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the mold. As the molten steel cools it solidifies; water is sprayed onto the steel billet as it leaves
the mold to further cool and solidify the steel.
Shearing - The steel billet is continuously drawn by pincher rolls towards a hydraulic shear which
cuts the billet into preset lengths of 2 meters (01). These billets are transferred to a cooling bed
and then to the stockyard.
2.2.2 RoIling Mill Process
The rolling mill consists of two reheating furnaces and two separate rolling mill lines, one with a 10
T/hr capacity and one with a 12 T/hr. Reinforcement bars of different dimensional sizes, ranging in
08 to 032, can be produced depending on the rollers used. Figure 2, Rolling Mill Process and Water
Balance Flow Diagram, provides a block flow diagram of the process operations. The individual
operations involved in this process are described below.
The rolling mill has a production capacity of 90,000 T /yr. The production rate will vary based on the
orders received and the hours of operation; the 1994 production was 34,000 T. When the rolling mill
is operating both lines for 16 hrs/d, production is approximately 80,000 T /yr. Currently, the rolling
mill is operated for 8 hrs/d. TIle rolling mill can use all of the billets ~roduced by the meltshop plus
additional imported billets.
Reheating - Cold billets arc loat.!et.! into the two fuel (oil) fired reheating furnaces where the billets
are heatet.! to 1,200°C. In one reheating furnace as the cold billets enter one side, the hot billets
are removed from the other sit.!e. llJis furnace requires no cooling water. In the other reheating
furnace, a pusher rod ejects the heatet.! billets, one at a time, from the side of the furnace onto a
conveyor. The pusher rod and gear box are cooled by a recirculating water bath.
Roughing -TIle conveyor carries the billets to the first rolling stand, the 3-high mill roughing stand.
\Vater is used to cool the neck of the cylinder, the plastic bearing, and the roll where the hot steel
is in contact with the roll.
Prefinishing - The billets then sllccessively pass to the 2-high mill pre-finishing stand. Water is used
to cool the roll stant.!s as described above.
Finishing - The finishing stand produces the final reinforcement bars. Water is used to cool the roll
stands as described above.
Cutting. Cooling. and Packaging - The bars are cut by a hydraulic shear. The shear can be preset
to automatically cut to the desired length. Different lengths can be produced. Once-through
cooling water is used to cool a pipe that directs the bar to the cutting shear. The bars are conveyed
to a cooling bet.! and then bundled.
2.2.3 Power Station
The power station generates electricity for use by the electric arc furnaces. The power station has 4
diesel generators, each 4,600 horsepower. Two generators are in operation 24 hrs/d. Noncontact
recirculating cooling water is used to cool the generators.
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