CN113800928A

CN113800928A - Low-porosity high-strength clay refractory material and preparation method thereof

Info

Publication number: CN113800928A
Application number: CN202111184885.1A
Authority: CN
Inventors: 杨俊�; 董良军; 陆国峰; 程伦
Original assignee: Yixing Dingshan Refractory Material Co ltd
Current assignee: Yixing Dingshan Refractory Material Co ltd
Priority date: 2021-10-12
Filing date: 2021-10-12
Publication date: 2021-12-17
Anticipated expiration: 2041-10-12
Also published as: CN113800928B

Abstract

The invention discloses a low-porosity high-strength clay refractory material and a preparation method thereof, which takes flint clay, mullite, alumina, soft clay, silicon micropowder and the like as main raw materials, is added with a certain bonding agent, and is prepared by mixing ingredients, the silicon micropowder, a matrix material and water in proportion to prepare slurry, mixing the materials, ageing the mixture, molding the mixture at low pressure for a high frequency, drying and firing the mixture to obtain the clay refractory material with porosity lower than 15 percent and strength higher than 85 Mpa. The invention can improve the appearance of the refractory material, further improve the compressive strength of the refractory material, reduce the porosity of the refractory material, ensure that the refractory material can work more stably and for a long time, is particularly suitable for refractory products with the size of more than or equal to 350mm multiplied by 350mm and the thickness of more than 150mm, and prolongs the service life of a furnace body.

Description

Low-porosity high-strength clay refractory material and preparation method thereof

Technical Field

The invention belongs to a clay refractory material, and particularly relates to a low-porosity high-strength clay refractory material and a preparation method thereof.

Background

The clay refractory material is most commonly used in the refractory industry, is the refractory material which has the longest history and is most widely applied, and is related to a heating furnace, a soaking furnace, a heat treatment furnace, a blast furnace, a hot blast furnace, a coke oven and the like in the steel industry. The clay refractory materials used in the current market comprise common clay bricks, low-creep clay bricks for hot blast furnaces, low-porosity compact clay bricks, clay bricks for blast furnaces and the like. However, the existing clay bricks belong to refractory products with low strength and high apparent porosity, and because the strength is too low, the brick body is often damaged due to various collisions, especially for products with the thickness of more than 150mm and the forming area of 350mm multiplied by 350mm and above, when a traditional forming mode mainly based on high-speed impact stamping is adopted, because the instantaneous pressure is large, the gradient of gradual reduction during force transmission is large, the reaction force on the products is not uniform, the upper force is too large, the lower force is small, the uneven force difference is generated, and the product spalling phenomenon is caused, so that the yield of the obtained blank body is lower than 80%. Therefore, it is important to research how to prepare a high-strength and low-porosity clay brick.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a clay refractory material which has low porosity and high strength; the second purpose of the invention is to provide a method for preparing the clay refractory material by adopting a high-frequency low-pressure forming mode.

The technical scheme is as follows: the invention relates to a low-porosity high-strength clay refractory material, which comprises the following components in percentage by weight:

further, the binder comprises one or a mixture of dextrin dry powder, calcium lignosulfonate dry powder and sodium lignosulfonate dry powder.

Further, the average grain size of the flint clay is 1-3 mm, and the average grain size of the mullite is 1-3 mm; the average grain diameter of the alumina is less than or equal to 320 meshes.

Further, the average grain size of the silicon micro powder is less than or equal to 240 meshes; SiO in silica micropowder₂The mass fraction of (A) is 97-99%.

Further, the soft clay has an average particle size of 300 to 360 mesh.

The invention further provides a preparation method of the low-porosity high-strength clay refractory material, which comprises the following steps:

(1) mixing and stirring the silicon micropowder and water uniformly according to a proportion to form slurry, and placing for later use;

(2) taking flint clay, mullite and alumina according to a certain proportion and premixing to obtain a matrix material;

(3) putting soft clay into a mixing mill, mixing and stirring, adding a binder, stirring, adding slurry, continuously stirring, adding a base material, stirring, bagging, placing in a cool and dry place, and standing to obtain a mixed pug;

(4) putting the mixed pug obtained in the step (3) into a press, and pressing and forming by adopting a high-frequency and low-pressure mode;

(5) and drying and calcining the pressed finished product to obtain the clay refractory material.

