2B09870-P001 RSP BF5 - Blow in Discussion Rev0

7/23/2019 2B09870-P001 RSP BF5 - Blow in Discussion Rev0

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Ironmaking

Steelmaking

Energy & Environment

Since 1977

RSP BF5 – 2B09870

Blow in discussion

March 2013

rev0, 2-March-2013

FOR DISCUSSION



2. Contents

• DC Concept

• Light-up

• Putting blast on furnace

• Furnace ramp-up

– Drying the furnace burden

– Normalizing process, reducing [Si]

• Connecting the GCP

• Removing blow out pipes

• First Casts

• Separation slag/iron

• Furnace parameters during blow in

• Burden design, slag chemistry• Data required



3. Blow-in Overview

• Blow-in is heating up furnace and

stabilizing the process• Two major interdependent areas:

1. Shaft process stabilization

– Stable BF process / burden distribution

– Casthouse requirements

• Stable casting

2. Casthouse stabilization

– Ready and tested for normal tapping

– Process Requirements

• Good slag fluidity and temperature (low

basicity IB2 0.7 – 0.8, HMT > 1450degC)

• Good HM chemistry and temperature(HM Silicon < 2.5%, > 1450 degC)



4. DC Concept

• Blow out pipes to bring heat from raceway into hearth – Dog house to protect blow out pipes

• Wood charge to hold coke blank above tuyeres. Thus all

coke passes tuyeres and is heated bringing heat to hearth

• Sufficient coke blank to fill hearth and provide heat to heat

hearth coke and burden materials

• First charges with high coke rate and low IB2 to get

process/casthouse started safely

• Fast but safe reduction of coke rate to stabilize [Si]

• Maintain low IB2 until [Si] is low stable and processstabilized



5. Preparation: BF Filling

Burden A:

800 kg/thm

Coke for

energy, maybe

fluxed

Coke for hearth

and deadman,

no flux

Wood:

To tuyeres +1 m

Dog house

Blow out pipex2

60% WV



6. Wood charge

• Dog house (3x3x3 m) wood “sleepers” – Width 200 – 300, Length 2000 – 2500 mm

• “Waste wood”, not large heavy wood

– Width < 150 mm, Length < 1000 mm for easyhandling



7. Blow out pipes

• 1 in each taphole

• At normal taphole angle



8. Typical burden plan

• To be finalized based on actual raw material quality and conditions

• Coke blank to fill hearth, deadman and active coke zone and to provide heat to

dry and heat burden

• Lowering coke rate according to plan



9. Slag chemistry

• The slag chemistry is chosen for good fluid slag at the expectedhigh expected silicon at the start of the blow in

• A chemical buffer is used by choosing a low basicity slag such that

high hot metal silicon and low hot temperatures will still give a fluid

slag

• Chemistry

– Al2O3 < 17% – MgO 7 to 8%

– IB2 initially 0.7 - 0.8

• The basicity can only be increased when the hot metal silicon is low

and in control ([Si] < 1.5%)

• The maximum IB2 is to be 0.9 during the first weeks due to the high

chance of an unplanned shutdown



10. Slag basicity and liquidus temperature

– The lower the basicity the lower the liquidus temperature

– IB2 0.7 = 1300 degC, IB2 1.2 = 1480 degC.

– Slag analysis of every cast is essential

1300°C

1400°C

1500°C

1600°C

1800°C

CaO MgO

SiO2

10

10

10

20

20

20

30

30

30

40

40

40

50

50

50

60

60

60

70

70

70

80

80

80

15% Al2O3

IB2 0.7

1.0

1.2



11. Wood and charging of wood

• Dog house is to be constructed or railway sleepers

or equivalent (3x3x3 m)

• The rest of the wood can be old pallets charged through

to top hatch using the top crane and large bucket (a few

hours)

– This wood is not needed for its calorific value, only it ability to

hold the coke temporarily above the tuyeres

• If large wood is used (logs) it must be loaded manually

through the tuyeres and this takes much longer

– Such large wood is not required however often used



12. Heating bustle main

• Bustle main is to be heated as much as possible tomaximize initial hot blast temperature

• After wood has been charged blow pipes down legs can

be blinded and tuyere blocked and bustle main to be

heated through 4 or 5 removed blow pipes

– This can be done after the doghouse is constructed if the wood is charged from the top

• Blind flanges must be removed before light-up



13. Filling and burdening

• DC will provide charging sheet on charge per charge basis

• Burden distribution to be chosen and defined,

– Minimize burden hitting lining at low stockline elevation

– Limiting size of coke center as it could become too large

with the high coke rates leading to loss of EtaCO• Suitable layer thickness will be chosen

