In the Name of God
(Applied Chemistry)
Inorganic Industrials Chemistry
Iron and Steel
R. Pourata
Outlines
Introduction
Properties
Production of Iron
Steel Production
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1
Introduction
In the terminology a distinction is made between primary reduction
(iron production), and refining (Steel). The production of iron can
take place in the blast furnace which produces pig iron, or by means
of other processes which yield equivalents such as sponge iron. Steel
production refers to the processing step that involves the refining and
the adjustment of certain solute contents in the iron (steel),
irrespective of whether the raw material is crude iron, scrap, or
sponge iron.
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Properties
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2
Properties
General
Name, symbol, number
iron, Fe, 26
Element category
transition metals
Group, period, block
8, 4, d
Appearance
lustrous metallic
with a grayish tinge
Standard atomic weight
55.845(2) g·mol−1
Physical properties
Phase
solid
Density (near r.t.)
7.874 g·cm−3
Liquid density at m.p.
6.98 g·cm−3
Melting point
1811 K
(1538 ºC, 2800 ºF)
Boiling point
3134 K
(2862 ºC, 5182 ºF)
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Production
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3
Production
The production of iron can take place in the blast furnace which
produces pig iron, or by means of other processes which yield
equivalents such as sponge iron. Steel production refers to the
processing step that involves the refining and the adjustment of
certain solute contents in the iron (steel), irrespective of whether the
raw material is crude iron, scrap, or sponge iron. This separation of
processes is useful because the properties of steel (hot formability,
strength) are acquired during the process of steelmaking and steel
differs from raw materials such as pig iron and sponge iron with
respect to these properties.
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Production
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Production
The most important metallurgical processing units for the
manufacture of large quantities of liquid crude steel from ore are:
For ore preparation
Sintering plants
For the reduction of oxide ores
Blast furnaces
For refining and alloying of steel and for scrap melting
Converters operated with pure oxygen
Open hearth furnaces
electric arc furnaces
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Production
Schematic flow sheet of steel production
a) Pelletizing drum; b) Sintering grate; c) Coking plant; d) Blast furnace; e) Torpedo ladle; f)
Pig-casting plant; g) Basic oxygen converter; h) Siemens Martin furnace; i) Electric arc
furnace; j) Continuous casting; k) Soak pit; l) Ingot casting; m) To rolling mill; n) To shipping
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Production
Raw Materials
iron ore and scrap iron
solid, liquid, or gaseous reducing agents
solid, liquid, or gaseous fuels to supply the heat needed for reaction
and melting.
slag-forming agents
Production
Important minerals in iron ores
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Production
Schematic diagram of
iron-ore preparation
Production
Reducing Agents
Carbon and hydrocarbon carriers, chiefly in the form of coke, are
gasified to the primary reducing agents (CO, H2) in blast furnaces.
Coke can be replaced partly by carbon and by hydrocarbon carriers
injected via the tuyeres. Examples of hydrocarbon carriers are coal,
oil, natural gas, coke oven gas, or plastics wastes. But for physical
reasons a blast furnace cannot be operated without coke. As iron ores
change their chemical and physical properties from top to the hearth
of the furnace according to reduction, softening and melting, the coke
remains the only solid material below the smelting zone of the iron
bearing materials.
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Production
Reducing Agents
Production
Reducing of oxide ores
C + 1/2 O2 → CO
C + CO2 → 2 CO
CH4 + H2O → CO +3H2
CH4 + CO2 → 2 CO + 2 H2
FeOn + n(CO, H2) → Fe + n(CO2 , H2O)
FeOn + nC → Fe + nCO
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Production
slag-forming agents such as silica and silicates; sources of calcium
and magnesium such as limestone, dolomite, olivine; and coke – ash
constituents.
Production
Blast furnace material balance where all quantities represent the amount per metric ton of
hot metal. The dry top gas contains 23.4% CO, 21.2% CO2, and 2.5% H2; the slag contains
38% SiO2, 9% Al2O3, 42% CaO, 10% MgO, and 1.3% S; and the hot metal contains 4.5%
C, 0.48% Si, 0.59% Mn, 0.029% S, and 0.060% P
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Production
Crude Steel Production
The object of all steel production processes is the removal of
unwanted metallic, nonmetallic, and gas-forming elements from the
raw materials, and the controlled addition of alloying elements to
obtain the required characteristics of the various grades of steel.
Production
Crude Steel Production
Raw Materials
1) Molten iron from blast furnaces (hot metal), mainly used for steel
production by the basic oxygen furnace (BOF) process
2) Scrap, sponge iron, and solidified blast-furnace iron (pig iron),
mainly used for melting steel in electric furnaces
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Production
Basic oxygen furnace
The carbon monoxide produced is a source of thermal energy. After
thorough purification, it is collected in gasholders and burned to
provide heat for associated production plant. The oxides SiO2 and
P2O5 dissolve in the liquid slags formed from the added lime and the
iron oxide produced during the oxidative decarburization processes.
C + O ↔ CO
Si + 2O ↔ SiO2
Production
Bessemer converter
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Production
Electric Steel Process
Production
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The End
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