Furthermore, in the step (4), the molding frequency is 1.5-2 times/second, and the molding pressure is 85-105 MPa.

Further, in the step (4), when the press operates for the first pressing, the control speed is reduced at a constant speed of 2-3 cm/s, and after the displacement of the pug is filled in the dead angle of the steel die, a high-frequency and low-pressure pressing mode is performed. The control of the initial pressing speed can prevent the phenomena of compact upper layer, loose lower layer and uneven performance of the product.

Further, in the step (5), the calcination temperature is 1200-.

Furthermore, the thickness of the clay refractory material is 150-300 mm, and the molding area is 350mm multiplied by 350 mm-450 mm multiplied by 450 mm.

According to the invention, by limiting the average particle size of each component, the silicon micropowder and water are mixed and stirred to form slurry, and then the slurry can be effectively attached to the surface of the silica micropowder when being mixed with soft clay particles, and then the slurry is mixed with a matrix material consisting of flint clay, mullite and alumina, so that the matrix material is wrapped on the outermost layer; when the soft clay is fired, the soft clay starts to form a liquid phase at a high temperature at the temperature of 1000 ℃, oxides such as potassium, sodium, iron and the like in the soft clay form a liquid phase at the high temperature, the silicon micro powder forms a mixed liquid phase on the surface of clay particles under the influence of metal oxides and is combined with the liquid phase, and simultaneously, active silica, alumina and the like in a matrix material are attracted to be close to each other slightly, so that favorable conditions and reaction sites are provided for the reaction to generate a mullite phase; meanwhile, alumina reacts with free silica in the soft clay and silica in a liquid phase formed by the silicon micropowder to generate mullite in the process of continuously rising the temperature (1100-1350 ℃), the mullite continuously develops and grows in the area along with the rise of the temperature to form irregular columns which are inserted in the liquid phase, the granular materials and the granular materials are connected together to form an irregular network structure, and after cooling, a molten solid formed by a mixed liquid phase is filled in gaps of the irregularly inserted mullite structure and is fully distributed with the granular gaps of the materials, so that the porosity of the materials is reduced; and the particles are linked to form an integral structure, so that the mechanical property of the material is improved.

The forming frequency of the invention is 1.5-2 times/second, which is 0.7-1 times/second higher than that of the traditional punch forming mode, and the forming pressure is controlled between 85-105MPa and is lower than that of the traditional punch forming mode, which is more than 200 MPa. The reason is that in the traditional punch forming mode, because the instantaneous pressure is high, the reaction force on the product is larger, the gradient of descending during force transmission is large, the reaction force on the product is not uniform, the upper part force is too large, the lower part force is smaller, and the nonuniform force difference is caused, so that the product spalling phenomenon is caused, and the effect of reducing the forming pressure is achieved.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:

1. the invention can make the silicon micropowder attach to the surface of the particle material, between the powder and the particle material, form a liquid phase during firing, adsorb the reaction product of the matrix material, make the silicon micropowder attach to the surface of the particle material more easily, increase the contact between the particle material and the matrix material, improve the reaction efficiency, reduce the gaps among the material particles, and improve the mechanical property and the physical property of the material.

2. The invention adopts a high-frequency low-pressure mode for molding, can effectively inhibit the phenomenon of spalling, and can improve the yield to more than 95 percent. Through low-pressure pressing, the reaction force generated by the raw materials can be reduced, residual air in the brick body can be effectively discharged, and phenomena such as layer cracking and cracking of the green brick are prevented; the high-frequency pressing can ensure the strength and the density of the green body of the brick body.

3. The forming mode of the invention mainly aims at larger products, especially products with the size of more than or equal to 350mm multiplied by 350mm and the thickness of more than 150mm, has stronger adaptability, and can be manufactured by only a press of 400T.

Drawings

FIG. 1 is a schematic view of a molded product of example 1;

FIG. 2 is a schematic view of a product obtained by molding in comparative example 2.

Detailed Description

The technical solution of the present invention is further described in detail with reference to the accompanying drawings and examples.

The experimental methods described in this example are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.

