Thermal stress damage. When the iron is tapped, the center of the iron hole is drilled by a drill bit, and hot molten iron and molten slag flow out from the iron hole, making the iron hole gun taphole clay withstand high temperature above 1500 ℃. When the iron slag is discharged and the iron hole is re-blocked with gun taphole clay, the old gun taphole clay touches the newly plugged gun taphole clay, and the temperature drops rapidly from 1500°C to about 200°C. This repeated action generates huge heat inside the old gun taphole clay. Stress can easily lead to arc-shaped cracks with the iron hole as the center.
Thermal chemical attack. Prolonged contact with molten iron and molten slag can cause chemical reactions to cause erosion of the taphole clay. The reaction generates a low-melting mineral phase, which is lost with the scouring of the molten iron slag during iron tapping, which enlarges the hole diameter of the tap hole, causing the molten iron to rush out of the tap hole quickly, affecting the stability of the tap hole.
The biggest weakness of the current blast furnace taphole clay is that the iron mouth expands quickly and the resistance to hot metal erosion is insufficient, which causes the molten iron in the hearth of the blast furnace to be unclean, affects the output, and is not conducive to the smooth movement of the blast furnace. In addition, it is difficult to open the iron hole, which causes the iron hole to be unable to open on time, affecting the normal iron casting. Therefore, many large-scale blast furnaces at home and abroad adopt the plunger method or are equipped with opening machines with strong forward and reverse impact capabilities to solve the problem of difficult opening of blast furnace taphole clay. Under normal circumstances, after the blast furnace is finished, the surface of the original gun taphole clay seeps into the iron slag. After the new gun taphole clay is plugged into the iron hole, a barrier is formed at the junction of the old and the new gun taphole clay, which is not conducive to bonding. As a result, the molten iron in the blast furnace will enter along the gap between the new and old gun taphole clay, resulting in a slag-iron penetration area in the middle of the gun taphole clay. The formation of the slag-iron penetration area also increases the difficulty of the taphole opening to a certain extent. The iron gate is not easy to open, which can easily lead to major safety production accidents. At home and abroad, great attention is paid to the on-site operability of blast furnace taphole taphole clay.
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