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Feature Article
Advanced Blowing and Stirring Conditions in
the BOF Process
Three examples are used to
demonstrate how the basic
oxygen furnace (BOF) process
can be improved. Thanks to a
new calibration procedure for the
BOF top lance, a quick check can
be performed to find whether the
supersonic nozzles are operating
at the design point.
Authors
Hans-Jürgen Odenthal
general manager, R&D Technical Department, SMS
Siemag AG, Düsseldorf, Germany
[email protected]
Pavlo Grygorov
formerly SMS Siemag AG,
risk control officer, Stadtwerke München GmbH,
München, Germany
Markus Reifferscheid
vice president, R&D Technical Department, SMS
Siemag AG, Düsseldorf, Germany
[email protected]
Jochen Schlüter
vice president, Special Technologies, SMS Siemag
AG, Düsseldorf, Germany
[email protected]
This paper is the 2014 Charles H. Herty Jr. Award winner. For more
information about AIST awards, visit AIST.org.
T
he basic oxygen furnace
(BOF) with top lance and
bottom plugs combines different components and processes in order to obtain specific
metallurgical results. The vessel geometry, charge materials,
fluxes, refractory lining, top
lance and bottom plugs have to
be designed well to ensure high
productivity and safe operation.
For example, the interaction
between the oxygen blowing cavities and the inert gas bubbles in
the form of heterogeneous buoyant plumes plays a major role in
the metal-slag reaction. The oxygen jets must not impact the melt
where the inert gas bubbles are
rising toward the free surface.3,5
Despite all innovations in recent
decades — such as advanced
process models for BOF endpoint prediction, new measuring
techniques such as laser-optical
methods to determine the residual brick thickness of the refractory, the lamellar suspension,
the post-combustion top lance
and the slag-splashing, and the
use of special single/multi-hole
bottom plugs — there is, even
today, potential to improve the
BOF process. Three possibilities
for improvement are:
1. Top lance calibration:
device and method to
calibrate the BOF top
lance, with the objective
of operating the supersonic nozzles in the lance
tip precisely at the design
point.
2. Adaptive top lance nozzle: a mechanical adjustment device which controls the oxygen flowrate
through the supersonic
nozzles over an extended
pressure range in such
a way that flow disturbances (shock waves,
expansion waves) are
suppressed in the supersonic region. The device
which is currently under
development allows the
nozzles to be operated at
the design point.
3. Alternating bottom stirring: a method specifically developed for the BOF
converter which is able
to save about 30% inert
gas without affecting the
metallurgical analyses.
This article is available online at aist.org for 30 days following publication.
142 ✦ Iron & Steel Technology
A Publication of the Association for Iron & Steel Technology

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