Example 1

The product proportion is as follows:

wherein the average particle diameter of the flint clay is 2mm, the average particle diameter of the mullite is 2mm, the average particle diameter of the alumina is 300 meshes, and the average particle diameter of the silicon micropowderSiO with a diameter of 240 meshes₂The content of the soft clay is 97 percent, the average grain diameter of the soft clay is 360 meshes, and the adhesive is dry dextrin powder.

The preparation method comprises the following specific steps:

(1) weighing the raw materials of each component, and placing for later use;

(2) mixing the weighed silicon micro powder with water, uniformly stirring to form slurry, and placing for later use;

(3) premixing the weighed flint clay, mullite and alumina uniformly to form a matrix material, and placing for later use;

(4) placing soft clay into a mixing mill, mixing and stirring, adding dextrin dry powder, stirring for 2min, adding the mixed slurry, stirring for 4min, adding the premixed matrix material, stirring for 8min, discharging, packaging, placing in a cool and dry place, and standing for 24h to obtain a mixed pug;

(5) placing the mixed pug in a 400T press, controlling the speed to descend at a constant speed of 3cm/s when the press operates for the first time, ensuring that the pug has enough time to realize displacement filling to each dead angle of a steel die, then adopting a high-frequency and low-pressure mode to press and form, wherein the forming frequency is 2 times/second, the forming pressure is 90MPa, and finally obtaining a product with the thickness of 150mm and the forming area of 350mm multiplied by 350 mm;

(6) and drying and sintering after forming to obtain a product, wherein the calcination temperature is controlled to be 1300 ℃, the calcination time is controlled to be 6h, and the temperature rise rate is controlled to be 4 ℃/min.

Example 2

The product proportion is as follows:

wherein the average particle size of the flint clay is 3mm, the average particle size of the mullite is 3mm, the average particle size of the alumina is 320 meshes, the average particle size of the silicon micropowder is 200 meshes, and the SiO is₂The content of the soft clay is 98 percent, the average grain diameter of the soft clay is 300 meshes, and the caking agent is calcium lignosulphonate dry powder.

The preparation method comprises the following specific steps:

(1) weighing the raw materials of each component, and placing for later use;

(4) placing soft clay into a mixing mill, mixing and stirring, adding calcium lignosulphonate dry powder, stirring for 3min, adding the mixed slurry, stirring for 5min, adding the premixed matrix material, stirring for 7min, discharging, bagging, placing in a cool and dry place, and standing for 24h to obtain a mixed pug;

(5) placing the mixed pug in a 400T press, controlling the speed to descend at a constant speed of 2cm/s when the press operates for the first time, ensuring that the pug has enough time to realize displacement filling to each dead angle of a steel die, then adopting a high-frequency and low-pressure mode to press and form, wherein the forming frequency is 1.5 times/second, the forming pressure is 85MPa, and finally obtaining a product with the thickness of 200mm and the forming area of 400mm multiplied by 400 mm;

(6) and drying and sintering after forming to obtain the product, wherein the calcining temperature is controlled to be 1200 ℃, the calcining time is controlled to be 8h, and the temperature raising rate is controlled to be 2 ℃/min.

Example 3

The product proportion is as follows:

wherein the average grain diameter of the flint clay is 1mm, the average grain diameter of the mullite is 1mm, the average grain diameter of the alumina is 300 meshes, the average grain diameter of the silicon micropowder is 230 meshes, and the SiO is₂The content of the soft clay is 99 percent, the average grain diameter of the soft clay is 330 meshes, and the adhesive adopts sodium lignosulfonate dry powder.

The preparation method comprises the following specific steps:

(1) weighing the raw materials of each component, and placing for later use;

(4) placing soft clay into a mixing mill, mixing and stirring, adding sodium lignosulfonate dry powder, stirring for 1min, adding the mixed slurry, stirring for 3min, adding the premixed matrix material, stirring for 5min, discharging, packaging, placing in a cool and dry place, and standing for 24h to obtain a mixed pug;

(5) placing the mixed pug in a 400T press, controlling the speed to descend at a constant speed of 2cm/s when the press operates for the first time, ensuring that the pug has enough time to realize displacement filling to each dead angle of a steel die, then adopting a high-frequency and low-pressure mode to press and mold, wherein the molding frequency is 2 times/second, the molding pressure is 105MPa, and finally obtaining a product with the thickness of 300mm and the molding area of 450mm multiplied by 450 mm;

(6) and drying and sintering after forming to obtain the product, wherein the calcining temperature is controlled to be 1400 ℃, the calcining time is 4h, and the temperature increasing rate is controlled to be 5 ℃/min.

