Introduction to Self-flowing Refractory Castables

2023-12-23 17:25:40

In recent years, self-flowing refractory castables have been widely used in thermal equipment. The refractory castables of this new construction method are innovatively developed based on low-cement series refractory castables and are based on the solid closest packing principle and rheology theory. Self-flowing refractory castables not only have significant economic benefits but have also achieved initial success in thermal equipment such as spoons, tundishes, blast furnace tap trenches, slag trenches, boiler tube protective layers, incinerator grates, heating furnaces, and cement kilns. Results.

Self-flowing refractory castable (S.F.C) is a highly thixotropic mixture that can flow and degas by its gravity. Compared with vibration-type low-cement series refractory castables, self-flowing refractory castables have better performance and do not require vibration equipment, steel drills, or beating of external molds, thereby reducing construction costs, noise pollution, and labor intensity. However, raw material costs increase slightly due to the high quality and large quantities of matrix materials.

To improve the performance of self-flowing refractory castables, research and development work mainly focuses on the optimization of critical particle size and particle gradation (including ultrafine powder), binders, and admixtures of refractory aggregates. The application of ultrafine powder technology has created a new era for low-cement series refractory castables. In the future, nanotechnology will further change the appearance of refractory castables. By optimizing the aggregate critical particle size and particle gradation, the service life of the ladle refractory castable is improved.

The key to self-flowing refractory castables lies in the rational selection of aggregate particles and particle gradation, binders, and water-reducing agents, as well as the appropriate amount of water. Unreasonable particle gradation will lead to reduced density and self-flowing properties, while suitable binders and water-reducing agents can reduce water demand, fully disperse ultrafine powder, and improve thixotropy. In addition, the appropriate amount of water is crucial to reduce the viscosity of the mix and improve the fluidity, but care must be taken to avoid segregation during the molding of the castables and the emergence of gas after drying. In addition, the construction of self-flowing refractory castables there are also some features. Due to its high thixotropy, it can be constructed directly by pouring or injecting, without the need to use vibration equipment or steel drills to ram or hit the outer mold. Therefore, the construction cost of self-flowing refractory castables is lower, and it can reduce noise pollution and labor intensity, and improve construction efficiency.

At the same time, in terms of refractory aggregates, self-flowing refractory castables use refractory aggregates that are approximately spherical have low water absorption to facilitate flow, and need to be processed into an approximately circular shape to ensure their self-flowing, exhausting, and dense properties. In terms of binders, self-flowing refractory castables usually use aluminate cement, and the variety and dosage of ultrafine powder are reasonably selected as needed to meet the needs of self-flowing refractory castables. In addition, it is also essential to choose the appropriate water-reducing agent, which can reduce the water demand of cement, fully disperse ultrafine powder and fill materials, improve thixotropy, reduce the viscosity of the mix, and enable the castable to flow freely.

Generally speaking, self-flowing refractory castable is a new type of refractory material with the characteristics of high thixotropy, good fluidity, and convenient construction. It is widely used in thermal equipment where the lining is thin and difficult to construct or repair and has significant economic benefits. At the same time, self-flowing refractory castables have also been applied to thermal equipment such as spoons and tundishes, blast furnace tap trenches and slag trenches, boiler tube protective layers and incinerator grates, heating furnaces, and cement kilns, and have achieved initial results.

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