CN104973869B - Mullite light heat-insulation fire-resistant brick and production method thereof - Google Patents

Abstract

The invention relates to a mullite lightweight heat-insulating refractory brick and its production method. The raw materials are 25-35% of aluminum hydroxide, 10-30% of burnt gemstone clinker, 10-30% of kyanite, and 35% of binder. ~50%, using the above raw materials as raw materials, adding 1.0~2.0m ³ of expandable polystyrene balls and 0.3~0.5m ³ of sawdust; the binder is kaolin or alumina cement. The product of the present invention has the advantages of high compressive strength, low thermal conductivity, low change rate of high-temperature reburning line, good thermal shock stability, etc., and the product performance is excellent, meeting the requirements of American ASTM and other related product standards. The use of aluminum hydroxide instead of alumina raw materials has low energy consumption and cost, can generate more mullite crystal phases, effectively reduces the content of corundum phases in products, and improves the thermal shock stability of products. This product can be widely used in heat insulation layer and refractory layer of various thermal equipments to achieve dual functions of energy saving and fire resistance, which is conducive to popularization and application.

Description

Mullite lightweight heat-insulating refractory brick and production method thereof

technical field

The invention relates to a lightweight heat-insulating refractory brick, in particular to a mullite light-weight heat-insulating refractory brick for thermal equipment and a production method thereof.

Background technique

Energy is scarce in the world, and various thermal equipment are important facilities in industrial production, and they are also large energy consumers. Therefore, the refractory layer and heat insulation layer of various thermal equipment require heat preservation, fire resistance, and heat insulation. Long-term safe use, energy saving and consumption reduction guarantee greater economic benefits. At present, heat insulation and heat preservation refractory bricks of various materials are basically used (1) adding combustible materials, such as sawdust, poly light balls; (2) low density, low refractoriness lightweight materials, such as expanded perlite and closed cell perlite. However, adding a large amount of low-density and light-weight materials will often destroy the overall refractoriness, linear change rate and other high-temperature performance of the product, and the product will not meet the relevant national standards, thereby reducing the service life of the industrial furnace, and even leading to production accidents in severe cases. occur.

The patent application with application number 200810015228.2 discloses a mullite lightweight thermal insulation brick, whose components include Zhanjiang soil, kyanite, sillimanite, calcined alumina, and recycled waste products of the same type. The cost of raw materials for this product is relatively high, and the raw materials such as calcined alumina used are high-energy-consuming and high-value raw materials, which are not economical to use in the production of heat-insulating bricks. The performance of the product is average, and the cost performance of the product is low.

Contents of the invention

The technical problem to be solved by the present invention is to provide a mullite lightweight heat-insulating refractory brick with high compressive strength, low thermal conductivity, low linear change rate, good thermal shock stability and low production cost and its production method.

Technical scheme of the present invention:

A mullite lightweight heat-insulating refractory brick, expressed in weight percentage, raw materials are 25-35% of aluminum hydroxide, 10-30% of burnt gemstone clinker, 10-30% of kyanite, and 35-50% of binder %, based on the above raw materials, add 1.0~2.0m ³ of expandable polystyrene balls and 0.3~0.5m ³ of sawdust per ton of basic raw materials; the binder is kaolin or alumina cement.

The aluminum content of the aluminum hydroxide is ≥ 30%, and the particle size is 200-325 mesh; the aluminum content of the burnt gemstone clinker is 42-55%, and the particle size is 200-325 mesh; the aluminum content of the kyanite is The particle size is 48~58%, and the particle size is 180~325 mesh; the particle size of the binder is 200~325 mesh.

The expandable polystyrene balls are spherical particles formed from expandable polystyrene raw particles processed by high-temperature steam, with a bulk density of 15-20kg/m ³ and a particle size of 0.5-1.5mm.

The sawdust is sieved with a 14-mesh sieve, and then soaked in water for no less than 30 days.

