FIELD OF THE INVENTION
The present invention relates to a process for producing steel in electric arc furnace. More
particularly, the present invention is directed to a process for steel production in electric arc
furnace using lancing slag generated during cutting of scrap, as partial substitution of steel
scrap in charge mix. The present invention thus favour usage of lancing slag which contains
about 70-83% FeO but is considered as a solid waste and is successfully used as partial
substitute to scrap for cost effective production of steel through EAF, whereby for average
5.5 tons addition of lancing slag, the average metallic recovery is achieved to the tune of
2.35 tons.
BACKGROUND OF THE INVENTION
Steel scrap is an important metallic feed for Electric Arc Furnace (EAF) steel making. The
size and quality of the steel scrap has a bearing on the productivity as well as techno-
economic parameters such as power consumption, electrode consumption & tap to tap time.
Since the size of the steel scrap has a profound influence on techno-economics of EAF steel
production, the scrap received through internal & external sources needs to be cut to size
for making it useful for charging in EAF. Cutting of the scrap is done with oxygen lancing.
Cutting losses are to the tune of 5% to 10% depending of the shape & size and the scrap.
While cutting, good amount of slag is generated as solid waste. Considering the high FeO of
this slag, it finds use as an alternative to iron ore for sinter making. However, there has
been need in the art of steel making to explore cost effective newer use of this iron
containing solid waste.
The present invention involves optimized use of lancing slag as iron source as partial
substitute to scrap for cost effective production of steel through EAF which was never
attempted before.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to a process for steel production in
electric arc furnace using lancing slag generated during cutting of scrap, as partial
substitution of steel scrap in charge mix.

A further object of the present invention is directed to a process for steel production in
electric arc furnace using lancing slag as partial substitution of steel scrap in charge mix
ensuring cost effective utilisation of solid waste to achieve economy in steel production.
A still further object of the present invention is directed to a process for production of steel
in electric arc furnace using lancing slag as partial substitution of steel scrap in charge mix
to ensure higher metal recovery from lancing slag as solid waste.
A still further object of the present invention is directed to a process for production of steel
in electric arc furnace using lancing slag as partial substitution of steel scrap in charge mix
which would not increase power consumption in EAF and with no change in power to tap
time compared to conventional EAF process.
A still further object of the present invention is directed to a process for production of steel
in electric arc furnace using lancing slag as partial substitution of steel scrap in charge mix
which would not cause any damage of the refractory lining due to charging of lancing slag
and ensure satisfactory lining life.
A still further object of the present invention is directed to a process for production of steel
in electric arc furnace using lancing slag as partial substitution of steel scrap in charge mix
wherein the usage of the lancing slag having good basicity does not require extra lime
addition in EAF.
A still further object of the present invention is directed to a process for production of steel
in electric arc furnace using lancing slag as partial substitution of steel scrap in charge mix
wherein amount of addition of lancing slag in charge mix is optimized based on requirement
of desired metal recovery, addition of cold pig iron and petroleum coke for balancing
carbon, increase in slag volume etc.
A still further object of the present invention is directed to a process for production of steel
in electric arc furnace using lancing slag as partial substitution of steel scrap in charge mix
wherein use of lancing slag to the tune of 8%-12% of the charge weight as a cheaper
alternative to steel scrap.

SUMMARY OF THE INVENTION
The basic aspect of the present invention is thus directed to a process for steel production in
EAF involving lancing slag comprising the steps of providing lancing slag with FeO content in
the range of 70%-83% as partial substitute to scrap in charge mix maintaining of
(a) said lancing slag in amounts of 8%-12% of the total charge mix weight
introduced in the middle of the initial charging buckets preferably first
and second buckets comprising steel scrap, pig iron and pet coke;
(b) restricting cold pig iron to upto 35% of the charge weight ;
(c) balancing the carbon of the charge based on said pig iron addition and
petroleum coke with provision for oxygen lancing for providing chemical
energy input.
A further aspect of the present invention is directed to said process for steel production
in EAF comprising the steps of:
(i) providing said lancing slag to the tune of 8%-12% of the total charge weight in
the middle of first and second charging buckets comprising steel scrap, pig iron
and pet coke limiting the cold pig to upto 35% by wt.;
(ii) Arcing for melting of the charge;
(iii) balancing the carbon of the charge with pig iron and petroleum coke, lime
addition and refining melt with provision for oxygen lancing for providing chemical
energy input;
(iv) De-slagging; and
(v) Tapping.
A further aspect of the present invention is directed to said process wherein said lancing
slag in charge mix amounting 5-7 tons for a total charge weight for EAF of about 60 tons.
A still further aspect of the present invention is directed to said process, wherein said pig
iron is preferably kept at 20 ton and pet coke is in the range of 0 ton to 0.60 ton preferably
0.30 ton, in a total charge weight for EAF of about 60 tons.

