Castable for hot-state repair of hot blast stove and application thereof

Abstract

The application discloses a castable for hot-state repair of hot blast stove and application thereof, and the castable is composed of the following components in percentage by mass: fused mullite 50-60%, dense corundum powder 22-32%, alpha-Al2O3 micro powder 5-10%, submicron silicon micro powder 2-5%, perlite 4-7%, foaming agent 0.5-1%, and solidifying agent 0.4-1%; the mass of the above components is 100%, and 7-9% of the weight of the above components is added with silicon sol; wherein the perlite is closed perlite; and the foaming agent has a decomposition temperature of 110-160 DEG C. The castable has the advantages of high medium-high temperature strength, volume stability, effective resistance to hot blast erosion and corrosion, good heat preservation and heat insulation performance, reduced heat loss, safe and stable protection of the tube shell, and prolonged service life of the hot blast pipe network.

Description

Technical Field

[0001] This invention belongs to the field of castable technology, specifically relating to a castable for hot blast stove repair and its application. Background Technology

[0002] With the rapid development of blast furnace ironmaking technology and the significant increase in smelting intensity, hot blast stoves provide high-temperature hot air for blast furnace smelting. With the advancement of high blast temperature and high blast pressure technology, the lining of its pipeline system is in a more demanding operating environment. The phenomenon of lining brick falling off and collapsing occurs frequently, and the phenomenon of air leakage in the pipeline is serious. The temperature of the steel shell rises to 130-300℃ or even turns red, resulting in a series of equipment damages, reducing the efficiency of the hot blast stove, and seriously affecting the operational safety of the pipeline. It is necessary to repair the pipeline lining.

[0003] The hot blast stove piping typically consists of a heavy brick layer, a light brick layer, fiber felt, a sprayed coating, and a steel shell, from the inside out. The heavy brick layer is in direct contact with the hot air, resisting erosion from the airflow, while the others serve as insulation layers to reduce heat loss and protect the steel shell. When the piping lining is damaged and spalled off, requiring hot-state repair, heavy high-strength castable refractory is generally used in the upper half-ring repair area of ​​the steel shell. The castable refractory completely replaces the heavy brick layer and other insulation layers. While the material effectively resists erosion from the hot air, the removal of the insulation layers makes it difficult to lower the steel shell surface temperature below 100°C, resulting in poor thermal insulation performance, significant heat loss, and reduced hot blast stove efficiency. Adding ordinary insulation materials directly to the castable refractory, while improving insulation performance, reduces its wear resistance and erosion resistance.

[0004] Ensuring both the mechanical properties and thermal insulation performance of the castable during hot blast stove repair is a pressing issue. Summary of the Invention

[0005] The purpose of this invention is to provide a castable for hot repair of hot blast stoves and its application. The castable can form an integral structure from the inside out, consisting of a heavy, high-strength, dense castable working layer, a thermal insulation casting layer, and a lightweight insulation layer. It not only has the advantages of high strength at medium and high temperatures, volume stability, and effective resistance to hot air erosion, but also has good thermal insulation performance, reducing a large amount of heat loss, protecting the steel shell for safety and stability, and extending the service life of the hot air pipeline network.

[0006] To achieve the above objectives, the following technical solution is adopted:

[0007] A castable refractory for hot repair of a hot blast stove is provided, the composition of which, by mass percentage, is:

[0008] The composition comprises: 50-60% fused mullite, 22-32% dense corundum powder, 5-10% α-Al₂O₃ micro powder, 2-5% submicron silica micro powder, 4-7% perlite, 0.5-1% foaming agent, and 0.4-1% curing agent; the above components constitute 100% by weight, plus 7-9% by weight of silica sol; wherein:

[0009] The perlite is closed-cell perlite;

[0010] The foaming agent decomposes at a temperature of 110–160°C.

[0011] According to the above scheme, the electrofused mullite has Al2O3≥70%, Fe2O3≤0.8%, and the particle size is composed of 0~1mm, 1~3mm, 3~5mm, and 5~8mm.

[0012] According to the above scheme, the dense corundum powder has an Al2O3 content of ≥99% and a particle size of ≤0.074mm.

[0013] According to the above scheme, the α-Al2O3 micro powder meets the following requirements: Al2O3≥99%, D50≤1.5μm.

[0014] According to the above scheme, the submicron silicon powder SiO2 ≥ 99%, 100nm ≤ D90 ≤ 1 micron.

[0015] According to the above scheme, the perlite is closed-cell perlite with a particle size of 1–3 mm and a bulk density of 0.1–0.2 g / cm³. 3 .

[0016] According to the above scheme, the foaming agent is a nitrosamine derivative with a decomposition temperature of 110–160°C; preferably, the average particle size is 7–9 μm; more preferably, it is a WT-9 type white solid powder. The decomposition product of the foaming agent is CO2, which is used for foaming.

[0017] According to the above scheme, the curing agent is magnesium oxide.

