CN111592340A

CN111592340A - Preparation method of magnesium oxide light heat-insulation brick

Info

Publication number: CN111592340A
Application number: CN202010474319.3A
Authority: CN
Inventors: 张昂; 王海啸; 韩伟; 向帅
Original assignee: Shandong Jiateng Industrial Co ltd
Current assignee: Shandong Jiateng Industrial Co ltd
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2020-08-28

Abstract

The invention relates to a preparation method of a magnesium oxide light heat-insulation brick, belonging to the technical field of heat-insulation bricks. The preparation method of the light heat-insulating magnesia brick provided by the invention takes magnesia as a main material, and combines a gel casting method with a foaming process to prepare the light heat-insulating magnesia brick. The product prepared by the invention has excellent refractoriness and erosion resistance, higher porosity, lower heat conductivity coefficient and excellent heat preservation and insulation performance.

Description

Preparation method of magnesium oxide light heat-insulation brick

Technical Field

The invention relates to a preparation method of a magnesium oxide light heat-insulation brick, belonging to the technical field of heat-insulation materials.

Background

The magnesia refractory material is an important high-grade refractory material, belongs to an alkaline refractory material, generally has higher refractoriness and good erosion resistance to alkaline substances, and has wide application in the aspects of steel-making furnaces, glass kilns, cement kilns, nonferrous metal smelting furnaces, calcination of the alkaline refractory material and the like.

In the prior art, when the magnesia refractory material is prepared, a dry pressing process is generally adopted for production, higher porosity cannot be realized, and the light heat insulation function is difficult to achieve; some slurry pouring processes are used, but the performance of products prepared by slurry pouring is not ideal, and the difficulties of high volume density, high heat conductivity coefficient, high drying shrinkage rate of products, low molding qualification rate and the like exist.

CN 104402456A discloses a method for self-foaming injection molding gel forming porous ceramics, which comprises the steps of preparing weakly acidic water-based slurry A containing citric acid, lactic acid, acetic acid and the like and water-based slurry B containing carbonate such as ammonium bicarbonate, calcium carbonate, magnesium carbonate and the like, and performing ball milling to obtain A, B two-component water-based suspension slurry; the slurry is subjected to a degassing process, an initiator and catalyst adding process and a surfactant adding process, then the component A, B is mixed and foamed under the condition of halving, and the two are subjected to chemical reaction to generate non-coagulation CO₂Pouring the foam slurry into a non-water-absorbing mold, and solidifying the gel to form a porous gel blank; the porous ceramic is obtained by the technological processes of demoulding, drying, sintering and the like of the green body. The method is simple and convenient to operate, simple and practical, and is suitable for preparing the porous ceramic material with the pore size distribution within the range of 200-5000 microns. In the patent, a large amount of carbon dioxide gas is generated by using the principle of acid-base neutralization, and then small bubbles are formed, so that the porous ceramic is formed. But is not applicable to the field of magnesia insulating bricks.

Disclosure of Invention

The invention aims to provide a preparation method of a magnesium oxide light heat-insulating brick, and the prepared product has excellent refractoriness and erosion resistance, higher porosity, lower heat conductivity coefficient and excellent heat-insulating property.

The preparation method of the light heat-insulating magnesia brick provided by the invention takes magnesia as a main material, and combines a gel casting method with a foaming process to prepare the light heat-insulating magnesia brick.

Preferably, the magnesite is fused magnesite or sintered magnesite.

The granularity ratio of the magnesia is as follows:

wherein D1, D2, D3 and D4 respectively represent the particle size of the magnesite.

The magnesia is subjected to grain grading adjustment, so that the compact packing principle is met, the risk of spalling during forming is reduced, and the forming qualification rate is improved.

The raw materials are measured by mass percentage as follows: 70-99% of magnesite and 1-30% of auxiliary materials.

Preferably, the auxiliary material is industrial calcined alumina or bauxite with 1000 meshes to 2000 meshes.

