Low cement castable

Low cement castable

　　 1. What kind of refractory is the low cement castable?

Low-cement castables are unshaped refractory materials, mainly used for cement kiln back kiln mouth, kiln door cover, cooler back end, etc. The aggregates and powders used in this product have many textures, such as mullite, high alumina Quality, clay, corundum, carbon and silicon carbide, etc.

　　 Low cement castable is a high-tech refractory developed on common castables using rheological principles, tight packing theory and ultra-fine powder technology. It has the characteristics of low porosity, small pore size, high density, good volume stability, high strength and small water addition, and overcomes the characteristics of a significant decrease in strength of ordinary castables at 800-1200℃, and increases with temperature And increase, so that the thermal shock of the furnace body can be more than doubled.

Different from ordinary refractory castables, low-cement castables use superfine powder with the same or similar chemical composition as the main material of the castable to replace part or most of the calcium aluminate cement, and at the same time add a small amount of dispersant (water reducing agent) and A certain amount of delayed-acting coagulant. The setting and hardening mechanism of low cement castables is different from that of ordinary calcium aluminate cement. Cement mainly relies on hydration and low cement castables coexist with hydration and cohesion.

　　 low cement castables are mainly used in metallurgy, electric power, nonferrous metals, petrochemical, building materials and other industries. Such as the bottom of the glass kiln, the front end of the front and rear kiln door cover cooler of the cement kiln, the front and rear kiln mouths, coal injection pipes, etc.; various heat treatment furnaces such as heating furnaces and soaking furnaces; medium frequency induction furnace lining, petrochemical catalysis High temperature wear-resistant lining of cracking reactor, lining of other industrial furnaces. Let's go on to understand what low cement castable is.

　　 2. What is low cement castable

　　 Low-cement castables use calcium aluminate cement as the binder, and the castables with a CaO content of less than 2.5% are generally called low-cement castables. Different from traditional castables: low-cement castables are used to replace most or all of the high-alumina cement with the same or similar chemical composition of the main material and have the same or similar cohesive and combined ultra-fine powder (particle size less than 10 microns) to optimize the particle gradation, micro-powder, It is formulated by adding a small amount of dispersant (water reducing agent) and an appropriate amount of retarder and other compound additives to factors such as particle shape.

　　Low cement castable characteristics: Because ultra-fine powder (micropowder) is used instead of calcium aluminate cement, the low cement castable has the following characteristics:

　　(1) The low content of CaO in the castable can reduce the formation of eutectic phase in the material and improve the refractory temperature, high temperature strength and slag corrosion resistance.

　　 (2) The water consumption of the castable during construction is 4%-6% of the ordinary castable, with low porosity and high bulk density.

　　(3) After pouring and forming, there is less cement hydrate generated during curing, and there is no large amount of water spline bond damage during heating and baking, which causes the medium temperature strength to decrease. With the increase of heat treatment temperature, the strength gradually increases.

　　 (4) Proper adjustment of the particle size and composition of the castable can be made into self-flowing castable and pump castable.