CN108558418A - A kind of preparation method of the high-strength calcium hexaluminate refractory material of light weight - Google Patents

Abstract

A kind of preparation method of the high-strength calcium hexaluminate refractory material of light weight, it is characterised in that：It the described method comprises the following steps：（1）The aluminium hydroxide of the carbonic acid calcareous raw material of 38~60wt% and 40~62 wt% are mixed, the bonding agent of the sum of the above-mentioned raw materials water of 80~120 wt%, the dispersant of 0.02~0.05wt% and 1~4 wt% is added later, ball milling 3~5 hours obtains mixed slurry；（2）By mixed slurry mist projection granulating, spherical fine particles are obtained；（3）Spherical fine particles are calcined under the conditions of 1000~1200 DEG C and obtain light porous bead；（4）The aluminum oxide raw material of the light porous ball of 15~30wt% and 70~85 wt% are mixed, the bonding agent of 2~6wt% of the sum of above-mentioned raw materials is added later, after stirring evenly, 10~30MPa pressure compression mouldings, it is calcined 6~8 hours under conditions of 1600~1700 DEG C, obtains the high-strength calcium hexaluminate refractory material of light weight.

Description

Preparation method of a light-weight high-strength calcium hexaaluminate refractory material

technical field

The invention belongs to the technical field of refractory materials or porous ceramics, and in particular relates to a light-weight high-strength calcium hexaaluminate refractory material and a preparation method thereof.

Background technique

High temperature industries are characterized by high energy consumption and high emissions. With the society's great emphasis on energy and environmental protection, reducing energy consumption, green production is the most urgent task in the current high-temperature industry. Most of the heat in high temperature industries is dissipated and lost from refractory materials. The development of heat-insulating refractory materials with low thermal conductivity, high service temperature and good high-temperature performance is the key to reducing energy consumption and emissions in high-temperature industries. CA ₆ (calcium hexaaluminate) has the excellent characteristics of high refractoriness (1875°C), good chemical stability in alkaline environment, and low wettability to metals. It is an excellent refractory material. At the same time, CA ₆ has a flake or plate-like structure, which can maintain a large specific surface area at high temperatures and exhibit good thermal insulation performance at high temperatures. These characteristics make lightweight CA ₆ have a very wide application prospect in the field of high temperature insulation.

At present, calcium hexaaluminate lightweight refractory materials are mainly prepared by burning out or foaming methods, such as the Chinese patent "A calcium hexaaluminate and corundum composite porous lightweight heat-insulating refractory material and its preparation method" (CN 101928153 A). The method uses calcium carbonate and alumina as main raw materials, adds polystyrene balls and sawdust and other organic burnt matter as pore-forming agents, and obtains calcium hexaaluminate light-weight refractory materials after calcining. During the preparation process of this kind of method, the burnt matter generates gas and is discharged from the inside of the material, forming mostly continuous open pores, which reduces the performance of the refractory material. At the same time, the organic incineration will produce harmful gas and a large amount of CO ₂ , which will pollute the environment. Chinese patent "a high-strength calcium hexaaluminate lightweight heat insulation material and its preparation method" (CN 103496993 A), using nano-calcium carbonate and ρ-Al ₂ O ₃ micropowder as main raw materials, and adding alkaline foaming agent to prepare A calcium hexaaluminate thermal insulation material with a micro-closed cell structure has been developed. The obtained material has a small volume density and good thermal insulation performance, but the process control of the foaming method is relatively complicated, which easily leads to uneven materials and low production efficiency.

Chinese patent "a high-strength microporous calcium hexaaluminate lightweight aggregate and its preparation method", (CN 105948772 A) uses alumina hydrate and calcium carbonate as the main raw materials, and uses alumina hydrate and calcium carbonate as raw materials in the calcining process. Calcium hexaaluminate lightweight aggregate with microporous structure was prepared by the method of site decomposition. This method has simple process and no pollution in the production process, but the chemical reaction rate is not easy to control, and it is easy to crack during the calcination process.

Contents of the invention

The purpose of the present invention is to provide a light-weight high-strength calcium hexaaluminate refractory material and its preparation method in view of the deficiencies in the above-mentioned prior art. The light-weight high-strength calcium hexaaluminate refractory material prepared by the present invention It has the characteristics of high compressive strength, high service temperature and good volume stability at high temperature. The process adopted by the invention is simple and easy, and no harmful gas is generated during the preparation process, which is beneficial to environmental protection.

