CN113416067B

CN113416067B - Anti-oxidation impact-resistant castable for ladle, preparation method and ladle

Info

Publication number: CN113416067B
Application number: CN202110658645.4A
Authority: CN
Inventors: 周旺枝; 徐国涛; 赵元; 张洪雷; 刘黎
Original assignee: Wuhan Iron and Steel Co Ltd
Current assignee: Wuhan Iron and Steel Co Ltd
Priority date: 2021-06-15
Filing date: 2021-06-15
Publication date: 2022-08-26
Anticipated expiration: 2041-06-15
Also published as: CN113416067A

Abstract

The invention discloses an anti-oxidation and anti-impact castable for a ladle, which comprises the following substances in percentage by mass: sintering the mullite aggregate: 50-65%, andalusite: 3-8%, silicon carbide: 3-14%, electrically fused mullite fine powder: 10-30%, zirconium mullite fine powder: 0.01% -5%, alumina micropowder: 0.1-3%, aluminum powder: 0.05-0.1%, pure calcium aluminate cement binder: 3-6% of NaHCO ₃ : 0.01-0.1%, boric acid: 0.02-0.12%, water glass: 0.01-0.3%; water reducing agent FDN: 0.03 to 0.13 percent. The invention also discloses a preparation method of the anti-oxidation and anti-impact castable for the ladle and the ladle. The invention enhances the strength of the ladle bottom and the working layer at the lower side of the ladle wall, and the impact resistance and the oxidation resistance of molten steel and scrap steel blocks, and solves the problem of the lower side of the ladle bottom and the ladle wall in a targeted manner.

Description

Anti-oxidation impact-resistant castable for ladle, preparation method and ladle

Technical Field

The invention relates to a castable for a ladle, in particular to an anti-oxidation and anti-impact castable for the ladle, and also relates to a preparation method of the castable and the ladle, belonging to the field of refractory materials for steelmaking.

Background

The ladle is an important carrier for bearing molten iron transportation, and the safety and stability of the operation of the ladle directly influence the smooth operation of steel-making production and influence the energy consumption and cost of the working procedure. During the use of the ladle, the ladle lining is subjected to the scouring, soaking, thermal shock, mechanical abrasion and erosion of slag and iron of 1300-1400 ℃, and some steel plants also need to perform desulfurization operation on the ladle. With the demand of steel works for reducing the iron-steel ratio, the steel works in China add scrap steel into ladles, so that the scrap steel ratio in the steel production process is improved, but the impact and erosion on ladle linings are also aggravated, for example, the furnace life is checked for 800 times before 150t of ladles are added in a certain steel plant, and the furnace life is reduced to 600 times after the scrap steel is added.

As a refractory material for a ladle, the refractory material has the key requirements of thermal shock impact resistance, desulfurizing agent and slag corrosion resistance and mechanical stress impact resistance for cleaning slag bonding at the bottom of the ladle. At present, ladles of many steel mills adopt a masonry mode that an aluminum silicon carbide carbon brick working layer and a light clay brick are used as a permanent layer. The working layer of the ladle is directly contacted with high-temperature molten iron and scrap steel, the carbon materials such as graphite and the like in the working layer are oxidized and loosened by iron oxide to cause poor strength, the working layer is firstly corroded, the anti-scouring capability is rapidly reduced, and meanwhile, under the condition of containing carbon, the heat conductivity coefficient is higher, so that the temperature drop of the molten iron is increased. The scrap steel is added into the ladle, the temperature is reduced after the scrap steel is added into the ladle, the scrap steel is not melted or solidified into lumps, thermal shock and mechanical stress shock of the ladle bottom and the ladle lining at the lower side are increased, the ladle bottom and the ladle lining of the ladle are damaged, and the service life of the ladle is seriously influenced.

