CN106518138B - A kind of preparation method of foam ceramic thermal insulation building block - Google Patents

Abstract

The invention discloses a preparation method of a foam ceramic thermal insulation block. A uniformly mixed foam ceramic blank is used, and after adding water, stirring, and stale, it is laid on a porous refractory pallet; a special molding die and a refractory pallet are used to press the porous blank; the molding die is made of punching needles. The bottom mold and the porous platen are composed. After the pressing is completed, the bottom mold and the porous platen are separated, and the porous body is taken out together with the porous refractory support plate; it is dried to a moisture content of less than 2%, and heated in a high-temperature furnace at 3-5℃/min To 1050 ~ 1200 ℃, heat preservation for 0.5 ~ 1.5h, so that the foaming agent decomposes to form pores; after cooling with the furnace, it is cut into foam ceramic blocks. The porous body structure designed by the invention accelerates the infiltration and discharge of gas, promotes the oxidative decomposition of minerals inside the body, realizes the rapid firing of large-volume foamed ceramics, effectively reduces the temperature difference between the inside and outside of the product, and solves the problem of large volume and thickness. Cooling cracking problem of quality foam ceramics.

Description

A kind of preparation method of foam ceramic insulation block

technical field

The invention belongs to the technical field of composite materials, and in particular relates to a preparation method of a foamed ceramic block.

Background technique

As a new type of inorganic porous thermal insulation material, foam ceramics have been widely used in the field of wall thermal insulation materials due to their light weight, heat insulation, fire resistance, waterproofing, sound insulation and other properties. At present, in order to reduce the preparation cost of foamed ceramics, the rapid sintering of solid wastes and large-volume thick green bodies has become the development trend of foamed ceramics. For example: a large amount of solid waste such as polished brick slag, fly ash, coal gangue and metal tailings is used to sinter large-volume ceramic foam test blocks larger than 2000*1000*300mm at one time, and the sintering cycle is shortened as much as possible ,reduce manufacturing cost. However, due to the complex mineral composition of the tailings slag, many oxidative decomposition reactions are involved at high temperatures, and these reactions are greatly affected by the firing conditions (such as firing atmosphere), plus the infiltration and removal of gas inside the large-volume foamed ceramics Difficulties, so that the foam ceramics prepared by using tailings waste slag has different foaming effects inside and outside, and the performance is significantly reduced. At present, this problem is mainly dealt with by reducing the utilization rate of tailings and prolonging the heating rate to increase the permeation and discharge time of the gas, but this measure reduces the production efficiency and increases the production cost.

In addition, cooling cracking of large-volume foamed ceramics is also one of the difficult problems to solve in the production of foamed ceramics. Due to the low thermal conductivity of foamed ceramics, the internal heat is only dissipated outwards by conduction during the cooling process, and the efficiency is low. The problem of green body cracking caused by temperature stress is more significant in large-volume foamed ceramics. Therefore, the limitation of product size and cooling rate has become an urgent problem to be solved in the industrial production of large-volume and thick foamed ceramics.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of foamed ceramic insulation material, which solves the problems of slow heat and mass transfer in the production of existing large-volume and thick foamed ceramics, large temperature difference inside the green body, difficulty in infiltration and discharge of gas, and limited large-scale production. The problem of volume thick foam ceramic production, and solve the problem of foam ceramic cooling cracking.

In order to achieve the above purpose, the technical solutions are as follows:

A preparation method of a foamed ceramic thermal insulation block, comprising the following steps:

The uniformly mixed foam ceramic blanks are laid on the porous refractory pallet after adding water, stirring, and stale;

A special molding die and a refractory pallet are used to press into a porous body; the molding die is composed of a bottom die with a punching needle and a porous press plate. After the pressing is completed, the bottom die and the porous press plate are separated, and the porous body is combined with the porous refractory. Take out the pallet together;

Dry to moisture content <2%, heat up to 1050-1200°C at 3-5°C/min in a high-temperature furnace, hold for 0.5-1.5h to decompose the foaming agent to form pores; remove the porous refractory support after cooling in the furnace boards, cut into foam ceramic blocks.

