High-aluminum low-creep heat-insulation refractory mortar

Abstract

The invention discloses a high-aluminum low-creep heat-insulation refractory mortar. The slurry comprises the following components in percentage by mass in an anhydrous manner: 40-60% of recycled white corundum sand blasting powder; 20-30% of recycled titanium iron slag powder; 7-15% of calcined alumina powder; 3-7% of 95SiC dust extraction powder; 4-6% of floating bead powder; 4-6% of a polymer plasticizer; 0.05-0.15% of sodium tripolyphosphate is added, and 0.1-0.2% of sodium carbonate is added; wherein the calcined alumina powder is a-Al2O3 micro powder obtained by mixing industrial alumina and hydrated alumina powder, performing high-temperature calcination and then performing grinding treatment, particles of the calcined alumina powder are mainly sheet-shaped and columnar, and particle size distribution is of a unimodal structure. The obtained slurry is high in bonding breaking strength, high in refractoriness under load, small in slurry reheating linear change rate and small in high-temperature creep deformation, meanwhile, a large number of recycled waste materials are adopted, mineral resources are saved, and the method has wide application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory slurries, and in particular relates to a high-aluminum low-creep heat-insulating refractory slurry. Background Art

[0002] With the rapid development of the steel industry, the refractory materials used in furnace linings have increased significantly. Refractory mud is a joint material used for masonry of refractory bricks, unburned bricks, prefabricated parts or industrial kilns. The common amount is about 3-5% of the shaped products. In the past three years, the annual consumption of refractory mud has reached more than 600,000 tons, and the market demand is huge.

[0003] Refractory slurry is required to have good construction performance, good spreadability, no water seepage, kneading, to ensure that the slurry joints are full, and the thickness of the joints is met in accordance with the furnace construction specifications. It is required to have sufficient bonding strength to bond large volumes of refractory masonry into a solid whole; it is required to have excellent volume stability, so that the masonry will not be damaged due to excessive expansion or contraction due to high temperature when the temperature fluctuates; it is required to have good high temperature performance, and can effectively resist the erosion of the atmosphere and slag. When laying insulation bricks, it is required to have a certain thermal conductivity, and the creep of the refractory slurry is small.

[0004] High-temperature equipment such as blast furnace hot blast furnaces are built with refractory materials. In high-temperature use environments, the materials need to have high load softening temperature and good creep resistance. When the temperature of the hot blast furnace is greater than 1300℃, the hot blast furnace will be deformed due to high-temperature mechanical loads, and cracked and peeled due to frequent temperature changes. In particular, the high-alumina bricks used to build the top of the hot blast furnace are built with traditional high-alumina insulation mud. Traditional high-alumina insulation mud uses a large amount of high-alumina powder. Under long-term high temperature and load, the material will creep and deform and the structure will be damaged. Therefore, it is particularly important to develop low-creep high-alumina insulation refractory mud.

[0005] In order to meet basic needs, traditional refractory mud adds a lot of raw clay, sodium carboxymethyl cellulose, yellow dextrin, phosphate, cement or organic resin to the mud powder to adjust its various properties. During construction, 20-35% of the powder mass of liquid is added to make it an easy-to-apply slurry. While these binders and additives meet the basic use requirements of the mud, they affect the high-temperature performance of the refractory mud. Especially at the top of the hot blast furnace where the working environment is relatively harsh, high-aluminum insulating refractory mud is often the weakest link, which is the root cause of the masonry body going offline early, seriously affecting the safety and life of the industrial kiln.

[0006] Invention patent CN 201410836277.8 discloses a high-alumina slurry and a preparation method thereof. The slurry is prepared using high-alumina powder, dextrin, sodium carboxymethyl cellulose, and silicon micropowder to solve the problem of insufficient slurry due to low water addition ratio when laying high-alumina bricks for ladle. However, there are problems such as large high-temperature shrinkage of the material and low load softening temperature of the material.

[0007] Invention patent 202211149068.7 discloses a high-alumina mud and its use method, which uses 35-45% specially calcined high-alumina bauxite fine aggregate; 6-10% alumina powder; 9-10% submicron SiO2 powder; 36-48% specially calcined high-alumina bauxite powder, 0.5-1.5% aluminum lactate, and 0.3-0.5% dispersant. The high-alumina mud has the characteristics of low water addition, good density, and no low melting point bonding phase, which can achieve synchronous damage of bricks and mud. However, there are problems of high material cost and poor material creep performance.