The purpose of the present invention can be achieved through the following technical measures:

The preparation method of the lightweight high-strength calcium hexaaluminate refractory material of the present invention comprises the following steps:

(1) Mix 38-60wt% calcium carbonate raw material and 40-62wt% aluminum hydroxide, then add 80-120wt% water, 0.02-0.05wt% dispersant and 1- 4 wt% binder, ball milled for 3 to 5 hours to obtain a mixed slurry;

(2) Spray and granulate the mixed slurry to obtain spherical fine particles;

(3) Spherical fine particles are calcined at 1000-1200°C to obtain lightweight porous pellets;

(4) Mix 15-30wt% lightweight porous balls and 70-85wt% alumina raw materials, and then add 2-6wt% of the above raw materials as a binder, stir evenly, and press 10-30MPa to form , Calcined at 1600-1700°C for 6-8 hours to obtain a lightweight high-strength calcium hexaaluminate refractory material.

The calcium carbonate raw material described in the present invention is taken from any one of nano-calcium carbonate, light calcium carbonate, common calcium carbonate or limestone, and the particle diameter of the raw material is all <0.074mm; the described dispersant is taken from tripolymer Any one of sodium phosphate, sodium hexametaphosphate or sodium lignosulfonate; the binder is any one of sulfurous acid pulp waste liquor, dextrin, methylcellulose, polyvinyl alcohol or silica sol .

The lightweight porous balls prepared in the step (3) of the present invention have a bulk of ≤0.7g/cm ³ and a particle size of 0.044-0.3mm; the alumina raw materials described in the step (4) are obtained from industrial alumina, Any one of α-alumina, fused corundum, and calcined corundum, or a combination of the two, the particle size of the raw material is ≦0.088mm.

The light-weight high-strength calcium hexaaluminate refractory material prepared by the present invention has a spherical pore structure, a bulk density of 1.3-1.6g/cm ³ , a compressive strength ≥ 60MPa, and a reburning line at 1600°C for 6 hours is - 0.4%～+0.2%.

In the present invention, calcium carbonate raw materials and aluminum hydroxide are used as main raw materials, and high C/A (calcium oxide/alumina) porous pellets are prepared by an in-situ decomposition method. Then, the high C/A porous pellets are combined with alumina raw materials, and the pore-forming mechanism of reaction diffusion is used to prepare CA ₆ with spherical pore structure.

Compared with the prior art, the present invention has the following beneficial effects: (1) The light-weight and high-strength calcium hexaaluminate refractory material has a spherical pore structure, high closed porosity, and controllable pore size;

(2) The light-weight and high-strength calcium hexaaluminate refractory material has high compressive strength, good heat insulation performance, and high service temperature, which can meet the requirements of the working layer of high-temperature kilns;

(3) The light-weight and high-strength calcium hexaaluminate refractory material adopts the pore-forming mechanism of in-situ decomposition and reaction diffusion. During the production process, no ignition loss and foaming agent are added, no harmful gas emissions, and high production efficiency. It is suitable for large-scale industrial production.

Detailed ways

The present invention will be further described below in conjunction with embodiment.

Example 1

(1) Mix 38 wt% nano-calcium carbonate and 62 wt% aluminum hydroxide, then add 90 wt% water, 0.05 wt% sodium tripolyphosphate as dispersant and 4 wt% dextrin As a binding agent, ball milled for 3 hours to obtain a mixed slurry;

(2) Spray and granulate the mixed slurry to obtain a spherical granule body;

(3) Calcining the spherical particle body at 1100°C to obtain lightweight porous balls, the bulk density of the porous balls is 0.63g/cm ³ , and the particle size is 0.044-0.3mm;

(4) Mix 30wt% lightweight porous balls and 70wt% α-alumina fine powder (raw material particle size≦0.074mm), add 4wt% dextrin as a binder of the sum of the above raw materials, and stir evenly, 10MPa pressure compression molding, calcination under the condition of 1600 ℃ for 8 hours, to obtain high-strength and light-weight calcium hexaaluminate refractory material.

The technical indicators of the lightweight high-strength calcium hexaaluminate refractory material prepared in this example are:

The compressive strength is 65.8MPa, the bulk density is 1.35 g/cm ³ , and the permanent line change rate after burning at 1600°C for 6 hours is -0.3%.

Example 2

(1) Mix 52 wt% light calcium carbonate and 48 wt% aluminum hydroxide, add 100 wt% water, 0.03 wt% sodium lignosulfonate as dispersant and 2 wt% formazan The base cellulose is used as a binding agent, and ball milled for 4 hours to obtain a mixed slurry;

(2) Spray and granulate the mixed slurry to obtain a spherical granule body;

(3) Calcining the spherical pellet body at 1150°C to obtain lightweight porous balls, the bulk density of the porous balls is 0.52g/cm ³ , and the particle size is 0.044-0.3mm;

(4) Mix 22wt% lightweight porous balls, 40wt% calcined corundum fine powder (raw material particle size ≦0.074mm) and 38% industrial alumina for analysis, and add the sum of the above raw materials as a binder of methyl fiber 3wt% element, after stirring evenly, press molding under 20MPa pressure, and calcined at 1650°C for 7 hours to obtain high-strength and light-weight calcium hexaaluminate refractory material.

