CN111533542A

CN111533542A - Low-heat-conduction high-strength anti-scouring cap opening brick and preparation method thereof

Info

Publication number: CN111533542A
Application number: CN202010391643.9A
Authority: CN
Inventors: 宋政德
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-05-11
Filing date: 2020-05-11
Publication date: 2020-08-14

Abstract

The invention discloses a low-heat-conductivity high-strength anti-scouring cap opening brick which comprises 87-92% by weight of high-alumina bauxite; 0-8% of white mud; 0-1% of zircon powder; 4.5-6% of lignin. The invention also discloses a preparation method of the low-heat-conductivity high-strength anti-scouring cap opening brick, which comprises the steps of a, mixing the high-alumina, the white mud and the zircon powder in proportion and then crushing; b. mixing the mixed particles obtained in the step a with a lignin aqueous solution in proportion to obtain a mixed raw material; c. pressing the mixed raw materials in the step b into green bricks; d. and (c) sintering the green brick in the step c at 1450 ℃ for 2 hours to obtain the low-heat-conduction high-strength anti-scouring cap brick. The invention provides a low-heat-conductivity high-strength anti-scouring cap brick which has the characteristics of low heat conductivity coefficient, good thermal stability and strong anti-scouring capability, and the service life of the cap brick is as long as 5-7 times. The invention also provides a processing method of the low-heat-conduction high-strength anti-scouring cap opening brick, which has the characteristics of simplicity, convenience and short processing period.

Description

Low-heat-conduction high-strength anti-scouring cap opening brick and preparation method thereof

Technical Field

The invention relates to the technical field of refractory materials, in particular to a low-heat-conduction high-strength anti-scouring cap brick for the tail end of a large steel ingot of more than 50 tons in vacuum casting and a preparation method thereof.

Background

The vacuum casting is a method of casting molten steel melted in the atmosphere into an ingot mold in a vacuum chamber to form an ingot, and the method can prevent the molten steel from absorbing gas and secondary oxidation, can play a role of degassing, and is suitable for casting large forging steel ingots.

The vacuum casting guide pipe is an indispensable appliance for steel ingot vacuum casting and is formed by combining a plurality of cap opening bricks. The guide pipe is directly contacted with the molten steel in the casting process, and the probability of floating impurities after the molten steel enters the steel ingot through the guide pipe is very small, so that the erosion resistance of the cap opening brick directly influences the internal quality of the molten steel and influences the quality of the steel ingot.

In order to improve the purity of the steel ingot, the cap opening brick is required to have the characteristics of good erosion resistance, thermal stability, high temperature resistance and the like, but the current cap opening brick cannot meet the requirement, is easy to fall off when the large steel ingot is poured, and reduces the purity of the large steel ingot. And the service life of the existing cap opening brick is only 1.5 times, so that the production cost of an enterprise is greatly increased.

Disclosure of Invention

The invention provides a low-heat-conductivity high-strength anti-scouring cap brick for overcoming the problems in the prior art, which has the characteristics of low heat conductivity coefficient, good thermal stability and strong anti-scouring capability, and the service life of the cap brick is as long as 5-7 times. Meanwhile, the invention also provides a processing method of the low-heat-conduction high-strength anti-scouring cap opening brick, which has the characteristics of simplicity, convenience and short processing period.

The technical scheme adopted by the invention is as follows:

the low heat conducting high strength anti-scour cap opening brick comprises the following raw materials in percentage by weight

Further, the bauxite comprises, by weight, 10-26% of bauxite particles with the particle size of 0-1mm, 50-65% of bauxite particles with the particle size of 1-3mm and 23-30% of bauxite particles with the particle size of less than 200 meshes.

Further, the medium Al of the high bauxite₂O₃65-70% of SiO₂20-25% of Fe₂O₃The content is less than or equal to 5 percent, and the particle density is 2.6-2.7 g/cm 3.

Further, the grain size of the white mud is smaller than 180 meshes.

Further, the particle size of the zirconium quartz powder is less than 180 meshes.

Further, the lignin adopts pulp waste liquor with a pH value of 6.5.

The preparation method of the low-heat-conduction high-strength anti-scouring cap opening brick comprises the following steps

a. Mixing high-alumina bauxite, white mud and zircon powder in proportion and then crushing to obtain mixed particles;

b. mixing the mixed particles obtained in the step a with a lignin aqueous solution in proportion to obtain a mixed raw material;

c. pressing the mixed raw materials in the step b into green bricks;

d. and (c) sintering the green brick in the step c at 1450 ℃ for 2 hours to obtain the low-heat-conduction high-strength anti-scouring cap brick.

The invention has the beneficial effects that:

1. the invention designs a low-heat-conduction high-strength anti-scouring cap brick for the tail end of a large steel ingot vacuum poured by more than 50 tons in order to solve the problems that the cap brick in the prior art can not meet the requirement of large steel ingot casting and has short service life. The cap opening brick has the characteristics of low heat conductivity coefficient, good thermal stability and strong anti-scouring capability, and the service life of the cap opening brick is as long as 5-7 times.

2. The invention also provides a processing method of the low-heat-conduction high-strength anti-scouring cap opening brick, and the method has the advantages of simple flow, convenience in operation and short processing period.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 shows XRD detection results of the brick pattern of the top hat in example 5.

FIG. 2 shows the first result of SEM test of the brick-like shape of the cap opening in example 5.

FIG. 3 is a second SEM test result of the brick pattern of the hat opening in example 5.

FIG. 4 shows the third SEM test result of the brick pattern of the hat opening in example 5.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention.

The following describes in detail embodiments of the present invention with reference to the accompanying drawings.

