Types of furnaces is present in this file.

1. AITS-RAJKOT
Sub :-Melting Furnaces
Prepared by :-

2. Melting
Furnaces

3. Introduction
 • A melting furnace is an appliance capable of heating materials to
such
 a high temperature that they melt, which from a chemical
perspective
 basically means that they reach the critical threshold temperature at
 which they convert from a solid to a liquid.
 • Not all materials will melt, and those that do

4. Types of furnaces:
 1. Electric arc furnace
2. Basic oxygen furnace
3. Blast furnace
4. Induction furnace

5. 1. Electric arc furnace
 An Electric Arc Furnace (EAF) is
a furnace that heats charged
material by means of an electric arc.
 Industrial arc furnaces range in
size from small units of
approximately one ton capacity up
to about 400 ton units
 Industrial electric arc furnace
temperatures can be up to 1,800 °C

6. Construction
 • the shell, which consists of the sidewalls
and lower steel "bowl";
 • the hearth, which consists of the
refractory that lines the lower bowl;
 • the roof, which may be refractory-lined or
water-cooled, and ca

7. Operation
 • Scrap metal is delivered to a scrap bay, located next to the melt shop.
 • The scrap is loaded into large buckets called baskets, and the furnace is
charged with scrap from the basket.
 • After charging, the roof is swung back over the furnace and meltdown
commences.
 • The electrodes are lowered onto the scrap, an arc is struck and the
electrodes are then set to bore into the layer of shred at the top of the
furnace.
 • Oxygen is blown into the scrap, combusting or cutting the steel, and extra
chemical heat is provided by wall-mounted oxygen-fuel burners. Both
processes accelerate scrap meltdown

8. 2.Basic Oxygen furnace
 • Basic Oxygen Steelmaking (BOS, BOP, BOF, and OSM), also known
as Linz–Donawitz-steelmaking or the oxygen converter process.
 • It is a method of primary steelmaking in which carbon-rich molten pig
iron is made into steel.
 • Blowing oxygen through molten pig iron lowers the carbon content of
the alloy and changes it into low carbon steel.
 • The process is known as basic because fluxes of burnt lime or
dolomite, which are chemical bases, are added to promote the removal
of impurities and protect the lining of the converter

9. Process
 • Molten pig iron from a blast furnace is poured into a
large refractory-lined container called a ladle.
 • Pre-treatment stage
 • Filling the furnace with the ingredients(cold metal) is
called charging.
 • copper tipped lance with 3-7 nozzles is lowered down
into it and high purity oxygen is d

10. 3.BLAST FURNACE
 •The purpose of a blast furnace is to reduce and convert iron
oxides into
liquid iron called "hot metal”.
 • The blast furnace is a huge, steel stack lined with refractory
brick.
 • Iron ore, coke and limestone are put into the top, and
preheated air is
blown into the bottom.

11. Method
 Three substances are needed to enable to extraction
of iron from its ore. The combined mixture is called
the Charge:
 • Iron ore, haematite - often contains sand with
iron oxide, Fe 2 O 3 .
 • Limestone (calcium carbonate).
 • Coke - mainly carbon
 • The charge is placed a giant chimney called a
blast furnace. The blast furnace is around 30
metres high and lined with fireproof bricks. Hot
air is blasted through the bottom.

12. 4.INDUCTION FURNACE
 •An Induction Furnace is an electrical furnace in which the heat is
applied by induction heating of metal. Induction furnace capacities
range from less than one kilogram to one hundred tonnes, and are
used to melt iron, steel, copper, aluminium, and precious metals.
 •The advantage of the induction furnace is a clean, energy-efficient
and well-controllable melting process compared to most other
means of metal melting.
 •Most modern foundries use this type of furnace, and now also more
iron foundries are replacing cupolas with induction furnaces to melt
cast iron, as the former emit lots of dust and other pollutants.

13. Operation
 •An induction furnace consists of a nonconductive crucible
holding the charge of metal to be melted, surrounded by a coil
of copper wire.
 •A powerful alternating current flows through the wire. The coil
creates a rapidly reversing magnetic field that penetrates
the metal.
 •The magnetic field induces eddy currents, circular electric
currents, inside the metal, by electromagnetic induction.
 • The eddy currents, flowing through the Electrical resistance of
the bulk metal, heat it byJoule heating. Once melted, the eddy
currents cause vigorous stirring of the melt, assuring good
mixing.
 • An operating induction furnace usually emits a hum or whine
(due to fluctuating magnetic forces), the pitch of which can
be used by operators to identify whether the furnace is
operating correctly or no.

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