• High Fe Content and high degree of metallization.
• Uniform and Consistent quality.
• Lower Sulphur & Phosphorus content.
• Negligible tramp elements.
• Minimum dust generation during handling.
• Good flow ability in bins and conveyors for continuous and trouble free charging.
• Superior Technical Support to Furnace operators.

Production Flow Chart

Production ProcessShakambhari Ispat Purilia unit is a automated integrated steel plant comprising of:

• DRI Unit.
• Steel Melting Shop equipped with Electric Arc Furnace.
• Continuous Billet Casting Unit; and
• Rolling Mill with Thermex system.

1) DRI Unit :

In the Direct Reduced Iron (DRI) plant, production of sponge iron using a solid reductant involves reducing iron ore (lumps/pellets) with a carbonaceous material such as coal. The reduction is carried out in a rotary kiln (which is inclined and rotates at a pre-determined range of speeds) at a stipulated temperature (850°C -1,500°C). The inclination and the rotary motion of the kiln ensures that the raw materials moves from the feed end to the discharge end of the kiln and during this movement the actual reduction of iron ore to iron takes place. The material discharged from the kiln is taken to a rotary cooler for cooling and the cooled product is separated from the coal char. The basic reactions involved are as follows: 3Fe2MO3 + CO = 2Fe3O4 + CO2 (1) Fe3O4 + CO = 3FeO + CO2 (2) FeO + CO = Fe + CO2 (3)

2) Electric Arc Furnace :

Steps involved in an Arc Furnace can be summarized as follows:

a) Charging :

The charge is prepared according to the proposed chemistry for the targeted grade. Sponge Iron and other ingredients along with lime in a close requisite ratio is charged in the Arc Furnace.

b) Melting :

Melting is accomplished by injecting energy to the charge materials in the form of electrical energy through three graphite electrodes. Carbon injected inside the furnace reacts with oxygen producing CO, which bubbles through the bath creating foamy slag. The excess CO reacts with oxygen, converting to CO2 again generating heat. Oxygen will react with several components present in the bath including silicon; manganese; phosphorus and sulphur. The oxides thus formed will end up in the slag. In arc furnace charged materials gets melted at about 1800°C. Once sufficient charge has been melted and enough space has been created, second charge can be taken and the process is repeated. Once the final charge has been melted and is reached at melt stage, temperature measurement is taken and sample is drawn for determining the amount of oxygen to be blown during refining.

c) Refining :

Refining means reduction of undesirable elements in steel like sulphur, phosphorous etc and also bringing down the carbon to required levels. Phosphorus and sulphur which cannot be removed in Induction Furnace, can be easily removed in EAF. Phosphorous is removed in the early stage of refining. Sulphur is removed as sulphides in slag and is better achieved during reducing stage. Aluminium, silicon and manganese react with oxygen before carbon to form oxides which goes into the slag. CO, which is produced due to the reaction of carbon with oxygen, bubbles through the bath causing the slag to foam and has many beneficial effects. The foaming also helps in bringing down nitrogen and hydrogen levels in steel. At the end of refining stage temperature measurement is done and sample is drawn for analysis.

d) De-slagging :

De-slagging is the process by which the slag layer above the steel is removed from the furnace. This process is important for removing impurities from the molten material. The furnace is tilted towards the slag door for slag removal. Phosphorus is transferred to the slag, during the early stage of the heating while the temperature is relatively low. The first deslagging (at the beginning of refining) removes a substantial portion of the phosphorous as P2O5, thus preventing phosphorous reversal to the metal. Typically during the refining stage, the furnace may be de-slagged several times.

e) Tapping :

After reaching the required temperature and composition, the tap hole is opened and metal is tapped into the ladle and sent to continuous casting unit for casting of billets. During the tapping process bulk alloys are added based on the bath analysis for the desired steel grade. De-oxidizers may be added to the steel to control the oxygen content, prior to further processing. This is commonly referred to as killing of steel. This is done by adding aluminum or silicon in the form of ferrosilicon or silicon manganese. A typical construction of Arc Furnace has shown below:

3) Continuous Billet Casting :

Molten steel from EAF is tapped into a ladle and taken to the continuous casting machine. Liquid steel flows out of the ladle into the tundish and then into a watercooled mold. Solidification begins in the mold. The continuous billets coming out from the CCM is sized according to the length required.

4) Rolling Mill with Thermex Technology :

The billets manufactured are re-heated at a temp. of 1200°C in the re-heating furnace and are rolled into specific sections of finished material in the Rolling Mill Unit. In the case of manufacturing TMT Re-bars, from the finishing stand of the rolling Mill, the Re-Bars are guided through a specially designed proprietary Thermex pipes to obtain special property ‘Thermex Process’ as explained below:

Quenching :

The hot rolled bar from the finished mill stand enters into the ‘Thermex System’ and is rapidly quenched by a special water spray system. This rapid quenching hardens the surface of the TMT Re-bars to a depth optimized for each section, forming a Martensitic rim while the core remains hot & Austenitic.

Self Tempering :

After Re-bars leave the quenching box, the core remains hot compared to the surface allowing heat to flow from the core to the surface causing Tempering of the outer Martensite layer thus forming a structure called ‘Tempered Martensite’.

Atmospheric Cooling :

This takes place on the cooling bed, where the Austenitic core is transformed into ductile Ferrite-Perlite structure. Thus the final structure consists of stronger outer layer (Tempered Martensite) with ductile core (Ferrite-Pearlite). This process increases the tensile strength of the material while keeping high ductility and weldability. This whole process is a patented technology from HSE, Germany under the brand name of ‘Thermex’.