Example 1

A preparation method of a low-heat-conduction high-strength anti-scouring cap opening brick comprises the following steps

b. b, mixing the mixed particles obtained in the step a with a density of 1.22-1.25 g/cm³Mixing the lignin aqueous solution in proportion to obtain a mixed raw material;

c. pressing the mixed raw materials in the step b into green bricks;

Examples 2 to 5 the low thermal conductivity and high strength anti-erosion cap brick processed by the method of example 1 had the following raw material composition as shown in the following table:

TABLE 1 raw material composition

	Example 2	Example 3	Example 4	Example 5
					1-3mm high alumina bauxite	57.15％	57.15％	57.15％	47.17％
0-1mm high alumina bauxite	9.52％	9.52％	9.52％	23.58％
					<200 mesh high alumina bauxite	20.95％	23.81％	28.57％	20.75％
<180 mesh white mud	7.62％	4.76％	0	1.89％
					<180-mesh zirconium quartz powder	0	0	0	0.94％
Pulp waste liquor	4.76％	4.76％	4.76％	5.67％

Cutting/pressing the cap opening brick samples in the embodiments 2-5 into strip-shaped samples 140mm x 25mm, and detecting the normal-temperature compressive strength and the normal-temperature bending strength of the strip-shaped samples according to GB/T3001-2007 test method for normal-temperature bending strength of refractory materials and GB/T5072-2008 test method for normal-temperature compressive strength of refractory materials; the test results of the polar volume density and the apparent porosity of the strip-shaped sample according to GB/T2997-2000 test method for the volume density, the apparent porosity and the true porosity of the compact-shaped refractory product are shown in the following table.

TABLE 2 test sample physical Properties test results

	Example 2	Example 3	Example 4	Example 5
					Flexural strength/MPa	14.64	13.82	12.08	11.24
Compressive strength/MPa	59.86	44.23	33.20	78.55
					Apparent porosity/%	23	26	29	28
Bulk density/g/cm³	2.16	2.24	2.18	2.31
					Post-fire line change/%)	+1.12	+0.89	+1.04	/
Thermal conductivity at 900 ℃/W/(m.k)	1.667	1.534	1.253	1.477
					1400 ℃ thermal expansion rate/%)	0.47	0.45	0.42	0.49

The physical property detection results of the test samples show that the cap opening brick has higher strength, lower heat conductivity coefficient and thermal expansion rate and good dimensional stability, and can meet the requirements of steel ingot casting.

The chemical composition analysis of the prepared low-thermal-conductivity high-strength anti-scouring cap tile is carried out by taking the example 5 as an example, and the detection results are shown in the following table.

Chemical composition of the samples of Table 3

As can be seen from the detection results, the low-thermal-conductivity high-strength anti-scouring cap opening brick in the embodiment is mainly made of SiO₂And Al₂O₃。SiO₂And Al₂O₃Has positive effect on ensuring the dimensional stability and the thermal stability of the cap opening brick sample.

XRD analysis is carried out on the prepared low-heat-conductivity high-strength anti-scouring cap brick by taking the example 5 as an example, and the detection result is shown in the attached figure 1.

As can be seen from FIG. 1, the main phases of the cap tile sample of example 5 are mullite and corundum, and a small amount of cristobalite phase is contained. Brick for hat openingSample m (Al)₂O₃)/m(SiO₂) Is 3.03, slightly higher than the theoretical composition of mullite. The cristobalite residue in the brick sample of the hat-opening brick is mainly due to amorphous SiO generated by aluminum spinel in the mullite process₂The result of the transformation. The mullite and corundum have the characteristics of high temperature resistance and small coefficient of heat conductivity, so that the cap opening brick can meet the requirement of steel ingot casting.

SEM analysis is performed on the prepared low-heat-conductivity high-strength anti-scouring cap opening brick by taking the example 5 as an example, and the detection results are shown in the attached figures 2-3.

The detection result shows that the bone material particles in the cap-opening brick sample are surrounded by a large amount of matrix, which indicates that the content of fine powder with the particle size of less than 1mm in the proportioning composition of the brick sample is higher. The cap opening brick sample has low void ratio and high compactness, and ensures the mechanical strength of the cap opening brick sample. The grains in the matrix are not completely developed and are connected with the neck. Elongated acicular mullite can also be observed in the voids of the matrix, which can be improved by further formulation adjustments.

Claims

1. The low-heat-conduction high-strength anti-scouring cap opening brick is characterized by comprising the following raw materials in percentage by weight

2. The low-thermal-conductivity high-strength anti-scouring cap tile according to claim 1, wherein the bauxite comprises 10-26 wt% of bauxite particles with a particle size of 0-1mm, 50-65 wt% of bauxite particles with a particle size of 1-3mm and 23-30 wt% of bauxite particles with a particle size of less than 200 meshes.

3. The low thermal conductivity high strength erosion resistant cap tile of claim 1, wherein the bauxite has a medium Al content₂O₃65-70% of SiO₂20-25% of Fe₂O₃The content is less than or equal to 5 percent, and the particle density is 2.6-2.7 g/cm³。

4. The low thermal conductivity high strength erosion resistant cap tile of claim 1, wherein the white mud has a particle size of less than 180 mesh.

5. The low thermal conductivity and high strength anti-scouring cap tile according to claim 1, wherein the particle size of the zircon quartz powder is less than 180 meshes.

6. The low-heat-conduction high-strength anti-scouring cap tile according to claim 1, wherein the lignin is pulp waste liquor with a pH value of 6.5.

7. A method for preparing the low-heat-conductivity high-strength anti-scouring cap tile as claimed in any one of claims 1 to 6, characterized by comprising the steps of

c. pressing the mixed raw materials in the step b into green bricks;