The production method of the mullite light-weight heat-insulating refractory brick includes weighing raw materials, mixing materials, molding, drying and firing, firstly the basic raw materials aluminum hydroxide, burnt gemstone clinker, kyanite, bonding Mix the agent in proportion and stir evenly; then add expandable polystyrene pellets and sawdust, stir and mix evenly; add water, the weight ratio of basic raw materials to water is 1.0~1.75:1, and stir to make a flowing slurry Then pour into the mold to form adobe, dry the adobe and put it into the kiln; heat the adobe from normal temperature to a high temperature of 1350~1400℃, keep it warm for 2~3 hours, and fire it.

The adobe drying is carried out in two stages, the first stage is low-temperature drying, the drying temperature is 20-35°C, and the drying time is 24-36h; the second stage is forced drying, the drying temperature is 90-110°C, and the drying time is 24 hours. ~36h, the moisture content of the adobe after drying is controlled below 5%.

When the bricks are dried, the honeycomb aluminum alloy drying pallet is used. The aluminum alloy plate has ventilation and drainage holes. The aluminum alloy plate is covered with a cotton cloth layer. The aluminum alloy plate and the cotton cloth layer are bonded by adhesive.

The firing temperature system for heating the adobe from normal temperature to high temperature is: the adobe is heated from room temperature to 700-750°C for 8-10 hours, and kept for 1-1.5 hours; it is heated for 5-6 hours to 1000-1050°C, and kept for 1.5-2 hours; After 5-6 hours, the temperature is raised to 1250-1300 ℃, and the temperature is kept for 1-1.5 hours; after 2-3 hours, the temperature is raised to 1350-1400 ℃, and the temperature is kept for 2-3 hours; then the temperature starts to drop, from 1350-1400 ℃ to 1100-10 hours after 8-10 hours 1150°C, keep warm for 1-1.5 hours; then cool down to 800-850°C after 7-7.5 hours, and finally cool naturally to 100°C, and leave the kiln.

The mold is a wooden mold, the upper surface of the mold frame is provided with a groove, and an iron block is inlaid in the groove, the width of the bottom of the groove is greater than the top of the groove, and the shape of the iron block matches the groove. The cross section of the groove is trapezoidal or square.

Raw material performance requirements:

1. Performance requirements of aluminum hydroxide fine powder:

2. Performance requirements of burnt stone clinker fine powder:

Al ₂ O ₃ (%) Fe ₂ O ₃ (%) Refractoriness (℃) Burn reduction (%) 42-55 ≤1.0 ≥1770 ≤1

3. Performance requirements of kyanite fine powder:

Al ₂ O ₃ (%) SiO ₂ (%) Fe ₂ O ₃ (%) Na ₂ O + K ₂ O (%) Burn reduction (%) 45~52 40-48 ≤1.0 ≤0.4 ≤0.1

4. Performance requirements of kaolin fine powder:

Al ₂ O ₃ (%) SiO ₂ (%) Fe ₂ O ₃ (%) Na ₂ O + K ₂ O (%) Burn reduction (%) 35~50 48-63 ≤1.0 ≤0.4 ≤10

5. Performance requirements of pure alumina cement:

Al ₂ O ₃ (%) CaO (%) Fe ₂ O ₃ (%) SiO ₂ (%) Burn reduction (%) 68~80 2-17 ≤0.5 ≤0.5 ≤0.1

Positive beneficial effect of the present invention:

(1) The mullite lightweight heat-insulating refractory brick of the present invention uses aluminum hydroxide, coke gemstone, kyanite and binder as basic raw materials, the ratio of raw materials is reasonable, the compatibility is good, and the product has compressive strength High, low thermal conductivity, low change rate of high-temperature reburning line, good thermal shock stability, etc., the product performance is excellent, meeting the requirements of ASTM and other related product standards in the United States, see Table 1 below.

Remarks: The American standard in Table 1 refers to the American ASTM standard; the performance parameter is the typical value of the product of the present invention, which can meet the different performance requirements of the user through the optimal ratio of raw materials, and the unit of the bulk density is g/cm ³ .