[0018] According to the above scheme, the silica sol has a specific gravity of 1.21 to 1.25, a pH of 7 to 9, and an average particle size of 10 to 20 nm.

[0019] This invention provides an application of the aforementioned castable material in the hot repair of the lining of a hot blast stove pipe network.

[0020] According to the above scheme, the specific application is as follows: first, formwork is erected for the part that needs to be poured, then the well-mixed casting material is introduced into the pouring part, and the casting material is compacted by vibrating tools.

[0021] The hot air temperature inside the pipe is generally between 1200 and 1300℃. After the hot air furnace stops supplying air, the temperature inside the pipe drops. Construction is carried out when the temperature drops to 500-800℃, completing the hot repair at high temperature. Based on the pipe thickness, the internal pouring thickness is generally about 600-800mm. The closer to the center, the higher the temperature, and vice versa. During the construction of the castable refractory of this invention, the portion of the castable refractory with a thickness of 200-300mm near the center of the inner side of the ring is directly exposed to a high temperature of 500-800℃. At this temperature, the foaming agent in the castable refractory becomes ineffective. In this portion of the castable refractory, mullite and dense corundum have good wear resistance and erosion resistance. When used together, the material has good thermal shock stability. Combined with α-Al2O3 micro powder, ultrafine submicron silica powder and silica sol, the resulting castable refractory has high strength, high density, and volume stability after sintering at medium and high temperatures. It effectively resists hot air erosion and has good integrity, avoiding weak parts such as brickwork joints. It can be used as a working layer. For the portion of the castable refractory outside the 300mm of the ring, since the ambient temperature drops below 200℃, the foaming agent in the castable refractory decomposes. During the vibration process, bubbles are generated and evenly distributed inside the castable refractory in this portion. After the castable refractory hardens, it forms a porous thermal insulation casting layer. Meanwhile, perlite, being lightweight, floats to the surface of the castable during the compaction process. After hardening, it forms a lightweight insulation layer, further enhancing its thermal insulation properties. Upon completion of the casting, an integrated structure is formed, comprising a heavy, high-strength, dense castable working layer, a thermal insulation casting layer, and a lightweight insulation layer. This conforms to the design principles of each layer in a hot air duct, saving significant heat energy loss and effectively protecting the steel shell for safety and stability.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention provides a castable for hot repair of hot blast stoves. The main components are fused mullite, dense corundum powder, α-Al₂O₃ micropowder, submicron silica, a curing agent, and added silica sol. It is combined with a foaming agent with a suitable decomposition temperature and lightweight closed-cell perlite with low water absorption. By cleverly utilizing the characteristic that the distance between the castable rings and the center varies with temperature, an integral structure is formed from the inside out, consisting of a heavy, high-strength, dense castable working layer, a thermal insulation casting layer, and a lightweight insulation layer. After sintering at medium to high temperatures, it exhibits high strength, high density, volume stability, effective resistance to hot air erosion, and good overall integrity. It also possesses excellent thermal insulation properties, effectively saving energy and protecting the safety and stability of the steel shell, demonstrating significant application potential. Detailed Implementation

[0024] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0025] This invention provides a castable for hot repair of a hot blast stove, the composition of which, by mass percentage, is as follows:

[0026] The composition consists of 50-60% fused mullite, 22-32% dense corundum powder, 5-10% α-Al2O3 micro powder, 2-5% submicron silica micro powder, 4-7% perlite, 0.5-1% foaming agent, and 0.4-1% curing agent; the above components constitute 100% by weight, plus 7-9% by weight of silica sol.

[0027] In the following detailed implementation method, the specific indicators of each raw material are as follows:

[0028] The electrofused mullite contains Al2O3≥70%, Fe2O3≤0.8%, and its particle size ranges from 0 to 1 mm, 1 to 3 mm, 3 to 5 mm, and 5 to 8 mm.

[0029] Dense corundum powder with Al2O3 ≥ 99% and particle size ≤ 0.074 mm.

[0030] α-Al2O3 micro powder meets the following requirements: Al2O3≥99%, D50≤1.5μm.

[0031] Submicron silicon powder SiO2 ≥ 99%, 100nm ≤ D90 ≤ 1 micron.

[0032] The perlite is closed-cell perlite, with a grain size of 1–3 mm and a bulk density of 0.1–0.2 g / cm³. 3 .

[0033] The foaming agent is a white solid powder of type WT-9, which is a nitroso salt derivative with a decomposition temperature of 110-160℃ and an average particle size of 8μm.

[0034] The curing agent is magnesium oxide.

[0035] Silica sol has a specific gravity of 1.21–1.25, a pH of 7–9, and an average particle size of 10–20 nm.

[0036] Example 1

[0037] A castable refractory for hot repair of a hot blast stove is provided, the composition of which, by mass percentage, is:

[0038] The composition consists of 55% fused mullite, 30% dense corundum powder, 5% α-Al2O3 micro powder, 3% submicron silica micro powder, 6% perlite, 0.5% foaming agent, 0.5% curing agent, and 8.6% silica sol by weight of the above components.

