Open Hearth Furnace - Open Hearth Process

Open Hearth Process

The open hearth process is a batch process and a batch is called a "heat". The furnace is first inspected for possible damage. Once it is ready or repaired, it is charged with light scrap, such as sheet metal, shredded vehicles or waste metal. Once it has melted, heavy scrap, such as building, construction or steel milling scrap is added, together with pig iron from blast furnaces. Once all steel has melted, slag forming agents, such as limestone, are added. The oxygen in iron oxide and other impurities decarburize the pig iron by burning the carbon away, forming steel. To increase the oxygen contents of the heat, iron ore can be added to the heat.

The process is far slower than that of Bessemer converter and thus easier to control and take samples for quality control. Preparing a heat usually takes 8 h to 8 h 30 min to complete into steel. As the process is slow, it is not necessary to burn all the carbon away as in Bessemer process, but the process can be terminated at given point when desired carbon contents has been achieved.

The furnace is tapped the same way a blast furnace is tapped; a hole is drilled on the side of the hearth and the raw steel is let to flow out. Once all the steel has been tapped, the slag is skimmed away. The raw steel may be cast into ingots; this process is called teeming, or it may be used on continuous casting for the rolling mill.

The regenerators are the distinctive feature of the furnace and consist of fire-brick flues filled with bricks set on edge and arranged in such a way as to have a great number of small passages between them. The bricks absorb most of the heat from the outgoing waste gases and return it later to the incoming cold gases for combustion.

Read more about this topic:  Open Hearth Furnace

Famous quotes containing the words open, hearth and/or process:

    In that open field
    If you do not come too close, if you do not come too close,
    On a summer midnight, you can hear the music
    Of the weak pipe and the little drum
    And see them dancing around the bonfire
    The association of man and woman
    In daunsinge, signifying matrimonie....
    —T.S. (Thomas Stearns)

    Nor does the man sitting by the hearth beneath his roof better escape his fated doom.
    Aeschylus (525–456 B.C.)

    You can read the best experts on child care. You can listen to those who have been there. You can take a whole childbirth and child-care course without missing a lesson. But you won’t really know a thing about yourselves and each other as parents, or your baby as a child, until you have her in your arms. That’s the moment when the lifelong process of bringing up a child into the fold of the family begins.
    Stella Chess (20th century)