[0008] Invention patent 201510533914.9 discloses a low-temperature sintering refractory slurry and a preparation method thereof, which uses clay powder, andalusite powder, carboxymethyl cellulose, dextrin, boric glass and sodium tripolyphosphate to solve the problem that the refractory slurry in the premixing chamber of the hot blast furnace cannot be sintered. However, there are problems such as poor high-temperature performance of the material, low load softening temperature of the material, and easy melting of the material at high temperature. Summary of the invention

[0009] The purpose of the present invention is to provide a high-aluminum low-creep insulating refractory slurry with strong bonding flexural strength, high load softening temperature, small slurry reburning line change rate, small high-temperature creep and excellent comprehensive performance.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] Provided is a high-aluminum low-creep heat-insulating refractory slurry, which, in terms of anhydrous, comprises the following components by mass percentage: 40-60% of recycled white corundum sandblasting powder; 20-30% of recycled ferrotitanium slag powder; 7-15% of calcined alumina powder; 3-7% of 95SiC dust extraction powder; 4-6% of floating bead powder; 4-6% of polymer plasticizer; 0.05-0.15% of sodium tripolyphosphate and 0.1-0.2% of soda ash; wherein:

[0012] The calcined alumina powder is a-Al2O3 powder obtained by mixing industrial alumina and hydrated alumina powder in a mass ratio of 48 to 50:1, calcining at 1450-1500°C for 4.5-5.5h, and then grinding. The calcined alumina powder is mainly in the form of flakes and columns, and the particle size distribution presents a single peak structure. The particle size distribution D 10=0.21-0.25μm, D50=0.61-0.68μm, D90=2.18-2.25μm, D99=5.31-5.48μm.

[0013] According to the above scheme, the Al2O3 content of the calcined alumina powder is 99.5-99.8wt%, and the Na2O content is 0.15-0.30wt%.

[0014] According to the above scheme, the recycled white corundum sandblasting powder is the dust removal powder collected and processed during the production of white corundum powder.

[0015] Preferably, the recycled white corundum sandblasting powder has an Al2O3 content of 93.0-96.5wt%, a SiO2 content of 1.0-2.0wt%, and a Fe2O3 content of 0.5-1.5wt%.

[0016] Preferably, the particle size of 0.074 mm to 0.5 mm accounts for 20-30% and the particle size of <0.074 mm accounts for 70-80%.

[0017] According to the above scheme, the recovered ferro-titanium slag powder is obtained by grinding the recovered waste slag produced by smelting ferro-titanium alloy, and the main phases are calcium hexaaluminate, calcium dialuminate and calcium titanate.

[0018] Preferably, in the recovered ferro-titanium slag powder, the Al2O3 content is 74.0-78.0wt%, the SiO2 content is 0.3-0.7wt%, the Fe2O3 content is 0.15-0.25wt%, the TiO2 content is 11.3-13.9wt%, the CaO content is 9.0-11.5wt%, and the MgO content is 0.7-1.3wt%.

[0019] Preferably, the particle size of 0.074 mm to 0.5 mm accounts for 10-40% and the particle size of <0.074 mm accounts for 60-90%.

[0020] According to the above scheme, the 95SiC dust powder is waste material recovered when producing silicon carbide fine powder, with a SiC content of 94.5-96.5wt%, a SiO2 content of 1.0-1.5wt%, and a particle size of <0.044mm.

[0021] According to the above scheme, the Al2O3 content of the floating bead powder is 25-35wt%, the SiO2 content is 45-65wt%, of which the particle size of 0.075mm-0.5mm accounts for 25-55% and the particle size of <0.074mm accounts for 45-75%.

[0022] According to the above scheme, the polymer plasticizer is prepared by reacting carboxymethyl cellulose, polyurethanes and glycol ether. Preferably, the molar ratio of carboxymethyl cellulose, polyurethanes and glycol ether is (1.5-2):1:(9-11). The plasticizer binder adopts a clever polymer combination, has high purity, can thicken and retain water, can adjust the bonding time of mud, and improve the bonding strength of mud.