A still further aspect of the present invention is directed to said process wherein said lancing
slag composition comprising

Yet another aspect of the present invention is directed to said process, wherein high FeO
content in the slag requiring stoichiometric amount of carbon for balancing deciding the
amount of cold pig iron and petroleum coke for balancing carbon.
A still further aspect of the present invention is directed to said process wherein amount of
cold pig iron is restricted to 35% of the charge weight to avoid sticking along the furnace
walls with steel scrap due to its low melting point.
Yet another aspect of the present invention is directed to said process wherein for average
5.5 tons of lancing slag addition in charge mix, the average metallic recovery is to the tune
of 2.35 tons.
A further aspect of the present invention is directed to said process wherein effective de-
phosphorization is achieved with low opening phosphorus level of 0.02% or less in furnace.
The objects and advantages of the present invention are described hereunder in greater
details with reference to non limiting illustrative example.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURE
Figure 1: is a flow chart showing the details steps involved in producing steel in EAF using
lancing slag as partial substitute to scrap according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURE
The present invention is directed to a process for production of steel in electric arc furnace
using lancing slag as partial substitution of steel scrap in charge mix. The usage of lancing
slag as solid waste as partial substitute to scrap for cost effective production of steel
through EAF, involved the following considerations:
(a) Analysis of the constituents in the slag to assess the amount of use in EAF; (b)
Collection and segregation of lancing slag in a separate yard; (c) Bagging of the slag of one
ton in HDPE jumbo bags to avoid spillage while charging in charge bucket; (d) Optimization
of the mode and amount of lancing slag for effective recovery with improved techno-
economics;
(a) Analysis of the constituents of the slag to assess its use in EAF:
Analysis of lancing slag samples revealed that the slag contains FeO content ranging from
70% - 83% and basicity of the slag was found to be more than 1. This indicates that the
usage of this slag in EAF does not require extra lime addition. The high FeO content of this
slag calls for stoichiometric amount of carbon for balancing.
The detailed analysis of the constituents of the lancing slag is presented in following Table
1:


(b)Collection and segregation of lancing slag
Considering the high FeO and good basicity of this slag, the slag was separately collected
and stored in a separate yard for ease in bagging and transportation to the charging bay of
the EAF.
(c) Bagging of the slag of one ton in HDPE jumbo bags
To avoid spillage while charging in charge bucket, the slag was bagged in HDPE woven
jumbo bags to the tune of one ton per bag.
(d) Optimization of the mode and amount of lancing slag for effective recovery
1. Optimizing the mode of lancing slag addition in charge bucket :
Addition of lancing slag along the furnace bottom was anticipated to increase furnace
refractory erosion as FeO is acidic and eats away the basic MgO lining of the furnace.
Also, the presence of the lancing slag along the surface was expected to create
problems of arcing in EAF. Based on the above, the lancing slag addition is optimized as
addition in the middle of first and second charging buckets for charging in EAF to take
care of furnace erosion.
2. Optimizing the amount of lancing slag addition :
Since the charge weight for EAF is about 60 tons, amount of addition was optimized
based on the following assumptions:
(a) Low amount of lancing slag addition i.e. less than 8% does not provide sufficient metal
for accounting the actual metallic recovery. Also, excessive addition of lancing slag
necessitates excessive amount of cold pig iron and petroleum coke for balancing carbon
and hence, the addition was restricted to 8%-12% of the charge weight.
(b) Increased amount of lancing slag over 12% is anticipated to increase slag volume thus
necessitating addition of facilities such as high slag pot volume as well as increased
chances of reduced metallic yield;

(c) Need for restricting cold pig iron to 35% of the charge weight as excess addition over
this might cause sticking along the furnace walls with steel scrap due to its low melting
point which is anticipated to increase the furnace power consumption;
(d) Balancing the carbon of the charge with pig iron (addition to the tune of 35% of the
charge weight) and petroleum coke with provision for oxygen lancing for providing
chemical energy input.
Based on the above, the addition of lancing slag was optimized to be restricted to 5-7 tons
in 60 ton charge weight considering the high FeO content in the slag and balancing the
carbon burden with pig iron and pet coke addition for reaction with FeO.
Accompanying Figure 1 shows a flow chart showing the details steps involved in producing
steel in EAF using lancing slag as partial substitute to scrap according to the present
invention as described above.
The advantages and results of the process of steel making in EAF according to the present
invention using lancing slag in charge mix are illustrated by way of the following example:
Example:
In order to optimizing the process of steel making for effective recovery and improved
techno-economics involving use of lancing slag in EAF charge mix, 20 heats were carried
out as per the following steps:
(i) Providing lancing slag(having composition as given above) to the tune of 8%-12% of
the charge weight amounting 5-7 tons for a total charge weight for EAF of about 60 tons, in
the middle of first and second charging buckets comprising steel scrap, pig iron and pet
coke;
(ii) Arcing for melting of the charge;
(iii) balancing the carbon of the charge with pig iron (addition to the tune of 35% of the
charge weight) and petroleum coke, lime addition and refining melt with provision for
oxygen lancing for providing chemical energy input;
(iv) Deslagging; and
(v) Tapping.

