistance of refractory materials under the aforementioned harsh operating conditions, chromium-containing (Cr2O3) refractory materials are often used, such as alumina-chrome bricks made primarily of corundum and chromite. These bricks possess excellent resistance to the erosion of high-temperature melts. However, under alkaline environments and alternating redox atmospheres, Cr... 3+ It will be converted into toxic Cr 6 + It causes environmental pollution, harms human health, and has poor resistance to slag erosion.

[0004] CN102731126B discloses a composite spinel zirconium refractory material for non-ferrous heavy metal smelting, which is made from the following raw materials in the following weight proportions: 30-45 parts of 5mm-0mm corundum sand, 10-30 parts of 5mm-0mm magnesia-chrome sand, 15-25 parts of 3mm-1mm magnesia-alumina spinel sand, 7-20 parts of 3mm-0mm magnesia sand, 1-5 parts of ≤0.045mm chrome green, and 2-8 parts of ≤0.045mm zirconium dioxide, with liquid aluminum dihydrogen phosphate as the binder; the composite spinel zirconium refractory material is formed by a hydraulic press and fired in a high-temperature tunnel kiln. The composite spinel zirconium refractory material has a Cr2O3 content of less than 10%, and has certain resistance to slag erosion, high-temperature melt scouring, metal melt penetration, and thermal shock stability. However, its slag penetration depth is still relatively large, and its thermal shock stability is difficult to meet the requirements of extremely harsh parts.

[0005] CN109626970B discloses a refractory material for the furnace wall below the liquid line in a non-ferrous smelting melting furnace. This refractory material is suitable for use in the furnace wall below the liquid line in non-ferrous smelting melting furnaces. The composition of the refractory material is: aluminum-chromium eutectic, magnesium-chromium spinel, magnesium-aluminum spinel, α-alumina micropowder, aluminum-magnesium spinel, and a gel binder. This invention uses readily available and inexpensive ceramics made from aluminum-chromium eutectic, magnesium-chromium spinel, magnesium-aluminum spinel, α-alumina micropowder, and aluminum-magnesium spinel as raw materials. These materials are dry-mixed, pressed with water, dried, kiln-fired, and held at a constant temperature to finally obtain a refractory material for the furnace wall below the liquid line in a non-ferrous smelting melting furnace. The ceramics co-fired with magnesium-chromium spinel, α-alumina micropowder, and aluminum-magnesium spinel can reduce the porosity and pore size of the material, reduce slag accumulation in the refractory material, and improve the material's impermeability. However, its Cr2O3 content is 20% or even higher, which poses a high risk of environmental pollution, and its thermal shock resistance is generally poor.

[0006] CN110734275A discloses a low-silicon chromium corundum composite brick and its preparation method. It is made from fused white corundum, tabular corundum, fused chromium oxide, desilicationized zirconium, ultrafine alumina powder, and a binder. This method solves the problem of chromium corundum bricks resisting corrosion in weakly alkaline atmospheres, significantly extending the service life of kilns. However, the Cr2O3 content is still as high as 10% or more, and its resistance to molten metal penetration and thermal shock stability are generally poor.

[0007] CN105585322A discloses a slag-resistant magnesia spinel brick and its preparation method. The brick is composed of the following components by mass percentage: 61-81% fused magnesia sand particles and fine powder; 0-8% magnesia-alumina spinel particles; 3-10% magnesia-alumina spinel fine powder; 2-8% metallic aluminum powder; 0.5-3% titanium dioxide; 0.5-10% zirconium oxide fine powder; and 0.1-0.5% yttrium oxide powder. The magnesia spinel brick is obtained through material preparation, premixing, mixing, and molding steps. This method improves the high-temperature oxidation resistance and density of the magnesia spinel brick and does not contain Cr2O3. However, its thermal shock stability and resistance to copper slag erosion are generally poor, making it difficult to meet the harsh conditions of non-ferrous metal pyrometallurgical processes.