The preparation method of the magnesium oxide light heat-insulation brick comprises the following steps:

(1) mixing the materials according to mass percent, namely stirring and mixing magnesia and auxiliary materials which are not less than 1mm and not more than D1 and not more than 2mm, not less than 75 mu m and not more than D2 and not more than 1mm, not less than 10 mu m and not more than D3 and not more than 75 mu m, and not less than 1 mu m and not more than D4 and not more than 10mm in a mixer for 10-60 minutes;

(2) adding 40-70% of water, 4-10% of acrylamide, 0.5-3% of cross-linking agent and 0.1-1% of dispersing agent into the mixture obtained in the step (1), and continuously stirring and mixing for 30-40 minutes;

(3) adding 0.05-0.2% of foaming agent into the mixture obtained in the step (2), and stirring and foaming for 10-30 minutes to obtain foaming slurry;

(4) adding 0.2-2% of initiator, 0.02-0.1% of catalyst and 0.05-0.2% of sodium silicate into the foaming slurry obtained in the step (3), and stirring for 1-3 minutes;

(5) injecting the slurry obtained in the step (4) into a mold, putting the mold into a heating chamber at 50-70 ℃, preserving heat and curing for 1-3 hours, then demolding, heating to 60-90 ℃, and drying for 24-72 hours;

(6) the mixture is sintered in an electric furnace, the heating rate is 30-50 ℃/h, and the temperature is preserved for 2-5 hours at 1400-1480 ℃.

The used water, organic monomer, initiator and the like are used based on the total mass of the magnesite and the auxiliary materials in the step (1).

Preferably, the crosslinking agent is N, N' -methylenebisacrylamide.

Preferably, the dispersant is D3021.

Preferably, the initiator is ammonium persulfate; the catalyst is triethanolamine; the foaming agent is sodium dodecyl benzene sulfonate or sodium fatty alcohol-polyoxyethylene ether sulfate.

The triethanolamine not only plays a role of a catalyst, but also can play a role of adjusting pH.

And (3) sodium silicate is added, wherein sodium can be melted at low temperature to form a liquid substance, so that the fluidity of the product is improved, and silicon in the product does not react, so that the sintered product forms closed air holes, and the heat insulation performance is improved.

In the prior art, when the magnesium refractory material is prepared, a light product is difficult to achieve, the magnesium refractory material is generally produced by a dry pressing process, high porosity cannot be realized, and the light heat insulation function is difficult to achieve; the slurry casting process is also used, but the product prepared by slurry casting has unsatisfactory performance and has the difficulties of high volume density, high heat conductivity coefficient, high product drying shrinkage rate, low molding qualification rate and the like. The invention adopts the gel injection molding method and the foaming process, when the magnesium oxide light heat-insulation brick is prepared, only the raw materials need to be added at normal temperature, and the slurry is filled in each edge and each corner of the mold under the action of pressure during foaming, so that the molding size of the product is complete; the liquid is solidified through coagulation reaction after being simply heated, and the solidified blank has higher strength, stable size and high qualification rate and can be cut into a required shape; meanwhile, as the foaming process is adopted, the porosity is increased, the volume density is reduced, the heat conductivity coefficient of the product is reduced, and the heat insulation performance of the product is enhanced.

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

(1) the raw materials used in the invention are conventional raw materials and have wide sources;

(2) according to the invention, a gel injection molding method is combined with a foaming process, when the magnesium oxide light heat-insulation brick is prepared, only raw materials need to be added at normal temperature, and liquid is easy to solidify after the raw materials are simply heated, so that the strength of a blank body is improved, and the porosity is increased;

(3) the product prepared by the invention has the volume density of 0.6-0.75g/cm³The room temperature compressive strength is 5.6-6.5MPa, the 0.1MPa refractoriness under load is 1400-0.30W/(m.k)；

(4) The method is simple and easy to implement, is beneficial to industrial production, and has remarkable economic benefit.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the practice of the invention.