(2) The present invention uses aluminum hydroxide to replace the commonly used alumina raw material. Aluminum hydroxide is an intermediate product in the production of calcined alumina, with low energy consumption and low cost. It is decomposed into active Al ₂ O ₃ particles during product sintering, and combined with raw materials The SiO ₂ contained in it forms mullite crystal phase, the process is very energy-saving, and can effectively reduce the production cost of the product. The active Al ₂ O ₃ particles formed by the decomposition of aluminum hydroxide are very reactive and can generate more mullite. The crystal phase can effectively reduce the content of corundum phase in the product and improve the thermal shock stability of the product.

(3) The honeycomb aluminum alloy drying pallet is used for drying bricks in the present invention. Since the aluminum alloy plate has ventilation and drainage holes and a cotton cloth layer is laid at the same time, the drying effect is good, energy saving and consumption reduction; two-stage drying is adopted, and Set the drying temperature and drying time for each section according to the type of raw material; firstly carry out low-temperature drying, at this stage, the moisture in the brick body is large, and the drying temperature needs to be controlled to prevent the rapid discharge of water and cause cracks in the brick body, and then forced drying to control the moisture content of the brick body to meet the requirements , to ensure the quality of the product after sintering.

(4) The mold in the present invention installs the iron block in the wooden mold by embedding. When in use, the device with magnets can be used to suck the mold from the upper part, so that the mold can be demoulded, and part of the mechanized operation can be realized, which can reduce labor intensity ;The width of the bottom of the mold groove is larger than that of the top of the groove, which is convenient to fix the iron block and prevent the iron block from falling off; the iron blocks are symmetrically distributed, and the operation is stable and safe.

(5) The present invention adopts the set firing temperature, which is beneficial to the improvement of product processing and product performance, and is conducive to improving its performance indicators such as compressive strength.

(6) The product of the present invention can be widely used in heat insulation layers and refractory layers of various thermal equipment to achieve dual functions of energy saving and fire resistance, which is conducive to popularization and application.

Description of drawings

Fig. 1 is the wooden mold structural representation of clay brick with inlaid iron block;

Fig. 2 One of the cross-sectional structural diagrams of A-A in Fig. 1;

Fig. 3 The second schematic diagram of the cross-sectional structure of A-A in Fig. 1.

In the figure, 1 is a frame, 2 is an iron block, and 3 is a groove.

detailed description

The following examples further illustrate the present invention. The performance requirements of each raw material are shown in the technical solution section. The raw materials are calculated in weight percentage, and the consumption can be adjusted according to the technical performance required by the user.

Example 1: Mullite lightweight heat-insulating refractory bricks (specific gravity is 1.3), the proportions are shown in Table 2, and 35% of aluminum hydroxide fine powder, 15% of burnt gemstone fine powder, and kyanite fine powder are weighed by weight percentage 10%, binder kaolin fine powder 40%, add the above raw materials into a forced mixer and mix them for 5-6 minutes; take the above raw materials as basic raw materials, add 1.0m3 ^of expandable polystyrene balls per ton of basic raw materials, Sawdust 0.4m ³ , stir for 5-6 minutes; add water in proportion, the weight ratio of basic raw materials and water is 1.0~1.75:1, stir to make a flowing slurry, stir for 5-6 minutes; then pour into the mold and cast Make bricks, dry the bricks, and then put them into a kiln; heat from room temperature to 1350~1400°C, keep warm for 2~3 hours, and fire.

The adobe drying is carried out in two stages, the first stage is low-temperature drying, the drying temperature is 20-35°C, and the drying time is 24-36h; the second stage is forced drying, the drying temperature is 90-110°C, and the drying time is 24 hours. ~36h, the moisture content of the adobe after drying is controlled below 5%. When the bricks are dried, the honeycomb aluminum alloy drying pallet is used. The aluminum alloy plate has ventilation and drainage holes, and the aluminum alloy plate is covered with a cotton cloth layer. The aluminum alloy plate and the cotton cloth layer are bonded by adhesive.

