STEEL + TECHNOLOGY 04/2019 EXTRACT

Figure 2
STEEL TECHNOLOGY | 43
Plant overview
In the first phase BRS installed the steelmaking
plant, a one strand CSP ® plant with
a capacity of 1.5 million t/ year, one pickling
line/tandem cold mill (PL/TCM), a continuous
annealing and hot dip galvanizing
line, batch annealing furnaces and an
offline skin pass mill (figure 1).
The overall layout is based on a “U”
shape and enables short distances
between the facilities as well as simple
coil handling. In order to ensure flexible
response to market demands, the plant is
built in a way that BRS can obtain products
for sale after various stages of the overall
process (figure 2).
The steel making plant consists of a
direct current electrical arc furnace with a
tapping weight of 150 t. Charge material
includes commercial scrap grades and –
depending on the steel grade produced,
pig iron, DRI or HBI. For metallurgical refining
and alloying a ladle furnace is used
designed as twin station with joint electrodes
to reduce idle time due to ladle handling.
Also for vacuum treatment a Ruhrstahl-Heraeus
(RH) degasser is installed
with TOP lance for forced decarburization
and chemical heating. The RH degasser
has a capacity of 145 t per ladle. The process
is characterized by short treatment
time and flexible ladle handling. This gives
BRS the opportunity of economical mass
production of high-quality steel grades
with ultra-low carbon and low gas content.
The combination of EAF and RH degasser
is the first one in North America.
The CSP ® plant is designed to produce
strips with a width of up to 1,930 mm (76”)
and a final thickness between 1.4 mm and
25.4 mm. The CSP ® Caster is a vertical
solid bending (VSB) type. Slab thickness is
85 mm which can be flexibly reduced
down to 55 mm by liquid core reduction
(LCR). The caster is equipped with mold
temperature mapping (MTM), X-Pact ® solid
process model, breakout detection and
electromagnetic brake (EMBR) for reduced
turbulence thereby improving steel internal
as well as surface quality.
The CSP ® furnace was designed to minimize
energy consumption and to nevertheless
achieve ideal heating-through of
the thin slabs. The entire roller hearth furnace
is equipped with environmentally
compatible ultra-low NO x burners. At a
measured average NO x emission of 85
mg/Nm³. The furnace of Big River Steel
HRC
0.433 m t/year
HRC P&O
0.127 m t/year
CAL/CGL
Steelmaking plant
CSP® plant
Pickling line
CRC galvanized
0.476 m t/year
Tandem cold mill
BAF
CRC tempered
0.464 m t/year
Figure 2. Phase 1 configuration and material flow at Big River Steel (Picture: SMS group)
sets a standard with regard to environmental
compatibility. This emission level is far
below the statutory limit value.
Slab transport through the furnace is
carried out by water-cooled rollers with a
special insulation. These rollers reduce the
energy loss by more than 30% in comparison
with conventional rollers. This significant
increase in energy efficiency reduces
the gas consumption and hence allows
saving of operating costs. The overall
reduction of energy consumption in the
furnace is more than 20%. Energy consumption
of the furnace when fed with
slabs with a cross-section of 65 mm x
1800 mm and a casting speed of 5.0 m/
Table 1. Specific energy consumption for different slab dimensions
Slab dimensions and
casting speeds
65 mm x 1,600 mm
4.0 m/min
65 mm x 1,800 mm
4.5 m/min
65 mm x 1,800 mm
5.0 m/min
Mass flow
in t/h
TM
minute is as low as 35.2 kWh/t over 100
m of furnace length (table 1). The control
of the furnace uses the powerful X-Pact ®
Dynamic Furnace Control Model (DFC).
This model ensures the heating of the slab
to the desired temperature at a high
degree of uniformity over length, width
and thickness.
The 6-stand CSP ® rolling mill is fitted
with all technologies and components for
the cost-effective production of high-quality
hot strip with excellent product tolerances.
These include the advanced guiding
system to improve strip stirring, the
latest descaling technology, hydraulic
gauge adjustment, CVC plus ® technology,
189 0.542
240 0.421
267 0.352
Specific energy
consumption
in kWh/(t m)
Novembe
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STEEL + TECHNOLOGY 1 (2019) No. 4