Lancing slag was used in 20 nos. of heats and the results are shown in following Table2. This
illustrates that for average 5.5 tons of lancing slag addition in charge mix, the average
metallic recovery was to the tune of 2.35 tons.


There was no change in power to tap time and the furnace power consumption compared to
the heats without any lancing slag. Furnace slag was collected for each heat and the
analysis results are shown in following Table 3.

De-phosphorization was found effective as evident from opening phosphorus level in furnace
shown in Table 2. There is a variation in metallic recovery attributed to the heterogeneity of
the lancing slag (variation of FeO content), carbon balancing of the charge and the effective
use of oxygen as chemical input during the melting process. The metallic recovery from a
solid waste like lancing slag is significant thus making this slag as a cheaper alternative to
scrap for use in EAF.
It is thus possible by way of the present invention to providing a process for production of
steel in electric arc furnace using lancing slag as partial substitution of steel scrap in charge
mix and more particularly involving use of lancing slag to the tune of 8%-12% of the charge
weight as a cheaper alternative to steel scrap in EAF steel making process, favouring
significant metal recovery such as for average 5.5 tons of lancing slag addition in charge
mix, the average metallic recovery to the tune of 2.35 tons is achieved, with same power
consumption and favourable opening phosphorus level in furnace of making the process a
cost effective method of steel production in EAF by the iron and steel industry.

We Claim:
1. A process for steel production in EAF involving lancing slag comprising the steps of
providing lancing slag with FeO content in the range of 70%-83% as partial substitute to
scrap in charge mix maintaining of
(d) said lancing slag in amounts of 8%-12% of the total charge mix weight
introduced in the middle of the initial charging buckets preferably first
and second buckets comprising steel scrap, pig iron and pet coke;
(e) restricting cold pig iron to upto 35% of the charge weight ;
(f) balancing the carbon of the charge based on said pig iron addition and
petroleum coke with provision for oxygen lancing for providing chemical
energy input.
2. A process for steel production in EAF as claimed in claim 1 comprising the steps of:
(ii) providing said lancing slag to the tune of 8%-12% of the total charge weight in
the middle of first and second charging buckets comprising steel scrap, pig iron
and pet coke limiting the cold pig to upto 35% by wt.;
(ii) Arcing for melting of the charge;
(iii) balancing the carbon of the charge with pig iron and petroleum coke, lime
addition and refining melt with provision for oxygen lancing for providing chemical
energy input;
(iv) De-slagging; and
(v) Tapping.
3. A process as claimed in anyone of claims 1 or 2 , wherein said lancing slag in charge
mix amounting 5-7 tons for a total charge weight for EAF of about 60 tons.
4. A process as claimed in anyone of claims 1 to 3 , wherein said pig iron is preferably
kept at 20 ton and pet coke is in the range of 0 ton to 0.60 ton preferably 0.30 ton, in a
total charge weight for EAF of about 60 tons.

5. A process as claimed in anyone of claims 1 to 4, wherein said lancing slag composition
comprising

6. A process as claimed in anyone of claims 1 to 5, wherein high FeO content in the slag
requiring stoichiometric amount of carbon for balancing deciding the amount of cold pig iron
and petroleum coke for balancing carbon.
7. A process as claimed in anyone of claims 1 to 6, wherein amount of cold pig iron is
restricted to 35% of the charge weight to avoid sticking along the furnace walls with steel
scrap due to its low melting point.
8. A process as claimed in anyone of claims 1 to 7, wherein for average 5.5 tons of lancing
slag addition in charge mix, the average metallic recovery is to the tune of 2.35 tons.
9. A process as claimed in anyone of claims 1 to 8, wherein effective de-phosphorization is
achieved with low opening phosphorus level of 0.02% or less in furnace.

ABSTRACT

The present invention relates to a process for producing steel in electric arc furnace using
lancing slag which is a solid waste as cost effective substitute to steel scrap. More
particularly, the present invention is directed to a process for steel production in electric arc
furnace using lancing slag generated during oxy-cutting of scrap, as partial substitution of
steel scrap in charge mix. The present invention thus favour usage of lancing slag which
contains about 70-83% FeO as partial substitute to scrap for cost effective production of
steel through EAF, whereby for average 5.5 tons addition of lancing slag, the average
metallic recovery is achieved to the tune of 2.35 tons, with effective de-phosphorisation,
without increase in lime addition and without any increase in power consumption.