With the commissioning of 3600 mm Plate Mill under 4 MT expansion programme, Bhilai has entered into the area of flat products in a big way. This giant rolling mill complex which extends to over a kilometer in length has an overall covered area of about 15680 m². It consists of six main bays; 1-3 bays of span 36 meters each, 2 bays of span 30 meters each and one bay of 18 meters span, also, two open gantries for scrap removal. The mill is intended for an annual production of 0.95 million tones of finished plates in 5600 operating hours. The thickness of the plates range from 5-120 mm. It is called 3600 mm Plate Mill because the barrel length of the work roll is 3600 mm. Continuously cast slabs in the length range of 5.6-10.2 M are delivered in hot condition to the slab yard. These slabs are cut to smaller lengths in 3 non flame cutting machines as per requirement. Inspection and conditioning is carried out after cutting of the slabs to the required sizes. Inspected slabs with proper identification are supplied to Plate Mill.The sequence of operations are : Slab heating, rolling, levelling, cooling,inspection and shearing to required size. Heating of slabs is done in three continuous double row pusher type furnaces with an estimated capacity of 120 T/hr each. These furnaces have five heating zones : Soaking Zone, top and bottom preheating zone, top and bottom heating zone. The soaking zone has a flat roof with sixteen small capacity vertical burners through the roof. The other four zones have six burners each. Mixed gas of calorific value 2500 K cal/cum is used as a fuel. In time of gas shortage, provision for oil firing is also there in the four zones, heating and preheating zones. Air for combustion is supplied by individual blowers. This is preheated in multicellular cross paralled flow type of metallic recuperators. The slabs move on skid pipes in the heating and preheating zones and over a solid hearth in the soaking zone. The skid pipes are cooled by evaporative cooling system instead of the conventional water cooling system. The solid hearth in the soaking zone is made of electro cast corundum blocks. Programmed slabs from the slab yard are placed by the means of overhead crane of the lifting and lowering table. The slabs are pushed one by one on the charging side roller table. The slabs are positioned with respect to the furnace skids with the help of movable hydraulic stopper. They are pushed in to the furnace in cold condition for heating up to the required temperature. The first slab on the delivery side is pushed to pre-determined position by the pusher and then it is extracted by shock free slab extractors. Heated slabs are passed through the Hydraulic descaler. Here the scale formed during the process of heating will be washed off by means of water spray at a pressure of about 150170 atm. The sprays impinge on both top and bottom of the slab. Additional hydraulic descalers are also provided in the stands. The rolling complex consists of one reversible vertical edger, one reversible four high roughing and one four high reversible finishing stand. The vertical edger placed before the roughing stand helps in the production of plates with good edges. This ensures minimum side trimming losses and increases net yield. The vertical edger is driven by two 1800 KW motors placed on top of the stand itself.The roughing and finishing stands are made of stationery closed top roof housings. These are designed for a maximum rolling force of 4500 tonnes. The working rolls of the roughing and finishing stands are driven by two 4000 KW and two 6300 KW motors. The maximum speed of rolling in these stands are 3.5 m and 6 m/sec respectively. Back-up rolls are not power driven. They rotate due to friction. The rolls and spindles are balanced hydraulically. Working rolls are mounted on conventional roller type bearings. Backup rolls are mounted on oil film bearings. Since the housings are of closed top type, roll changing is carried out through the sides. The rolls are pushed in and out by electrically driven carriages and roll changing is effected by a traverse attached to the over head crane. Since the weight of back up roll, chocks and traverse is around

300 tons, a 320 ton crane with motorised hook rotation is provided in the mill bay. Heavy plates (63-120mm) are finished in the roughing stand and they are drawnaway from the rolling line to the heavy plate bay with the help of transfer cars. splates (5-60 mm) are rolled to the required thickness in the finishing stand. After rolling the front and back ends are cut using the hot crop shear, which is a cross cut shear with a cutting force of 1250 T is of down cut type. The shear can also be used to cut the plate into two pieces so as to accommodate them in the cooling beds. The crop ends are further cut into small pieces by a crop shear and are removed by the crop conveyor to the crop hopper. After hot shearing the plates are levelled, cooled, inspected and cut to required widths and lengths. Levelling is also done by roller type levellers with small working rolls supported by back-up rolls. Lighter gauges (5-20mm) cools fast and hence they are levelled at leveller-1 placed immediately after hot shear. Heavier gauge plates (21-60mm) do not cool faster and hence these are levelled at leveller-II placed after the hot transfer bed. This process also helps in reducing the internal stresses developed during rolling.For accurate cooling to the desired levelling temperature, spray coolers are kept immediately after finishing stand. This reduces secondary scale formation resulting in improvement of the plate surface.