FIELD OF APPLICATION
The present invention relates to a method for desulphurization of high carbon ferro-
chrome in an induction melting furnace. More particularly, it relates to desulphurisation
of high carbon ferrochrome in a covered induction melting furnace without using costly
stirring agents or media like nitrogen gas.

BACKGROUND OF THE INVENTION
Desulphurisation of high carbon ferrochrome is generally carried out using
desulphurising reagents in a very fine powder form, which can be pneumatically
injected into the molten metal bath.

The molten metal bath has to be kept constantly stirred using stirring agents
such as nitrogen gas. Using such stirring may reduce the temperature of the
bath as the nitrogen gas takes away a lot of heat from the molten metal.
The desulphurising reagents are introduced in the bath using a carrier gas and
steel tubing in a cored wire injection process. Such a reagents addition process
is very expensive.
Further the uncovered induction furnace used for desulphurisation may also
result in oxidation of the metal by atmospheric oxygen at the top surface.
A need was therefore, felt for developing a method for desulphurising of high
carbon ferrochrome avoiding the use of costly stirring agents and using an easy
and inexpensive way of adding the desulphurising reagents to the bath.

SUMMARY OF THE INVENTION
The main object of the present invention therefore, is to carry out
desulphurisation of high carbon ferrochrome avoiding the use of costly stirring
agents like nitrogen gas.
Another object of the invention is to avoid using a carrier gas and steel tubing in
a cored wire injection process for adding desulphurising reagents in order to
minimize the cost.
Yet another object of the present invention is to minimize oxidation of the metal
by atmospheric oxygen at the top surface of the bath.
These and other objects of the present invention are achieved by adding the
desulphurising reagents in the bath and using a covered induction melting
furnace which results in natural stirring action of the molten metal due to
electromagnetic effect resulting in intense mixing of the metal with the added
desulphurising reagents.

thus the present invention provides a method for desulphurisation of high
carbon ferrochrome in an induction melting furnace comprising the step of
adding desulphurising reagents to the molten bath in a covered induction melting
furnace, resulting in intense mixing of the molten metal with desulphurising reagent
due to electromagnetic effect with minimum oxidation of the metal by atmospheric
oxygen.
DETAILED DESCRIPTION OF A PREFERRED
EMBODIMENT OF THE INVENTION
The present invention uses a covered induction melting furnace. Desulphurising
reagents calcium carbide compound are added to the molten metal bath in the furnace.
The natural stirring action of the molten metal available in the induction melting
furnace results in intense mixing of the metal with the desulphurising reagents
added to the bath.
This results in efficient desulphurisation of the ferrochrome. Use of covered
induction furnace for desulphurisation also minimizes oxidation of the metal by
atmospheric oxygen at the top surface. Substantial reduction in cost of addition
of the reagent compound can be achieved compared to a cored wire injection
process. The invention can also be used for producing ferroalloys other than
ferrochrome.
The ultra low sulphur ferrochrome or other ferroalloys produced by using the
process of the present invention can fetch extra premium for the product in
addition to substantial savings in using costly stirring agent, the resultant loss of
heat from the molten metal bath, and using expensive carrier gas and steel
tubing in a cored wire injection process for adding desulphurisation reagents.
The novelty of the present invention is the utilization of the natural stirring action of the
molten metal available in an induction melting furnace due to the electromagnetic effect
resulting in intense mixing of the metal with desulphurising reagents so that efficient

desulphurization results. Also, use of covered induction furnace for desulphurization to
minimize oxidization of the metal by atmospheric oxygen at the top surface is also a
novel innovative idea.
The present invention is non obvious because of the following inventive steps.
1) High temperature heating and stirring in one go without any external medium.
2) Easy and cheap means to handle and to add the desulphurising reagents in to the
bath without carrier gas or steel tubing (in case of cored wire injection) resulting in
minimum direct as well as indirect cost of reagents additions.
The advantage of the present invention is that it avoids the use of costly stirring agents
/ media such as nitrogen gas which also take away a lot of high temperature heat from
the molten metal.
The desulphurising reagents is used in the present invention in relatively coarser form
(100% below 1 mm) instead of that in very powder form which is a must in case of
pneumatic injection.
*
Even if only 20% of the high carbon ferrochrome produced is desulphurised by this
process the expected net profit on account of the extra premium assumed to be at the
rate of Rs. 2000 per ton shall be Rs (2000-1500) x 50,000 x 0.2 = Rs. 0.5 crore per
year. It can be doubled by adopting this process for the FeCr produced in the
conversion agents as well.

WE CLAIM
1. A method for desulphurisation of high carbon ferrochrome in an induction
melting furnace comprising the step of:
adding desulphurising reagents calcium carbide compound to the molten bath;
utilizing the natural stirring action of the molten metal available in induction melting
furnace due to electromagnetic effect to achieve intense mixing of the metal with
desulphurising reagent;
Characterized in that,
a covered induction furnace for desulphurization is utilized to minimize oxidation of the
metal by atmospheric oxygen at the top surface when high temperature heating and
stirring takes place in the bath.
2. A method as claimed in claim 1, wherein a coarsed form of desulphurising reagents is
mixed in the molten bath.

ABSTRACT
A METHOD OF DESULPHURIZATION OF HIGH CARBON FERRO-CHROME
The invention relates to a method for desulphurisation of high carbon ferrochrome in an
induction melting furnace comprising the step of: adding desulphurising reagents
calcium carbide compound to the molten bath; utilizing the natural stirring action of the
molten metal available in induction melting furnace due to electromagnetic effect to
achieve intense mixing of the metal with desulphurising reagent; wherein, a covered
induction furnace for desulphurization is utilized to minimize oxidation of the metal by
atmospheric oxygen at the top surface when high temperature heating and stirring
takes place in the bath.