With the continuous development of technology, there are more and more new products on the market, and the things we will encounter are more and more abundant. The price of magnesia bricks provides us with more choices. When we need to use something , We must first understand what it is, what is its use, whether it is easy to use and a series of related knowledge. Let's take a lightweight refractory brick as an example to talk about what it is and related knowledge content.
What is a lightweight refractory brick is first understood from the definition of the name. Refractory products with low density, light weight and low thermal conductivity are used for thermal insulation. For example: clay thermal insulation bricks, high alumina poly light bricks, and mullite Stone insulation bricks, floating bead bricks, alumina hollow ball bricks, etc. are all lightweight refractory brick products.
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The heat storage loss of industrial kiln masonry and the heat dissipation loss on the surface of the furnace body generally account for about 24 to 45% of the fuel consumption. Using lightweight bricks with low thermal conductivity and small heat capacity as the structural material of the furnace body can save fuel consumption; at the same time Because the furnace can quickly heat up and cool, it can improve the production efficiency of the equipment; it can also reduce the weight of the furnace body, simplify the structure of the furnace, improve product quality, reduce environmental temperature, and improve working conditions.
1. The definition of lightweight refractory bricks:
Generally refers to refractory bricks with a density of less than 1.3×103Kg/m3. Light weight means that this refractory brick is light in weight.
2. Lightweight refractory bricks have the following characteristics:
1.Small density and light weight, which can reduce the weight of the furnace body and simplify the structure of the furnace;
2. High porosity, low thermal conductivity, good thermal insulation, which can save fuel consumption and improve equipment production efficiency;
3. The mechanical strength is low and cannot be used for load-bearing structures;
4. The wear resistance is poor, and it is not suitable for the parts that are in contact with the charge and are severely worn;
5.The porosity is large and cannot be used for direct contact with molten slag and liquid metal parts.
Lightweight refractory bricks are light in weight and heat insulation, but they are not strong and have poor wear resistance and cannot be exposed to high-temperature flames; among the weight of heavy refractory bricks, they have poor thermal insulation and heat insulation capabilities, but have high strength and high wear resistance and high temperature resistance. For high-temperature equipment, light refractory bricks and heavy refractory bricks can be combined and used according to the design plan according to the actual situation according to the needs. Good results will be achieved and the service life and use efficiency of the equipment will be improved.
Third, the production method of lightweight refractory bricks
(1) Combustible additives method, which is to add combustibles such as wood chips or coke powder in the matching. When the combustibles are burned during the brick firing process, many pores are left in the brick. This is commonly used The way;
(2) Foaming method, that is, adding foaming agents such as rosin soap in the formulation, and then firing into porous products;
(3) Chemical method, by adding a certain substance in the formulation, a chemical reaction that can cause foaming, such as dolomite or periclase plus gypsum, using dilute sulfuric acid as a foaming agent, a lot of CO2 will be generated, and it will be cast immediately, and it will be boring. After firing, the refractoriness of lightweight refractory bricks is not much different from that of refractory bricks of the same raw material, and the load softening point is slightly lower.
If lightweight bricks are used at high temperatures for a long time, they will continue to be sintered and shortened, forming cracks and even damage. Therefore, most lightweight bricks have a problem with the operating temperature, such as light clay bricks as long as 1150 ℃, and the high can reach 1400 ℃ , The light high alumina brick does not exceed 1350℃, and the light silica brick can reach 1600℃. Because the light silica brick does not have the problem of high temperature shortening, the volume is relatively stable, so it can be used for masonry to directly touch the furnace gas. lining.
Lightweight refractory bricks have poor slag resistance, so lightweight refractory bricks cannot directly touch molten metal and molten slag. The mechanical strength and wear resistance of this kind of brick are also slightly poor, and it is not suitable for high-speed airflow erosion and sensation Large parts. Similar to the process of lightweight refractory bricks, in the refractory concrete mix guess, add the appropriate foaming agent, can be made into lightweight refractory concrete, the bulk density is only one-half of the clay brick, and the thermal conductivity is that of the clay brick One-third. If materials such as vermiculite or ceramsite are used as aggregates, the density and thermal conductivity will be lower.