Comparative example 1

The specific preparation process is the same as that of example 1, except that no silica powder is added.

The product proportion is as follows:

comparative example 2

The specific product ratio is the same as that in example 1, except that the molding manner is different from that in example 1.

In the specific forming mode, the step (5) adopts an old-fashioned punch forming mode, the frequency is 0.7-1 times/second, the forming instantaneous pressure is 200MPa, a 630T press is adopted, and the first pressing speed of the press is not controlled.

The test data for examples 1-3 and comparative examples 1-2 are given in Table 1 below

TABLE 1 Performance test data for the examples

Referring to fig. 1, the product prepared in example 1, the formed green body was compact and smooth in surface; referring to fig. 2, the surface of the product prepared in comparative example 2 had cracks.

As can be seen from Table 1 and FIGS. 1-2, the products obtained in examples 1-3 all had test results within the range of the standard values, and their compressive strength and porosity were greatly improved, indicating that the obtained products were low-porosity, high-strength clay refractories. In the comparative example 1, because the silica powder is not contained, the compressive strength of the obtained product is obviously reduced and is lower than the standard value, which shows that the silica powder can be between the matrix material and the soft clay in the forming process, a liquid phase is formed during firing, and the reaction product of the matrix material is adsorbed, so that the silica powder is easier to attach to the surface of the particle material, the contact between the particle material and the matrix material is increased, the reaction efficiency is improved, the gaps among the material particles are reduced, and the strength of the material is improved; in comparative example 2, the compressive strength and the porosity of the obtained product can not reach the standard values, and the product has spalling, which shows that the old punch forming mode is adopted, because the instantaneous pressure is large, the larger the reaction force on the product is, the larger the gradient of descending during force transmission is, the non-uniform reaction force on the product is reflected, the problems of overlarge upper force, small lower force and uneven force difference are easy to occur, and the phenomenon of spalling of the product is caused.

Claims

1. A low-porosity high-strength clay refractory material is characterized in that: comprises the following components in percentage by weight:

2. the low porosity, high strength clay refractory according to claim 1, wherein: the binder comprises one or more of dextrin dry powder, calcium lignosulfonate dry powder and sodium lignosulfonate dry powder.

3. The low porosity, high strength clay refractory according to claim 1, wherein: the average grain size of the flint clay is 1-3 mm, and the average grain size of the mullite is 1-3 mm; the average grain diameter of the alumina is less than or equal to 320 meshes.

4. The low porosity, high strength clay refractory according to claim 1, wherein: the average grain diameter of the silicon micro powder is less than or equal to 240 meshes; SiO in silica micropowder₂The mass fraction of (A) is 97-99%.

5. The low porosity, high strength clay refractory according to claim 1, wherein: the soft clay has an average particle size of 300 to 360 meshes.

6. The method for preparing a low porosity, high strength clay refractory according to claim 1, comprising the steps of:

7. The method for preparing a low-porosity high-strength clay refractory according to claim 6, wherein: in the step (4), the molding frequency is 1.5-2 times/second, and the molding pressure is 85-105 MPa.

8. The method for preparing a low-porosity high-strength clay refractory according to claim 6, wherein: in the step (4), when the press operates for the first pressing, the control speed is reduced at a constant speed of 2-3 cm/s, and a high-frequency and low-pressure pressing mode is performed after the pug displacement is filled in a steel die dead angle.

9. The method for preparing a low-porosity high-strength clay refractory according to claim 6, wherein: in the step (5), the calcining temperature is 1200-1400 ℃, the calcining time is 2-8h, and the temperature raising rate is controlled to be 2-5 ℃/min.

10. The method for preparing a low-porosity high-strength clay refractory according to claim 6, wherein: the thickness of the clay refractory material is 150-300 mm, and the molding area is 350mm multiplied by 350 mm-450 mm multiplied by 450 mm.