The firing temperature system for heating the adobe from room temperature is as follows: the adobe is heated from room temperature to 700-750°C for 8-10 hours, and kept for 1-1.5 hours; Rise to 1250-1300°C in ~6 hours, keep warm for 1-1.5h; heat up to 1350-1400°C in 2-3 hours, keep hold for 2-3 hours; then start to cool down, from 1350-1400°C to 1100-1150°C in 8-10 hours , keep warm for 1~1.5h; then cool down to 800~850℃ after 7~7.5h, and finally cool naturally to 100℃.

After the product is out of the kiln, its physical and chemical properties, surface quality and external dimensions are inspected; after the product is qualified, it is ground and assembled according to the size standard or contract requirements; finally, the product is packed into the warehouse for storage or delivery. The specific gravity (ie bulk density) of the product is related to the amount of polystyrene pellets and sawdust added.

Embodiment 2: The raw material ratio of mullite lightweight heat-insulating refractory bricks is shown in Table 2, and the production method is basically the same as Example 1, except that:

Add the above raw materials into the forced mixer according to the ratio, mix and stir; add expandable polystyrene balls and sawdust, and stir for 5-6 minutes; add water in proportion, the weight ratio of basic raw materials and water is 1.0:1, and it is made by stirring The flowing mud-like material is stirred for 5-6 minutes; then poured into the mold and cast into adobe, the adobe is dried, and then loaded into a kiln; heated from room temperature to 1350°C, kept for 2 hours, and fired.

The adobe drying is carried out in two stages, the first stage is low-temperature drying, the drying temperature is 20°C, and the drying time is 36h; the second stage is forced drying, the drying temperature is 9°C, the drying time is 6h, and the moisture content of the adobe after drying is controlled at 5 %the following. When drying bricks, use honeycomb aluminum alloy drying pallets, in which the aluminum alloy board has ventilation drainage holes, and the aluminum alloy board is laid with a cotton cloth layer.

The firing temperature system for heating the adobe from room temperature is as follows: the adobe is heated from room temperature to 700°C for 8 hours, and kept for 1.5 hours; heated to 1000°C for 5 hours, kept for 2 hours; heated to 1250°C for 5 hours, kept for 1.5 hours; heated for 2 hours To 1350°C, keep warm for 3 hours; then start to cool down, from 1350°C to 1100°C over 8 hours, keep warm for 1 hour; then cool down to 800°C after 7 hours, finally cool naturally to 100°C, and leave the kiln.

The mold is a wooden mold, the upper surface of the mold frame is provided with a groove, and an iron block is inlaid in the groove, the width of the bottom of the groove is greater than the top of the groove, and the shape of the iron block matches the groove. The cross section of the groove is trapezoidal or square.

Embodiment 3: The raw material ratio of mullite lightweight heat-insulating refractory bricks is shown in Table 2, and the production method is basically the same as Example 1, except that:

Add the above raw materials into the forced mixer according to the proportion, mix and stir; add expandable polystyrene balls and sawdust, and stir for 5-6 minutes; add water according to the proportion, the weight ratio of basic raw materials and water is 1.75:1, and it is made by stirring The flowing mud-like material is stirred for 5-6 minutes; then poured into the mold and cast into bricks, dried and then loaded into the kiln; heated from room temperature to 1400°C, kept for 3 hours, and fired.

The adobe drying is carried out in two stages, the first stage is low-temperature drying, the drying temperature is 35°C, and the drying time is 24h; the second stage is forced drying, the drying temperature is 110°C, the drying time is 24h, and the water quality of the adobe after drying The content is controlled below 5%. When drying bricks, use honeycomb aluminum alloy drying pallets, in which the aluminum alloy board has ventilation drainage holes, and the aluminum alloy board is laid with a cotton cloth layer.

The firing temperature system for heating the adobe from room temperature is as follows: the adobe is heated from room temperature to 750°C for 10 hours, and kept for 1 hour; it is heated to 1050°C for 6 hours, and kept for 1.5 hours; it is heated to 1300°C for 6 hours, and kept for 1 hour; 1400°C, keep warm for 2 hours; then start to cool down, from 1400°C to 1150°C over 10 hours, keep warm for 1.5 hours; then cool down to 850°C after 7.5 hours, finally cool naturally to 100°C, and leave the kiln.

