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The blast furnace taphole is the passage of high-temperature molten iron and slag after melting in the blast furnace. It is easily damaged by high-temperature molten iron and slag during use. When the lining of refractory castable is used for maintenance, the construction process is cumbersome and the construction period is long. , seriously affecting the output of the blast furnace. Henan Resistant Selection recommends the use of refractory castable prefabricated parts as the blast furnace tapping ditch lining. The performance is good and convenient and fast, which can significantly improve economic benefits.
First, the working environment of the iron ditches
The working environment of the blast furnace tapping ditch is very bad. When the iron is discharged, the temperature of the molten iron is about 1500 °C. Calculated by a blast furnace of 4000 m3, the iron output per minute is 5-7 tons, and the iron output per day is about 10,000 tons. The amount of slag is 3,200 tons. When the tapping is stopped, the temperature of the tapping groove is 500 °C. Therefore, the iron lining lining has been washed and eroded by high temperature molten iron for a long time.
The main factors that damage the refractory material in the iron channel are: 1) thermal shock of high-temperature molten iron; 2) reaction between iron slag and refractory material, resulting in structural damage, degraded performance, and increased erosion rate of the trench lining. 3) The high temperature is 1500 °C when the iron is discharged, and the temperature is 500 °C when the iron is stopped. Under the intermittent working environment, the sudden change of the temperature causes the thermal shock resistance of the lining to decrease, and cracks and peeling are prone to occur, thereby aggravating the material damage. 4) The permeability of molten iron to the lining is also one of the factors causing damage to the lining.
Second, the selection of prefabricated materials for refractory castables
With the continuous innovation of technology, the refractory materials for tapping trenches have also evolved from the initial ramming, pumping castables, and self-flowing castables to the most effective refractory castables.
The refractory castable prefabricated parts for tapping ditch mainly choose ASC low cement refractory castable. In the preparation of materials, the castable aggregate acts as a skeleton support, the powder is used for filling, and the aggregate and powder are mainly white corundum and brown. Corundum, high alumina aggregate, silicon carbide, carbon, etc. The binder is a high alumina cement or a pure calcium aluminate cement, an additive such as a water reducing agent, and the like.
Third, the production of precast parts for refractory castables
The manufacturing process of the iron refractory castable preform is roughly the same as that of the general preform.
1. Preparation before prefabrication Clean the prefabricated work area, check the size of the model and fix it firmly. Apply oil or other lubricant to the model.
2. Stirring Pour the prepared castable into a forced blender, first dry mix, then add water according to the required amount of water and stir for 3~4 minutes.
3. Pouring The evenly poured castables are poured into the prepared model. The material is vibrated evenly with the vibrating rod, the surface is filled with pulp and exhausted. Finally, the surface is leveled before the material is first set, and the surface is marked and marked.
4. Maintenance After casting, the castables are naturally condensed in 4~6h, and finally condensed at 24h~48h. The pre-formed parts after final setting can be demoulded for curing. The curing temperature is 15~25°C, and the best is 2~3 days. It should be noted that during the curing period, the preforms cannot see water.
5. Baking The prefabricated parts should be baked at a low temperature (500~600 °C) before leaving the factory or before the furnace is built, so that the internal moisture of the prefabricated parts can be discharged and the drying time after construction can be shortened.
Fourth, the use of prefabricated parts of refractory castables
The technology of using refractory castable prefabricated parts to carry out iron gully trench lining construction has achieved good results in domestic large steel mills such as Tangshan Iron and Steel Co., Ltd., Baosteel and Anshan Iron and Steel. Practice has proved that the prefabricated parts made of ASC low cement refractory castables have good erosion resistance, high temperature resistance and thermal shock resistance in the use of iron tapping grooves, and can effectively resist the erosion of molten iron and slag on materials.
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