[0023] According to the above scheme, the soda ash is Na2CO3, the purity is greater than 99.5%, and the color is white.

[0024] According to the above scheme, the mud also includes 20-25% of water.

[0025] According to the above scheme, the Al2O3 in the high-alumina refractory slurry is ≥70% (%), the bonding flexural strength (110℃×24h) is ≥3.0MPa, the bonding flexural strength (1500℃×3h) is ≥8.0MPa, the load softening temperature (0.2MPa, T2.0) is ≥1600℃, the bonding time (S) is 60-180s, the re-firing line change rate (1500℃×3h) is -1%-+1%, and the low creep rate is -0.3%-+0.3%.

[0026] The present invention provides a high-alumina low-creep heat-insulating refractory slurry, which is prepared by using calcined activated alumina powder as a binder, coordinating the recovery of white corundum sandblasting powder, titanium iron slag powder and polymer plasticizer, and then combining 95SiC dust extraction powder, floating bead powder, sodium tripolyphosphate and soda ash, wherein:

[0027] Calcined activated alumina is obtained by high-temperature calcination of industrial alumina and hydrated alumina powder. The powder has a small particle size, a single-peak structure in particle size distribution, a staggered structure of flaky and columnar shapes, and self-binding properties. It can be directly used as a binder for high-alumina mud, effectively avoiding the production of low-melting phase at high temperatures when using traditional binders such as yellow dextrin, clay, and dihydrogen aluminum phosphate solution. Using calcined activated alumina powder as a binder can greatly improve the load softening temperature and creep resistance of the mud at medium and high temperatures, so that the high-alumina mud and high-alumina bricks can maintain consistency in erosion damage at medium and high temperatures.

[0028] The recovered titanium iron slag powder contains a certain amount of TiO2, which can promote the reaction of Al2O3 and SiO2 in high-alumina mud at 1300℃ to generate mullite and amorphous SiO2. This reaction is accompanied by volume expansion. At the same time, amorphous SiO2 reacts with the binder calcined alumina powder to undergo secondary mullitization, which produces corresponding volume expansion. The recovered dust powder contains a large amount of SiC. SiC begins to oxidize and decompose to generate SiO2 at about 1250℃, which expands in volume. The generated SiO2 reacts with the binder calcined alumina powder, and mullitization again produces volume expansion. These reactions can occur quickly and efficiently, which is also based on the characteristics of calcined alumina powder with small particle size, large specific surface area, high activity, and close combination with the mud components as a binder. At the same time, the calcined alumina powder participates in the mullitization reaction, which further promotes the combination between the mud components and better plays the role of the binder. It is precisely because the volume expansion caused by multiple mullite formations offsets the contraction of the high-alumina slurry at high temperature, which causes the load softening temperature of the high-alumina slurry to have a multi-peak superposition effect, further increasing its load softening temperature.

[0029] In addition, polymer plasticizers can further enhance the strength of calcined activated alumina powder as a binder at low temperatures, because polymer plasticizers increase the viscosity of the material and make various powders more tightly packed. Polymer plasticizers will burn out at high temperatures and will not affect the high-temperature performance, which can maintain the relative "purity" of the material at high temperatures. Ultimately, it can also improve the high-temperature performance of the material.

[0030] The beneficial effects of the present invention are as follows:

[0031] The invention provides a high-aluminum low-creep heat-insulating refractory mud, which uses calcined active alumina powder as a binder, synergistically recovers white corundum sandblasting powder, recovers ferrotitanium slag powder and a polymer plasticizer, and is further prepared by combining 95SiC dust extraction powder, bleaching bead powder, sodium tripolyphosphate and soda ash. The obtained mud has a low water addition ratio, strong material bonding flexural strength, high load softening temperature, small mud reburning line change rate, small high-temperature creep, and excellent comprehensive performance, and avoids the problem of mud and brick delamination and brick falling caused by aggravated sintering shrinkage of high-aluminum heat-insulating mud. At the same time, the mud of the invention uses a large amount of recycled waste, protects the environment, saves mineral resources, and has broad application prospects. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] The specific indicators of the raw materials in the embodiments of the present invention are as follows:

[0034] The recycled white corundum sandblasting powder has an Al2O3 content of 93.0-96.5wt%, a SiO2 content of 1.0-2.0wt%, and a Fe2O3 content of 0.5-1.5wt%. The recycled white corundum sandblasting powder is dust-removed powder collected and processed during the production of white corundum powder, of which 0.074mm-0.5mm particle size accounts for 20-30% and <0.074mm particle size accounts for 70-80%.