The mold is a wooden mould, the upper surface of the mold frame is provided with a groove, and an iron block is inlaid in the groove, the width of the bottom of the groove is greater than the top of the groove, the shape of the iron block matches the groove, and the groove The cross section is trapezoidal or square.

Embodiment 4: The raw material ratio of mullite lightweight heat-insulating refractory bricks is shown in Table 2, and the production method is basically the same as Example 1, except that:

Add the above raw materials into the forced mixer according to the ratio, mix and stir; add expandable polystyrene balls and sawdust, and stir for 5-6 minutes; add water in proportion, the weight ratio of basic raw materials and water is 1.5:1, and it is made by stirring The flowing mud-like material is stirred for 5-6 minutes; then poured into the mold and cast into adobe, the adobe is dried, and then loaded into a kiln; heated from room temperature to 1380°C, kept for 2.5 hours, and fired.

The drying of the adobe is carried out in two stages, the first stage is low-temperature drying, the drying temperature is 30°C, and the drying time is 30h; the second stage is forced drying, the drying temperature is 100°C, the drying time is 30h, and the water quality of the adobe after drying The content is controlled below 5%. When drying bricks, use honeycomb aluminum alloy drying pallets, in which the aluminum alloy board has ventilation drainage holes, and the aluminum alloy board is laid with a cotton cloth layer.

The firing temperature system for heating the adobe from room temperature is as follows: the adobe is heated from room temperature to 720°C for 9 hours, and kept for 1.2 hours; it is heated to 1020°C for 5.5 hours, and kept for 1.8 hours; it is heated to 1280°C for 5.5 hours, and kept for 1.2 hours; After 2.5 hours, the temperature was raised to 1380°C, and the temperature was maintained for 2.5 hours; then the temperature was lowered, and the temperature was lowered from 1380°C to 1130°C for 9 hours, and the temperature was maintained for 1.2 hours; after 7.5 hours, the temperature was lowered to 820°C, and finally cooled naturally to 100°C.

Embodiment 5: The raw material ratio of mullite lightweight heat-insulating refractory bricks is shown in Table 2, and the production method is basically the same as Example 1, except that:

Add the above raw materials into a forced mixer according to the proportion, mix and stir; add expandable polystyrene balls and sawdust, and stir for 5-6 minutes; add water in proportion, the weight ratio of basic raw materials and water is 1.35:1, and it is made by stirring The flowing mud-like material is stirred for 5-6 minutes; then poured into the mold and cast into adobe, the adobe is dried, and then loaded into a kiln; heated from room temperature to 1360°C, kept for 2-3 hours, and fired.

The drying of the adobe is carried out in two stages, the first stage is low-temperature drying, the drying temperature is 30°C, and the drying time is 30h; the second stage is forced drying, the drying temperature is 100°C, the drying time is 30h, and the water quality of the adobe after drying The content is controlled below 5%. When drying bricks, use honeycomb aluminum alloy drying pallets, in which the aluminum alloy board has ventilation drainage holes, and the aluminum alloy board is laid with a cotton cloth layer.

The firing temperature system for heating the adobe from room temperature is as follows: the adobe is heated from room temperature to 720°C for 9 hours, and kept for 1.2 hours; heated to 1000°C for 5 hours, kept for 2 hours; heated to 1300°C for 6 hours, kept for 1.5 hours; heated for 3 hours To 1360°C, keep warm for 3 hours; then start to cool down, from 1360°C to 1100°C over 10 hours, keep warm for 1.5 hours; then cool down to 800°C after 7.5 hours, and finally cool naturally to 100°C.

The raw material ratio of other embodiments is shown in Table 2, and the production method is basically the same as that of Example 1, and will not be described in detail.

