Release Time：2018-03-29
Lightweight thermal insulation castable is currently the most widely produced and used amorphous refractory material, mainly used to construct overall structures of various heating furnace linings. Some high-quality varieties can also be used in smelting furnaces. Aluminate cement castables can be widely used in various heating furnaces and other slag free, acid alkali free thermal equipment. In areas where the working temperature is high due to erosion by molten iron, steel, and slag, such as the tapping tank, steel drum, blast furnace shaft, and tapping channel, high-quality granular and powder materials with high alumina content and good sintering can be used, which are combined with low calcium and pure high alumina cement.
Lightweight thermal insulation castable refers to castable refractory materials with a true porosity of not less than 45%, also known as lightweight refractory castable. It includes light aggregate refractory castables, foam refractory castables, aerated refractory castables, etc. In practical applications, light aggregate refractory castables are mainly used. Because it has: small volume density, low thermal conductivity, can reduce equipment weight, good insulation performance, make furnace temperature uniform, save energy, high refractory strength, strong overall performance, good peeling resistance, long service life, and can be repaired and processed in various shapes or as a whole. Easy construction and low cost. It is now widely used in industrial kilns and thermal equipment in industries such as metallurgy, machinery, power, chemical, and petroleum, saving more than 20% energy compared to ordinary refractory materials.
1. Classification of lightweight thermal insulation castables
It is divided into three categories based on production methods, types of binders, and types of lightweight aggregates. According to the production method, it is mainly divided into the preparation of insulating refractory castables with light aggregate and the preparation of insulating refractory castables with foam method or air entrainment method. Classified by the type of binder, it is the same as general refractory castables. According to the type of lightweight aggregate, it can be divided into thermal insulation and refractory castables such as expanded perlite, expanded vermiculite, ceramic particles, porous clay clinker, lightweight brick sand, alumina hollow balls, etc. In practical applications, in addition to using a single lightweight aggregate ingredient, several lightweight aggregate composites are often used to form thermal insulation and refractory castables.
2. Composition elements of lightweight thermal insulation castable
Light aggregate thermal insulation and refractory castables are composed of refractory light aggregates, powders, binders, and admixtures. Foam thermal insulation refractory castable is composed of refractory powder, binder and foam agent, among which the refractory powder is composed of clay clinker powder, refractory clay brick powder, fly ash, etc. The binder is mainly silicalite cement or aluminate cement, etc. The foam agent often uses rosin soap foam agent, saponin grease foam agent, aluminum petroleum sulfonate foam agent, etc. The rosin soap foam agent is used. The aerated insulating refractory castable is composed of refractory powder, binder and aerating agent. The binder and refractory powder are the same as the materials used in the foam method. Aeration agents are usually certain metal powders that react with acid to produce hydrogen gas to produce porous castables. Some also use dolomite or periclase with quartz as a stabilizer to react with sulfuric acid, or use calcium carbide with water to form acetylene gas for aeration. In addition, when using clay clinker powder, bauxite hot material powder, or industrial alumina powder as powder, phosphoric acid is used as a binder, At the same time, hydrogen gas generated by the reaction between phosphoric acid and iron also plays a role in gas addition, making gas insulated and refractory castable.
3. The characteristics of lightweight thermal insulation castable
High porosity and low thermal conductivity of thermal insulation and refractory castable materials