Material Handling of Highest Complexity

Raw Materials Handling

Material Handling of Highest Complexity

Large-scale Raw Materials Handling at Bushan Steel's Integrated Steel Plant
For the expansion of Bhushan Steel’s steel plant at Meramandali, India, Larsen and Toubro carried out the design, engineering, supply, erection, testing and commissioning of the raw material handling system that included 43 kilometres of belt conveyors, a wagon and truck unloading system, eight stacker/reclaimers and three bucket wheel reclaimers.
(ed. WoMaMarcel - 09/10/2015)
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The Coal Handling System

The coal handling system is designed for a nominal capacity of 750 t/h and caters to the total coal requirement of two coke oven batteries and the plant will operate 365 days per year (two shifts per day). Its major sub systems are coal reclaiming from yard, coal blending, coal crushing and mixing and coal tower feeding.

Coking coal stored in the yard is reclaimed by a stacker/reclaimer machine and fed to one of 12 storage bins in the coal blending building. The bins are designed for a total storage capacity of 8800 t (735 t each) corresponding to 20 hours storage availability and Nitrogen inertising system is provided in each of the bins to avoid any risks. To achieve the desired blend, coal stored in the bins is reclaimed at the required proportion with the help of belt weigh feeders installed below each of the bins.

The blended coal is fed to the rotating conveyor in the coal crushing building which can feed to any of the four surge hoppers (one in future). Vibro feeders installed below the surge hoppers feed the coal to four reversible hammer mill crushers (2W+2S). The feed (0 to 50 mm) is ground to predominantly (-3 mm).

After crushing, the coal is transported to the mixing station using high angle conveyors. A distribution system consisting of reversible belt feeders and diverter gates feeds the material to three 750 t/h mixers (BSL scope). Subsequently after crushing and mixing the blended coal is fed to the coal tower through a series of conveyors. A coal sampler station is also installed in one of the conveyors to collect samples to check the quality of blending.

The Coke Handling System

The 500 t/h coke handling system is designed to operate continuously on three shifts per day, 365 days a year. The quenched coke is dumped on the wharf and fed to the wharf conveyor by means of 400 t/h plough feeders (BSL Scope). A cooling water system is installed in both the wharf conveyors to avoid damage of belt conveyors due to hot pieces (if any).

The material is then fed to the two vibrating grizzly screens (separation -80 mm) inside the coke treatment building. The oversize material is fed onto two smooth double roll crushers (BSL scope) to reduce the grain size. Subsequently the screened out and crushed material (-80 mm) is screened by three double deck screens (BSL scope) to segregate coke fines (0 to 15 mm), nut coke (15 to 25 mm) and coke for blast furnace (15 to 80 mm).

The blast furnace coke is conveyed to either of the Blast Furnace 1,2 (and, in the future, 3) as per requirement and the excess coke is stacked in a covered storage yard and reclaimed by a scraper type reclaimer. The coke fines and nut coke are stored in eight bins (each of 1000 m3 capacity) inside the coke fines and nut coke building. Each of these bins is provided with the option of discharging coke to trucks or feed to the sinter plant. The coke fines and the nut coke can be conveyed directly to the base blending building through the sinter plant feeding conveyors.

Blast Furnace Materials

A blast furnace requires continuous feed of raw materials; hence the input material is stored in the stock house and then fed to the blast furnace to ensure uninterrupted feed. The raw materials coke, sinter, ore, pellets and additives are received at the top of the stock house and subsequently stored in corresponding bins. Coke is fed to six bins through a rotating conveyor. The undersize material is screened out and fed onto the trucks while the desired material is fed to the blast furnace charging conveyors. Sinter stored in two bins, ore stored in one bin, and additives stored in four bins are also fed to the blast furnace charging conveyors. All these materials are fed to the blast furnace charging conveyors through weigh feeders and gates operated in a sequential manner (BSL scope).

The slag generated from the blast furnace BF1, BF2 and, in future, BF3 are conveyed to the wagon loading area for transportation outside the plant boundary. The stock piling in the storage yard is carried out by two trippers.

Power Plant and Coal Washery

Bhushan Steel’s expansion plans included enhancement of its power production capacity and L&T was given the Coal Handling Plant (CHP) works of this captive power plant and the details of the same are covered in the forthcoming section. The incoming coal (0 to 300 mm) encompasses screens, double roll crushers, hammer mill crushers to facilitate the feed to captive power plant and coal washery as per system requirement. Coal is initially screened for -75 mm separation and the oversize material is crushed to -75 mm by double roll crushers in the primary screen and crusher house. The undersize material is conveyed to the six bins inside the secondary screen house using two reversible shuttle conveyors.

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