Application of fly ash in the production of lightweight refractories Research and Application Li Dezhou Miao Wenming (Henan Pingdingshan New Refractories Co., Ltd.) Yin Yanhui (Henan Fly Ash Research Center). This paper analyzes and researches fly ash and float beads, and elaborates the process of production of refractory materials from fly ash floating beads. It aims at accelerating the popularization and application process of fly ash production refractories. 1 Basic principle: Lightweight refractories are It refers to high porosity and low bulk density. (Lightweight refractories produced with fly ash floating beads effectively overcome the traditional methods, such as flammables addition method, foam method, chemical method, etc.) Non-uniform structure, low mechanical strength, large change in shape, long production cycle, low production efficiency, poor thermal insulation, and many other shortcomings, so it has a good prospect of popularization and application of the physical and chemical properties of fly ash floating beads 21 fly ash physics 21 Characteristics Fly ash is a kind of volcanic ash active material, the general particle size is 0.ymr2501, the wall thickness is 1~m, the color density is related to the contained impurities, generally grayish white, gray black, specific surface area 2000~400Cbm2/g powder The density of coal ash varies depending on the size of the particles, and is generally 1. 22 Fly Ash chemical composition of fly ash Fly Ash Homologous material Drift beads have excellent properties such as heat resistance, heat insulation, etc. It is a kind of raw material and filling material with many uses. The floating beads are filled with CO2, which are respectively 58~85% and 15~4%. The physical and chemical characteristics vary with the type of coal used in the power plant, the state of coal burning, and the combustion method.
The chemical composition of some fly ash drift beads at home and abroad is shown in Table 1 Table 1 Chemical composition of fly ash drift beads at home and abroad Origin of production composition in Shandong Guiyang, China Pingdingshan United States, the United Kingdom, Poland The mineral composition of the burn minus beads is: silicate glass Phase 80 to 85%, mullite 10 to 15%, and other minerals about 5% (including quartz variants); the refractoriness of float beads varies with the AI2O3 content, and Al23 content is 1610 to 1650° at 25% to 30° C. Changes in the thermal phase of 2.3 floating beads According to relevant data, from room temperature to 1000C, the bead ball changes, its chemical composition does not change; from cristobalite crystals appear from 1000 °C, the spheres begin to shrink; 1200 °C analysis Obvious crystals; During 120屮1250°C, the mullite content formed by Ab3 and Si2 in the material tends to be stable, the cristobalite content also reaches a high value, the ball deformation of the float beads is significant, and the spheres are bonded to each other; when the temperature reaches Above 1300C, the degree of melting of the silicate glass phase in the float beads is intensified, and the application of the fly-ash 3 fly ash in lightweight insulating refractories 3.1 Overview Drift beads have a light weight, a thin wall, a smooth surface, Good resistance to high temperature and heat insulation, using floating beads With these features, it can be used to make lightweight insulating refractories with excellent insulation properties.
3.2 Production Process of Lightweight Heat-insulating Brick The floating bead brick is made of fly ash floating bead as the main raw material, combined with clay, high-alumina bauxite, clinker and other raw materials. The floating bead brick has high mechanical strength and high temperature resistance. Thermal conductivity and performance are superior to existing mid-range insulation materials, and even comparable to aluminum silicate fibers. Therefore, it is a new type of insulating refractory material that is also good and widely used.
The production of floating bead bricks is mostly semi-dry, and the molding method is simple and does not require plastic processing. The process flow is roughly as follows: (2) Production process of lightweight high-strength heat-insulating bricks a. The physical and chemical properties of raw material hollow-drift beads vary greatly depending on the type of coal and operating methods, and can be applied according to the production conditions of the plant. Bead grading in order to facilitate the dumping In general, the use of floating beads should be less than 0.4g/cm3, ball surface smooth, more than 98% of the whole pearl color than the lower iron content in production, but also attaches great importance to beads The composition of the particle size, it has a great impact on the molding properties, burning or process and performance of the product. The beads are non-plastic material. The beads are fine and have a large specific surface area. Therefore, the binding agent can be reasonably selected and the amount is determined to be production. One of the keys to drifting bricks. According to experience, it is appropriate to choose aluminum dihydrogen phosphate and aluminum sulfate as binding agent. c Formula When formulating a floating bead brick formula, the amount of beads and binder should be determined according to the technical indicators of the beading, and the proportion of raw meal and clinker in the formula should be noted. At the same time, it is also possible to adjust the bulk density and improve the performance of the product by adding burned materials or other light aggregates.
