Low-cement castable has a series of advantages such as simple production technology and convenient construction, and is very suitable for the use conditions of heating furnaces. The original heating furnace used a large number of clay bricks, also need to be processed to masonry, resulting in poor overall performance and low strength. The application of low-cement castables overcomes the low strength of ordinary castables at room temperature and makes up for the shortcomings of medium-temperature, improves its structure uniform strength. The material has anti-penetration, corrosion resistance, and anti-corrosion properties. It has the characteristics of impact wear resistance and good mechanical properties, and has a wide range of applications. Today we will talk about the application of low cement castables in heating furnaces:
1. Parameters of low cement castables
The material is made of high-aluminum clinker, the Al2O3 content is above 70%, the refractoriness is 1770°C, and the grain size of the aggregate is required to be at the 5-8, 3-5, 1-3 particle level; the fine powder adopts high-aluminum clinker fine powder. The grain size < 0.088mm is less than 90%, and the particle grading is required to be uniform and reasonable, so as to have better compactness and high temperature performance.
2. Low cement castable construction method
Mechanically stir the low-cement castable packaged by 25kg bags, add an appropriate amount of tap water according to the instructions, and hold the mixed mixture tightly into a ball by hand. After the fiberboard, lightweight insulating bricks and anchor bricks are well laid on the inner side of the furnace shell steel plate as required, then surported the formwork for construction.
The construction of low-cement castables should be continuous, and each layer of paving should not exceed 300mm. When vibrating, the vibrating rod should be inserted quickly, pulled out gently, and moved slowly. Pay attention to observe to prevent cavities caused by the vibrating rod from affecting the pouring quality. The castable shall be provided with an expansion joint every 2000mm in accordance with the design and specifications, and the expansion joint shall be filled with fiber cotton or fiberboard during construction. After 48 hours of natural curing after the pouring, remove the formwork and bake according to the oven curve. In particular, free water and crystal water in the castable should be completely discharged during the low temperature holding time of 150℃ and 350℃.
3. Performance of low cement castables
According to the observation of the use of low cement castable in the reheating furnace for nearly 4 years, the overall performance of the furnace body is very good, the surface does not fall off, the refractory material of the furnace body is basically not damaged, the surface temperature of the furnace shell is about 70℃, and the gas consumption per forging part is reduced from 5300m3/t to 3500m3/t, and good economic results have been achieved. The use of low cement castable in heating furnace not only reduces a large amount of bricks, improves the labor intensity of construction, shortens the construction period, but also has good integrity of castable lining, excellent thermal insulation performance, and greatly reduces energy consumption, thus achieving the effect of energy saving and emission reduction. Compared with the early clay bricks, the price of castable is 3 times that of ordinary clay bricks, but the service life of the kiln is increased by 5 times, and the economic benefits are obvious.
With the continuous development of refractory material technology, many companies now use prefabricated blocks made of low-cement castables to build kilns. The advantage is that the refractory prefabricated blocks are baked after production by the manufacturer and can be installed directly on site , reducing construction time and reducing the presence of free water, which will more effectively remove moisture during drying and improve the service life of the kiln.