[0008] CN106278324A discloses a modified high-purity magnesium-aluminum spinel composite brick and its preparation method. The raw materials of the aggregate are composed of the following by weight: 65-80 parts of high-purity magnesia sand and 15-35 parts of high-purity magnesium-aluminum spinel; the raw materials of the powder are composed of the following by weight: 1-5 parts of fused magnesia sand powder, 1-5 parts of fused magnesia-aluminum spinel sand micro powder, 1-3 parts of fused magnesia-aluminum spinel sand ultrafine powder, 1-3 parts of desilicationized zirconium oxide, 1-3 parts of titanium oxide, 0.1-0.5 parts of sintering agent, 1-3 parts of activated alumina micro powder; and 3-4 parts of binder. This modified high-purity magnesium-aluminum spinel composite brick exhibits only average compressive strength and thermal shock resistance, making it difficult to meet the harsh conditions of non-ferrous metal pyrometallurgical processes.

[0009] With increasingly stringent environmental regulations, the development of chromium-free high-performance refractory materials has become an urgent need in the industry. However, the aforementioned chromium-free refractory materials struggle to achieve an ideal balance between thermal shock resistance, corrosion resistance, and high-temperature strength, and cannot completely replace traditional chromium-containing materials in extremely demanding applications. Summary of the Invention

[0010] In order to solve the above-mentioned technical problems in the existing technology, the purpose of this invention is to develop a chromium-free long-life magnesium-aluminum-zirconium composite refractory brick, which can avoid the environmental pollution problem of chromium, and has excellent high-temperature strength, excellent thermal shock resistance and strong resistance to slag erosion and penetration, thus meeting the requirements of modern non-ferrous smelting industry for long-life, high-efficiency and environmentally friendly furnace linings.

[0011] This invention discloses a chromium-free, long-life magnesia-alumina-zirconium composite refractory brick. The raw material composition, by mass percentage, comprises 75%-85% aggregate, 15%-25% matrix powder, and additives. The aggregate and matrix powder constitute 100% of the total mass, while the additives comprise 3%-5% of the total mass of the aggregate and matrix powder. The key feature is that the aggregate consists of 40%-60% fused magnesia particles and 10%-25% plate-shaped alumina particles, comprising the total mass of the aggregate and matrix powder. The composite refractory brick is composed of granules and 5%-15% pre-synthesized magnesium aluminum spinel particles; the matrix fine powder is composed of 5%-10% fused magnesia fine powder, 3%-8% active α-Al2O3 micro powder, 2%-6% zirconium dioxide micro powder and 1-3% metallic aluminum powder, accounting for 5%-10% of the total mass of the aggregate and matrix fine powder; the additive is thermosetting phenolic resin; the composite refractory brick is pressed and cured at 150℃-200℃, and then sintered at 1550℃-1650℃.

[0012] The aggregate consists of 40%-60% fused magnesia particles, 10%-20% plate-shaped alumina particles, and 10%-15% pre-synthesized magnesium aluminum spinel particles, accounting for 40%-60% of the total mass of the aggregate and matrix fine powder.

[0013] The matrix powder consists of 5%-10% fused magnesia powder, 3%-5% active α-Al2O3 micro powder, 2%-5% zirconium dioxide micro powder and 1-3% metallic aluminum powder, accounting for 1%-3% of the total mass of the aggregate and matrix powder.

[0014] The aggregate has the following particle size distribution: 3-5mm accounts for 15%-25%, 1-3mm accounts for 20%-30%, 0.1-1mm accounts for 20%-30%, and <0.1mm accounts for 15%-25%.

[0015] The MgO content in the fused magnesia particles and fused magnesia fine powder is ≥97.5wt%.

[0016] The Al2O3 content in the plate-shaped alumina particles is ≥99.5wt%.

[0017] The pre-synthesized magnesium aluminum spinel particles contain MgAl2O4 content ≥ 95 wt%.

