CN113956056A

CN113956056A - Micro-expansion carbon-containing refractory mortar for sliding gate and production method thereof

Info

Publication number: CN113956056A
Application number: CN202111399371.8A
Authority: CN
Inventors: 赵臣瑞; 牛智旺; 韩彦锋; 梁保青; 徐跃庆; 李宏宇; 李雪翠; 来丽苹; 王海霞
Original assignee: Henan Rongjin High Temperatrue Materials Co ltd
Current assignee: Henan Rongjin High Temperatrue Materials Co ltd
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2022-01-21
Anticipated expiration: 2041-11-24
Also published as: CN113956056B

Abstract

The invention provides micro-expansion carbon-containing refractory mortar for a sliding gate, which comprises the following raw materials in percentage by weight: 55-68% of fused mullite, 5-10% of kyanite, 8-12% of fused white corundum powder, 5-10% of calcined alumina micro powder, 5-10% of Guangxi white mud, 3-5% of crystalline flake graphite, 2-4% of solid aluminum dihydrogen phosphate and 1-2% of boron nitride, wherein the total amount of the raw materials is 100%, and 0-2% of Arabic gum powder and 0.5-1% of carboxymethyl cellulose are additionally added. The obtained refractory mortar has good oxidation resistance; the adhesive has good adhesiveness and plasticity in a cold state; the sheet-shaped falling-off is easy to clean during replacement, so that the damage to the brick cup during cleaning can be effectively reduced; the molten steel penetration resistance is strong, the molten steel penetration caused by shrinkage in high-temperature use is effectively blocked, and the shrinkage rate of the fire clay in high-temperature use is effectively reduced.

Description

Micro-expansion carbon-containing refractory mortar for sliding gate and production method thereof

Technical Field

The invention relates to micro-expansion carbon-containing refractory mortar for a sliding gate and a production method thereof, belonging to the field of sliding gate materials.

Background

The sliding gate is a control device of molten steel in the casting process of a continuous casting machine, and can accurately adjust the water flow from a ladle to a continuous casting tundish to balance the inflow and outflow molten steel, so that the continuous casting operation is easier to control and an indispensable part in smelting is realized. The sliding gate valve generally consists of a driving device, a mechanical part and a refractory material part (i.e. an up-down slide plate, a down gate valve).

The refractory mortar is also called fire clay, is used as a joint-building material for refractory brickwork and mainly comprises refractory powder, a bonding agent and an additive. The finished product of the refractory mortar is prepared by mixing raw materials and clinker in proportion in manufacturers, and only needs to add water according to standards and stir uniformly when the refractory mortar is used on site; the semi-finished product or non-finished product refractory mortar is prepared by mixing raw materials and clinker together, and adding water according to the specification and stirring uniformly when the refractory mortar is used on site.

The existing fire clay for bonding refractory materials uses more aluminum-chromium fire clay, uses clay or phosphate as a binding agent, so that the fire clay contracts greatly at high temperature, the large contraction causes the risk of steel leakage, and meanwhile, the aluminum-chromium fire clay is used and sintered with a sliding gate nozzle product to be strong, is difficult to clean, increases the labor intensity when the sliding gate nozzle product is replaced by hot repair, and is long in use.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide micro-expansion carbon-containing refractory mortar for a sliding gate and a production method thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

the micro-expansion carbon-containing refractory mortar for the sliding gate comprises the following raw materials in percentage by weight: 55-68% of fused mullite, 5-10% of kyanite, 8-12% of fused white corundum powder, 5-10% of calcined alumina micro powder, 5-10% of Guangxi white mud, 3-5% of crystalline flake graphite, 2-4% of solid aluminum dihydrogen phosphate and 1-2% of boron nitride, wherein the total amount of the raw materials is 100%, and 0-2% of Arabic gum powder and 0.5-1% of carboxymethyl cellulose are additionally added.

The electrofused mullite comprises: the granularity of 0.2mm is less than or equal to 1 and less than or equal to 0.5mm, the granularity of 0.074mm is less than or equal to 2 and less than or equal to 0.2mm, the granularity of 3 is less than or equal to 0.074mm, and the weight ratio of different granularities is as follows: particle size 1: particle size 2: particle size 3 ═ 8: 5-10: 42-50.

