Group Companies :

TMT Rebars
Sponge Iron
Ingots / Billets
 
Introduction
Properties of the product
Quality and certification
Technology
Process
Raw Materials and procurement of the same
Any specific features if any
 
 
Introduction :

Sponge iron is a metallic product produced through direct reduction of iron ore in the solid state. It is a substitute for scrap and is mainly used in making steel through the secondary route. The process of sponge iron making aims to remove the oxygen from iron ore. The quality of sponge iron is primarily ascertained by the percentage of metallization (removal of oxygen), which is the ratio of metallic iron to the total iron present in the product.  

Sponge iron manufacture is highly sensitive to raw material characteristics. Therefore, it is essential to examine the chemical and physical characteristics of raw materials, both individually and in combination. The basic raw materials for the production of sponge iron are iron ore, non-coking coal and dolomite. Sizing of the Raw materials also play vital role in sponge iron manufacturing process. The required size of Iron ore, MPS (Mean particle size) , its physical properties like T.I., A.I. & chemical properties  like Fe (T), LOI, gangue  content In Sponge Iron Process , two types of coal are being used such as feed coal and injection coal.

 
 
Properties of the product :

Properties of Sponge Iron

 

High iron content and high degree of metallization
Uniform and consistent quality
Lower sulphur and phosphorus content
Negligible tramp element
Minimum dust generation during material handling
Good flow ability in bins, pipes and conveyors for continuous and trouble free charging
Superior technical support to induction furnace operators
 
 
Quality and certification :

Quality

 

WPSL Employees at all levels shall continually strive to provide consistent and reliable, Quality products & services to their external and internal customers and try to exceed in their expectations. This goal shall be sustained, through committed teamwork and continual improvements in the Quest for excellence.

 

WPSL takes pride in its product quality and the timeliness of its delivery schedules.

 

This modern plant is equipped with a digital control system. The advanced microprocessor based control allows for a complete automized functioning, ensuring a high quality of output. 

 

Strict metallurgical control is maintained at every stage of production, from receipt of raw materials to dispatch of finished products. The Company has a dedicated Quality Assurance Department with a well equipped laboratory and trained technicians to monitor the process and materials at different points.

 

Pursuing EMS 14001 and OHSAS 18001 certification, expected to get certified by July 2011

 

 

Products Specification

 

WPSL has 4 x 100 tonnes per day (TPD) rotary kilns. The combined capacity will be 1,30,000 TPA. A part of the sponge iron is consumed ourself to produce steel, the rest is sold to other Steel Manufactures.

 

Chemical Properties :
Elements
Sponge Iron Lumps
Sponge Iron Fines
Fe (M)
80 ± 2%
80 ± 2%
Fe (T)
90 ± 2%
90 ± 2%
Mtz %
88± 2%
88± 2%
P
0.06%
0.06%
S
0.03%
0.04%
C
0.10-0.25% 
0.25-0.35% 

Non-magnetic

(Char & Other Process Contaminants)

0.8% (max.)
1% (max.)
Sio2 + Al2O3
6% (max.)
6% (max.)
Cao + Mgo
1% (max.)
1% (max.)
Size (mm)
3 to 20
0 - 4 mm

 

 

Physical Properties :
Elements
Sponge Iron Lumps
Sponge Iron Fines
Bulk Density (gm/cc)
1.80
1.75
Cold Crushing Strength
-
-

 

(WPSL) reserves tech right to change specifications with out notice consequent to improvements effected in the process)
Chemical analysis indicated above refers to only magnetic fraction of material and not in combination with Char and other contaminants.
Estimation of metallic iron is by “By Mercuric Chloride" or “Ferric chloride” method.
Degree of metallization indicated the degree of reduction to iron oxide to iron metallic.
 
 
Technology :
S - Steel company of Canada
L - Lurgi of Germany
R - Republic Steel Corporation
N - National lead of USA
SL/RN technology is a coal based rotary kiln direct reduction process
 
 
Process :

Summary

 

A long slightly inclined (2.5%) to the horizontal slowly rotating kiln is employed to carry out the reduction. The charges are fed from that end which is at a higher level it travel under gravity aided by the rotating motion through several heating zones & the reduced charge comes out from the other end of the kiln. This is a solid  phase and gaseous reaction and no liquid phase occurs inside the kiln. 

