11:00 am
Steel ladle: capacity increase, lining concepts and recycling experience over 25 years
Reinhard Exenberger | voestalpine Stahl GmbH | Austria
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Authors:
Reinhard Exenberger | voestalpine Stahl GmbH | Austria
Georg Grimm | voestalpine Stahl GmbH | Austria
The annual production in Linz has grown from 3.6 mt/a in BY 1998 to almost 5.7 mt/a in BY 2022. In order to provide these figures, an increase of heat weight from 150 t/heat to 173t/heat had been necessary. When we had been changing the LD vessels to bigger sizes in 2001 and BY2009/BY2010, we also had to purchase new ladle vessels to handle the bigger heat size. In order to relax the pressure in the daily converter production, we procured bigger steel shells in 2022 again.
Whilst changing the steel ladle vessels, we realized modifications to the lining concepts, for an increase of ladle capacity. We changed dimensions and gained experience with brick lined and monolithic ladles. In the case of steel shell deformation, dimensional accuracy of the lining was easier to receive by bricking, while adjusting the steel capacity was easier with monolithic walls. There has been no influence of the lining type on the steel quality.
Regarding refractory breakout material we have relied on our decades of experience in recycling. Magnesia breakout has been recycled to Magnesia Carbon bricks in the in house brick plant, whereas fine grains from the bag filters have been charged into the LD vessel as Magnesia carrier. It is worth mentioning that 100% recycling raw material has been used for the production of slag line bricks for our steel ladles. Alumina breakout has been recycled into slag formers for the secondary metallurgy.
11:20 am
ECO-TAB – A new alumina aggregate for steel ladle lining
Dr. Sebastian Klaus | Almatis GmbH | Germany
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Dr. Sebastian Klaus | Almatis GmbH | Germany
Dr. Andus Buhr | Almatis GmbH | Germany
Dr. Hans-Leo Gross | Almatis GmbH | Germany
Dagmar Schmidtmeier | Almatis GmbH | Germany
Wouter Zwijnenburg | Almatis BV | Netherlands
Jerry Dutton | United Kingdom
ECO TAB is a new alumina refractory aggregate with lower density when compared to global tabular alumina T60/T64 (3.3 vs. 3.55 g/cm³). The business case for the development of this new aggregate is based on the application as steel ladle wear lining.
Two aspects are relevant here. The heat capacity and the thermal conductivity of the wear lining material are important for reducing the thermal losses of steel into the refractory lining during the thermal cycling of the ladle in use. With lower heat capacity and thermal conductivity of the lining, the heat losses during the empty phase of the ladle can be reduced and accordingly the heat losses from the steel to the refractory lining afterwards. In addition, a lower weight of the refractory lining enables higher tapping weight of steel into the ladle when the maximum crane weight in the steel works becomes the limiting factor during the ladle campaign. First, the volume is the limit but with increasing refractory wear, the crane weight becomes the new limit instead. ECO TAB contributes to energy saving, capacity improvement, and reduced material consumption through lower weight of the refractory lining.
The paper discusses the material properties and application testing of the new aggregate including induction furnace slag testing and thermal conductivity.