RECOMMENDED GUIDELINE FOR IRON & STEEL SECTOR MINISTRY OF STEEL, Doc. No: RG / 04 GOVT. OF INDIA BLAST Rev no.: 00 FURNACE Effective Date: --
1. OBJECTIVE Blast furnace produces Hot metal (Liquid Iron) using Iron ore, Coke, Sinter, Pellets and fluxes such as Lime-stone, Pyroxenite, Quartzite reacting with oxygen from pre heated air. This entire process of production of hot metal is associated with various safety hazards like hit / entanglement with mobile equipment, burns, fire, slip & fall, exposure to dust, smoke, noise, heat & gas etc.
2. SCOPE This code of safety is applicable to Blast furnace Dept. of an Integrated Steel Plant.
3. PROCESS
In the Blast Furnaces (BF) liquid iron (popularly termed as ‘Hot Metal’) is produced by the process of reduction at high temperature from raw materials like iron ore, base mix, sinter, coke, fluxes (limestone / quartzite), etc. &also air blast / O2. In blast furnace the process is also known as “Counter current process” as solid raw material is being charged from the top and hot air is being blown from bottom. During the process the impurities are removed in the form of slag and hot metal is produced. Coal is being injected to reduce consumption of main fuel coke which is a cost reduction measure.
Liquid metal and slag are being separated in the area known as cast house. The liquid Hot Metal is transported in Hot Metal Ladles / Torpedoes to the Steel Melting Shops (SMS) for the production of steel by the process of oxidation of the Hot Metal in specially designed Convertors.
Sometimes the Hot Metal is poured in the Pig Casting Machine (PCM) to produce Pig Iron.
Slag produced is granulated by high pressure water jets in the Cast House itself or sent to Slag Dumping in the Slag Pots.
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Blast Furnace Process Flow:
Coke Plant Sinter Plant RMH Pellet Plant (Coke) (Sinter) (Iron Ore & Fluxes) (Pellet)
Raw material Storage
Charge Skip/Belt Stock House Hot Metal SMS
O2 Torpedo
Hot Granulated Air SGDP
Cold Air Stoves Cinder SLAG Ladle Steam Coal Injection Different Sections of Blast Furnace: i) Furnace Proper:
In the Furnace Hot Metal (along with slag) is processed from the raw materials. ii) Cast House:
In the Cast House, Hot Metal & slag are tapped from the Furnace tap hole and after flowing through a system of refractory lined troughs / runners flow into Hot Metal Ladles / Torpedoes & Slag Pots, placed on the iron & slag side respectively of the Furnace. iii) Stoves:
Stoves heat the air blast provided by Turbo Blowers to the Blast Furnaces through the Tuyeres. iv) Raw material storage and Raw Material Charging Section:
In this there are designated bunkers for raw materials transported from mines / Sintering Plant (SP) / Raw Materials Handling Plant (RMHP) / Coke Ovens (CO) by wagons / conveyors. v) Gas Cleaning Plant (GCP):
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The blast furnace gas (BFG) generated in the BF is cleaned through a series of steps before transporting it to the BFG Holder.
vi) Slag Granulation Plant (SGP) / Slag Dumping Yard:
During the process of iron making, the impurities are fluxed and removed as slag. The hot liquid slag is made into slag granules by means of high pressure water jets in the Slag Granulation Plant in the Cast House itself (sometimes separate SGP is located at a distance from the furnace proper).
If the slag is not granulated in SGP, it is poured in the Slag Dumping Yard.
vii) Pig Casting Machine (PCM):
Sometimes when there is poor off take of Hot Metal by SMS or if the Hot Metal chemistry is very adverse, Hot Metal is taken to this section for casting into Pig Iron.
viii) Pulvarised coal Injection:
In this section coal is pulvarised to fine dust in mills and injected in the furnace.
Some of critical Equipments/ facilities in Blast Furnace Department are as follows:
Sl. No. Area Major equipments / facilities 1. Blast Furnace & Blast Furnace proper, stoves, skip auxiliary sections car, yard equipments, conveyors, bunkers, Coal Dust Injection / Coal Tar Injection units, drill machine, mud gun, pusher cars, ladle/ torpedo, TRT, Gas Cleaning Plant, Tilting/ Rocking Runner, Pig Casting Machine, Utility lines, EOT cranes etc.
4. PROCESS HAZARD ANALYSIS &NECESSARY RISK CONTROL MEASURES
Sl. Section Hazard Risk Control Measures No. 1) 1. Furnace Gas leakage Installation of On-line Gas monitor Proper at strategic locations & use of Portable “CO” monitors to detect gas leakage. Prohibition of people going above cast house level around the furnace, as there are chances of gas leakage. If at all, one needs to go, he should be accompanied by Page 3 of 8
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gas safety man with proper safety precautions under intimation to control room.
(Refer:SC-18: Safety code for Personal Protective Equipment (PPE) management, SC-16: Safety code for Fire Safety, SC-21: Safety code for Handling Fuel Gas)
Shell crack Regular inspection & repair as per Corroded structure requirement
Fine Dust Installation of ESP & regular cleaning deposition Sound from Plug the leakage points, use Ear Plugs Leakages etc. Slip, Trip and fall Ensure proper housekeeping. hazards. Prevent materials or objects falling. Material falling Uses of appropriate PPE, such as from height. helmets, gloves, aprons and boots.
(Refer: SC-18:Safety code for Personal Protective Equipment (PPE) management).