 

 

Details

 

For the direct reduction of iron ore the main furnace used is rotary kiln. The rotary kiln is the refractory lined cylindrical vessel on which blowers are mounted & the air pipes, to provide combustion air to the inside of the kiln. During lite  up there is a start up burner at the kiln discharge end which is oil fired to heat up the rotary kiln. To ignite the injected coal from outlet of the kiln. When the desired temp. is reached, Iron ore, coal & lime stone or dolomite are fed from kiln feed end and also coal is injected from from kiln discharge end. 


The start up burner which uses oil for initial heat up is withdrawn after getting the ignition temperature of the injected coal. Now the coal if the desired temp. for reduction process is obtained , iron ore with dolomite is fed from inlet of the kiln. Since the kiln has a downward slope of 2.5% from the feed end side to discharge end side, its rotation causes the iron ore & coal to mix and travel through the system. The rotational speed of the kiln is adjustable as per the feed rate & percentage of metallization. The % age of inclination, rotational speed the length of the kiln and time the material is exposed to the reducing agent CO, the temperature all to be taken into consideration the kiln has three functions.

 

It is a heat exchanger
It is a vessel for chemical reaction
It is conveyor of solids
Degree of metallization indicated the degree of reduction to iron oxide to iron metallic.

 

Fr the Better the heat transfer & better the metallization

 

 

The following reaction take place inside the kiln.

 

C+O2=CO2;
CO2+C=2CO;


The above reaction is known as bound ward reaction which is reversible.


Fe2O3+CO=Fe3O4+CO2;
Fe3O4+CO=FeO+CO2;
FeO+CO=Fe (Metallic) +CO2;

 

However the reduction from oxide to metal does not occurs in one step but by a gradual removal of oxygen giving rise to various intermediate oxides the reduction chain may be expressed as follows:

 

2 Fe2O3 ------------------------- 2 Fe3O4 ------------------- 6 FeO -------------6 Fe

 

Hematite Magnetite Wustite Iron

 

The degree of reduction between each stage is as follows:

 

11%     22%     67%

 

3Fe2O3--------------------- 2Fe3O4-------------------------- 6FeO--------------6 Fe

 

The byproduct of above reaction is carbon die oxide (CO2).

 

This Co2 reacts with carbon from coal to produce CO.

 

CO2 + C = 2 CO.

 

The above reaction is known as bound ward reaction which is reversible.

 
 
Raw Materials and procurement of the same :

Raw Materials for Sponge Iron Making :

 

Coal

Important factors determining coal quality are :

 

Chemical properties such as fixed carbon, ash content, volatile matter, etc.: &
Physical properties viz., reactivity and ash fusion temperature.

 

Welspun sources its entire coal requirement from the imported coal by the China & South Africa.

 

 

Iron Ore

In sponge iron making, iron ore is reduced in solid state. Unlike in the conventional steel melting processes, the gangue content of iron ore cannot be separated as a slag. Therefore, it becomes imperative to select an ore with a high Fe content and a low gangue content, to optimize yield during steel making. Apart from this, to ensure a better kiln campaign life and output, the iron ore is subjected to undergo a series of other tests viz. shatter, tumbler & abrasion indices, reducibility etc. at present Iron Ore Pellet is used in the DRI section.

 

By virtue of its location, Hospet & Orissa regions which has one of the finest quality iron ore in the region.

 

 

Dolomite

Dolomite acts in the process as a desulphuriser, removing sulphur from the feed mix during the reduction process. It is mixed in small proportion along with other raw materials before charging into the kiln. It is procured from Rajasthan regions.

 
 
Any specific features if any :

Environment :

 

The sponge iron kilns give off hot gases rich in carbon di-oxide. WSL has installed 4 Nos of 10 TPH Waste Heat Recovery Boilers (WHRB) and 1 Nos of AFBC Boiler of 20 TPH and these flue gases are used to generate steam to produce 12 Mw power.

 

WPSL has in place 8 nos of varies capacity pollution control system ( Bag Filter). It has also been planting trees in and around the premises to keep it green.. Apart of Above activity Company has introduced the Water Sprinkler system to control the pollution of Open Field & Road Aera. The company's commitment to environment is visible on the plant site.

 

 

Advantages of Sponge Iron :

 

Chemical composition is uniform.
It contains no undesirable impurities.
It permits dilution with low cost scrap.
Easy to handle & transport.
Permits automatic continuous charging.
Less noise during melt down.
More predictable price structure.
No trump elements.
No requirement of metallurgical coal.
 
 
 
 

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