CN116135815A

CN116135815A - Lining castable for integral casting of blast furnace belly pipe

Info

Publication number: CN116135815A
Application number: CN202111354871.XA
Authority: CN
Inventors: 阮国智; 张智慧; 邱文冬; 王庆恒
Original assignee: Baowu Equipment Intelligent Technology Co Ltd
Current assignee: Baowu Equipment Intelligent Technology Co Ltd
Priority date: 2021-11-16
Filing date: 2021-11-16
Publication date: 2023-05-19

Abstract

The invention discloses a lining castable for integral casting of a blast furnace belly pipe, which comprises the following components in parts by weight: 10-12 parts of liquid silica sol, 2-5 parts of calcium aluminate cement, 50-60 parts of mullite with 70 aluminum content, 10-20 parts of brown corundum, 7-20 parts of silicon carbide, 6-12 parts of alpha-activated alumina micropowder and 3-8 parts of silica micropowder. The castable overcomes the preparation problems that the castable of the conventional belly pipe needs to be maintained for a long time after casting is finished and needs to be baked at the temperature of more than 450 ℃ according to a strict baking system, has high wear resistance and good thermal shock resistance stability, and can effectively resist corrosion of slag iron to refractory materials when slag is poured into a blast furnace tuyere.

Description

Lining castable for integral casting of blast furnace belly pipe

Technical Field

The invention belongs to the technical field of refractory materials, and particularly relates to a lining castable for integral casting of a blast furnace belly pipe.

Background

With the development of blast furnace smelting technology and the application of high wind temperature, high wind pressure, high oxygen enrichment and large coal injection, the working condition of a blast furnace air inlet device is worsened, the air inlet device is equipment for feeding hot air (1150-1300 ℃ and 0.3-0.55 MPa) in a hot air surrounding pipe of an ironmaking blast furnace into the blast furnace, and in practical application, the air inlet device is easy to crack, burn or burn through and other accidents, particularly a belly pipe, is limited by objective conditions such as a small sleeve of an air inlet, and has the advantages of thinner pipe body, thinner refractory material layer, complex working condition, easy occurrence of accidents such as redness, burning through and the like, has to be changed by damping down and severely restricts ironmaking production.

Another important reason for the occurrence of the above phenomenon is that the strength and the heat insulation performance of the refractory material are contradictory, and the refractory material with high strength has poor heat insulation performance, causes high surface temperature, has large heat loss and has short service life; the refractory material with good heat insulation has low strength, is not resistant to hot wind scouring and has short service life. With the progress of blast furnace smelting technology, high wind temperature and high wind pressure operation, and popularization and application of oxygen-enriched blowing technology, the air inlet device, in particular to a belly pipe, have higher requirements. In order to ensure the safe operation of the blast furnace air inlet device under the severe working condition for a long time, and simultaneously to provide safety guarantee for the development of blast furnace smelting to high wind temperature, high wind pressure, oxygen enrichment, coal injection and the like, the design, manufacturing quality and performance of the air inlet device must be higher and higher, and in particular, higher requirements are put forward on lining refractory materials of the belly pipe.

Besides reasonable structural design, the belly pipe is very important to internally cast refractory materials. The belly pipe needs to have long service life, and the refractory material has the functions of high temperature resistance, scouring resistance, heat preservation and heat insulation. The higher the density of the refractory material is, the higher the strength is, and the better the scouring resistance is; however, the higher the density is, the better the heat conducting property is, which not only causes the surface temperature of the belly pipe to be too high and even red, but also causes the heat to be greatly lost. Conversely, the smaller the density, the poorer the heat conducting property, the better the heat preservation and insulation of the refractory material, and the lower the surface temperature of the belly pipe. However, the lower the density of the refractory, the lower the strength, and the poorer the resistance to flushing, and the refractory is easily damaged by hot air flushing.

In order to improve the service life of the belly pipe, chinese patent document CN207567262U discloses a safe long-life blast furnace air supply device belly pipe, which comprises an outer steel shell and a refractory lining layer, wherein the shell comprises an outer layer pipe body and an inner layer pipe body, a cooling water circulation cavity is arranged between the outer layer pipe body and the inner layer pipe body, and a water inlet pipe and a water outlet pipe are arranged at the rear section of the shell. The belly pipe is reinforced by adopting a water cooling design, so that the safety design of the belly pipe is improved; the lining of the resistant material is made of cement combined corundum mullite, the resistant material of the belly pipe needs long-time maintenance, the requirement on baking equipment is high, otherwise, the castable is easy to crack, and the use is influenced.