According to the above solution, the dry basis of the foamed ceramic blank comprises SiO ₂ +Al ₂ O ₃ : 65-85wt%, CaO+MgO: 5-20wt%, Na ₂ O+K ₂ O: 2-15wt%, Fe ₂ O ₃ : 1 to 10 wt %.

According to the above scheme, the foamed ceramic blank adopts any one or a mixture of CaCO ₃ , SiC, CaSO ₄ , and graphite as the foaming agent, and the particle size of the powder particles is less than 80 μm.

According to the above scheme, the water addition amount is 6-12wt%, and the aging time is 24-48h.

According to the above scheme, the staggered cylindrical upright holes of 15-25 mm in diameter are distributed in the porous body; the porosity is 18-26%.

According to the above scheme, cylindrical upright holes with diameters of 5-15 mm arranged in parallel are distributed in the porous body; the porosity is 12-22%.

Using a forming die together with a refractory support plate to press into a porous body, when the pressed porous body is distributed with staggered cylindrical upright holes with a diameter of 15 to 25 mm and a porosity of 18 to 26%, the A-type foamed ceramic is obtained after firing. A porous block with staggered upright holes, the upright hole diameter is 10-20mm, the porosity is 12-26%, and the bulk density is 350-500kg/m ³ . When there are cylindrical upright holes with a diameter of 5-15mm arranged in parallel in the porous body, and the porosity is 12-22%, the B-type foam ceramic obtained after firing is a solid block without upright holes, and the bulk density is 150-350kg/ ^m3 . .

The preparation method of the foamed ceramic block proposed by the patent of the present invention, by designing a foamed ceramic body with communicating pores, accelerates the penetration and discharge rate of gas in the body, and effectively solves the problem of the internal and external performance of the product caused by the firing atmosphere. One problem, and shorten the firing cycle of foam ceramics.

Through the design of pore size and firing temperature, the retention form of the upright holes of the green body in the product can be controlled, and the A-type blocks with upright holes and the B-type blocks without holes can be prepared respectively.

During the cooling process of the A-type porous block, the heat inside the green body can be quickly discharged by convection, which can effectively reduce the temperature difference between the inside and outside of the product and solve the problem of cooling cracking of large-volume and thick foam ceramics. At the same time, compared with traditional porous bricks, the porous foamed ceramic blocks prepared by this method have lower bulk density, outstanding thermal insulation performance and low water absorption rate, and are porous lightweight walls that integrate flame retardant thermal insulation, sound insulation and durability. Material.

The positive effects of the present invention are:

1) The porous green body structure designed in the present invention accelerates the infiltration and discharge of gas, promotes the oxidation and decomposition of minerals inside the green body, and realizes the rapid firing of large-volume foamed ceramics.

2) The A-type porous ceramic foam block prepared by the method of the present invention quickly discharges the heat inside the green body through the air flow channel formed by the upright holes, reduces the temperature difference between the inside and outside of the foam ceramic during the cooling process, and effectively solves the problem caused by the temperature difference stress. cooling cracking problem.

3) The preparation method of the foamed ceramic block proposed by the present invention improves the production efficiency and product quality, and is beneficial to the application of large amount of tailings waste residue in foamed ceramics. The prepared product integrates the advantages of foamed ceramics and porous bricks, and has the advantages of light weight, heat preservation, fire resistance, frost resistance, aging resistance and the like.

Description of drawings

Figure 1: Schematic diagram of the A-type blank structure;

Figure 2: Schematic diagram of the structure of the B-type blank;

Figure 3: Schematic diagram of the pressure forming die.

Detailed ways

The following examples further illustrate the technical solutions of the present invention, but are not intended to limit the protection scope of the present invention.

Example 1

1) Take the foamed ceramic blanks that have been uniformly mixed and the particle size is less than 80 μm, spray 10wt% of water evenly, and after 48 hours of stale homogenization, lay them on a porous refractory pallet with a thickness of 150 mm.