[0035] The recovered ferrotitanium slag powder has an Al2O3 content of 74.0-78.0wt%, a SiO2 content of 0.3-0.7wt%, a Fe2O3 content of 0.15-0.25wt%, a TiO2 content of 11.3-13.9wt%, a CaO content of 9.0-11.5wt%, and a MgO content of 0.7-1.3wt%. The ferrotitanium slag is waste slag produced by smelting ferrotitanium alloy, and its main phases are calcium hexaaluminate, calcium dialuminate and calcium titanate. The recovered ferrotitanium slag powder is collected and ground into powder, wherein the particle size of 0.074mm-0.5mm accounts for 10-40% and the particle size of <0.074mm accounts for 60-90%.

[0036] The 95SiC dust powder is waste material recovered when producing silicon carbide fine powder, with a SiC content of 94.5-96.5wt%, a SiO2 content of 1.0-1.5wt%, and a particle size of <0.044mm.

[0037] The Al2O3 content of the floating bead powder is 25-35wt%, the SiO2 content is 45-65wt%, of which the particle size of 0.075mm-0.5mm accounts for 25-55% and the particle size of less than 0.074mm accounts for 45-75%.

[0038] The high-efficiency mud plasticizer binder PT2301 is a product of a chemical company in Wuhan. It is a white powder. PT2301 is a polymer plasticizer binder prepared by the reaction of carboxymethyl cellulose: polyurethane: glycol ether = 2:1:10. The plasticizer binder adopts a clever polymer combination, has high purity, can thicken and retain water, can adjust the bonding time of mud, improve the bonding strength of mud, and improve the load softening temperature of mud.

[0039] The soda ash is Na2CO3, the purity is greater than 99.5%, and the color is white.

[0040] The calcined alumina powder is a-Al2O3 powder obtained by mixing 98% industrial alumina and 2% hydrated alumina powder, calcining at 1480°C for 5 hours, and then grinding. The particles are mainly flake and columnar, and the Al2O3 content is 99.5-99.8wt%, and the Na2O content is 0.15-0.30wt%. The particle size distribution of the calcined alumina powder presents a single peak structure, and its particle size distribution D 10=0.23μm, D50=0.65μm, D90=2.21μm, D99=5.38μm. The calcined alumina powder has a certain viscosity after being dissolved in water. The alumina powder is added into 35% pure water and stirred to form, and its demoulding compressive strength can reach 2MPa.

[0041] Example 1

[0042] Provided is a high-alumina low creep heat-insulating refractory slurry, wherein the components of the slurry are calculated by mass percentage as follows on an anhydrous basis:

[0043]

[0044] Example 2

[0045] Provided is a high-alumina low creep heat-insulating refractory slurry, wherein the components of the slurry are calculated by mass percentage on an anhydrous basis:

[0046]

[0047] Example 3

[0048] Provided is a high-alumina low creep heat-insulating refractory slurry, wherein the components of the slurry are calculated by mass percentage on an anhydrous basis:

[0049]

[0050] Comparative Example 1

[0051] Provided is a high-alumina heat-insulating refractory slurry combined with traditional yellow dextrin and clay, wherein the components are calculated by mass percentage as follows:

[0052] White corundum powder 50%, 83 high alumina powder 33.5%, floating bead powder 4%, 98 silicon carbide powder 5%, clay powder 6%, yellow dextrin 1.5%, sodium tripolyphosphate 0.18% (added), soda ash 0.15% (added).

[0053] Table 1 Physical and chemical properties test results of high aluminum low creep insulation refractory slurry of the present invention

[0054]

[0055] The high-aluminum low creep insulation refractory mud obtained in the embodiment of the present invention is applied to Indonesian export hot blast furnace projects, Jiangsu steel plant projects, Shandong Lingang hot blast furnace projects, etc. The mud has high bonding strength, high load softening temperature, and low high-temperature creep, which avoids the problem of mud and brick delamination and brick falling due to the aggravated sintering shrinkage of high-aluminum insulation mud. At the same time, the mud of the invention uses a large amount of recycled waste, protects the environment, and saves mineral resources.