Chinese patent document CN208038483U discloses a fire-resistant belly pipe for blast furnace air supply device, which comprises a housing and a refractory material layer arranged in the housing, wherein the housing is formed by welding a ball head housing and a carbon steel housing, the refractory material layer extends from the inner wall of the ball head housing to the outer port of the ball head housing, and the refractory material layer coats the outer port of the ball head housing. The belly pipe is formed by wrapping the outer port of the ball head shell by the refractory material layer, so that hot air is isolated from directly blowing the ball head shell, and the situation that the joint part between the refractory material layer and the ball head shell is cracked and falls off under the action of the hot air is avoided; and two ring grooves are formed in the ball head shell, and the refractory material layer is tamped in the ring grooves, so that the contact area between the refractory material layer and the ball head shell can be increased, the integral adhesive force between the heat-insulating refractory material and the ball head shell is increased, and the high-temperature incineration tendency of the heat-insulating refractory material layer is reduced. However, the refractory material and the steel shell have different coefficients of thermal expansion, and when the blast furnace is in a damping down operation, the abrupt temperature change easily causes the falling off of the refractory material and the steel shell, thereby affecting the use of the belly pipe.

Chinese patent document CN204298416U discloses a prefabricated liner belly pipe, which comprises a steel shell, an inner prefabricated pipe and a light heat-insulating layer casting material filled between the steel shell and the inner prefabricated pipe, wherein the prefabricated pipe is formed by combining two or three sections of pipe fittings. The belly pipe is made of a prefabricated part by using a working layer refractory material contacted with hot air, and a light heat insulation material is adopted between the prefabricated part and the steel shell. The joint part of the prefabricated member combination is Z-shaped, and the joint part is bonded and sealed by fire clay. The working layer of the belly pipe adopts the high-strength prefabricated pipe, the heat-insulating layer adopts the light heat-insulating material, the contradiction between the heat-resistant wind scouring and the heat insulation of a single refractory material is solved, the surface temperature of the steel shell is low, the energy is saved, and the service life of the belly pipe is prolonged by more than 50 percent. And the three sections of prefabricated pipe fittings are combined into the integral working layer pipe, so that the yield is improved. The prefabricated pipe casting material adopts high aluminum refractory casting material, the heat preservation layer adopts mullite light casting material, and the thickness of the prefabricated pipe is designed to be about 20-30 mm according to the blast furnace belly pipe structures with different furnace capacities. And curing the prefabricated pipe for 72 hours at normal temperature after demoulding. Curing, then putting into a drying furnace, heating slowly, and baking (500-600 ℃) for 24 hours. However, the thickness of the effective working layer is thinner, the thickness of the prefabricated pipe is only about 30mm under the process conditions of high wind temperature, high wind pressure, high oxygen enrichment and large coal injection, the heat preservation layer cannot be used continuously after abrasion, and the service life is difficult to be effectively improved.

The journal literature (China metallurgy, 2020,30 (8): 15-20, cui Yuanyuan, etc.) "describes the damage cause and mechanism of the belly pipe castable in detail, and indicates that the mullite castable combined by aluminate cement has low medium temperature strength and is easy to generate structural flaking; poor slag resistance and is easy to be corroded by blast furnace slag. Therefore, it is suggested to improve the quality of the raw material, reduce the impurity mass fraction, and reduce the influence of alkali metal on aluminate cement in particular; and andalusite or kyanite sintering agent is added, so that the medium-temperature strength and slag resistance of the castable are improved, the porosity is reduced, and the overall service life of the belly pipe is greatly prolonged.

Disclosure of Invention

The invention aims to solve the technical problem of providing a lining castable for integral casting of a blast furnace belly pipe, which overcomes the preparation problems that the castable of the existing belly pipe needs to be maintained for a long time after casting is finished and needs to be baked at the temperature of more than 450 ℃ according to a strict baking system, has high wear resistance and good thermal shock stability, and can effectively resist corrosion of slag iron to refractory materials during slag filling at a blast furnace tuyere.

In order to solve the technical problems, the lining castable for integrally casting the blast furnace belly pipe comprises the following components in parts by weight: 10-12 parts of liquid silica sol, 2-5 parts of calcium aluminate cement, 50-60 parts of mullite with 70 aluminum content, 10-20 parts of brown corundum, 7-20 parts of silicon carbide, 6-12 parts of alpha-activated alumina micropowder and 3-8 parts of silica micropowder.