Chinese patent publication No. CN108101556A discloses a carbonaceous unshaped refractory for foundry ladles, which comprises: the refractory aggregate is silica, the powder comprises quartz sand, fly ash and metallurgical coke powder, and the binder comprises coal-based asphalt, wherein the mass ratio of the components is as follows: quartz sand: fly ash: metallurgical coke powder: 40-60 parts of coal-based asphalt: 5-10 parts of: 10-20 parts of: 10-20 parts of: 5 portions, the carbonaceous refractory material and the aluminate refractory material of the invention have the advantages of high temperature resistance and lower cost of the refractory material produced by adopting silica and fly ash. However, the carbonaceous material is easily oxidized when directly contacted with high-temperature molten iron and scrap steel, so that the material is loosened and damaged, and the service life of the ladle is reduced. The Chinese patent with publication number CN107344860A discloses a casting material for a hot metal ladle, which comprises the following components in parts by weight: alumina: 50-70 parts of silicon dioxide: 10-40 parts of mullite: 10-20 parts of heat-resistant steel fiber: 3-6 parts, adding water: 5-7 parts. The pouring method comprises the following steps: cleaning the interior of the molten iron tank and the mold, and coating lubricating grease on the contact surface of the mold and the casting material; building a layer of high-alumina bricks with the thickness of 35mm in a molten iron tank as a permanent layer, and installing and adjusting an inner membrane tool; sequentially carrying out dry mixing and wet mixing on the components of the castable; pouring the wet mixed pouring material into a mould, and vibrating by using a vibrating rod during pouring; after the casting material is molded, naturally curing for 24 hours, and demolding; and after the mould is removed, naturally curing in the air for 48 hours, and then baking. The castable for the hot metal ladle has high strength and good thermal shock resistance, but has insufficient slag and desulfurizer erosion resistance.

Under the trend of large scrap ratio in the metallurgical industry, a novel thermal shock impact resistant heat preservation ladle is urgently developed. In order to prolong the service life of the ladle lining, a novel ladle with good impact resistance, erosion resistance and heat preservation property must be developed according to the problems in the existing using process of the ladle and the targeted improvement of the structure and the material.

Disclosure of Invention

The technical problem to be solved by the invention is to provide an anti-oxidation and anti-impact castable for a ladle, which overcomes the limitations that a refractory material of a working layer at the lower side of the ladle is easy to oxidize, the thermal shock impact resistance is poor, the heat preservation performance is poor and the like in the use process of adding scrap steel into the existing ladle, and meets the process requirement of adding scrap steel into the ladle at a large scrap steel ratio.

The invention is realized in such a way that:

an anti-oxidation impact-resistant castable for a ladle comprises the following substances in percentage by mass: sintering the mullite aggregate: 50-65%, andalusite: 3-8%, silicon carbide: 3-10%, electrically fused mullite fine powder: 10-30%, zirconium mullite fine powder: 0.01% -5%, alumina micropowder: 0.1-3%, aluminum powder: 0.05-0.1%, pure calcium aluminate cement binder: 3-6% of NaHCO ₃ : 0.01-0.1%, boric acid: 0.02-0.12%, water glass: 0.01-0.3%; water reducing agent FDN: 0.03 to 0.13 percent.

The mullite is adopted because the mullite has the advantages of high content, large volume density, good thermal shock stability, small creep at high temperature, good chemical corrosion resistance and the like, and is suitable for the use environment of the casting material of the ladle reinforcing layer. The aggregate is sintered mullite, and the matrix is fused mullite fine powder, so that the performance of the castable can be ensured, and the cost can be saved.

The zirconium mullite is prepared by introducing ZrO into mullite ₂ Can further improve the chemical resistance of the mulliteErosion, thermal shock resistance and reduced expansion coefficient.

The silicon carbide and the alumina micro powder are added to partially replace the binding agent calcium aluminate cement to form low-cement combination, thereby improving the medium-high temperature strength of the castable. Meanwhile, silicon carbide is added, so that the wear resistance of the castable can be effectively improved, and the erosion resistance of the inner lining of the ladle can be more effectively improved. However, the addition of excessive silicon carbide can affect the medium-low temperature strength of the castable.

The added alumina micropowder can play a role of a matrix on one hand, and can fill pores among large, medium and small particles so as to improve the volume density of the castable blank and reduce the porosity. The purpose of reducing the water adding amount can be achieved due to the extrusion of air. The micro powder has larger specific surface area and reactivity, so that the sintering can be carried out at lower temperature.

The andalusite expands in the mullite generating process at high temperature, so that sintering shrinkage at high temperature can be effectively counteracted, the volume stability of the reinforced layer casting material is ensured, the andalusite is not completely mullite, a multi-item composite material structure is formed, and the mismatch of various mineral expansion coefficients is facilitated to improve the thermal shock stability. After the andalusite is mullite at high temperature, the matrix forms a network microstructure with mutually interwoven knitted mullite, so that the refractoriness under load and creep resistance of the product can be improved.

The metal aluminum powder is added, in the process of sintering the sample, the metal aluminum powder is melted to fill aggregate particles, the volume expansion effect generated by the oxidation of aluminum enables the material to become more compact, the metal aluminum is melted at high temperature and then is agglomerated, and the formed local continuous metal phase is filled among the particles of the material, thereby playing a positive role in absorbing stress and preventing stress expansion.

