Excessive Electrode Working End Length: When the electrode working end remains excessively long for an extended period, a significant amount of refractory material at the furnace bottom is consumed. This leads to an abnormal rise in furnace bottom temperature or, in severe cases, furnace bottom burn-through.
Insufficient Electrode Working End Length: Conversely, if the electrode working end is insufficient for a prolonged time, the high-temperature zone shifts upward. Consequently, the furnace wall near the electrode's high-temperature area experiences an abnormal temperature increase, resulting in burn-through around the tap hole due to iron leakage and slag.
Inappropriate Slag Type and Alkalinity Control: An unreasonable slag type or improper alkalinity control can lead to severe overheating of the molten iron. This, in turn, causes chemical corrosion of the furnace body, damaging its refractory materials.
Furnace Shutdown and Startup Cycles: Prolonged furnace shutdowns render the furnace body susceptible to expansion and cracking. Frequent startups and shutdowns exacerbate this issue, causing the furnace body steel plate to crack due to temperature fluctuations, necessitating timely repairs.
Oxygen Blowing and Eye-Opening Operations: These operations impose significant wear on the furnace eye and wall. Whether carbon or magnesia bricks are used, oxidation reactions can occur under high temperatures, forming a false furnace wall that fails to provide protection and accelerates physical deterioration.
Water Leakage and Excessive Material Moisture: Water leakage from the furnace body and excessive material moisture can lead to corrosion. Although some moisture evaporates upon entering the furnace, the remaining portion decomposes at high temperatures, forming oxygen that corrodes the furnace wall.
Chemical Erosion and Mechanical Impact at Thaiman Temperature: When the temperature reaches the Thaiman point, magnesia bricks in the working layer, where high-carbon ferrochromium contacts the slag, undergo chemical erosion and mechanical impact from hot molten iron and slag. This alters the composition and mineral structure of the magnesia bricks, initiating diffusion even below the melting point.
Melting Phenomenon: Refractory materials exceed their refractoriness at working temperatures, leading to corrosion. Melting often occurs in the furnace wall near the arc zone and the furnace bottom at the electrode end. Temperature measurement patch and thermocouple data from the furnace bottom reveal that the highest temperatures are at the electrode end. If the electrode working end is too long, furnace bottom temperatures rise significantly.
Chemical Attack: Chemical reactions between refractory materials and slag, molten metal, dust, exhaust gases, and other substances constitute chemical attack. This includes gas-solid, liquid-solid, liquid-liquid, and gas-liquid reactions. As the working temperature of refractory materials approaches or exceeds their refractoriness, metal-induced chemical attack becomes more pronounced.
Mechanical Action: In the working layer, refractory materials above the load's softening temperature are highly susceptible to mechanical forces from metal and slag, leading to loss.
Spalling and Cracking: Rapid temperature changes or uneven heat loads cause internal thermal stresses in refractory materials to exceed their structural strength, resulting in localized damage. Prolonged furnace shutdowns and startups are particularly evident in causing furnace body expansion and cracking, with similar scenes observable in the tap chute.
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