The technical indicators of the lightweight high-strength calcium hexaaluminate refractory material prepared in this example are:

The compressive strength is 70.2MPa, the bulk density is 1.41 g/cm ³ , and the permanent line change rate after burning at 1600°C for 6 hours is -0.1%.

Example 3

(1) Mix 60 wt% of ordinary calcium carbonate and 40 wt% of aluminum hydroxide, add 100 wt% of water, 0.05 wt% of sodium hexametaphosphate as a dispersant and 4 wt% of sulfurous acid pulp The waste liquid is used as a binding agent, and ball milled for 5 hours to obtain a mixed slurry;

(2) Spray and granulate the mixed slurry to obtain a spherical granule body;

(3) Calcining the spherical particle body at 1200°C to obtain lightweight porous balls, the bulk density of the porous balls is 0.61g/cm ³ , and the particle size is 0.044-0.3mm;

(4) Mix 20wt% light porous balls and 80wt% industrial alumina fine powder (raw material particle size 0.074mm), add 3wt% methyl cellulose as the binder of the sum of the above raw materials, stir well, Compressed under the condition of 15MPa, and calcined under the condition of 1650°C for 7 hours, a high-strength and light-weight calcium hexaaluminate refractory material is obtained.

The technical indicators of the lightweight high-strength calcium hexaaluminate refractory material prepared in this example are:

The compressive strength is 60.5MPa, the bulk density is 1.43 g/cm ³ , and the permanent line change rate after burning at 1600°C for 6 hours is -0.2%.

Claims (7)

1. a kind of preparation method of the high-strength calcium hexaluminate refractory material of light weight, it is characterised in that：It the described method comprises the following steps：

（1）By the aluminium hydroxide of the carbonic acid calcareous raw material of 38~60wt% and 40~62 wt% mix, later be added above-mentioned raw materials it With the water of 80~120 wt%, the bonding agent of the dispersant of 0.02~0.05wt% and 1~4 wt%, ball milling 3~5 hours is mixed Close slurry；

（2）By mixed slurry mist projection granulating, spherical fine particles are obtained；

（3）Spherical fine particles are calcined under the conditions of 1000~1200 DEG C and obtain light porous bead；

（4）The aluminum oxide raw material of the light porous ball of 15~30wt% and 70~85 wt% are mixed, above-mentioned raw materials are added later The sum of 2~6wt% bonding agent, after stirring evenly, 10~30MPa pressure compression mouldings are forged under conditions of 1600~1700 DEG C It burns 6~8 hours, obtains the high-strength calcium hexaluminate refractory material of light weight.

2. the preparation method preparation method of the high-strength calcium hexaluminate refractory material of light weight according to right 1, it is characterised in that：Institute The carbonic acid calcareous raw material stated is derived from any one in nano-calcium carbonate, precipitated calcium carbonate, ordinary calcium carbonate or lime stone, raw material Grain size it is equal<0.074mm.

3. the preparation method preparation method of the high-strength calcium hexaluminate refractory material of light weight according to right 1, it is characterised in that：Institute The dispersant stated is derived from any one in sodium tripolyphosphate, calgon or sodium lignin sulfonate.

4. the preparation method preparation method of the high-strength calcium hexaluminate refractory material of light weight according to right 1, it is characterised in that：Institute The bonding agent stated is any one in lignosulfite, dextrin, methylcellulose, polyvinyl alcohol or Ludox.

5. the preparation method preparation method of the high-strength calcium hexaluminate refractory material of light weight according to right 1, it is characterised in that：Step Suddenly（3）In prepared light porous ball, accumulation≤0.7g/cm³, particle size is 0.044~0.3mm.

6. the preparation method preparation method of the high-strength calcium hexaluminate refractory material of light weight according to right 1, it is characterised in that：Step Suddenly（4）Described in aluminum oxide raw material be derived from commercial alumina, Alpha-alumina, electro-corundum, calcining corundum in it is any one Kind or two kinds of combination, Yuan expect Li Jing≤0.088mm.

7. the preparation method preparation method of the high-strength calcium hexaluminate refractory material of light weight according to right 1, it is characterised in that：Institute It is 1.3~1.6g/cm that the high-strength calcium hexaluminate refractory material of light weight of preparation, which has spherical pore structure, bulk density,³, pressure resistance The reheat linear change of intensity >=60MPa, 1600 DEG C of heat preservations 6 hours is -0.4%~+0.2%.