NaHCO ₃ And boric acid as a retarder can delay the hardening time of the casting material, and is beneficial to ensuring the site construction time.

The sodium silicate can effectively improve the workability and plasticity of the casting material and can improve the compactness and strength of the casting material. The water reducing agent FDN has obvious water reducing and dispersing effects, the water reducing rate is 15-30%, the water adding amount can be effectively reduced, and the strength of the reinforced layer casting material is improved.

The further scheme is as follows:

ZrO in fine zirconium mullite powder ₂ The weight percentage content of the components is as follows: 5-25%;

the further scheme is as follows:

the grain diameter of the mullite aggregate is as follows: 1-5 mm;

the further scheme is as follows:

the particle size of the andalusite is as follows: 0.1-0.01 mm;

the further scheme is as follows:

the grain diameter of the silicon carbide is less than 0.088 mm;

the further scheme is as follows:

the particle size of the aluminum powder is as follows: less than 0.01 mm;

the further scheme is as follows:

the grain diameters of the zirconium mullite fine powder and the electric smelting mullite fine powder are as follows: less than 0.074 mm;

the further scheme is as follows:

the grain diameter of the alumina micro powder is as follows: 3-6 μm;

the invention also discloses a preparation method of the anti-oxidation and anti-impact castable for the ladle, which specifically comprises the following steps:

putting andalusite and calcium aluminate cement which are weighed according to the mass ratio into a mixer to be mixed for 5-25 min to obtain premix A for later use; adding silicon carbide, fused mullite, zirconium mullite fine powder, aluminum powder and an additive which are weighed according to a mass ratio into a mixer, and stirring for 15-35 min to obtain a premix B for later use; and (3) dry-mixing the premix A and the premix B in a stirrer for 10-30 min to obtain the refractory castable for the ladle.

The invention also provides a foundry ladle, which is structurally divided into 3 layers from outside to inside: the outer layer is a light mullite casting material heat preservation permanent layer, the middle is a mullite andalusite silicon carbide brick working layer which is built by staggered joints, and the innermost reinforcing layer is formed by casting an anti-oxidation and anti-impact casting material for a ladle.

For those skilled in the art, the lightweight mullite castable thermal insulation permanent layer and the mullite andalusite silicon carbide brick are conventional materials in the field, and are not described in detail herein.

The further scheme is as follows:

the pouring height of the casting material of the reinforcing layer is 1/4-1/3 from the ladle bottom to the height of the inner lining of the ladle.

The further scheme is as follows:

the thickness of the casting material of the reinforcing layer is 30-120 mm.

Compared with the prior art, the invention has the beneficial effects that:

(1) the permanent layer is made of light mullite casting material, so that the heat preservation of the ladle is improved, and the temperature drop of the ladle during transportation and waiting after receiving iron is reduced.

(2) The bricks of the working layer are constructed by adopting mullite silicon carbide andalusite bricks in staggered joints, so that the thermal shock resistance, impact resistance, oxidation resistance and tightness of the working layer are enhanced.

(3) In the prior art, the ladle bottom and the lower side of the ladle wall are subjected to the largest impact force of molten iron and scrap steel, which is the link which is most easily damaged, and the reinforcing layer is additionally built, so that the strength of the working layer at the lower side of the ladle bottom and the ladle wall, the impact resistance and the oxidation resistance of molten steel and scrap steel blocks are enhanced, and the problem of damage to the lower side of the ladle bottom and the ladle wall is solved in a targeted manner.

(4) The pouring of enhancement layer includes 1/4 ~ 1/3 of ladle bottom and ladle inner wall height, and is not whole ladle inner wall, and this kind of selective pouring of science not only is favorable to practicing thrift the cost, can improve the life of ladle again.

(5) Mullite is selected in the whole refractory material system of the ladle lining, and has the advantages of uniform expansion, excellent thermal shock stability, high refractoriness under load, small high-temperature creep value, high hardness and good chemical corrosion resistance.

(6) The mullite silicon carbide andalusite brick and the anti-oxidation and anti-impact castable for the ladle replace the aluminum silicon carbide carbon brick in the prior art, so that the anti-oxidation property of the refractory material is enhanced, and the thermal stability of the refractory material is improved. The heat conductivity of the working layer is reduced, and the temperature drop of the molten iron is effectively reduced.

Drawings

FIG. 1 is a schematic view of the structure of a ladle according to the present invention.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments.

