Suez University
Faculty of Petroleum and Mining Engineering
Metallurgical and Materials Engineering Department
Summer Training Report:
Suez steel company
Melt shop section
From 1/8/2021 to 12/8/2021
By:
Ibrahim Hassan Mohamed El sheikh
Sec 1
Melt shop
Introduction
Worldwide, approximately 40% of steel is produced based on electric arc furnace. The
main task of modern EAFs is to convert the solid raw materials to liquid crude as fast as
possible. Electric arc furnace operates as a batch process and the steel batch produced
is known as “heat”. Its operating cycle is known as “tap-to-tap” cycle. Modern operations
aim for a tap-to-tap cycle of less than 60 minutes.
Construction
The furnace is primarily split into three sections:
• The shell, which consists of the sidewalls and lower steel bowl, The hearth, which
consists of the refractory (Magnesia carbonate) that lines the lower shell and The
roof, which may be refractory-lined or water-cooled, and can be shaped as a
section of a sphere through which one or more graphite electrodes enter the
furnace.
Charged Materials
• Scrap (20-30%) which is as light scrap (0.2 ton/ m3) in the top and bottom line of
charge in order to make a foaming slag. Scrap is divided into reclaimed scrap,
industrial scrap and revert scrap.
• DRI (70-80%).
• Fluxing materials (lime, dolomite, coke).
• Other materials as Oxygen, argon, nitrogen, CH4.
Operating cycle
1- Preparation
Tapping hole is inspected and filled with Olivia sand, EAF roof opened and EAF
refractory inspected and repaired if there is any need for repair. Repairs can be made
by EBT repair, EAF gunning and EAF fettling.
2- charging
Scrap is brought into the melt shop inside rail cars. An overhead crane is used to load the
scrap into the charging bucket. When the charge bucket has been loaded, the loading
crane picks up the charge bucket and puts the scrap into the EAF.
3- Melting
It’s the heart of EAF operation accomplished by supplying energy to the furnace interior.
The electric arc furnace can have temperatures risen between (1630 – 1650 ⁰C). Source
of energy are Electric energy (60-70%) to melt scrap and DRI and chemical energy (30-
40%). Energy needed for melting scrap is about 330 KWh/ton and about 530 Kwh/ ton for
the DRI.
Electrical energy is supplied via the graphite electrodes and is usually the largest
contributor in melting operations. Chemical energy is being supplied via several sources
including oxyfuel burners and oxygen lances. Heat is transferred within the scrap by
conduction oxygen from lance will react with several components in the bath including,
aluminum, silicon, manganese, phosphorus, carbon, and iron.
• Slag is generated during the melting process by the addition of lime and the effect of
non-metallic materials which generally contaminate the scrap. In addition, slag
contains all the solid productions generated by the oxidation of some metals contained
in the scrap (Si, Al, Ti, Mn, etc.).
• Function of foaming slag is to cover the arcs to protect the refractories from arc-flair,
improving steel quality by absorbing deoxidation products and inclusions, reduction of
electrical disturbance and noise and to isolate steel to minimize heat losses.
4- Refining
It’s started from melting process as aimed to remove undesirable elements as
phosphorus from the steel from steel before tapping. De-phosphorisation process is
necessary because Phosphorous has a bad effect on steel properties as it decreases
ductility and strength and cause cold shortness during rolling. So; the reduction of its
content in the steel bath is a must before steel is sent for casting.
5- De-slagging
The furnace is tilted backwards, then slag is poured out of the furnace through the slag
door. Removal of the slag eliminates the possibility of phosphorus reversion. If the high
phosphorus slag has not been removed prior to this operation, phosphorus reversion will
occur.
6- Tapping
By reaching the required steel analysis and tapping temperature (1640 ⁰C), the taphole is
opened, then the steel is poured into a ladle for transfer to the next operation (usually a
ladle furnace). During tapping, additions of Ferroalloys, deoxidizers and slag formers are
performed. Tapping period is (3-5 minutes).
3-1 Ladle Refining Furnace
Ladle refining furnace is probably the most important part of steel making process as it
changes steel to high quality product. The goal of the furnace is to deliver a ladle of good
quality steel to the caster on time at right temperatures meeting total chemical
specifications. Also a very important function is to increase productivity in the melt shop
(decrease refining time at EAF).
The Main Objectives of Ladle Metallurgy are:
1- Homogenization of chemical composition and temperature of liquid steel in the
ladle by stirring.
2- Heating of the liquid steel to a temperature suitable for continuous casting and to
compensate the energy losses during ladle furnace treatment time and energy
requirements for alloys.
3- De-oxidization or killing by removal of oxygen to avoid porosity and blowholes.
4- Ferro alloys and carbon additions to adjust in the chemistry of liquid steel.
5- De-sulfurization by reduction of sulfur content as low as 0.002% because sulfur
has a great tendency to segregate and react with iron causing hot shortness. This
done by using deoxidized basic slag and temperature about 1620 oc.
6- Micro cleanliness by removal of undesirable nonmetallic elements.
7- Mechanical properties improvement as toughness, ductility, and transverse
properties.
8- Inclusions modification by calcium treatment.
1- Continuous Casting
The most effective method that used in steel industry to produce billets or slabs is called
continuous casting and this is the method used in EZZ steel. Continuous casting, also
called strand casting, is the process whereby molten metal is solidified into a "semi-
finished" billet, bloom, or slab for subsequent rolling in the finishing mills. The machine
is shown in Fig.
▪ Continuous casting process
1- The ladle from ladle furnace is transported to the top of the casting machine.
2- Molten metal is transferred via a refractory shroud to a holding bath called tundish
acting as a buffer of hot metal, as well as smoothing out flow, regulating metal feed
to the molds and cleaning the metal.
3- Metal is drained from the tundish through another shroud into the top of an open-
base copper mold. The mold is water-cooled to solidify the hot metal directly in
contact with it; this is the primary cooling process.
4- The mold oscillates vertically and a lubricant is added to the metal in the mold to
prevent the metal sticking to the walls and to trap any slag particles that may be
present in the metal bringing them to the top of the pool to form a floating layer of
slag.
5- The shroud is set so the hot metal exits below the surface of the slag layer in the
mold and is thus called a submerged entry nozzle (SEN).
6- In the mold, a thin shell of metal next to the mold walls solidifies before the middle
section called a strand. The bulk of metal within the walls of the strand is still
molten.
7- The strand is immediately supported by closely spaced, water-cooled rollers which
support the walls of the strand against the Ferro static pressure of the still-
solidifying liquid within the strand.
8- To increase the rate of solidification, the strand is sprayed with large amounts of
water as it passes through the spray-chamber; this is the secondary cooling
process.
9- The molten metal is continuously passed through the mold, at the same rate to
match the solidifying casting. This results in casting of long strands of metal.