Example 1

A preparation method of a magnesium oxide light heat-insulation brick comprises the following steps:

(1) mixing the materials according to mass percent, namely stirring and mixing magnesia and 5-micron alumina in a mixer, wherein the magnesia is larger than or equal to 1mm and smaller than D1 and smaller than or equal to 2mm and 15%, the magnesia is larger than or equal to 75 microns and smaller than or equal to D2 and smaller than 1mm and 30%, the magnesia is larger than or equal to 10 microns and smaller than or equal to D3 and smaller than 75 microns and 35%, and the magnesia is larger than or equal to 1 micron and smaller than or equal to D4 and; the mass ratio of the magnesia to the alumina is 94: 6;

(2) adding 60% of water, 7.5% of acrylamide, 1.2% of N, N' -methylene bisacrylamide and 0.2% of D3021 dispersing agent into the mixture obtained in the step (1), and continuously stirring and mixing for 30 minutes;

(3) adding 0.2% of sodium dodecyl benzene sulfonate into the mixture obtained in the step (2), and stirring and foaming for 10 minutes to obtain foaming slurry;

(4) adding 0.5% of ammonium persulfate, 0.04% of triethanolamine and 0.05% of sodium silicate into the foaming slurry obtained in the step (3), and stirring and foaming for 1 minute;

(5) injecting the slurry obtained in the step (4) into a mold, immediately placing the mold into a heating chamber at 60 ℃, preserving heat and curing for 2 hours, then demolding, heating to 80 ℃, and drying for 48 hours;

(6) the mixture is sintered in an electric furnace, the heating rate is 50 ℃/h, and the temperature is preserved for 3 hours at 1480 ℃.

The physical properties of the prepared magnesium oxide light heat-insulating brick are as follows:

bulk density 0.6g/cm³；

The room temperature compressive strength is 5.8 MPa;

the softening starting temperature under load of 0.1MPa is 1400 ℃;

the thermal conductivity is 0.22W/(m.k).

Example 2

(1) mixing the materials according to mass percent, namely stirring and mixing magnesia and bauxite with the mass percent of 1 mm-2 mm 30% of D1, 75μm-1 mm 20% of D2, 10μm-75 μm 20%, 1μm-10 μm 20% of D3, 1μm-10 mm 30% of D4 and 5 μm 30% in a mixer for 30 minutes; the mass ratio of the magnesia to the bauxite is 90: 10;

(2) adding 55% of water, 4% of acrylamide, 2.5% of N, N' -methylene bisacrylamide and 0.8% of D3021 dispersing agent into the mixture obtained in the step (1), and continuously stirring and mixing for 30 minutes;

(3) adding 0.05% of sodium dodecyl benzene sulfonate into the mixture obtained in the step (2), and stirring and foaming for 15 minutes to obtain foaming slurry;

(4) adding 1.5% of ammonium persulfate, 0.05% of triethanolamine and 0.10% of sodium silicate into the foaming slurry obtained in the step (3), and stirring and foaming for 1 minute;

bulk density 0.75g/cm³；

The room temperature compressive strength is 6.5 MPa;

softening starting temperature 1420 ℃ under load of 0.1 MPa;

the thermal conductivity is 0.30W/(m.k).

Example 3

(1) mixing the materials according to the mass percentage, namely stirring and mixing magnesia and bauxite with the particle size of 5 mu m in a mixer, wherein the mass percentage of the magnesia is larger than or equal to 1mm and smaller than or equal to D1 and smaller than or equal to 2mm 10%, the mass percentage of the magnesia is larger than or equal to 75 mu m and smaller than or equal to 1mm 40%, the mass percentage of the magnesia is larger than or equal to 10 mu m and smaller than or equal to D3 and smaller than or equal to 75 mu m 25%, the; the mass ratio of the magnesia to the bauxite is 99: 1;

(2) adding 50% of water, 10% of acrylamide, 1.5% of N, N' -methylene bisacrylamide and 0.5% of D3021 dispersing agent into the mixture obtained in the step (1), and continuously stirring and mixing for 30 minutes;

(3) adding 0.1% of fatty alcohol-polyoxyethylene ether sodium sulfate into the mixture obtained in the step (2), and stirring and foaming for 30 minutes to obtain foaming slurry;

(4) adding 0.6% of ammonium persulfate, 0.08% of triethanolamine and 0.20% of sodium silicate into the foaming slurry obtained in the step (3), and stirring and foaming for 2 minutes;

(5) injecting the slurry obtained in the step (4) into a mold, immediately placing the mold into a heating chamber at 60 ℃, preserving heat and curing for 1 hour, then demolding, heating to 90 ℃, and drying for 24 hours;

(6) the mixture is sintered in an electric furnace, the heating rate is 30 ℃/h, and the temperature is preserved for 2 hours at 1480 ℃.

bulk density 0.68g/cm³；

The room temperature compressive strength is 5.6 MPa;

a refractoriness under load of 0.1MPa is started at 1410 ℃;

the thermal conductivity is 0.25W/(m.k).

