The single DC furnace has an annual rated capacity of 1.7 million tons, about 140,000 tons per month or 32 heats per day. A relatively large heel of 100 tons enhances furnace bottom life, shortens the scrap melting period, and facilitates a slag-free tapping operation by minimizing slag entrapment.
The furnace operates at a production rate of 240 tons/hour, with a tap-to-tap time of 45 minutes and a charge to power-on time of 5 minutes. A typical furnace charge consists of 30% each pig iron and shredded scrap, 15% HBI, 20% bushelings, and 5% home scrap. The makeup of specific furnace charges will change to optimize particular end-product requirements.
The furnace charging operation is based on a one-bucket charge. A major portion of the HBI (as well as lime and dolomite) is fed directly through the furnace roof via a conveyor-fed chute.
The furnace is designed with a split shell configuration (roof/shell and bottom). It has an internal diameter of 24.6 feet and a bath volume of 6,700–7,000 cu. ft. The pin-type bottom electrode configuration includes 244 1-inch-diameter steel pins separated by a castable refractory and brick lining. The bottom is 45 inches thick. A total of 40 thermocouples are incorporated into the furnace bottom to monitor refractory conditions. The top carbon electrode has a 30-inch diameter with an anticipated consumption rate of 2.1 pounds/ton.
The furnace roof is spray cooled. The sidewall consists of spray-cooled copper panels, while the furnace bottom is forced-air cooled.
The furnace is equipped with eccentric bottom tapping (EBT) with a 7-inch-diameter taphole producing a 23-24 minute tap time.
Ancillary facilities include six safety-bottom ladles with slidegates and 2-inch-diameter nozzles. There are also three natural gas–fired horizontal and one vertical ladle preheat stations that preheat ladles to 2,000°F before use; preheat time for a newly-lined ladle is 12 hours.
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