The Importance of Furnace Baking after Construction

In the entire aluminum alloy industry chain, the melting and casting process is the source process that determines the internal quality of the ingot, and the melting furnace is the most basic hardware carrier of the melting and casting process. Whether it is a newly built fuel/gas flame melting furnace, resistance melting electric furnace, static insulation furnace, or a melting furnace that has undergone major repairs (complete dismantling and rebuilding of the furnace lining), medium repairs (partial large-scale repair of the furnace wall, furnace bottom, and furnace top refractory layer), or minor repairs (partial peeling repair of the refractory layer, repair of the furnace mouth and flow channel), the refractory mud, refractory bricks, magnesia sand knotting layer, and castables used for lining construction all contain extremely high levels of free adsorbed water and mineral crystal water. If the moisture inside the refractory masonry cannot be slowly and fully discharged before the formal melting of aluminum, once the aluminum ingot is directly put into the furnace and ignited for heating and melting, the temperature inside the furnace will rise sharply in a short period of time, and the moisture inside the refractory material will vaporize instantly to form high-pressure steam. The huge internal stress will directly cause cracking of the refractory brick, bulging and peeling of the magnesia sand furnace bottom, and large-scale peeling of the furnace lining; The detached refractory debris will be heavily mixed into the aluminum liquid to form solid slag inclusions, greatly increasing the difficulty of subsequent refining and slag removal, and seriously reducing the yield of aluminum alloy ingots.

A more serious hidden danger is that high-temperature water vapor will continue to react with molten aluminum: 2Al+3H2O=Al2O3+6 [H], generating a large amount of alumina inclusions suspended inside the aluminum liquid, and a large number of hydrogen atoms dissolved into the aluminum liquid, causing excessive hydrogen content in the melt. Subsequently, the ingot is prone to fatal defects such as porosity, looseness, and pinholes; In extreme cases, a large amount of water from the cracking and detachment of the furnace lining can concentrate and infiltrate into the high-temperature aluminum liquid, instantly generating a huge amount of steam and causing aluminum liquid splashing or even explosion accidents, threatening the safety of on-site personnel and equipment. Therefore, after the completion of the new construction or maintenance of the aluminum alloy melting furnace, direct feeding production is absolutely prohibited. The four preparatory work of natural drying, oven drying, furnace washing, and flue cleaning must be strictly completed in sequence. Only after the furnace body is completely dry, the refractory lining is sintered stably, and the furnace is clean and free of impurities can it be officially put into aluminum alloy melting, alloy blending, refining and static casting operations. This article will provide a layered and detailed explanation of the four major preparation processes, comprehensively sorting out the operational norms and control points of each stage.