Raw Materials Handling 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.
Bhushan Steel Ltd. (BSL) is a globally renowned company and one of the prominent players in the steel Industry. It is one of India’s largest manufacturers of auto-grade steel and has transformed itself as the third largest producer of cold rolled steel in the country.
Bhushan Steel’s Phase III expansion of its integrated steel plant at Meramandali, Orissa from 3 to 6 million tonnes per year comprised of facilities such as blast furnace, Direct Reduced Iron (DRI) kilns, sinter plant, basic oxygen furnace, coke oven, steel melting shop, matching lime and dolomite plant including auxiliary facilities such as coal/ore crushing, captive power plant, coal washery etc. Here it is noteworthy to mention that Larsen and Toubro (L&T) was entrusted with the responsibility for the complete Raw Material Handling System (RMHS) for Bhushan Steel’s Phase III Expansion which is the largest executed by L&T till date.
The Flow of Raw Materials
The production of steel requires various raw materials such as coal, coke, iron ore, flux, mill scale, sinter etc. and they undergo processes like unloading, stacking, reclaiming, blending, crushing, grinding and screening and are finally conveyed to the sinter plant, coke oven battery and blast furnace. The RMHS in a steel plant is designed to cater to these materials and is critical to achieve the desired production capacity. The course of the material in this system is shown in Fig. 2.
- Coal, limestone, dolomite and iron ore are unloaded by wagon tipplers, track hoppers and truck unloading systems (BSL scope) and stacked in the stock yard by yard machines and reclaimed.
- Coking coal is fed to the coke oven battery after blending, crushing and mixing. The quenched coke after segregation as per separation size is fed to blast furnace stock house or base blending system.
- Iron ore fines, limestone, dolomite from the stock yard, mill scale from trucks, nut coke/coke fines from coke oven, sinter fines from stock house are fed to base blending system for production of base mix. The sinter produced from base mix is fed to blast furnace and emergency storage is available to ensure continuous feed to blast furnace.
- Iron ore fines from blast furnace stock house is fed to stock yard for feeding to DRI plant and nut coke from blast furnace stock house is fed into base blending system.
- Non-coking coal is fed to coal washery and the washed coal (5 to 22 mm) is sent to DRI plant for further processing. Iron ore lump from stock yard through Raw Material Processing Plant (RMPP) and dolomite from trucks/ground hoppers is also fed to DRI plant for processing. The output DRI is then fed to the steel melting shop.
- Blast furnace once ignited need to operate continuously, hence to ensure continuous feed of material, all the raw materials such as blast furnace coke, sinter, iron ore, additives, pellets are stored in the stock house and proportionately fed to the blast furnace via charging conveyors.
- The slag generated from the blast furnace is conveyed to the wagon loading area for transportation outside the plant.
- Non-coking coal (-6 mm) from the stock yard through coal crushing and screening system is fed to a captive power plant
Based on the flow of material, the complete RMHS at Bhushan Steel is packaged into various systems such as base blending system for sinter plant, coal and coke handling system for coke oven, blast furnace stock house and charging conveyors, yard machines, wagon unloading equipment and associated conveying system and slag handling system. In addition to these systems, RMHS work for Bhushan’s captive power plant and coal washery was also carried out by L&T. The major scope (see Fig. 3) and working of each system is covered in the following sections.