The particle size of the electric melting white corundum powder is less than or equal to 0.045 mm; the granularity of the kyanite is less than or equal to 0.2 mm; the granularity of the Guangxi white mud is less than or equal to 0.2 mu m.

The particle size of the crystalline flake graphite is less than or equal to 0.074mm, and the carbon content is more than or equal to 98%.

The particle size D50 of the calcined alumina micro powder is 1-2 μm; the particle size D50 of the boron nitride is 1-2 μm.

The production method of the carbon-containing refractory mortar comprises the following steps:

(1) weighing the raw materials according to the proportion;

(2) mixing solid aluminum dihydrogen phosphate, boron nitride, carboxymethyl cellulose and gum arabic powder with 3-5% (wt%) of electrically-fused mullite powder in advance for later use;

(3) and (3) adding the mixture obtained in the step (2) and the rest raw materials into a conical mixer, mixing for 25-30 min, uniformly stirring, discharging, packaging, and sealing by using a packaging bag with a plastic lining to obtain a dry powder product.

The production method of the carbon-containing refractory mortar further comprises the following steps: and (3) adding the raw materials mixed in the step (3) into a stirrer, adding water accounting for 15% -23% of the mixed raw materials, stirring for 10min-15min, subpackaging the stirred refractory mortar into a plastic barrel with a plastic lining, tying the opening of the plastic lining, and covering the barrel cover to obtain a wet product.

The invention has the beneficial effects that:

the invention relates to a micro-expansion carbon-containing refractory mortar for a sliding gate, which takes electric-melting mullite, kyanite, Guangxi white mud, electric-melting white corundum powder, calcined alumina micro powder and crystalline flake graphite as main raw materials, boron nitride as an antioxidant and solid aluminum dihydrogen phosphate as a bonding agent. The obtained refractory mortar has good oxidation resistance; the adhesive has good adhesiveness and plasticity in a cold state; the sheet-shaped falling-off is easy to clean during replacement, so that the damage to the brick cup during cleaning can be effectively reduced; the molten steel penetration resistance is strong, the molten steel penetration caused by shrinkage in high-temperature use is effectively blocked, and the shrinkage rate of the fire clay in high-temperature use is effectively reduced. The specific analysis is as follows:

the invention adopts the crystalline flake graphite as a carbon source, mainly utilizes the good thermal conductivity, thermal shock resistance and corrosion resistance of the crystalline flake graphite, and simultaneously has the characteristic of non-wetting with steel slag, so that the product has excellent steel slag penetration resistance and corrosion resistance, and on the other hand, the high-temperature sintering property of the crystalline flake graphite is poor, so that the sintering property of the product at high temperature and the sintering property of a sliding water gap product are poor, and the product is easy to clean after being used. Meanwhile, boron nitride is selected as an antioxidant, and the boron nitride can preferentially react with oxygen at high temperature to protect carbon in the product from being oxidized.

The invention adopts solid aluminum dihydrogen phosphate as a bonding agent, the aluminum dihydrogen phosphate is a novel inorganic bonding agent, and the aluminum dihydrogen phosphate is mainly used for reacting with oxide in the heating process to generate aluminum monohydrogen phosphate and aluminum phosphate to form chemical bonding, so that the product has higher low-temperature strength.

The invention uses the gum arabic powder and the carboxymethyl cellulose as the plasticizer and the humectant, and the gum arabic powder and the carboxymethyl cellulose both have the functions of absorbing water and expanding to form a sticky colloidal solution. The carboxymethyl cellulose has the functions of thickening, plasticizing and suspending and stabilizing, improves the plasticity of the fire clay, and prevents the fire clay stirred by adding water from bleeding. The Arabic gum powder is an organic material, is used as a thickening agent and a colloid stabilizer, is matched with carboxymethyl cellulose for use, mainly plays roles in thickening, plasticizing and retaining water, can improve the viscosity and the water retention of the fire clay, and can promote the stability of sol formed by the Arabic gum powder and the carboxymethyl cellulose, so that the storage time and the stability of the fire clay are improved.