[0018] The active α-Al2O3 micro powder contains ≥99.0 wt% Al2O3 and has a median particle size d. 50 <5μm.

[0019] The zirconium dioxide micropowder is partially stabilized zirconium oxide, with a ZrO2 content ≥ 94.5 wt% and a median particle size d. 50 <2μm.

[0020] The aluminum powder contains an Al content ≥ 98.5 wt% and a median particle size d. 50 <50μm.

[0021] A second aspect of the present invention also relates to a method for preparing the above-mentioned chromium-free long-life magnesium-aluminum-zirconium composite refractory brick, characterized by comprising the following steps:

[0022] a) Ingredients and mixing: Weigh the aggregate and matrix powder according to the proportion, dry mix them evenly, then add thermosetting phenolic resin for wet mixing to obtain mud.

[0023] b) Trapping: Trapping the mud material in a closed environment;

[0024] c) Shaping: Press the bundled mud material into shape to obtain brick blanks;

[0025] d) Curing: The brick blank is heat-treated at 150℃-200℃ to cure the additives;

[0026] e) High-temperature firing: The cured brick blank is fired at 1550℃-1650℃ to obtain the chromium-free long-life magnesium aluminum zirconium composite refractory brick.

[0027] In step e), the firing atmosphere is a reducing or weakly oxidizing atmosphere; the firing regime is as follows: the temperature is increased from room temperature to 600℃ at 2-3℃ / min, and then increased to 1550℃-1650℃ at 3-4℃ / min, and held for 6-10 hours.

[0028] This invention also relates to the application of the above-mentioned chromium-free long-life magnesium-aluminum-zirconium composite refractory bricks, used as refractory lining bricks for non-ferrous smelting furnaces and kilns.

[0029] Among them, refractory lining bricks are used in the anode furnace mouth, spray gun, siphon mouth of fuming furnace, and volatile slag line area of ​​non-ferrous smelting furnaces.

[0030] Compared with the prior art, the chromium-free long-life magnesium-aluminum-zirconium composite refractory brick of the present invention has the following beneficial effects:

[0031] The magnesium-aluminate-zirconium composite refractory brick of this invention contains no chromium-containing raw materials, fundamentally eliminating the risk of hexavalent chromium pollution and aligning with the green and environmentally friendly industrial development direction. The composite refractory brick utilizes a multi-element composite design of an aggregate system of "electrominated magnesia-plate alumina-presynthetic spinel" and a matrix system of "fine magnesia powder-activated alumina-zirconium oxide-metallic aluminum," combined with optimized particle size distribution, resulting in a dense material structure and high strength. In the aforementioned aggregate and matrix systems of this invention, the introduction of zirconium dioxide (partially stabilized zirconium oxide) and metallic aluminum powder during firing causes phase transformation and in-situ generation of non-oxide reinforcing phases, producing a microcrack toughening effect and strengthening grain boundaries. These mechanisms work together to significantly improve the material's resistance to rapid temperature changes, exhibiting excellent high-temperature strength. The composite structure formed by the refractory brick of this invention possesses excellent chemical stability and refractoriness, exhibits non-wetting properties against various slags, and has strong resistance to grain boundary erosion, effectively preventing slag penetration and erosion, and demonstrating good resistance to both slag and non-ferrous metal melts. The magnesium-aluminum-zirconium composite refractory brick of the present invention is particularly suitable for harsh parts such as furnace mouth, spray gun, siphon inlet, and slag line zone of non-ferrous smelting furnaces and kilns for copper, lead, zinc and other non-ferrous metallurgical processes. Practice has shown that it can significantly extend the service life of furnace lining and reduce production costs. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solution will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only a part of the embodiments of this invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0033] Key components such as the furnace mouth and lance of copper smelting anode furnaces, and the siphon inlet and slag line zone of lead-zinc smelting fuming furnaces, are the weakest links in the furnace lining structure due to their direct contact with the molten material, severe mechanical erosion, and frequent temperature changes. The lifespan of the refractory materials in these areas directly determines the production cost and safety stability of the entire smelting furnace. The chromium-free long-life magnesia-zirconium composite refractory brick of this invention, through a multi-component composite phase design combined with in-situ reaction enhancement and phase transformation toughening mechanisms, enables the material to simultaneously possess excellent high-temperature strength, thermal shock resistance, and resistance to molten slag erosion and penetration. Specifically, this invention provides a method for preparing chromium-free long-life magnesia-zirconium composite refractory bricks. The raw materials for the refractory bricks include aggregates and matrix fine powders. The aggregate system is fused magnesia-plate alumina-pre-synthetic spinel, and the matrix system is magnesia fine powder-activated alumina-zirconium oxide-metallic aluminum. The additive is thermosetting phenolic resin. The preparation method includes the following steps:

