Page 25 - Steel Tech India eMagazine Volume January 2021

81. Ŗ 01 Ŗ ,CPWCT[

always operates in liquid bath steady operation. This
process generates an amount of electrical disturbances
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noise generated in the power grid by an EAF of similar
productivity.
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m ) than EAFs and do not operate with open, radiating
2
arcs as the EAFs do. Thanks to this feature, the slag
requirements are dramatically less stringent as the
protection of the sidewall refractories is achieved by a
sheer temperature gradient, keeping the slag next to
Fig. 6: TENOVA PYROMET Open Slag Bath Furnace. On the wall below its solidifyingtemperature.
the right: Soederberg type electrodes (TENOVA, 2019)
As the steady and static operation of an OSBF
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and reductants, is charged by gravity in the vessel and uses Söderberg electrodes. With this system, the
heated by means of resistive arcsthat spark through the gradual consumption of the electrodes near the tip
slag layer. The OSBF ispowered by three independent is compensated by adding a paste composed by
single-phase AC transformers feeding Soderberg anthracite, pet coke and graphite that graphitizes with
electrodes, independently regulated by means of the process temperature as the electrode slips down.
hydraulic systems. 6JKU OCVGTKCN EQUVU UKIPKſECPVN[ NGUU VJCP UVCPFCTF
graphite electrodes used in EAFs.
Periodically, the slag and metals are evacuated through
tapholes and launders placed at different heights in the Logistic-wise, for the plants where the assembly needs
vessel (higher for the slag and lower for the metal). The VQ DG KPUVCNNGF CYC[ HTQO VJG $1( UJQR C EQPſIWTCVKQP
tapping temperature can be adjusted by providing more quite common in the integrated cycle plants) the liquid
or less electric energy to the bath, whilethe carbon produced can be tapped into ladles ortorpedo cars
content can be trimmed by adding carburizing agents and transported with a modest temperature drop at a
to the feed. At the end of tapping, the holes are plugged UKIPKſECPV FKUVCPEG UCOG CU KV KU FQPG KP DNCUV HWTPCEGU
with a clay gun and the cycle is repeated. The process DR module and OSBF are integrated in an organic
maintains a large metal heel in the furnace sothe furnace automation package controlling the operating

Fig. 7: OSBF tapping in hot metal torpedo cars. On the right: DRI cooler for cold DRI discharge

STEEL TECH 23