• During filling testing is to be done on,

– Trajectories at set chute positions

– Material gate positions

– Stockhouse screening

– Stockhouse weigh bunkers



14. Trajectory measurements

ABP flange

≈SL 0 (38,050 mm)

≈SL -0.5 m



15. Trajectory probe



16. Casthouse preparation

• First casts will be sent to dry pit• Trough to be prepared as shown below



17. Lighting the furnace

• Before lighting steam/nitrogen must be on top withbleeders open

• Unblock all tuyeres and remove blind flanges in down

legs (if used), keep back door open

• Put flares in all tuyeres, the wood will ignite with the

natural draft – Not required if hot blast temperature is > 700 degC

– Bustle main must be well heated



18. Putting blast on the furnace

• When all tuyeres are open and burning on natural draft,blast may be put on the furnace

• Close all tuyeres and bring blast pressure to 0.3 bar bycontrolling snort valve

• Check for leakages on tuyere floor shaft and top, if foundfix

• Start following blast ramp up plan – During initial stages follow hot blast pressure not flow

measurement as it is unreliable at low rate

• Hot blast temperature to be as high as possible (aim 800degC). Use the hottest stove first

• No additional moisture



19. Connecting the GCP

• GCP must be completely purged and free of oxygenbefore furnace is ignited

– Should be kept at small positive pressure to stop air ingress

• GCP can be connected when no oxygen in the top gas is

measured (manual sample uptake)

– If no measurement available when blast is > 1000 Nm3/min for >15 min with all tuyeres brightly alight the GCP can be connected

as not oxygen can be present

• Connect GCP and then close bleeders

• Stop steam/nitrogen on top



20. Removal of blow out pipes

• After approx. +12 hours the pipes will start to sputter dueto liquids in hearth

• When the flame is almost stopped the pipe must be cutoff and lance open the taphole

• Blast pressure may have to be decreased to make iteasier

• After lancing a healthy flame should be in tapholeshowing good connection with tuyeres

• Plug with taphole 1/2 stripe (30 litres)

– Small amount not to foul connection

• Repeat with other pipe when its flame has almoststopped



21. First taps

• 2 CH will be chosen to be used for blow in (oppositesides)

• First cast will be on first side that blow out pipe isremoved

• First tap +1 hr after blow out pipe is removed to checkconnection

• Drill size larger for good connection (60-65 mm)

• Repeat with gap time of 1 to 1.5 hr

• A short gap time is chosen to ensure and testconnection, even though sufficient liquid has not beenproduced for a good cast

• Case casts with minimum amount of clay (1 stripe)



22. Separation real skimmer

• CH can be prepared for separation when

– Both tapholes have good stable connection

– Iron production is enough for separation ( 2 troughvolumes per hour, 70 – 80 thm/h)

– > 2 good casts from taphole to be used for separation

– [Si] < 2.5% and stable

– Slag fluidity is good• HMT > 1450 degC

• Good chemistry

• The next 2 to 4 casts must be on this taphole to maintain heatin trough, skimmer and connection

• When the separation and casting is going well the decision ismade to prepare the other casthouse for separation



23. Preparing for separation

• Remove sand, first ½ of trough from skimmer block – A plate in front of the skimmer can also be used,

discuss?

• Heat skimmer block

• During this period tap from other taphole (1 taphole

operation)• Gap time before first real separation must be chosen to

ensure enough liquid to fill and heat trough and skimmer

– > 2 times the trough volume



24. First casts: summary

2

1

Blow-in pipe removal

≈ 12-16h

Prep. Taphole 2For separation,Hot standby

One taphole operation

Iron and slag

Iron / slag separationGood conditions

for separation

Prep. Taphole 1

for separation

?



25. Drying the burden

• The coke and burden materials are wet and must bedried and heated so the reactions can start

• The burden is dry when the top temperature starts to

move (is alive)

• To maximize drying,

– Maximize hot blast temperature – No moisture addition to blast

– Minimize top pressure



26. Normalizing process

• The HM Silicon becomes high (4 – 4.5%) during a blow-indue to:

– very high melting zone, due to high coke rate

– low slag basicity, low pressure in furnace

• The process must be normalized as soon as possible (Si< 1.5%)

– Less work in casthouse

– Less fouling of torpedoes

– Stable furnace operation, useable hot metal



27. Normalizing process: [Si] control

• Burden plan should be followed, [Si] will only be reduced if coke

rate is reduced – Do not wait for [Si] to drop before dropping coke rate, “chicken and

egg”

• Control with moisture and blast temperature when HM Silicon is

high (>3%), connection is good, and slag is fluid, – Increase moisture to maximum 45 gr/Nm3 (total inc. ambient)