[0034] a) Ingredients and mixing: Weigh the aggregate and matrix powder according to the above proportions, mix these dry powders evenly, then add the added thermosetting phenolic resin for wet mixing until the mixture is evenly mixed to obtain mud.

[0035] b) Precipitation: The mud material is placed in a sealed environment for a period of time to allow the additives to fully penetrate and homogenize;

[0036] c) Molding: The trapped clay is placed in a mold and pressed into shape under a pressure of 100-150MPa to obtain a brick blank;

[0037] d) Curing: The brick blank is heat-treated at a temperature of 150℃-200℃ to fully cure the thermosetting phenolic resin;

[0038] e) High-temperature firing: The cured brick blank is placed in a kiln and fired at 1550℃-1650℃ for 6-10 hours to obtain the chromium-free long-life magnesium aluminum zirconium composite refractory brick of the present invention. The firing regime is as follows: the temperature is raised from room temperature to 600℃ at a heating rate of 2-3℃ / min, and then raised to the target temperature of 1550℃-1650℃ at a heating rate of 3-4℃ / min.

[0039] Unless otherwise specified in the following examples and comparative examples, for aggregates, the MgO content in the fused magnesia particles and fine fused magnesia powder is ≥97.5 wt%. The Al2O3 content in the plate-shaped alumina particles is ≥99.5 wt%. The MgAl2O4 content in the pre-synthesized magnesium aluminum spinel particles is ≥95 wt%. For matrix fine powder, the Al2O3 content in the active α-Al2O3 micro powder is ≥99.0 wt%, and the median particle size d... 50 <5μm; the zirconium dioxide micropowder is partially stabilized zirconium oxide, and the ZrO2 content is ≥94.5wt%, with a median particle size d50 <2μm; the aluminum powder contains ≥98.5wt% Al and has a median particle size d. 50 <50μm.

[0040] Example 1

[0041] The raw material ratio (wt%) of the magnesium-aluminum-zirconium composite refractory brick in this embodiment is as follows:

[0042] 75% aggregate

[0043] Fused magnesia particles: 40%, plate-shaped alumina particles: 20%, pre-synthesized magnesium aluminum spinel particles: 15%.

[0044] Aggregate particle size distribution: 3-5mm accounts for 20%, 1-3mm accounts for 25%, 0.1-1mm accounts for 25%, and <0.1mm accounts for 30%.

[0045] 25% fine matrix powder

[0046] Fused magnesia fine powder: 10%, activated α-Al2O3 micro powder: 8%, zirconium dioxide micro powder: 3%, metallic aluminum powder: 4%.

[0047] Additive: 4% thermosetting phenolic resin by weight of the total aggregate and matrix powder mentioned above.

[0048] The preparation method is as follows:

[0049] Weigh out each aggregate and matrix powder according to the proportion, and put them into the mixer and dry mix for 5 minutes.

[0050] Add thermosetting phenolic resin and wet mix for 15 minutes to obtain a uniform mud.

[0051] Transfer the mud into a sealed container and let it sit for 24 hours.