Further, the castable is a composite structure of liquid silica sol and calcium aluminate cement, wherein the solid phase content of silicon oxide in the liquid silica sol is 20-40%, and the solidification time regulator of the liquid silica sol is 2-8% of the liquid silica sol; the calcium aluminate cement is pure calcium aluminate cement with the alumina content of 68-72 percent.

Further, the granularity of the silicon carbide is 1-0 mm or 180 meshes.

Further, the brown corundum particle size is 1-0 mm or 180 meshes.

Further, the mullite is sintered mullite with aluminum content of 70 percent and granularity of 8-1 mm.

The lining castable for integral casting of the blast furnace belly pipe adopts the technical scheme that the castable comprises the following components in parts by weight: 10-12 parts of liquid silica sol, 2-5 parts of calcium aluminate cement, 50-60 parts of mullite with 70 aluminum content, 10-20 parts of brown corundum, 7-20 parts of silicon carbide, 6-12 parts of alpha-activated alumina micropowder and 3-8 parts of silica micropowder. The castable overcomes the preparation problems that the castable of the conventional belly pipe needs to be maintained for a long time after casting is finished and needs to be baked at the temperature of more than 450 ℃ according to a strict baking system, has high wear resistance and good thermal shock resistance stability, and can effectively resist corrosion of slag iron to refractory materials when slag is poured into a blast furnace tuyere.

Detailed Description

The lining castable for integral casting of the blast furnace belly pipe comprises the following components in parts by weight: 10-12 parts of liquid silica sol, 2-5 parts of calcium aluminate cement, 50-60 parts of mullite with 70 aluminum content, 10-20 parts of brown corundum, 7-20 parts of silicon carbide, 6-12 parts of alpha-activated alumina micropowder and 3-8 parts of silica micropowder.

Preferably, the castable is a composite structure of liquid silica sol and calcium aluminate cement, wherein the solid phase content of silicon oxide in the liquid silica sol is 20-40%, and the solidification time regulator of the liquid silica sol is 2-8% of the amount of the liquid silica sol; the calcium aluminate cement is pure calcium aluminate cement with the alumina content of 68-72 percent.

Preferably, the granularity of the silicon carbide is 1-0 mm or 180 meshes.

Preferably, the brown corundum particle size is 1-0 mm or 180 meshes.

Preferably, the mullite is sintered mullite with 70 percent of aluminum content and the granularity is 8-1 mm.

Example 1

54 parts of mullite, 13 parts of brown corundum, 10 parts of silicon carbide, 2.5 parts of calcium aluminate cement, 6 parts of alpha-activated alumina micropowder and 3.5 parts of silica micropowder are taken as a castable matrix, and 11 parts of silica sol is added for uniform stirring and casting molding.

Example 2

50 parts of mullite, 12 parts of brown corundum, 15 parts of silicon carbide, 2.5 parts of calcium aluminate cement, 6 parts of alpha-activated alumina micropowder and 3.5 parts of silica micropowder are taken as a castable matrix, and 11 parts of silica sol is added for uniform stirring and casting molding.

Example 3

50 parts of mullite, 10 parts of brown corundum, 15 parts of silicon carbide, 4.5 parts of calcium aluminate cement, 6 parts of alpha-activated alumina micropowder and 3.5 parts of silica micropowder are taken as a castable matrix, and 11 parts of silica sol is added for uniform stirring and casting molding.

Example 4

54 parts of mullite, 10 parts of brown corundum, 10 parts of silicon carbide, 2.5 parts of calcium aluminate cement, 9 parts of alpha-activated alumina micropowder and 5 parts of silica micropowder are taken as a castable matrix, and 10 parts of silica sol is added for uniform stirring and casting molding.

The castable properties of examples 1 to 4 were tested and the results are shown in the following table:

the data in the table show that the castable has high-temperature strength and good binding property, and the erosion resistance and durability of the material are obviously improved after sintering.

When the castable is practically applied, firstly, a layer of heat insulation coating with the thickness of 3 mm-7 mm is coated in the steel shell of the blast furnace belly pipe, the service temperature is more than 400 ℃, or a layer of nano heat insulation plate with the thickness of 5mm is attached, the heat insulation coating or the heat insulation plate forms a heat insulation layer of the steel shell of the belly pipe, the heat insulation layer is utilized to solve the heat insulation problem of the belly pipe, and the rest parts are integrally cast by adopting the castable.

