Novel abrasion resistant silicon-mullite-nitrogen brick for transition zones of rotary cement kiln

Abstract

The invention relates to a refractory material forming product applied to transition zones of a rotary cement kiln, and the refractory material forming product provided by the invention is formed by molding through machine pressing and high-temperature calcination. In the invention, silicon nitride or ferro-silicon nitride is introduced into the traditional silicon-mullite brick or silicon-mullite red brick. The temperature at which silicon nitride starts oxidizing in an oxidizing atmosphere is 1300 DEG C, and the temperature at which silicon carbide starts oxidizing in the oxidizing atmosphere is 800 DEG C, thus the oxidation resistance of the silicon-mullite brick can be obviously improved. In addition, since silicon nitride has less coefficient of linear expansion, lower coefficient of heat conductivity and stronger alkali corrosion resistance as compared with silicon carbide, the manufactured novel silicon-mullite-nitrogen brick has lower coefficient of heat conductivity, less volume change and more excellent alkali corrosion resistance. The silicon-mullite brick manufactured by the method is used for the transition zones of the rotary cement kiln, the temperature of a kiln body can be significantly reduced, and the silicon-mullite brick has less possibility of being oxidized, therefore, the service life of the abrasion resistant material of the transition zones of the cement kiln is prolonged and is up to 1.5-2 years. The novel abrasion resistant silicon-mullite-nitrogen brick is especially suitable for the upper and lower transition zones of the rotary kiln with frequent changes of atmosphere in the kiln.

Description

technical field [0001] The invention relates to a refractory brick, in particular to an anti-oxidation and low heat conduction silicon molybdenum brick used in the upper and lower transition zones of a large cement rotary kiln. Background technique [0002] At present, two kinds of bricks are commonly used in the upper and lower transition zones of the cement rotary kiln, magnesia-aluminum spinel bricks and silica molybdenum bricks. The magnesia-aluminum spinel brick mainly has a high thermal conductivity. At 1000°C, the thermal conductivity reaches 3.0, so that the temperature of the outer skin of the upper and lower transition zones reaches 380-400°C. In addition to causing waste of fuel, it is also easy to cause Deformation, so that the bricks in the kiln will fall off, peel off and be damaged, which will affect the service life. When silica bricks are selected for the upper and lower transition zones of the rotary kiln, the thermal conductivity of the silica bricks is r...

AI Technical Summary

Problems solved by technology

However, the fatal weakness of ordinary silica bricks is poor oxidation resistance. When in an oxidizing atmosphere, especially when solid waste is incinerated, the atmosphere in the kiln fluctuates greatly, and the concentration of alkali-sulfur vapor increases. Corrosion and oxidation are fatal, so how to prevent silica bricks from being oxidized has become a research topic

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