[0052] The well-conditioned clay is pressed into standard brick blanks under a pressure of 120MPa.

[0053] The brick blanks were cured at 180℃ for 12 hours.

[0054] The cured brick blanks are placed in a kiln and fired in a weak oxidizing atmosphere according to the following procedure: room temperature → 600℃ (heating rate of 2.5℃ / min), 600℃ → 1600℃ (heating rate of 3.5℃ / min), held at 1600℃ for 8 hours, and then cooled naturally to obtain the finished product.

[0055] Example 2

[0056] The raw material ratio (wt%) of the magnesium-aluminum-zirconium composite refractory brick in this embodiment is as follows:

[0057] 80% of aggregate

[0058] Fused magnesia particles: 50%, plate-shaped alumina particles: 20%, pre-synthesized magnesium aluminum spinel particles: 10%.

[0059] Aggregate particle size distribution: 3-5mm accounts for 20%, 1-3mm accounts for 25%, 0.1-1mm accounts for 25%, and <0.1mm accounts for 30%.

[0060] 20% fine matrix powder

[0061] Fused magnesia fine powder: 5%, activated α-Al2O3 micro powder: 8%, zirconium dioxide micro powder: 5%, metallic aluminum powder: 2%.

[0062] Additive: 4% thermosetting phenolic resin by weight of the total aggregate and matrix powder mentioned above.

[0063] The preparation method is as follows:

[0064] Weigh out each aggregate and matrix powder according to the proportion, and put them into the mixer and dry mix for 5 minutes.

[0065] Add thermosetting phenolic resin and wet mix for 15 minutes to obtain a uniform mud.

[0066] Transfer the mud into a sealed container and let it sit for 24 hours.

[0067] The well-conditioned clay is pressed into standard brick blanks under a pressure of 150MPa.

[0068] The brick blanks were cured at 150℃ for 20 hours.

[0069] The cured brick blanks are placed in a kiln and fired in a weak oxidizing atmosphere according to the following procedure: room temperature → 600℃ (heating rate of 2.5℃ / min), 600℃ → 1580℃ (heating rate of 3.5℃ / min), held at 1580℃ for 9 hours, and then cooled naturally to obtain the finished product.

[0070] Example 3

[0071] The raw material ratio (wt%) of the magnesium-aluminum-zirconium composite refractory brick in this embodiment is as follows:

[0072] 85% aggregate

[0073] Fused magnesia particles: 60%, plate-shaped alumina particles: 10%, pre-synthesized magnesium aluminum spinel particles: 15%.

[0074] Aggregate particle size distribution: 3-5mm accounts for 20%, 1-3mm accounts for 25%, 0.1-1mm accounts for 25%, and <0.1mm accounts for 30%.

[0075] 15% fine matrix powder

[0076] Fused magnesia fine powder: 5%, activated α-Al2O3 micro powder: 5%, zirconium dioxide micro powder: 3%, metallic aluminum powder: 2%.

[0077] Additive: 4% thermosetting phenolic resin by weight of the total aggregate and matrix powder mentioned above.

[0078] The preparation method is as follows:

[0079] Weigh out each aggregate and matrix powder according to the proportion, and put them into the mixer and dry mix for 5 minutes.

[0080] Add thermosetting phenolic resin and wet mix for 15 minutes to obtain a uniform mud.

[0081] Transfer the mud into a sealed container and let it sit for 24 hours.

[0082] The well-conditioned clay is pressed into standard brick blanks under a pressure of 150MPa.

[0083] The brick blanks were cured at 200℃ for 12 hours.

[0084] The cured brick blanks are placed in a kiln and fired in a weak oxidizing atmosphere according to the following procedure: room temperature → 600℃ (heating rate of 2.5℃ / min), 600℃ → 1650℃ (heating rate of 3.5℃ / min), held at 1650℃ for 9 hours, and then cooled naturally to obtain the finished product.