The kyanite is used as an expansion material, the kyanite is decomposed at high temperature to generate mullite and silicon dioxide, and simultaneously, certain volume expansion is carried out, so that sintering shrinkage of a product at high temperature can be effectively counteracted by utilizing the volume expansion effect, the volume stability of the product is improved, meanwhile, the addition amount of the kyanite is adjusted, the expansion effect of the product at high temperature is larger than that of the sintering shrinkage, the product shows a micro-expansion effect, the integrity of the fire clay and the bonded material thereof is improved, and steel leakage accidents caused by overflow of molten steel from fire clay seams in the steel making and steel pouring processes are effectively reduced.

The particle size ratio of the raw materials is reasonably set, wherein the particle size of the kyanite has obvious influence on the expansion rate, so that the kyanite with the critical particle size of 0.2mm is selected for the particle size, and the generation of the expansion effect of the kyanite at high temperature is facilitated. The plastic property and the fluidity of the fire mud can be influenced by the overlarge granularity of the fused mullite, and the shrinkage rate of the fire mud can be increased by selecting the full fine powder, so that the granularity of the fused mullite is divided into different granularity ranges and corresponds to different weight ratios, and the granularity proportion is reasonable.

The product obtained by the invention has good physical properties, wherein the apparent porosity (110 ℃ multiplied by 24h) is 23-26%, and the volume density (110 ℃ multiplied by 24h) is 2.0g/cm³～3.0g/cm³The adhesive has a room-temperature folding strength (110 ℃ x 24h) of 4.0MPa to 6.0MPa, a room-temperature folding-resistant adhesive strength (110 ℃ x 24h) of 2.0MPa to 3.0MPa, a room-temperature folding-resistant adhesive strength (1400 ℃ x 3h (buried carbon)) of 4.0MPa to 5.0MPa, a linear change rate (1500 ℃ x 3h (buried carbon)) of + 0.1% to + 0.4%, and a room-temperature folding-resistant strength (1500 ℃ x 3h (buried carbon)) of 5.0MPa to 6.0 MPa.

Detailed Description

The following examples further illustrate the embodiments of the present invention in detail.

Example 1:

the micro-expansion carbon-containing refractory mortar for the sliding gate comprises the following raw materials in percentage by weight: 68% of fused mullite, 5% of kyanite, 8% of fused white corundum powder, 5% of calcined alumina micro powder, 5% of Guangxi white mud, 5% of crystalline flake graphite, 2% of solid aluminum dihydrogen phosphate and 2% of boron nitride, and in addition, 2% of Arabic gum powder and 1% of carboxymethyl cellulose in the total amount of the raw materials are added.

Wherein the electrofused mullite comprises: the granularity of 0.2mm is less than or equal to 1 and less than or equal to 0.5mm, the granularity of 0.074mm is less than or equal to 2 and less than or equal to 0.2mm, the granularity of 3 is less than or equal to 0.074mm, and the weight ratio of different granularities is as follows: particle size 1: particle size 2: particle size 3 ═ 8: 10: 50.

the granularity of the electric melting white corundum powder is less than or equal to 0.045 mm; the granularity of the kyanite is less than or equal to 0.2 mm; the granularity of the Guangxi white mud is less than or equal to 0.2 mu m; the particle size of the flake graphite is less than or equal to 0.074mm, and the carbon content is more than or equal to 98 percent; the particle diameter D50 of the calcined alumina micropowder is 1-2 μm; the particle diameter D50 of the boron nitride is 1-2 μm.

(1) weighing the raw materials according to the proportion.

(2) Solid aluminum dihydrogen phosphate, boron nitride, carboxymethyl cellulose and gum arabic powder are mixed with 3-5% (wt%) of electric-melting mullite powder in advance for standby, and segregation caused by small material agglomeration when the materials are added into a mixer is avoided.

(3) And (3) adding the mixture obtained in the step (2) and the rest raw materials into a conical mixer, mixing for 25-30 min, uniformly stirring, discharging, packaging, sealing by using a packaging bag with a plastic lining, and preventing moisture to obtain a dry powder product.