– Decrease blast temperature to minimum 850 degC

– Maintain flame temperature > 1950 degC



28. Consuming coke buffer

• High initial coke rate required to dry and heat up burden

• This must be consumed to attain stable operation• Charging less coke allows the coke buffer to be consumed

Normal Coke Buffer≈ 2-3 mLarge Coke Buffer≈ 6 - 10 m

Stable operation

Si < 1.0%

Blow inSi > 2.5%



29. Furnace parameters during blow in

• Stockline

– Maintain normal stockline level during all stages of blow in

– This has little effect on drying and gives a buffer should there be

charging delays

• Top pressure

– Top pressure to be kept to minimum before top pressure is alive

to help drying – Must be increased to maintain DP < 1.0 bar during blow in

– Must not be increased too quickly to maintain high tuyere

velocity

• Tuyere velocity

– Maintain high given furnace parameters (aim > 180 m/s < 220m/s). Top pressure should not be too high

• Flame temperature

– Maintain between 1950 and 2300 degC



30. Typical schedule

# Task

1 Blow-in pipe completion

2 Preparation of trough and runners Continue heating

3 Dog house construction

4 Blow-in wood to tuyere level +1m5 Block tuyeres and blind down legs

6 Heat bustle main

7 Furnace filling and trajectory trials

8 Top spray check

9 Close top

10 Purge gas system and maintain > 200 mmWC N2 Continue small purge

11 Final check on all areas with separate teams

12 Start steam on top

13 Removed blanks from down legs

14 Open tuyeres

15 Ignite tuyeres, Pooja

16 Start blast plan

Day 1 Day 2 Day 3 Day 4

• Typical schedule as shown below

• From furnace handover, 3 to 4 days to blow in



31. Typical blast plan

Blow out pipes blocking First good casts > Separation



32. First hours

Blow out pipes blocking First good casts >



33. Shutdowns?

• During initial stages with coke blank small shutdown ispossible,

– Test all equipment possible, find issues early!

• Furnace leakages

• Charging system

• Stockrods• Stove valves

• Instrumentation

• After coke blank is consumed no shutdown is possible!

• First planned shutdown after >5 days to complete furnace

check and resolve issues



34. Data required from RSP

• Complete chemical, physical and metallurgical characteristics

of all burden materials

• Siliceous ore proximate, preferred to quartzite for low IB2

• If quartzite is to be used it should be < 25 mm

• Daily reports of typical operation in other BF’s as reference,

including burden make up

• When? and what? materials are being charged to stockhouse

• Is sinter plant already in operation and producing good sinter

• First sinter must be of best and stable quality



35. Shift structure

• Day and night shift teams for each area to be defined

before blow in, for all parties

2B09870Rourkela BF5 Blow-in - Shifts

Overall blow-in leaders

DC J. Plooij

TPL To befilled in by TPL

RSP To befilled in by RSP

S hi ft C om p. D 1 - A ut o. L 1 D 2- A ut o. L 2 F 1 - S to ck ho us e G 1 - B la st f ur na ce J 1 - C as th ou se H1 - H ot b la st s ys . J 3 - C H La b. K 1 - G as c le an in g K 2 - TG r ec . t ur bi ne K 3 - E TP L 1 - S la g gr an . N 1 - F ur na ce t op

Day DCDC

DC

DC

DC

TPL

TPL

TPL

TPL

TPL

RSP

RSP

RSP

RSP

RSP

N ig ht D C

DC

DC

DC

DC

TPL

TPL

TPL

TPL

TPL

RSP

RSP

RSP

RSP

RSP



36. MOM discussion with RSP

• SP1,2 and (new) 3 are all in operation

– SP3 in operation 6 months producing for BF 1 to 4

– SP2 and SP3 can feed to BF5 – Analysis given to DC

• CP1 (old) CP (2) new

– CP2 to be commissioned in next months

– Coke to BF5 is 50/50%

– Analysis provided by RSP

• Flux (LD slag and quartzite) data to be provided by RSP

• RSP to confirm all materials with DC before filling stockhouse• Daily and month reports of BF1 to 4 provided by RSP

• DC to comment on log books BF1 to 4 to be updated for BF5 instrumentation and practice (to be provided

by RSP)

• 10 torpedos, 6 in operation at one time 350 t

– Open ladles 140 tons (many)

– Torpedos can be used in BF4

• PCM 1000 tpd (Design 1500 tpd) for torpedos, been commissioned

– No dumping facility

• Tar bonded clay BRL BF1 to 4, BF5 Acecaldrys (supplying to other large BF in india Tata, JSW)

2B09870-P001 RSP BF5 - Blow in Discussion Rev0

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