[0085] Comparative Example 1

[0086] The raw material proportions (wt%) of the magnesium-aluminum-zirconium composite refractory bricks in this comparative example are as follows:

[0087] 80% of aggregate

[0088] Fused magnesia particles: 70%, pre-synthesized magnesium aluminum spinel particles: 10%.

[0089] Aggregate particle size distribution: 3-5mm accounts for 20%, 1-3mm accounts for 25%, 0.1-1mm accounts for 25%, and <0.1mm accounts for 30%.

[0090] 20% fine matrix powder

[0091] Fused magnesia fine powder: 5%, activated α-Al2O3 micro powder: 8%, zirconium dioxide micro powder: 5%, metallic aluminum powder: 2%.

[0092] Additive: 4% thermosetting phenolic resin by weight of the total aggregate and matrix powder mentioned above.

[0093] The preparation method is as follows:

[0094] Weigh out each aggregate and matrix powder according to the proportion, and put them into the mixer and dry mix for 5 minutes.

[0095] Add thermosetting phenolic resin and wet mix for 15 minutes to obtain a uniform mud.

[0096] Transfer the mud into a sealed container and let it sit for 24 hours.

[0097] The well-conditioned clay is pressed into standard brick blanks under a pressure of 150MPa.

[0098] The brick blanks were cured at 150℃ for 20 hours.

[0099] The cured brick blanks are placed in a kiln and fired in a weak oxidizing atmosphere according to the following procedure: room temperature → 600℃ (heating rate of 2.5℃ / min), 600℃ → 1580℃ (heating rate of 3.5℃ / min), held at 1580℃ for 9 hours, and then cooled naturally to obtain the finished product.

[0100] Comparative Example 2

[0101] The raw material proportions (wt%) of the magnesium-aluminum-zirconium composite refractory bricks in this comparative example are as follows:

[0102] 80% of aggregate

[0103] Fused magnesia particles: 50%, plate-shaped alumina particles: 20%, pre-synthesized magnesium aluminum spinel particles: 10%.

[0104] Aggregate particle size distribution: 3-5mm accounts for 20%, 1-3mm accounts for 25%, 0.1-1mm accounts for 25%, and <0.1mm accounts for 30%.

[0105] 20% fine matrix powder

[0106] Fused magnesia fine powder: 5%, activated α-Al2O3 micro powder: 8%, zirconium dioxide micro powder: 5%, metallic aluminum powder: 2%.

[0107] Additive: 4% thermosetting phenolic resin by weight of the total aggregate and matrix powder mentioned above.

[0108] The preparation method is as follows:

[0109] Weigh out each aggregate and matrix powder according to the proportion, and put them into the mixer and dry mix for 5 minutes.

[0110] Add thermosetting phenolic resin and wet mix for 15 minutes to obtain a uniform mud.

[0111] Transfer the mud into a sealed container and let it sit for 24 hours.

[0112] The well-conditioned clay is pressed into standard brick blanks under a pressure of 150MPa.

[0113] The brick blanks were cured at 150℃ for 20 hours.

[0114] The cured brick blanks are placed in a kiln and fired in a weak oxidizing atmosphere according to the following procedure: room temperature → 600℃ (heating rate of 2.5℃ / min), 600℃ → 1750℃ (heating rate of 3.5℃ / min), held at 1750℃ for 9 hours, and then cooled naturally to obtain the finished product.

[0115] Comparative Example 3

[0116] The raw material proportions (wt%) of the composite refractory bricks in this comparative example are as follows:

[0117] 80% of aggregate

[0118] Fused magnesia particles: 50%, plate-shaped alumina particles: 20%, pre-synthesized magnesium aluminum spinel particles: 10%.

[0119] Aggregate particle size distribution: 3-5mm accounts for 20%, 1-3mm accounts for 25%, 0.1-1mm accounts for 25%, and <0.1mm accounts for 30%.

