Firstly, the kiln environment, service location, service temperature and erosion performance should be considered.
In case of working layer, heavy refractory castable with high temperature resistance shall be selected. If the corrosivity is acidic and high-strength wear-resistant castable, the castable with acid resistance shall be selected. If the erosion is alkaline, the castable with alkali resistance shall be selected. Castable with strong slag erosion resistance shall be used at the part in contact with molten slag; Castables with high strength and wear resistance shall be selected for parts with serious impact of materials; If the temperature changes frequently, the castable with good thermal shock resistance shall be selected.
Lightweight refractory castable shall be selected as the castable for the insulation layer, mainly considering the load-bearing structure, reducing the furnace shell temperature and reducing heat loss. High strength and wear-resistant castable shall be selected, and then insulation castables with different bulk density shall be selected. Generally, thermal insulation castable with bulk density of 1.2 shall be selected. If the user has weight requirements, the thermal insulation castable with bulk density of 0.6-1.0 shall be selected.
No matter which kind of refractory castable is selected, it needs economic cost. The grade of castable also varies with temperature. The castables used at different temperatures are also different. Clay castables are generally used, high alumina castables are used at 1300 ~ 1400 ℃, and corundum castables are used at more than 1450 ℃; This is both economical and applicable.
The construction thickness of refractory castable is different. If the thickness is less than 50mm, coating or spraying shall be selected. If high strength and wear-resistant castable is used for maintenance or furnace top, plastic shall be selected. If the thickness of the castable is greater than 100mm, large particle aggregate needs to be used to improve the wear resistance of the castable. The pouring thickness of general castable shall be 200mm.
The use of refractory castables shall be calculated by volume because the storage time of castables is 6-9 months. If it cannot be used and the storage time is too long, caking or binder setting failure will occur, affecting the service life of castable.
In short, the selection of appropriate refractory castable must be based on the use position, use temperature and pouring thickness. High strength and wear-resistant castable, which not only reduces the cost, but also has reasonable application effect.
High strength refractory castables must be used in whole barrels and bags. Mixed castables must generally be used up within 30 minutes. In the high-temperature and dry working environment, the time shall be appropriately shortened.