Or adding the raw materials mixed in the step (3) into a stirrer, adding water accounting for 15% -23% of the mixed raw materials, stirring for 10min-15min, subpackaging the stirred fire clay into a plastic barrel with a plastic lining, tying the opening of the plastic lining, and covering the barrel cover to obtain a wet product.

The dry powder product of the invention is added with water accounting for 15 to 23 percent of the dry powder product in the using field and stirred to obtain wet fire mud for use. The wet product of the invention can be directly used without adding water and stirring when being used on site. When the device is used, the wet fire clay is uniformly coated on the outer surface of the upper nozzle, and the connection parts of the upper sliding plate, the upper nozzle, the lower sliding plate and the lower nozzle are connected.

The experimental data for the relevant performance parameters of the obtained refractory mortar are shown in table 1.

Example 2:

the micro-expansion carbon-containing refractory mortar for the sliding gate comprises the following raw materials in percentage by weight: 65% of fused mullite, 8% of kyanite, 8% of fused white corundum powder, 5% of calcined alumina micro powder, 5% of Guangxi white mud, 5% of crystalline flake graphite, 2% of solid aluminum dihydrogen phosphate and 2% of boron nitride, and in addition, 2% of Arabic gum powder and 1% of carboxymethyl cellulose in the total amount of the raw materials are added.

Wherein the electrofused mullite comprises: the granularity of 0.2mm is less than or equal to 1 and less than or equal to 0.5mm, the granularity of 0.074mm is less than or equal to 2 and less than or equal to 0.2mm, the granularity of 3 is less than or equal to 0.074mm, and the weight ratio of different granularities is as follows: particle size 1: particle size 2: particle size 3 ═ 8: 7: 50.

The production method of this refractory mortar is the same as in example 1. The experimental data for the relevant performance parameters of the obtained refractory mortar are shown in table 1.

Example 3:

the micro-expansion carbon-containing refractory mortar for the sliding gate comprises the following raw materials in percentage by weight: 63% of fused mullite, 10% of kyanite, 8% of fused white corundum powder, 5% of calcined alumina micro powder, 5% of Guangxi white mud, 5% of crystalline flake graphite, 2% of solid aluminum dihydrogen phosphate and 2% of boron nitride, and in addition, 2% of Arabic gum powder and 1% of carboxymethyl cellulose in the total amount of the raw materials are added.

Wherein the electrofused mullite comprises: the granularity of 0.2mm is less than or equal to 1 and less than or equal to 0.5mm, the granularity of 0.074mm is less than or equal to 2 and less than or equal to 0.2mm, the granularity of 3 is less than or equal to 0.074mm, and the weight ratio of different granularities is as follows: particle size 1: particle size 2: particle size 3 ═ 8: 5: 50.

Example 4:

the micro-expansion carbon-containing refractory mortar for the sliding gate comprises the following raw materials in percentage by weight: 59% of fused mullite, 10% of kyanite, 12% of fused white corundum powder, 5% of calcined alumina micro powder, 5% of Guangxi white mud, 5% of crystalline flake graphite, 2% of solid aluminum dihydrogen phosphate and 2% of boron nitride, and in addition, 2% of Arabic gum powder and 1% of carboxymethyl cellulose in the total amount of the raw materials are added.

Wherein the electrofused mullite comprises: the granularity of 0.2mm is less than or equal to 1 and less than or equal to 0.5mm, the granularity of 0.074mm is less than or equal to 2 and less than or equal to 0.2mm, the granularity of 3 is less than or equal to 0.074mm, and the weight ratio of different granularities is as follows: particle size 1: particle size 2: particle size 3 ═ 8: 5: 46.

Example 5:

the micro-expansion carbon-containing refractory mortar for the sliding gate comprises the following raw materials in percentage by weight: 55% of fused mullite, 10% of kyanite, 12% of fused white corundum powder, 10% of calcined alumina micro powder, 5% of Guangxi white mud, 4% of crystalline flake graphite, 3% of solid aluminum dihydrogen phosphate and 1% of boron nitride, and additionally 1% of Arabic gum powder and 0.8% of carboxymethyl cellulose in the total amount of the raw materials.