[0120] 20% fine matrix powder

[0121] Fused magnesia fine powder: 5%, titanium dioxide (TiO2≥99.5%, d 50 <0.5μm): 8%, Zirconia micro powder: 5%, Aluminum metal powder: 2%.

[0122] Additive: 4% thermosetting phenolic resin by weight of the total aggregate and matrix powder mentioned above.

[0123] The preparation method is as follows:

[0124] Weigh out each aggregate and matrix powder according to the proportion, and put them into the mixer and dry mix for 5 minutes.

[0125] Add thermosetting phenolic resin and wet mix for 15 minutes to obtain a uniform mud.

[0126] Transfer the mud into a sealed container and let it sit for 24 hours.

[0127] The well-conditioned clay is pressed into standard brick blanks under a pressure of 150MPa.

[0128] The brick blanks were cured at 150℃ for 20 hours.

[0129] The cured brick blanks are placed in a kiln and fired in a weak oxidizing atmosphere according to the following procedure: room temperature → 600℃ (heating rate of 2.5℃ / min), 600℃ → 1580℃ (heating rate of 3.5℃ / min), held at 1580℃ for 9 hours, and then cooled naturally to obtain the finished product.

[0130] Comparative Example 4

[0131] Fused magnesia-chrome bricks with a Cr2O3 content of approximately 20%.

[0132] The sample bricks prepared in the examples and comparative examples were tested for bulk density, room temperature compressive strength, high temperature flexural strength, and thermal shock resistance according to the testing standards for dense refractory materials. A static crucible method was used. Crucibles were prepared using the refractory materials from the examples and comparative examples described above. 100g of pyrometallurgical copper slag (the main components of the copper slag include: Cu 2.16wt%, S 1.29wt%, Fe 39.72wt%, SiO2 33.27wt%, Al2O3 3.48wt%, CaO 2.53wt%, PbO 0.82wt%) was placed in the crucible and then placed in an electric furnace. The furnace was heated to 1550℃ and held for 3 hours. This cycle was repeated 5 times. The slag was then longitudinally cut open to measure the penetration depth. The results are shown in Table 1 below.

[0133] Table 1 Performance Comparison of Examples and Comparative Examples

[0134]

[0135] The test results show that the chromium-free long-life magnesium-aluminum-zirconium composite refractory bricks provided in this embodiment of the invention are superior to the comparative example and traditional magnesium-chrome bricks in terms of room temperature compressive strength, high temperature flexural strength, and thermal shock resistance. At the same time, they exhibit much better resistance to slag erosion and can completely replace traditional chromium-containing refractory materials, meeting the usage requirements of key parts of non-ferrous smelting.

[0136] Industrial applicability

[0137] The refractory bricks prepared in Example 2 of this invention were applied to the furnace mouth of an anode furnace in a copper smelter. Compared with traditional magnesia-chrome bricks, the service life was extended from about 8 months to more than 14 months, an improvement of more than 75%, while avoiding chromium pollution, resulting in significant environmental and social benefits.

[0138] The above description is merely a preferred embodiment of the present invention. The present invention is illustrated through the above embodiments to demonstrate the concept and technical effects of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the scope of the principles of the present invention are permitted. Any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, selection of specific methods, etc., all fall within the protection scope of the present invention.

Claims

1. A chromium-free, long-life magnesium-aluminum-zirconium composite refractory brick, comprising, by mass percentage, 75%-85% aggregate, 15%-25% matrix powder, and admixtures, wherein the aggregate and matrix powder constitute 100% by mass, and the admixtures constitute 3%-5% by mass of the aggregate and matrix powder, characterized in that: The aggregate consists of 40%-60% fused magnesia particles, 10%-25% plate-shaped alumina particles, and 5%-15% pre-synthesized magnesium aluminum spinel particles, accounting for 40%-60% of the total mass of the aggregate and matrix fine powder; the matrix fine powder consists of 5%-10% fused magnesia fine powder, 3%-8% active α-Al2O3 micro powder, 2%-6% zirconium dioxide micro powder, and 1-3% metallic aluminum powder, accounting for 5%-10% of the total mass of the aggregate and matrix fine powder; the additive is thermosetting phenolic resin; the composite refractory brick is pressed and cured at 150℃-200℃, and then sintered at 1550℃-1650℃.