Example 1

As shown in fig. 1, the ladle provided by the invention comprises 3 layers, which are respectively from outside to inside: the outer layer of the mullite castable heat-insulating permanent layer 1, the middle staggered joint masonry mullite andalusite silicon carbide brick working layer 2 and the innermost reinforcing layer 3 are formed by pouring anti-oxidation and impact-resistant castable for a ladle. The core of the invention is the casting material of the reinforcing layer.

The following examples illustrate the oxidation-resistant and impact-resistant castable for ladles.

Example 2

The adopted ladle reinforcing layer has the thickness of 60mm, and comprises a ladle bottom and 1/3 of the height of the working layer. The castable for the enhancement layer comprises the following components in percentage by mass: electrically melting mullite aggregate: 60%, andalusite: 9%, silicon carbide: 10%, fine powder of zirconium mullite: 12%, alumina micropowder: 3% of aluminum powder: 0.05-0.1%, pure calcium aluminate cement binder: 5.75% of NaHCO ₃ : 0.05%, boric acid: 0.03%, water glass: 0.1 percent; water reducing agent FDN: 0.07 percent.

Putting andalusite and calcium aluminate cement which are weighed according to the mass ratio into a mixer to be mixed for 20min to obtain premix A for later use; adding silicon carbide, fused mullite, zirconium mullite fine powder, aluminum powder and an additive which are weighed according to the mass ratio into a mixer, and stirring for 30min to obtain a premix B for later use; and (3) dry-mixing the premix A and the premix B in a stirrer for 23min to obtain the refractory castable for the ladle.

The normal temperature compressive strength of the castable is 37MPa, and the volume density is 2.68g/cm ³ And the compressive strength after high-temperature firing is 65 MPa. After the enhancement layer is poured and baked, the ladle is put into use, the temperature drop of molten iron is reduced by 17 ℃, the bottom of the ladle and the lower side of the ladle wall are not damaged and corroded, and the number of furnaces is 923.

Example 3

The adopted ladle reinforcing layer has the thickness of 80mm and comprisesBottom and working layer height 7/24. The castable for the reinforcing layer comprises the following components in percentage by mass: electrically melting mullite aggregate: 63%, andalusite: 8%, silicon carbide: 11%, fine powder of zirconium mullite: 12%, alumina micropowder: 2%, aluminum powder: 0.07%, pure calcium aluminate cement binder: 3.65% of NaHCO ₃ : 0.02%, boric acid: 0.05%, water glass: 0.2 percent; water reducing agent FDN: 0.01 percent.

After the reinforcing layer is poured and baked, the ladle is put into use, the temperature drop of molten iron is reduced by 21 ℃, the bottom of the ladle and the lower side of the ladle wall are not damaged, and the number of furnaces 942 is used.

Although the present invention has been described herein with reference to the illustrated embodiments thereof, which are intended to be preferred embodiments of the present invention, it is to be understood that the invention is not limited thereto, and that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure.

Claims

1. A ladle is structurally divided into 3 layers, and comprises the following components from outside to inside: the outer layer of light mullite casting material heat preservation permanent layer, the middle mullite andalusite silicon carbide brick working layer built by staggered joints and the innermost reinforcing layer are characterized in that: the reinforcing layer is formed by pouring an anti-oxidation and anti-impact castable for a ladle;

the anti-oxidation impact-resistant castable for the ladle comprises the following substances in percentage by mass: sintering the mullite aggregate: 50-65%, andalusite: 3-8%, silicon carbide: 3-14%, electrically fused mullite fine powder: 10-30%, zirconium mullite fine powder: 0.01% -5%, alumina micropowder:0.1-3%, aluminum powder: 0.05-0.1%, pure calcium aluminate cement binder: 3-6% of NaHCO ₃ : 0.01-0.1%, boric acid: 0.02-0.12%, water glass: 0.01-0.3%; water reducing agent FDN: 0.03 to 0.13 percent.

2. The ladle according to claim 1, wherein:

ZrO in fine zirconium mullite powder ₂ The mass percentage of the components is as follows: 5 to 25 percent.

3. The ladle according to claim 1, wherein:

the grain diameter of the mullite aggregate is as follows: 1-5 mm;

the particle size of the andalusite is as follows: 0.1-0.01 mm;

the grain diameter of the silicon carbide is less than 0.088 mm;

the particle size of the aluminum powder is less than 0.01 mm;

the grain diameters of the zirconium mullite fine powder and the electric smelting mullite fine powder are less than 0.074 mm;

the grain diameter of the alumina micro powder is as follows: 3-6 μm.

4. The ladle according to claim 1, wherein:

5. The ladle according to claim 1, wherein:

the thickness of the casting material of the reinforcing layer is 30-120 mm.