Fire and explosion Fire fighting. Engineering controls. Administrative (procedural) controls.
(Refer: SC-16: Safety Code for Fire Safety)
2) 2. Cast House Hot metal/slag over Maintaining Runner depth flow from runner Development & adherence to SOP (Safe Operating Procedure).
Hot metal splinter Timely closing of Tap holes after during casting blow , Regular inspection & checking of Mud gun machines Development & adherence to SOP Use of PPEs like fire retardant suits, helmet with face shield, ankle guards hand gloves and safety shoes. Prohibition of people working on cast house cranes and its walkways during tapping Trial of rocking runner should be taken during tapping before the
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entire ladle is full. This will prevent overflow of hot metal from the ladle. (Refer: SC-18: Safety code for Personal Protective Equipment (PPE) management).
High radiant heat, Molten metal resistant jackets and molten metal, trousers, face shields or vented dross or slag, goggles, Safety gloves, protective fumes, dust. helmets; safety footwear insulated against heat, Safety goggles.
Dust and fume collectors ESP system.
(Refer: SC-18: Safety code for Personal Protective Equipment (PPE) management).
Use of wet sand in Use of dry sand runner
Water ingress in Regular inspection runner
Gas leakage from Provision of On line Gas monitor & surrounding area Portable “CO” (carbon Mono oxide) monitors Emergency Plan & mock drill.
( Refer SC-21: Safety code for Handling Fuel Gas)
Fire in Elect Portable fire extinguishers panel/cable nearby Development & adherence to SOP (Safe Operating Procedure).
( Refer SC-16: Safety Code for Fire Safety) Movement of Use of PPE’s. Cranes Keep away from moving Cranes Effective audible and visual communication devices should be installed on a crane or hoist.
(Refer SC-14: Safety code for work on Electric Overhead Travelling (EOT) Crane) 3) 3. Hot Metal / Accumulation of Regular inspection of tracks, Ladles& Slag water near rail drainage facility. Handling track /Ladles ( Refer SC-23 :Safety Code for Safe including handling of Liquid Metal) Ladle Wrong placement Proper coordination between BF &
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preparation of ladles TRM by defining & following SOP & Ladle Over flow of Inspection to ensure proper filling repair metal/slag of ladles, Development & adherence to SOP High radiant heat, Emergency measures. fumes, hot metal Fire fighting and fire prevention. splashes, high First aid facility. temperatures. PPE Management.
(Refer: SC-18:Safety code for Personal Protective Equipment (PPE) management).
4) 4. Stoves Gas leakage Provision of On line Gas monitor & Portable “CO” monitors to detect gas leakage. SOP & SMPs to be followed strictly to avoid gas leakage. Prohibition of people working on stove platform area when stove status is changed from isolation mode to heating mode.
(Refer SC-21: Safety code for Handling Fuel Gas)
Sound from Plug the leakage points, use Ear Plugs Leakages etc. 5. High lines Spillage Regular cleaning to be ensured & /Stock accumulation Engineering controls to be applied to House arrest the spillage points. Conveyor belt SOP (Safe Operating Procedures) for hazards conveyor safety to be followed strictly.
Cleaning running (Refer: SC-19:Safety code On conveyors Operation and Maintenance of conveyor belts). Fall into raw Railings are provided around the bins material bins Materials falling, Open-mesh walkways to prevent Releases of dust objects from falling through and causing injury to people below. Respiratory protection dusk mask. Dust and fume collectors ESP system. 6. Gas Gas leakage Provision of On line Gas monitor & Cleaning Portable “CO” (Carbon Mono Oxide) Plant (GCP) monitors to detect gas leakage.
(Refer SC-21: Safety code for Handling Fuel Gas)
Hot flue dust Development & Adherence to SOP dumping Usage of proper PPEs (Personal
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Protective Equipments) while working Water seal Regular inspection to be done & breakage due to Process parameters to be pressure monitored continuously to avoid fluctuation and any deviations. damaged water (Refer SC-21: Safety code for Handling seal Fuel Gas)
7. Slag Spillage Regular cleaning of settling tanks Granulation accumulation of cooling towers. Plant (SGP) / Slag Water Water draining system to be Dumping accumulation in maintained. Regular inspection to Yard slag pit be done.
Conveyor belt Development & adherence to SOP hazards conveyor safety.
( Refer SC-19: Safety code on Operation and Maintenance of Conveyor Belts ) Presence of hot Proper segregation of hot metal & slag metal in slag
Overflow of Hot Regular cleaning of Drains. water from drains 8. Pig Casting Overflow of hot Development & adherence to SOP Machine metal from runner (PCM) & machine
Handling hot liquid, Safety footwear and other leg dust, heat. protection guard. Effective audible and visual communication devices. 9. Pulverised Inhalable agents Work-related training programmes Coal (gases, vapours, to cover all workers including Injection dusts and fumes); contractors. (PCI) gases containing CO-gas (Carbon Mono Oxide) concentrations of detector, trained in to recognize the carbon monoxide, symptoms of carbon monoxide moving machinery, poisoning. conveyors Guarding of moving machineries and conveyors.
(Refer SC-09: Safety code in Equipment & machine Guarding, SC-21: Safety code for Handling Fuel Gas)
References:
1. SAIL Plants Safety procedures 2. Tata Steel Safety procedure Page 7 of 8
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3. ILO Code of safety & health for Iron & Steel Industry 4. IPSS:1-11-009-15 “Code of Practice for Safe Handling of Liquid Metal”
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