2. The chromium-free long-life magnesium-aluminum-zirconium composite refractory brick according to claim 1, characterized in that: The aggregate consists of 40%-60% fused magnesia particles, 10%-20% plate-shaped alumina particles, and 10%-15% pre-synthesized magnesium aluminum spinel particles, accounting for 40%-60% of the total mass of the aggregate and matrix fine powder.

3. The chromium-free long-life magnesium-aluminum-zirconium composite refractory brick according to claim 1, characterized in that: The matrix powder consists of 5%-10% fused magnesia powder, 3%-5% active α-Al2O3 micro powder, 2%-5% zirconium dioxide micro powder and 1-3% metallic aluminum powder, accounting for 1%-3% of the total mass of the aggregate and matrix powder.

4. The chromium-free long-life magnesium-aluminum-zirconium composite refractory brick according to any one of claims 1-3, characterized in that: The aggregate has the following particle size distribution: 3-5mm accounts for 15%-25%, 1-3mm accounts for 20%-30%, 0.1-1mm accounts for 20%-30%, and <0.1mm accounts for 15%-25%.

5. The chromium-free long-life magnesium-aluminum-zirconium composite refractory brick according to claim 1, characterized in that: The fused magnesia particles and fine fused magnesia powder contain MgO content ≥ 97.5 wt%, the plate-shaped alumina particles contain Al2O3 content ≥ 99.5 wt%, and the pre-synthesized magnesium aluminum spinel particles contain MgAl2O4 content ≥ 95 wt%.

6. The chromium-free long-life magnesium-aluminum-zirconium composite refractory brick according to claim 1, characterized in that: The active α-Al2O3 micro powder contains ≥99.0 wt% Al2O3 and has a median particle size d. 50 <5μm; the zirconium dioxide micropowder is partially stabilized zirconium oxide, and the ZrO2 content is ≥94.5wt%, with a median particle size d 50 <2μm; the aluminum powder contains ≥98.5wt% Al and has a median particle size d. 50 <50μm.

7. The method for preparing chromium-free long-life magnesium-aluminum-zirconium composite refractory bricks according to any one of claims 1-6, characterized in that... Includes the following steps: a) Ingredients and mixing: Weigh the aggregate and matrix powder according to the proportion, dry mix them evenly, then add thermosetting phenolic resin for wet mixing to obtain mud. b) Trapping: Trapping the mud material in a closed environment; c) Shaping: Press the bundled mud material into shape to obtain brick blanks; d) Curing: The brick blank is heat-treated at 150℃-200℃ to cure the additives; e) High-temperature firing: The cured brick blank is fired at 1550℃-1650℃ to obtain the chromium-free long-life magnesium aluminum zirconium composite refractory brick.

8. The method for preparing the chromium-free long-life magnesium-aluminum-zirconium composite refractory brick according to claim 7, characterized in that: In step e), the firing atmosphere is a reducing or weakly oxidizing atmosphere; the firing regime is to raise the temperature from room temperature to 600℃ at 2-3℃ / min, then raise it to 1550℃-1650℃ at 3-4℃ / min, and hold it for 6-10 hours.

9. The application of the chromium-free long-life magnesium-aluminum-zirconium composite refractory brick according to any one of claims 1-6, characterized in that: Refractory lining bricks used in non-ferrous metal smelting furnaces and kilns.

10. The application of the chromium-free long-life magnesium-aluminum-zirconium composite refractory brick according to claim 9, characterized in that: Refractory lining bricks used in the opening of anode furnaces, spray guns, siphon inlets of fuming furnaces, and volatile slag line zones of non-ferrous smelting furnaces.

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