[0039] After testing, the surface temperature of the steel shell dropped to below 100℃, which is within the normal range, reducing heat loss, strain and fatigue wear, and ensuring stable operation of the pipeline.

[0040] Comparative Example 1

[0041] The composition of the dense castable used in some of the repaired projects, by mass percentage, is as follows:

[0042] The composition consists of 69% mullite, 19.5% dense corundum powder, 8% α-Al2O3 micro powder, 3% silica micro powder, 0.4% curing agent, and 6.7% silica sol by weight of the above components.

[0043] After the hot air duct was repaired, the surface temperature of the steel shell was basically in the range of 110 to 130°C.

[0044] Example 2

[0045] A castable refractory for hot repair of a hot blast stove is provided, the composition of which, by mass percentage, is:

[0046] The composition consists of 58% fused mullite, 23% dense corundum powder, 8% α-Al2O3 micro powder, 5% submicron silica micro powder, 5% perlite, 0.5% foaming agent, 0.5% curing agent, and 8.3% silica sol by weight of the above components.

[0047] After testing, the surface temperature of the steel shell dropped to below 100℃, which is within the normal range, reducing heat loss, strain and fatigue wear, and ensuring stable operation of the pipeline.

[0048] Example 3

[0049] A castable refractory for hot repair of a hot blast stove is provided, the composition of which, by mass percentage, is:

[0050] The composition consists of 60% fused mullite, 22% dense corundum powder, 10% α-Al2O3 micro powder, 3% submicron silica micro powder, 4% perlite, 0.6% foaming agent, 0.4% curing agent, and 7.9% silica sol by weight of the above components.

[0051] After testing, the surface temperature of the steel shell dropped to below 100℃, which is within the normal range, reducing heat loss, strain and fatigue wear, and ensuring stable operation of the pipeline.

[0052] Example 4

[0053] A castable refractory for hot repair of a hot blast stove is provided, the composition of which, by mass percentage, is:

[0054] The composition consists of 53% fused mullite, 28% dense corundum powder, 6% α-Al2O3 micro powder, 4% submicron silica micro powder, 7% perlite, 1% foaming agent, 1% curing agent, and 8.9% silica sol by weight of the above components.

[0055] After testing, the surface temperature of the steel shell dropped to below 100℃, which is within the normal range, reducing heat loss, strain and fatigue wear, and ensuring stable operation of the pipeline.

[0056] Example 5

[0057] A castable refractory for hot repair of a hot blast stove is provided, the composition of which, by mass percentage, is:

[0058] The composition consists of 50% fused mullite, 32% dense corundum powder, 7% α-Al2O3 micro powder, 4% submicron silica micro powder, 5.5% perlite, 0.7% foaming agent, 0.8% curing agent, and 8.5% silica sol by weight of the above components.

[0059] After testing, the surface temperature of the steel shell dropped to below 100℃, which is within the normal range, reducing heat loss, strain and fatigue wear, and ensuring stable operation of the pipeline.

[0060] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. Use of castable for hot state repair of hot blast stove in hot state repair of hot blast stove pipe network lining, characterized in that, In a specific application, the castable is introduced into a casting site and vibrated and compacted; The castable comprises, by mass percentage: 50~60% of electrically fused mullite, 22~32% of dense corundum powder, 5~10% of α-Al2O3 micro powder, 2~5% of submicron silicon micro powder, 4~7% of perlite, 0.5~1% of foaming agent, 0.4~1% of curing agent, and the mass of the above components being 100%; additionally, 7~9% of silicon sol by weight of the above components is added; wherein: The perlite is closed perlite, bulk density 0.1~0.2 g / cm 3 ; The foaming agent has a decomposition temperature of 110~160℃.

2. Use according to claim 1, characterized in that, The electrically fused mullite has Al2O3≥70% and Fe2O3≤0.8%, and the particle size is composed of 0~1mm, 1~3mm, 3~5mm, and 5~8mm.

3. Use according to claim 1, characterized in that, The dense corundum powder has Al2O3≥99% and a particle size ≤0.074mm.

4. Use according to claim 1, characterized in that, The α-Al2O3 micro powder meets the following requirements: Al2O3≥99% and D50≤1.5μm.

5. The use according to claim 1, characterized in that, The submicron silicon micro powder has SiO2≥99% and 100nm≤D90≤1μm.

6. Use according to claim 1, characterized in that, The perlite has a particle size of 1~3mm.

7. The use according to claim 1, characterized in that, The foaming agent is a nitroso salt derivative.

8. The use according to claim 1, characterized in that, The curing agent is magnesium oxide.

9. The use according to claim 1, characterized in that, The silicon sol has a specific gravity of 1.21~1.25, a pH of 7~9, and an average particle size of 10~20nm.