The Bessemer process has limitations that make it outdated for steel production. It requires specific pig iron composition, can only remove some impurities, and produces steel with high nitrogen levels. The open hearth process overcomes many of these issues. It can use scrap iron alone, takes longer but allows for more control and uniform product quality. The open hearth process involves charging raw materials into a Siemens furnace, melting them, refining to the desired analysis, and then tapping the molten steel. Fettling repairs the furnace lining between heats to improve furnace life.

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Why Bessemer Process has become Out-dated?
This process has got some limitation:
 Pig iron of selected composition is required to be charged.
 Phosphorus and sulphur (to some extent) can only be oxidized by basic
Bessemer process.
 The steel contains high content of nitrogen, because air is blown for
oxidation. This provides adverse effects and makes the steel unsuitable for
most application such as deep drawing purpose.
Comparison between Bessemer and Open Hearth Process:
S.No Bessemer Process Open Hearth Process
1. Alone scrap iron cannot be used. Alone scrap iron can be used.
2. Refining and finishing requires 10
to 20 minutes.
Refining and finishing are completed
within 8 to 10 Hours.
3. Operation depends entirely on eye
judgment, so that it is very difficult
to produce a uniform product.
Operation is guided by laboratory
analysis, so that it is comparatively
possible to produce a uniform product.
4. It produces inferior quality steel
associated with blow-holes and
inclusion.
Open hearth steel is of much superior
quality containing lesser blow-holes
and inclusion.
5. Carbon is completely eliminated
first and so requires large amount
of recarburizer and the product
become less homogeneous.
Carbon is partially removed and
requires smaller amount of
recarburizers and the product is more
homogeneous.
6. Low capital investment. High capital investment.
7. Because of rapidity of the process,
the control of different operation is
rather difficult and careful working
is necessitated.
Operation is comparatively easy and
finishing up to the desired analysis is
feasible.

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Open Hearth Steel Making Process or Furnace (Siemens furnace):
 Introduction
 Working Procedure
 Construction of the Furnace
INTRODUCTION TO OPEN HEARTH PROCESS:

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Figure: Schematic arrangement of an early type of Siemens furnace with about a
4.5 metric ton (5 net ton) capacity.
A. gas and air enter B. pre-heated chamber C. molten pig iron D. hearth E. heating chamber (cold) F. gas and air
exit.
Working Procedure Steps:
The process is divided into four steps.
i) Fettling.

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ii) Charging.
iii) Melting.
iv) Refining.
v) Tapping

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i) Fettling:
 The furnace lining gets eroded because of the action of the slag and/or metal,
particularly at the slag-metal interface line.
 It is repaired after every heat this is called fettling.
 It is to be done to improve the furnace life.
 Earlier it was done manually but now fettling machine do the job very
efficiently.
 Granular material of the same composition as that of the furnace lining is used
for that purpose.