What are the selection tips for using refractory castables?
As refractory castables are used more and more widely, there are indeed certain methods and techniques for choosing what material to use or what index of castables to use. Topower sales staff will share with you some common tips for selecting castables.
1. There are many differences between refractories castables
Refractory castables are divided into neutral, acidic and alkaline, as well as heavy and light. Heavy refractories castables are generally used in the working layer, while lightweight castables are used in the insulation layer for insulation.
If it is a neutral high-aluminum series refractory castable, the index of the castable to be used is determined based on the temperature and erosion of the furnace lining. If the temperature is below 1200°C, clay castables can be used. If the temperature exceeds 1250°C, high-aluminum castables should be used. If the operating temperature exceeds 1350°C, corundum refractory castables should be used. If corrosiveness is extremely strong, chrome corundum castables should be used. If wear is severe, wear-resistant refractories castables should be used. The storage time of neutral materials is 6 months. Be sure to keep raw materials and binders separate.
2. Use acidic castables in acidic atmosphere
If the castable is used in an acidic atmosphere, acidic castables should be used. Acidic castables are combined with two binders, one is water glass and the other is phosphoric acid. If the temperature does not exceed the acidic atmosphere of 1250°C, acidic castables bonded with water glass can be used. If the temperature is too high, acid-resistant castables bonded with phosphoric acid can be used.
3. Use magnesium refractory castables in alkaline atmosphere
If the castable is used in an alkaline atmosphere, refractory magnesia castables should be used. If corrosion and wear resistance are encountered, refractory magnesia-aluminum castables or magnesia-chromium castables should be used. If the temperature is too high, magnesium castables with high specific gravity or magnesia castables with high content can be used. However, you must pay attention to the storage of magnesia castables and cannot store them in the open air, because magnesia castables cannot be exposed to water, otherwise they will pulverize.
4. Use lightweight insulation castables for the insulation layer.
If the castable is used for the insulation layer, it also depends on the temperature. If the temperature is low, ordinary lightweight insulation refractory castables can be used. If the temperature is too high, lightweight high-aluminum or alumina hollow ball lightweight castables should be used. Just use it as an insulation layer. You must also pay attention to the storage of lightweight castables. They cannot be placed together with materials that are too corrosive, otherwise they will cause damage to the lightweight castables.
5. The low requirements for the furnace shell can be solved by double-layer insulation.
If the requirements for the furnace shell are low, double-layer insulation should be used to solve the problem, that is, ceramic fiber first and then lightweight insulation refractory castables, or ceramic fiber blocks can be used directly. However, if there are weight requirements for the insulation area, use a specific gravity of 0.6-0.8 for the insulation layer. If the flue is used directly on the working layer, use a lightweight castable with a specific gravity of 1.3-1.5 for the lining. If it is a resistant atmosphere, you should choose to use lightweight acid-resistant castable as the lining.
In short, no matter what kind of refractory castable is selected, the castable must be selected according to the usage conditions, lining atmosphere, and temperature.
