Lightweight refractory brick is a kind of heat insulation refractory material, which refers to refractory bricks with high pores, low bulk density and low thermal conductivity. Lightweight refractory bricks are characterized by porous structure (the porosity is generally 40-85%) and high The thermal insulation.
1. There are many classification methods for lightweight refractory bricks:
1. Classified by bulk density: Lightweight refractory bricks with a bulk density of 0.4-1.3/cm3; ultralight refractory bricks below 0.4/cm3.
2. Classification by operating temperature: 600-900℃ is a low-temperature insulation refractory material; 900-1200℃ is a medium-temperature insulation refractory material, and a high-temperature insulation material over 1200℃.
3. Classification according to the shape of the product: one is shaped lightweight refractory bricks, including clay insulation bricks, high-aluminum insulation refractory bricks, siliceous refractory bricks and some pure oxide lightweight refractory bricks, the other is not Shaped lightweight refractory bricks, such as lightweight refractory concrete, etc. Powdery and granular lightweight refractories, shaped lightweight refractories, unshaped lightweight refractories, fibrous lightweight refractories and composite lightweight refractories.
4. Classification according to the conditions of use: ordinary lightweight refractories: do not directly contact the flame, only used as an insulation layer. Advanced lightweight refractories: directly contact the flame, it can be used as an insulation layer and a working layer.
5. Classification according to manufacturing method: materials made directly from porous materials, such as diatomaceous earth bricks; materials made by adding combustibles, such as wood chips, fly ash: materials made by foaming methods, such as foaming Agents (such as rosin soap); materials made by chemical methods, such as adding carbonates and acids, metallic aluminum and acids; lightweight refractory concrete; refractory fibers and products.
6. According to the existence and distribution of the solid phase and the gas phase, the gas phase is classified as a continuous phase and the old opponent is a light refractory material with a dispersed phase; because the phase is a continuous phase and the gas phase is a dispersed phase, the gas phase and the solid phase are both It is a continuous phase light refractory material.
2. There are usually four manufacturing methods for lightweight refractory bricks:
①The method of adding materials by burning out. It is also called the method of adding combustibles. Add combustibles that are easy to burn out, such as charcoal and sawdust, to make the refractory bricks have certain pores after firing.
②Foam method. Add foaming agent, such as rosin soap, etc. into the mud for making refractory bricks, and make it bubble by mechanical method, and obtain porous refractory brick products after firing.
③Chemical method. A kind of porous refractory brick product is obtained in the process of making refractory brick by using a chemical reaction that can properly generate gas. Usually, dolomite or periclase plus gypsum is used, and sulfuric acid is used as a foaming agent.
④Porous material method. Use natural diatomaceous earth or artificial dry earth foam clinker, alumina or zirconia hollow spheres and other porous raw materials to make lightweight refractory bricks.
3. The use of lightweight refractory bricks
The heat storage loss of industrial furnace masonry and the heat dissipation loss of the furnace surface 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 and simplify the furnace. Structure, improve product quality, reduce environmental temperature, and improve working conditions.
Precautions
1. Lightweight refractory bricks have large porosity and loose structure, and cannot be used for parts that directly contact molten slag and liquid metal;
2. The mechanical strength is low and cannot be used for load-bearing structures;
3. The wear resistance is very poor, so it is not suitable to be used in the parts that are in contact with the charge and are severely worn.
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