Lightweight thermal insulation materials has high porosity, low bulk density and low thermal conductivity. On the one hand, it has a great thermal resistance to heat transfer from high temperature, thereby reducing the heat loss of thermal equipment; on the other hand, its heat capacity is small, Less heat storage improves the utilization rate and thermal energy efficiency of thermal equipment for short-term and intermittent production. In addition, it can be constructed the same as other castables, and can be cast as a whole or made into prefabricated parts, which is very convenient to use.
Raw materials for the light weight mullite insulation castable is porous mullite as grain particles, powder and additives are added. Largest particle size of grain mullite is 12 mm, service temperature could reach 1350 ℃。
There are two main factors for choosing lightweight castables: one is the functional properties of the lightweight aggregate, and the other is the binding method and the type of binding agent. When a lightweight aggregate is selected to produce a lightweight castable, the function of the lightweight castable depends on the type of binder and the added value. The traditional lightweight castable is to add 20 to 30% of cement, or to add 10 to 15% of water glass as a binder. Cement and water glass are used as binders, so that the strength of the castable decreases during the heating process, which affects the use effect.
Mullite is the Al2O3-SiO2 phase with most excellent performance in different sides, especially its brilliant high temperature low creep, help the mullite to be widely used in industrial furnace.
The mullite refractory castable has strict request to binding agent, binding agent mustn’t influence great properties of mullite, so generally high alumina powder, silica-Alumina gel and high alumina cement are applied as binding agent, to get excellent mullite refractory castable.
Lightweight mullite refractory castable is composed of high-strength mullite as aggregate, superfine powder and compound additives are added. It has the characteristics of high refractoriness, high strength, low thermal conductivity and low bulk density, which can reduce the thermal energy consumption of industrial furnaces and reduce the weight of the furnace lining. Among the high-temperature lightweight raw materials, the following raw materials can be used as raw materials for high-temperature lightweight castables used above 1200°C: porous clinker or scrap porous bricks such as mullite, corundum, high alumina, silica and magnesia material. Such castables can be directly used in the lining of atmosphere furnaces operating at 1350°C.
Applied as Furnace insulation materials, such as insulation layer of heating furnace, annealing furnace, hot blast furnace etc.; Face insulation layer of pipelines for blast furnace, hot blast stove etc.; non-contact melt parts of melting furnace and melt container equipment, such as aluminum melting furnace cover and furnace door , fire monitoring hole door lining; smoke chimney and pipeline insulation layers, such as hot air duct lining, flue lining insulation, etc.