Wherein the electrofused mullite comprises: the granularity of 0.2mm is less than or equal to 1 and less than or equal to 0.5mm, the granularity of 0.074mm is less than or equal to 2 and less than or equal to 0.2mm, the granularity of 3 is less than or equal to 0.074mm, and the weight ratio of different granularities is as follows: particle size 1: particle size 2: particle size 3 ═ 8: 5: 42.

Example 6:

the micro-expansion carbon-containing refractory mortar for the sliding gate comprises the following raw materials in percentage by weight: 55% of fused mullite, 10% of kyanite, 12% of fused white corundum powder, 5% of calcined alumina micro powder, 10% of Guangxi white mud, 3% of crystalline flake graphite, 4% of solid aluminum dihydrogen phosphate, 1% of boron nitride and carboxymethyl cellulose accounting for 0.5% of the total amount of the raw materials.

TABLE 1 relevant Performance parameters in the use of the refractory mortar according to the invention

In the table, the comparative example is a phosphate-bonded aluminum-chromium based fireclay (which is an alternative type of fireclay of the present invention), and the raw materials of the comparative example comprise, in weight percent: 80% of tabular corundum, 5% of chromium oxide green, 10% of Guangxi white mud and 5% of aluminum dihydrogen phosphate.

As can be seen from table 1, from the comparison of performance parameters of the examples and the comparative examples, the line change of the examples is positive, the examples show micro expansion at high temperature, while the line change of the comparative examples is negative, the examples show volume shrinkage at high temperature, the products of the examples are favorable for the stability of bonding, the strength index of the examples is low, which indicates that the sintering property is slightly poor, and the cleaning of the used fire clay is more favorable, so the examples show the characteristics of micro expansion at high temperature and easy cleaning after use.

Claims

1. The micro-expansion carbon-containing refractory mortar for the sliding gate is characterized by comprising the following raw materials in percentage by weight: 55-68% of fused mullite, 5-10% of kyanite, 8-12% of fused white corundum powder, 5-10% of calcined alumina micro powder, 5-10% of Guangxi white mud, 3-5% of crystalline flake graphite, 2-4% of solid aluminum dihydrogen phosphate and 1-2% of boron nitride, wherein the total amount of the raw materials is 100%, and 0-2% of Arabic gum powder and 0.5-1% of carboxymethyl cellulose are additionally added.

2. The carbonaceous refractory according to claim 1, wherein the electrofused mullite comprises: the granularity of 0.2mm is less than or equal to 1 and less than or equal to 0.5mm, the granularity of 0.074mm is less than or equal to 2 and less than or equal to 0.2mm, the granularity of 3 is less than or equal to 0.074mm, and the weight ratio of different granularities is as follows: particle size 1: particle size 2: particle size 3 ═ 8: 5-10: 42-50.

3. The carbonaceous refractory mortar of claim 1, wherein the fused white corundum powder has a particle size of 0.045mm or less; the granularity of the kyanite is less than or equal to 0.2 mm; the granularity of the Guangxi white mud is less than or equal to 0.2 mu m.

4. The carbon-containing refractory mortar as claimed in claim 1, wherein the scale graphite has a particle size of 0.074mm or less and a carbon content of 98% or more.

5. The carbonaceous refractory mortar of claim 1, wherein the calcined alumina micropowder has a particle size D50 of 1 μm to 2 μm; the particle size D50 of the boron nitride is 1-2 μm.

6. The method for producing a carbonaceous refractory mortar as set forth in any one of claims 1 to 5, comprising the steps of:

(1) weighing the raw materials according to the proportion;

7. The method for producing a carbonaceous refractory mortar as set forth in claim 6, further comprising the steps of: and (3) adding the raw materials mixed in the step (3) into a stirrer, adding water accounting for 15% -23% of the mixed raw materials, stirring for 10min-15min, subpackaging the stirred refractory mortar into a plastic barrel with a plastic lining, tying the opening of the plastic lining, and covering the barrel cover to obtain a wet product.