2) Place the refractory support plate covered with the blank on the bottom mold of the pressure forming machine, make the punching needle pass through the holes and the blank of the refractory support plate, and then apply 1.0MPa pressure with the porous pressing plate to press the blank in the refractory support plate. Pressed into a type A porous body with a pore diameter of 20 mm and a porosity of 21.3% as shown in Figure 1, and then the bottom mold and the porous pressing plate were removed downward and upward respectively. The pressure forming die used is shown in Figure 3. The forming die consists of a bottom die with a punching needle and a porous press plate. After the pressing is completed, the bottom die and the porous press plate are separated, and the porous blank is taken out together with the porous refractory plate.

3) Dry the porous body at 60°C until the moisture content is less than 2%, then place it in a high-temperature furnace together with the porous refractory pallet, heat up to the firing temperature at 5°C/min, and keep the temperature for 40 minutes. After controlled cooling, the cooling rate is 1～10℃/min, and the cooling time is 6～10h.

4) After cooling to less than 50°C, remove the sidewall plate and the porous support plate, and cut it into demolding and cutting to prepare an A-type porous foam ceramic block with regularly arranged upright holes. 16mm, the hole rate is 13.6%.

Example 2

1) Take the foamed ceramic blanks that have been uniformly mixed and whose particle size is less than 80 μm, spray 8wt% of water evenly, and after 36 hours of stale homogenization, lay them on a porous refractory pallet with a thickness of 200 mm.

2) Place the refractory support plate covered with blanks on the bottom die of the pressure forming machine, make the punching needle pass through the holes and blanks of the refractory support plate, and then apply 0.5MPa pressure with the porous platen to press the blanks in the refractory support plate. Press into a B-type porous blank with a pore diameter of 10 mm and a porosity of 16.2% as shown in Figure 2, and then remove the forming bottom mold and the porous pressing plate downward and upward respectively. The pressure forming die used is shown in Figure 3. The forming die consists of a bottom die with a punching needle and a porous press plate. After the pressing is completed, the bottom die and the porous press plate are separated, and the porous blank is taken out together with the porous refractory plate.

3) Dry the porous body together with the porous refractory pallet at 80°C until the moisture content is less than 2%, then place it in a high-temperature furnace, heat up to the firing temperature at 5°C/min, and keep the temperature for 1.5h. And then controlled cooling, cooling rate 1 ~ 10 ℃/min, cooling time 8 ~ 12h.

4) After cooling to below 50°C, remove the sidewall plate and the perforated support plate, and then cut into a mold release and cut to prepare a B-type foam ceramic block without vertical holes.

Claims (4)

1. a preparation method of a foamed ceramic insulation block, is characterized in that comprising the following steps: The uniformly mixed foam ceramic blanks are laid on the porous refractory pallet after adding water, stirring, and stale; A special molding die and a porous refractory pallet are used to press into a porous body; the molding die is composed of a bottom die with a punching needle and a porous press plate. After the pressing is completed, the bottom die and the porous press plate are separated, and the porous body together with the porous Take out the refractory pallet together; Dry to moisture content <2%, heat up to 1050-1200°C at 3-5°C/min in a high-temperature furnace, hold for 0.5-1.5h to decompose the foaming agent to form pores; remove the porous refractory support after cooling in the furnace boards, cut into foam ceramic blocks; Wherein, the dry basis of the foamed ceramic blank includes SiO ₂ +Al ₂ O ₃ : 65-85 wt %, CaO+MgO: 5-20 wt %, Na ₂ O+K ₂ O: 2-15 wt %, Fe ₂ O ₃ : 1 to 10 wt%; and the foamed ceramic blank adopts any one or a mixture of CaCO ₃ , SiC, CaSO ₄ , and graphite as a foaming agent, and the particle size of the foamed ceramic blank is less than 80 μm. 2 . The preparation method of the foamed ceramic thermal insulation block according to claim 1 , wherein the amount of water added is 6-12 wt %, and the aging time is 24-48 h. 3 . 3 . The method for preparing a foamed ceramic thermal insulation block according to claim 1 , wherein the porous body has staggered cylindrical upright pores of 15-25 mm in diameter; the porosity is 18-26%. 4 . 4 . The preparation method of the foamed ceramic thermal insulation block according to claim 1 , wherein the cylindrical upright holes with diameters of 5-15 mm arranged in parallel are distributed in the porous body; the porosity is 12-22%. 5 .