Know your Project:

NMDC-Raw Material Handling System(RMHS)

Preface:

NMDC Ltd.is setting up its first green field 3MillionTons/year capacity integrated steel plant at Nagarnar,Chhattisgarh.

The main constituents of this plant include:

  • RMHS of the entire steel plant
  • Lime Dolomite Calcination Plant (LDCP) of 0.07MTPA capacity calcinated dolo & 0.3MTPA capacity calcinated lime
  • Coke Oven Battery of 0.2MTPA capacity coke breeze & 1.5MTPA capacity BF coke
  • Sinter Plant of 4.6MTPA capacity sinter
  • Blast Furnace(BF)of 3.3MTPA capacity hot metal
  • Basic Oxygen Furnace(BOF)with associated slab caster & hot strip mill of 3MTPA capacity liquid steel

Raw Material Handling System (RMHS):

BHEL-ISG bagged the Raw Material Handling System(RMHS) package for this plantat an order value of Rs.1395 crores. This package has the distinction of being the single largest RMHS order catering to the entire raw material requirement of an integrated steel plant. The contract for this package was signed between BHEL-ISG and NMDC in September 2011

This RMHS will transport about 12 MillionTons of different types of material per year which is four times the plant production capacity of 3 Million Tons/year.In brief, the RMHS facility will cater to unloading, stacking, reclaiming and distribution of various raw materials arriving in railway wagon/roads to different shops like Blast Furnace(BF),LDCP(Lime Dolomite CalcinationPlant),Coke oven. The sizing & distribution of various intermediate products such as coke, sinter, lime, calcinated dolomite etc., base mix preparation for the Sinter Plant & disposal of granulated slag is done by RMHS facility.

Asan EPC contractor,ISG’sscope includes design,supply, erection,testing & commissioning of complete plant & equipment,fabrication of building structure & technological structure,civil construction,power distribution,electrics, instrumentation & automation, illumination, telecommunication, all utilities & services,in-plant road,drainage,landscaping,fire detection & alarm system, control rooms,area repair shop, store,rest room, fire fighting pump house etc., The responsibility from design & engineering to commissioning & handing over of the plant is with ISG.The performance guarantee tests include meeting specific parameters for wagon tippler,stacker reclaimer,crushers,screens,iron content of output base mix etc.

Major Highlights & salient features:

Civil & Structural
-Estimated 1.2 lakh cum RCC work
-Estimated 8 lakh cum excavation
-16 nos.1550cum RCC Silos
-86 nos. of Bunkers
-12 nos.of Major Buildings
-Yards for Ore, coal & base mix preparation
-137 Nos.of conveyors covering total length of 30 KMs
-70 Junction Towers (JT)
-50,000MT fabrication / Electrics & Automation System
-HT & LT Distribution system
-Conventional & intelligent MCC
-Battery & charger
-PA system
-Instrumentation
-DG set
-Cabling
-Distributed PLC&SCADA system at 6 locationswith estimated Input/Output count of 6200
Major machines
- 7 nos. of stacker-reclaimers (SR)
-1 no. slew stacker with 1500TPH capacity for sinter pile
-2 nos.of barrel reclaimers with 1200TPH capacity for sinter pile
-4 nos. of wagon tipplers with rated capacity of 25 tips/hr
-Truck tipplers with underground hopper & storage facility / Other Major Items
-DS & DE system
-Fire fighting system
-AC & ventilation system
-Illumination
-Water system
-Crushers, Screens & vibro-feeders

The special features are:

  • Conveyor circuits: Complex system of conveyors,many of them conveying different materials
  • Wagon tippler: The wagon tippler meets the latest RDSO requirement of 25tips/hour. The downstream conveyors in the plant upto the stockyard have a capacity of 2700TPH to utilize the full capacity of the wagon tippler
  • Base blending: The project envisages base blending system to provide proper sinter mix .The system consists of bunker storage,belt weighers, screen slew stacker & retrieving using the barrel reclaimer.
  • Automation System: The distributed PLC & SCADA system has features for
  • Communication with intelligent MCC through communication bus
  • Communication with field instruments through fieldbus
  • Communication with SR PLC through wireless
  • Communication with belt-weighers through fieldbus
  • Base blending system control
  • Inventory, storage bed management & material tracking

System description:

The material flow is as in figure-1.The material conveyed using RMHS are coal, lump iron ore, iron ore fines, limestone, dolomite, quartzite, DRI material, slag,coke and sinter.

The simplified process is as in figure-2.The entire process can briefly be described in the following circuits:

The unloading systemfor unloading the coal and ore from wagontipplers(WT) and storing in the coal & ore yards. The DRI material is received through truck tippler and conveyed to storage bunkers.

Stacking & reclaiming systemstores the coal & ore in respective yards using stacker-cum-reclaimers(SR).

In the Lime Dolomite Calcination Plant(LDCP) feeding systemthe limestone & dolomite will be reclaimed from the ore yard and conveyed to LDCP after screening.The LDCP outputis conveyed to base blending station,BOF plant & transported in trucks.

The BOF system will be fed lump ore from the ore yard,DRI from truck tippler,calcinated lime and dolomite from LDCP and coke from ground hopper through a system of vibro-feeders & screens.

InFinished sinter transportation systemthe sinter output from Sinter plant is fed either to Blast furnace or yard conveyor. The sinter is also stored in emergency sinter storage bunkers.

In Supply of CDI (coal dust injection) Coal to CDI Bunker Building,the CDI coal from coal yard is fed to Blast furnace for coal dust injection through a 750TPH conveyor system.

In Coking coal processing & feeding to Coke oven,the coking coal will be fed to coke oven from the coal yard. The coal blending silos will store different varieties of coal and will be drawn out by belt-weighers below each silo. The blended coal will be brought to coal crushing building surge hoppers. The coal from these hoppers will be extracted by vibro-feders & fed to hammer mills for crushing & blending coal to -3mm.This is conveyed to the top of the coal tower.

Coke cutting,screening & feeding system to BF(Blast Furnace) & Sinter plant: The coke from coke oven complex isfed to screens. The oversized pieces will be fed to double roll toothed coke cutter. The coke is further screened. The surface coke & center coke are stocked in yards. The coke is also conveyed to wagons.

Stock House feeding system is for feeding the Blast furnace with lump ore quartize etc.,from the yard.

Sinter plant feeding system includes flux crushing,coke crushing,proportioning & base blending. The sinter mix yard(base mix yard) will receive the sinter mix from base blending bunker. The bunkers will store iron ore fine,mill scale, sinter fines,limestone,dolomite,coke fines etc. Belt feeders with VFD are located below each bunker & the material will be stacked by the slew stacker.The reclamation from these beds will be through the barrel reclaimer.

Granulated slag disposal systemcollects the slag formed at the Blast furnace andis conveyed to the slag yard through a 400TPH conveyor system.

Present Status of Project:

Presently the site activity is in full swing at the project site and civil works is simultaneously being carried out for wagon tippler 1&2,silos,all the SR & some JTs. The structural fabrication is in progress. Supplies for SR, WT,technological structure and fabricated structure are in full swing. The basic engineering has been completed for all wagon tipplers and stacker reclaimers.

ISG No:IS-1-11-2008Sheet 1