Table 2: Raw material ratio of high-alumina polycarbonate light-weight heat-insulating refractory bricks in the examples (in weight percentage, %)

Claims (9)

1. A mullite lightweight heat-insulating refractory brick is characterized in that: expressed in weight percentage, the raw materials are 25-35% of aluminum hydroxide, 10-30% of burnt gemstone clinker, 10-30% of kyanite, Binder 35-50%, based on the above raw materials, add 1.0-2.0m ³ of expandable polystyrene balls and 0.3-0.5m ³ of sawdust per ton of basic raw materials; the binder is kaolin or alumina cement . 2. The mullite lightweight heat-insulating refractory brick according to claim 1, characterized in that: the aluminum hydroxide content of the aluminum hydroxide is ≥ 30%, and the particle size is 200-325 mesh; the aluminum content of the burnt gemstone clinker is The aluminum content in the kyanite is 48-58%, and the particle size is 180-325 mesh; the particle size of the binder is 200-325 mesh; the content All are percentages by weight. 3. The mullite lightweight heat-insulating refractory brick according to claim 1, characterized in that: the expandable polystyrene balls are spherical particles formed by the expandable polystyrene raw particles after high-temperature steam processing , the bulk density is 15-20kg/m ³ , and the particle size is 0.5-1.5mm; the sawdust is screened with a 14-mesh sieve, and then soaked in water for no less than 30 days. 4. A production method of mullite lightweight heat-insulating refractory bricks as claimed in claim 1, comprising weighing raw materials, mixing, molding, drying and firing, characterized in that: basic raw materials aluminum hydroxide, coke Gemstone clinker, kyanite and binder are mixed in proportion and stirred evenly; then add expandable polystyrene pellets and sawdust, stir and mix evenly; add water, the weight ratio of basic raw materials to water is 1.0-1.75: 1. Stir to make a flowing mud-like material; then pour it into a mold and pour it into adobe, dry the adobe and put it into a kiln; heat the adobe from room temperature to a high temperature of 1350-1400°C, keep it warm for 2-3 hours, and fire; The firing temperature system for heating the adobe from normal temperature to high temperature is: the adobe is heated from room temperature to 700-750°C for 8-10 hours, and kept for 1-1.5 hours; it is heated for 5-6 hours to 1000-1050°C, and kept for 1.5-2 hours; After 5-6 hours, the temperature is raised to 1250-1300 ℃, and the temperature is kept for 1-1.5 hours; after 2-3 hours, the temperature is raised to 1350-1400 ℃, and the temperature is kept for 2-3 hours; then the temperature starts to drop, from 1350-1400 ℃ to 1100-10 hours after 8-10 hours 1150°C, keep warm for 1-1.5 hours; then cool down to 800-850°C after 7-7.5 hours, and finally cool naturally to 100°C, and leave the kiln. 5. The production method according to claim 4, characterized in that: said adobe drying is carried out in two stages, the first stage is low-temperature drying, the drying temperature is 20-35°C, and the drying time is 24-36h; the second stage For forced drying, the drying temperature is 90-110° C., the drying time is 24-36 hours, and the moisture content of the dried brick is controlled below 5%. 6. The production method according to claim 5, characterized in that: when the adobe is dried, a honeycomb aluminum alloy drying pallet is used, the aluminum alloy plate has ventilation and drainage holes, and a cotton cloth layer is laid on the aluminum alloy plate, and the aluminum alloy plate Adhesive bonding is used between the board and the cotton layer. 7. The production method according to any one of claims 4-6, characterized in that: the aluminum content of the aluminum hydroxide is more than or equal to 30%, and the particle size is 200 to 325 mesh; the aluminum content in the burnt gemstone clinker is 42-55%, the particle size is 200-325 mesh; the aluminum content in the kyanite is 48-58%, the particle size is 180-325 mesh; the particle size of the binder is 200-325 mesh; the content is is a percentage by weight. 8. The production method according to any one of claims 4-6, characterized in that: the mold is a wooden mold, the upper surface of the mold frame is provided with grooves, and iron blocks are embedded in the grooves, and the grooves The width of the bottom is greater than the top of the groove, the shape of the iron block matches the groove, and the cross section of the groove is trapezoidal or square. 9. The wooden mold according to claim 8, characterized in that: the wooden mold is square, and there are two or four iron blocks, which are respectively symmetrically distributed on opposite sides of the wooden mold, and the thickness of the iron blocks is 2.8-5mm .