The use of different grades of beads is shown in Table 2 Table 2 The amount of beads used for different grades Comparison of the use of beads (%c) In semi-dry molding, forced blenders should be used for blending, first dry blended and then wet blended. Mixed time control in 3 ~ 4min, wet mixing to 5min is appropriate, moisture should be between 13% ~ 20%, in the production process, but also due to seasonal changes and product specifications and appropriate adjustments e aging some raw materials in After homogenizing, it is very difficult to reach uniform moisture within a short time so it needs aging. The time is generally 8 hours. During aging, the surface of the mud should be avoided as much as possible. In addition, aging can also be used as a binder in the mud. Fully hydrolyzed to increase the plasticity of the mud, in order to facilitate the formation of the green body. The semi-dry method is used to form the green body. Because the bead is glassy, ​​the surface is smooth, the material is easy to move during molding, and the required pressure does not need to be large. The pressure of 15~30T is suitable for g. The body of the dried hollow drift beads is fine-grained and the water is relatively easy to discharge. The semi-dry method is adopted. The moisture content of the green body is not very high so it can be forced to dry quickly. Ways to increase production efficiency and drying Chamber can be drying, tunnel drying may also be employed. When the water content in the dried green body does not exceed 4%, it can be calcined in the kiln, but the green body must be prevented from being excessively dried. For example, if the green body is excessively dry, the green body is brittle and should not be transported. Generally, the firing temperature is controlled between 1200°C and 1290°C, and the heat preservation time is 2 to 4 hours. When the floating bead brick is fired, in addition to strictly following the firing system, special attention should be paid to the loading method. Unreasonable loading methods may result in a large area of ​​product quality. 3.3 Application of fly ash floating beads in unshaped refractories Unshaped refractories are mixtures of aggregates and one or more binders. Some can be used directly in the state of delivery, and some must be blended with one or more suitable liquids so that the fly ash floating beads can be used as a set of insulating fire-resistant mud because of their small particle size. Material, it can play a role in reducing the thermal conductivity of mud on the one hand, on the other hand is conducive to the construction of slime slurry lighter than the same size of heavy refractory mortar, due to the use of fly ash, so that the flow of mud Increased, easy to expand on the surface of the brick Come and fill the masonry mortar joints.
Fly ash is used to make porous clinker aggregates There are many varieties of porous clinker, usually porous pyrophyllite or siliceous clinker, porous clay and high aluminum clinker, porous mullite clinker or corundum clinker Porous clinker is a kind of porous clinker which is made up of various refractory powders with a pore-enlarging technique to form balls or compacts, obtained by calcining at a high temperature, and the inside of the refractory clinker is porous or honeycomb-like. The method for producing porous clinker is mainly combustible materials. Method, low-volume addition method, bubble method and chemical method. At present, the first two methods are used in China. The addition of fly ash and bismuth beads as a low volume material is a common method. Fly ash beads can be directly incorporated to maintain their own hollow spheres. The particle size and amount used can be based on porous clinker properties. Depending on the requirements. For example, in the production of high-strength clay porous clinker, besides refractory powders such as bauxite clinker and soft and hard clay, the low-melting material is a bead with Al23 greater than 33%, and the water is used for compacting, demoulding and drying. For firing, the finished product has a bulk density of about 1.13 to 1.17 g/cm3, and a bending strength of about 3.5 MPa after the firing temperature is reached. 3.4 Application in lightweight castables Fly ash beads are small in size and light in weight. The activity is certain, the beads are hollow, the wall is thin and hard, can reduce the bulk density of the lightweight refractory castables, and because there is a certain activity, and the strength is helpful, the relation between the amount of the beads in the lightweight refractory castable and the performance is as follows: The relationship between the amount of beads and the performance of the beads can be seen from the figure, with the increase of the amount of beads, the volume density of the lightweight refractory castables decreased, no significant change in the compressive strength In addition, the introduction of fly ash beads greatly improved light The workability of the castable material meets the construction properties of the castables. As the matrix material of the refractory castable, the fly ash floating beads and the lightweight porous aggregate form a relatively uniform gas phase continuous structure, thereby reducing the thermal conductivity of the material. The use of high-quality aggregates and binders complemented by beads It can be formulated in high-quality insulating refractory castable. The light-weight pouring cooking performance of a factory using the beads is shown in Table 3. Table 3 Production of Light-weight Casting by Drifting Beads Bulk Density (g/cm3) Flexural Strength (MPa) Compressive Strength (MPa) Heavy Burning Line Change (The thermal conductivity Note: marked with "The test temperature is 1100 °C 4 Factors that affect the performance of the bead product 4.1 Factors that affect the mechanical strength of the product There are many factors that affect the mechanical strength of the product, but mainly depends on the amount of beads added and combined Addition amount and type of agent The product of the same brand generally has a higher compressive strength with the increase of the amount of beads added, and the bond generally increases the strength of the product with an increase in the amount thereof.
4.2 Factors influencing the change of product reburning line The size of the reburning line directly affects the performance of the product. The main factors affecting the reburning line are the amount of raw material depletion and the amount of liquid phase produced under high temperature conditions. More, the greater the shrinkage of the product line, therefore, when selecting the raw materials, it is necessary to choose the small burning reduction and the low impurity content. In addition, in order to reduce the reburning line change of the product, some intumescent materials such as kyanite, quartz and the like may be introduced into the formulation in an appropriate amount. The introduction of supervised spar, etc. can also improve the softness of the product at a certain degree and within a certain range.
5 Conclusion The process technology for producing lightweight refractories using fly ash beads has matured and the products have excellent performance.
The use of fly ash beads for the production of lightweight refractories has prominent economic and social benefits, and has resulted in a positive push to the kiln industry.
The present invention provides a multifunctional pull faucet, comprising: a faucet body, a drawing part is provided at the water outlet port thereof, and the drawing part is connected to a main channel, wherein at least three are provided in the faucet body A branch channel, and the three branch channels are all connected to the main channel. A multifunctional pull faucet provided by the present invention, wherein the hot water channel, the cold water channel and the water purification channel (pure water channel) are all connected to the main channel , And the main channel is connected with the drawing part on the main body of the faucet, so that the drawing part can obtain the water quality (hot water, cold water, purified water or pure water) required by different users, thereby improving the user experience, and , By integrating the hot water channel, cold water channel and pure water channel (pure water channel) into the main channel, the internal structure of the faucet is simplified, and the production cost of the faucet is reduced..
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