[0056] The above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of the invention.

Claims

1. A high-alumina low creep insulating refractory slurry, characterized in that: On an anhydrous basis, the components of the slurry are calculated by mass percentage as follows: 40-60% of recycled white corundum sandblasting powder; 20-30% of recycled ferrotitanium slag powder; 7-15% of calcined alumina powder; 3-7% of 95SiC dust extraction powder; 4-6% of floating bead powder; 4-6% of polymer plasticizer; 0.05-0.15% of sodium tripolyphosphate and 0.1-0.2% of soda ash; wherein: The calcined alumina powder is an α-Al2O3 powder obtained by mixing industrial alumina and hydrated alumina powder in a mass ratio of 48 to 50:1, calcining at 1450-1500°C for 4.5-5.5h, and then grinding. The calcined alumina powder is mainly in the form of flakes and columns, and the particle size distribution presents a single peak structure. The particle size distribution D 10 =0.21-0.25μm, D50=0.61-0.68μm, D90=2.18-2.25μm, D99=5.31-5.48μm.

2. The refractory slurry according to claim 1, characterized in that: The calcined alumina powder has an Al2O3 content of 99.5-99.8wt% and a Na2O content of 0.15-0.30wt%.

3. The refractory slurry according to claim 1, characterized in that: The recycled white corundum sandblasting powder is dust-removed powder collected and processed during the production of white corundum powder; the recycled ferrotitanium slag powder is obtained by grinding the recycled waste slag produced by smelting ferrotitanium alloy, and its main phases are calcium hexaaluminate, calcium dialuminate and calcium titanate.

4. The refractory slurry according to claim 1 or 3, characterized in that: The recovered white corundum sandblasting powder has an Al2O3 content of 93.0-96.5wt%, a SiO2 content of 1.0-2.0wt%, and a Fe2O3 content of 0.5-1.5wt%; the recovered ferrotitanium slag powder has an Al2O3 content of 74.0-78.0wt%, a SiO2 content of 0.3-0.7wt%, a Fe2O3 content of 0.15-0.25wt%, a TiO2 content of 11.3-13.9wt%, a CaO content of 9.0-11.5wt%, and a MgO content of 0.7-1.3wt%.

5. The refractory slurry according to claim 1 or 3, characterized in that: In the recycled white corundum sandblasting powder, 0.074mm-0.5mm particle size accounts for 20-30% and particle size <0.074mm accounts for 70-80%; in the recycled titanium iron slag powder, 0.074mm-0.5mm particle size accounts for 10-40% and particle size <0.074mm accounts for 60-90%.

6. The refractory slurry according to claim 1, characterized in that: The 95SiC dust powder is waste recovered from the production of silicon carbide fine powder, with a SiC content of 94.5-96.5wt%, a SiO2 content of 1.0-1.5wt%, and a particle size of <0.044mm; the floating bead powder has an Al2O3 content of 25-35wt%, a SiO2 content of 45-65wt%, of which the particle size of 0.075mm-0.5mm accounts for 25-55% and the particle size of <0.074mm accounts for 45-75%.

7. The refractory slurry according to claim 1, characterized in that: The polymer plasticizer is prepared by reacting carboxymethyl cellulose, polyurethane and glycol ether.

8. The refractory slurry according to claim 7, characterized in that: The molar ratio of carboxymethyl cellulose, polyurethane and glycol ether is (1.5-2):1:(9-11).

9. The refractory slurry according to claim 1, characterized in that: The slurry also includes an additional 20-25% of water.

10. The refractory slurry according to claim 1, characterized in that: In the high-alumina refractory slurry, Al2O3≥70%, the bonding flexural strength at 110℃×24h≥3.0MPa, the bonding flexural strength at 1500℃×3h≥8.0MPa, the 0.2MPa, T2.0 load softening temperature≥1600℃, the bonding time is 60-180s, the re-firing line change rate at 1500℃×3h is -1%-+1%, and the creep rate at 1500℃×3h and 0.1MPa is -0.3%-+0.3%.

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