The solid raw materials of the casting material are uniformly stirred and then are packaged for standby, and the casting material is prepared according to the following steps during castingAdding liquid silica sol in proportion, and stirring uniformly for use. Silica sol is polysilicic acid dispersion system with particle size from several nanometers to tens of nanometers, when silica sol is mixed with Al ₂ O ₃ When the micro powder is mixed, the colloid particles can be adsorbed on Al ₂ O ₃ The particle surface forms single-layer saturation distribution and is filled with Al ₂ O ₃ The particle gaps are good in dispersibility and permeability. The colloid particles are combined by chemical bonds (Si-O-Si) to form a stable space network structure through drying or sintering treatment, and Al is added into the mixture ₂ O ₃ The particles are firmly bonded together and are bonded with Al ₂ O ₃ The surface of the particles forms a nanocomposite structure coated with nano-particles. Meanwhile, the silica sol is covered on the solid surface to form a firm silica gel film, so that the bonding, curing and forming properties of the material are enhanced. The silica sol binding material has the following characteristics that (1) the silica sol binding material can be quickly baked without maintenance, the sol binding castable is colloid gel to generate a binding refractory material, the sol gel is greatly influenced by pH value, and the curing time of the material meeting construction requirements can be effectively controlled by adjusting the pH value. The gel is crystallized in the material, and the produced micro pores can effectively discharge the water vapor generated in the material during the rapid baking, and has a higher water discharge temperature range than the cement binding material, and (2) the gel has good volume stability and thermal shock resistance, and a large number of experiments prove that the line change of the sol binding material after being sintered at 800 ℃ multiplied by 3 h is basically zero, and the line change rate after being sintered at 100 ℃ multiplied by 3 h is only about +0.2%. The requirement on the volume stability of the refractory material in the industrial kiln production is well met, and (3) the CO corrosion resistance is good.

The silicon carbide raw material has excellent wear resistance and molten iron and slag corrosion resistance, the wear resistance and slag corrosion resistance of the liner of the belly pipe can be improved by introducing the silicon carbide into the castable, and the oxidation behavior of the silicon carbide material is protective oxidation when the temperature of the silicon carbide material is lower than 1250 ℃, so that the silicon carbide can fully exert the excellent performance under the application condition.

The castable overcomes the difficulty that the existing belly pipe refractory needs special equipment for long-time baking production, can effectively avoid the bursting property during curing and quick baking compared with the traditional cement binding material, shortens the construction period and the baking period, effectively solves the problem that the low-temperature strength of the silica sol binding castable is lower by composite introduction of the calcium aluminate cement binding agent, improves the initial strength, is convenient for demoulding, and is more beneficial to use, production and manufacture; the method can also be used for on-site emergency maintenance and repair, and the cast iron runner is baked by using an on-site heat source near the iron runner of the blast furnace after casting, so that the method is particularly suitable for on-site use of the blast furnace. Meanwhile, the material has good wear resistance, so that the problems that the surface temperature is high and even the phenomenon of redness often occurs in the use of the belly pipe, burn-through occurs in severe cases, the belly pipe needs to be replaced by damping down, and the iron-making production is severely restricted are effectively solved. The castable can effectively improve the wear resistance, molten iron resistance and slag erosion resistance of the material, reduce the erosion of blast furnace tuyere slag filling to the castable, improve the thermal stability and the service life of the material, and realize long-life use of the belly pipe.

Claims

1. The utility model provides a inside lining castable that is used for blast furnace belly pipe integral casting which characterized in that: the lining castable comprises the following components in parts by weight: 10-12 parts of liquid silica sol, 2-5 parts of calcium aluminate cement, 50-60 parts of mullite with 70 aluminum content, 10-20 parts of brown corundum, 7-20 parts of silicon carbide, 6-12 parts of alpha-activated alumina micropowder and 3-8 parts of silica micropowder.

2. The lining castable for integral casting of blast furnace belly pipes according to claim 1, wherein: the castable is a composite structure of liquid silica sol and calcium aluminate cement, wherein the solid phase content of silicon oxide in the liquid silica sol is 20-40%, and the solidification time regulator of the liquid silica sol is 2-8% of the liquid silica sol; the calcium aluminate cement is pure calcium aluminate cement with the alumina content of 68-72 percent.

3. The lining castable for integral casting of blast furnace belly pipes according to claim 1, wherein: the granularity of the silicon carbide is 1-0 mm or 180 meshes.

4. The lining castable for integral casting of blast furnace belly pipes according to claim 1, wherein: the granularity of the brown corundum is 1-0 mm or 180 meshes.

5. The lining castable for integral casting of blast furnace belly pipes according to claim 1, wherein: the mullite is sintered mullite with aluminum content of 70 percent and granularity of 8-1 mm.