Example 4

(1) mixing the materials according to mass percent, namely stirring and mixing magnesia and 5-micron alumina in a mixer, wherein the magnesia is larger than or equal to 1mm and smaller than or equal to D1 and smaller than or equal to 2mm and 20%, the magnesia is larger than or equal to 75 microns and smaller than or equal to D2 and smaller than 1mm and 20%, the magnesia is larger than or equal to 10 microns and smaller than or equal to D3 and smaller than 75 microns and 35%, the magnesia is larger than or equal to 1 micron and smaller than or equal to; the mass ratio of the magnesia to the alumina is 85: 15;

(2) adding 65% of water, 7.5% of acrylamide, 1.2% of N, N' -methylene bisacrylamide and 0.3% of D3021 dispersing agent into the mixture obtained in the step (1), and continuously stirring and mixing for 30 minutes;

(3) adding 0.15% of fatty alcohol-polyoxyethylene ether sodium sulfate into the mixture obtained in the step (2), and stirring and foaming for 18 minutes to obtain foaming slurry;

(4) adding 0.5% of ammonium persulfate, 0.04% of triethanolamine and 0.2% of sodium silicate into the foaming slurry obtained in the step (3), and stirring and foaming for 3 minutes;

(5) injecting the slurry obtained in the step (4) into a mold, immediately placing the mold into a heating chamber at 60 ℃, preserving heat and curing for 2 hours, then demolding, heating to 70 ℃, and drying for 36 hours;

(6) the mixture is sintered in an electric furnace, the heating rate is 40 ℃/h, and the temperature is kept at 1400 ℃ for 5 hours.

bulk density 0.72g/cm³；

The room temperature compressive strength is 6.1 MPa;

softening starting temperature 1420 ℃ under load of 0.1 MPa;

the thermal conductivity is 0.23W/(m.k).

Comparative example 1

The others are substantially the same as in example 4 except that: no auxiliary materials are added.

bulk density 0.58g/cm³；

The room temperature compressive strength is 5.4 MPa;

the softening starting temperature under load of 0.1MPa is 1400 ℃;

the thermal conductivity is 0.24W/(m.k).

Claims

1. A preparation method of a magnesium oxide light heat insulation brick is characterized by comprising the following steps: magnesia is used as a main material, and a gel casting method is combined with a foaming process to prepare the magnesia light heat-insulating brick.

2. The preparation method of the magnesium oxide light heat-insulating brick according to claim 1, characterized in that: the magnesite is fused magnesite or sintered magnesite.

3. The preparation method of the magnesium oxide light heat-insulating brick according to claim 1, characterized in that: the granularity ratio of the magnesia is as follows:

4. The preparation method of the magnesium oxide light heat-insulating brick according to claim 1, characterized in that: the raw materials are measured by mass percentage as follows: 70-99% of magnesite and 1-30% of auxiliary materials.

5. The preparation method of the magnesia light heat insulation brick according to claim 4, characterized in that: the auxiliary material is aluminum oxide or bauxite.

6. The preparation method of the magnesium oxide light heat-insulating brick according to claim 1, characterized in that: the method comprises the following steps:

7. The preparation method of the magnesium oxide light heat-insulating brick according to claim 1, characterized in that: the cross-linking agent is N, N' -methylene bisacrylamide; the dispersant is D3021.

8. The preparation method of the magnesium oxide light heat-insulating brick according to claim 1, characterized in that: the initiator is ammonium persulfate; the catalyst is triethanolamine; the foaming agent is sodium dodecyl benzene sulfonate or sodium fatty alcohol-polyoxyethylene ether sulfate.