STEEL MELT SHOP

Billets are manufactured in the Steel Melting Shop with an installed capacity of 0.25 Million Tons per Annum. Our Steel Melt Shop is installed with Four Induction Furnaces of Capacity 9MW, 25Tons to produce the liquid steel and a 3Stand, 4/7 Continuous Caster can able to produce 100Sq, 110Sq and 130Sq Billets.
1. Scrap stocked in open scrap bay will be brought near Induction Furnace with the help of scrap bucket transfer cars and EOT cranes. DRI from the day bins will be conveyed to operating platform of Induction furnace.
2. The furnace crucible is lined with neutral ramming mass suitable for refining of steel for dephosphorization with basic slag, DRI and Mill Scale.
3. Before starting the furnace, the induction furnace crucible will be inspected for next heat. Initial quantity of scrap and Pig Iron will be charged into the induction furnace with the help of scrap transfer car or through electro magnets.
4. Removal of Phosphorus from the steel requires slag basicity and demands large oxidation potential of the slag. To maintain the basicity of slag, required amount of calcium oxide can be supplied in the bath using lime and dolomite. High oxidation potential of slag is achieved by providing high FeO content in the slag and it is maintained by addition of sponge iron and mill scale if required. Phosphorous from the liquid steel is removed into the form of P2O5 as a product of oxidation, is held in the slag which in turn can be removed from the induction furnace.
5. As soon as the charge is melted and the temperature of the melt reaches above 16500C, bath sample will be taken and the temperature will be measured. The steel at this stage is ready for tapping.
6. Liquid samples are collected for analysing the chemical composition before casting. The liquid molten metal from the induction furnace is poured in to a ladle with the help of hydraulic furnace tilting arrangement.
7. The liquid steel after addition of Ferro Alloys (Silico Manganese and Ferro Silicon) in the ladle, will be lifted by the EOT crane and placed on the ladle stand of the Billet caster. In the mean time a Tundish lined with cold insulating board and preheated nozzles and mounted on the Tundish car will be moved from the nozzle preheating position to the casting position. Ladle slide gate will be opened to allow flow of liquid steel into the Tunis .The liquid steel stream form the ladle Tunis will be protected by ceramic shroud to ensure superior quality of cast product.
8. Prior to starting of casting operation, rigid dummy bars will be introduced into the moulds. The gap between the dummy bar head and the mould walls will be sealed with asbestos chord. Small pieces of steel scrap will be placed over the dummy coils head for chilling of initial liquid steel. Water supply to moulds, secondary cooling zone and machine cooling will be switched on. When the liquid steel level, in the Tunis reaches a predetermined level, the nozzles of the Tunis will be opened for flow of metal into the moulds.
9. When the liquid steel level in the moulds reaches about 100-150 mm form its top, the drives of the mould oscillating mechanisms, withdrawal and straightening units are switched on. The withdrawal of the dummy bars begins at the minimum speed and gradually increases to normal casting speed within a few minutes. Adding requisite quantity of rapeseed oil dose the lubrication of the mould walls.
10. The partially solidified strands after leaving the moulds passes through the strand guide system where intensive but controlled cooling of the strands will be achieved by direct water spray nozzles. The solidified strands will be guided through withdrawal and straightening unit before the torch cutting zone .The dummy bars will be separated from the cast strands when dummy bars reach beyond the withdrawal and straightening unit and stored in a dummy bar storage device till their introduction is required for the next cast.
11. The cast strands will be cut into predetermined length by automatic oxy-acetylene gas cutting torches. About 80 %of the cut billets (to be rolled) are envisaged to hot charged to the rolling mill through inter bay roller table and the balance will be transferred to the cooling bed through cross transfer. Form the cooling bed billets will be lifted by billet handling magnet crane and stacked in the storage yard. For every heat, a sample is collected for laboratory analysis.
12. The Quality Assurance Plan (QAP) is ensured by the use of Spectrometer and chemical analysis to maintain the Carbon, Sulphur and Phosphorus within the specified limits.