WI-07

BHILAI STEEL PLANT DOC.NO.ISO/QPO/SMS-II (O)-07/00 BHILAI – 490001 Page 1 of 6 DATE OF ISSUE 10.08.2009

REVISIONS ARE NOT PERMITTED WITHOUT THE PRIOR APPROVAL OF CONTROLLING AUTHORITY.

WORK INSTRUCTION ON BLOWING OPERATION REVISIONS RECORD

REVISION NO./DATE

REVISIED PAGE NO.

BRIEF DESCRIPTION OF REVISION

PREPARED BY

CONTROLLING AUTHORITY APPROVED BY

00/ 10.08.2009

ORIGINAL DOCUMENT

N V JOSHI AGM(O) CONV

AK MOJUMDAR AGM(Q&S)

SMS-II

SOMDEV DAS DGM I/C SMS-II

HARD COPY DISTRIBUTION : 1. M.R. (For record/ control) 2. HOD (SMS-II) 3. I/C (Q &S) SMS-II SOFT COPY DISTRIBUTION : 1. I/c (O) CS. (For implementation) 2. Shift Mgr.CS 3. Blower (Conv-A , B & C )

�

� �

�

�

�



1 OBJECTIVE

To blow hot metal and scrap with oxygen and bulk material to achieve turndown temperature and chemistry required for tapping the desired grade of steel.

2 SCOPE Treatment of hot metal in converter A, B & C.

3 REFERENCES

ISO 9001: 2008 Cl. 7.5.1 & 7.5.2. Quality Manual: Chapter no 16. DOC NO. ISO/QPP/SMS-II (O)-01/**(Steel Making in converter). ISO/QL/SMS-II (G)-11/**(List of Quality records). ISO/QS/RCL (G)-176/** (Process chart for SMS-II). LD Automation-VESTN/** (Instruction for computer operation)

4 GENERAL/DEFINITION 4.1 GENERAL

4.1.1 SAFETY

4.1.1.1 Use required PPE's while on job.

4.1.1.2 Ensure there is no water logging around Converter area.

4.1.1.3 Do not use lance with heavy water leakage for blowing.

4.1.1.4 Lance skulls to be visually assessed for entering into lance thimble after every heat.

4.1.1.5 Check co-axiality of lance whenever a lance is changed.

4.1.1.6 Skirt should be lowered, 30 second after ignition.

4.1.1.7 During blowing if water goes into the converter: a. Lock converter in vertical position from MCP. b. Don’t tilt the converter till complete water is evaporated, it is

to be ensured through lance thimble.

4.1.1.8 If nitrogen pressure drops, keep converter in vertical position & lock.

4.1.1.9 If lance does not move during/after blowing, a. Inform Shift I/c (Mech /Elect) & reduce O2 flow gradually to the

minimum level i.e. 100 NM3/Min (approx.) with intermittent addition of lime in small doses to control bath temperature.

b. After the lance is lifted use the other lance. c. If the same lance is to be used for blowing again, thoroughly

inspect nozzles for any clogging.

4.1.1.10 In case of chain slack during lowering of lance: a. Inform electrical to reset the supply. b. After the supply is restored, first lift the lance by approx. 1 M

and than lower to required position. c. In case chain slack again take place, check the lance from lance

thimble platform for any obstruction in lance movement before asking Electrical Maint. For further resetting.

d. Even if lance slack persists, the same lance should not be used for blowing.

4.1.1.11 If lance is stuck up, empty out the converter before taking the job

of lance cleaning.



4.1.1.12 In case ID Fan is tripped, converter to be tilted towards charging side, away from the hood so that quencher water does not fall in to the converter.

4.1.1.13 When Cater pillar/ Dozer is working at zero metre charging/ blowing activities should not be performed.

4.1.2 INTERLOCKING

4.1.2.1 Lance movement downward is possible when a. G.C.P. ready. b. Converter is vertical. c. Lance cooling water temperature, flow and press are normal. d. Oxygen Pressure is normal. e. Lance is coaxial with converter.

4.1.2.2 Emergency lift of lance in any of the following conditions: a. Lance cooling water temp, press and flow below normal. b. Oxygen press is low. c. Blow stop condition from GCP.

4.1.2.3 Deleted

4.1.2.4 Converter tilting is possible only when lance is out of converter mouth.

4.1.2.5 Safety shut off valve will open if following conditions are satisfied a. Lance control selection switch is in

Manual - Remote or Auto - Remote or Computer - Remote position.

b. Isolation and concerned blowing valve fully open. c. SSV control selection switch in "Auto" position. d. Lance cooling water temp, press and flow are normal. e. Lance is coaxial with converter. f. Oxygen press normal g. GCP - Ready

4.1.3 AIM VALUES

4.1.3.1 FOR PROCESS

a. Blowing duration : 16-20 minutes (In return heat blowing duration will vary with amount of hot metal charged)

b. Tapping run : > 3 minutes

c. Blowing oxygen pressure

i. Line pressure : > 10.0 kgs/cm2

ii. For 4 hole lance : > 8.0 kgs/cm2

iii. For 5 hole lance : > 6.0 Kgs/cm2

d. Lance cooling water

i. Flow : 110 ± 20 M3/hr

ii. Pressure : 10 ± 2 kgs/cm2

iii. Temp. Difference (outlet-Inlet)

: 50° ± 5°

e. Nitrogen pressure : > 6.0 kg/cm2

4.1.3.2 FOR PRODUCT



a. Turndown temperature : 1630° -1720°

b. Slag

i. basicity : 2.8 min.

ii. Total Fe : < 20 %

c. Bath analysis

i. Carbon : 0.050 % Min.

ii. Sulphur : 0.025 % Max.

iii. Phosphorus

: 0.020 to 0.040% as per the requirement of the grade.

iv. Lime

i. Cao + MgO : 80.0 % Min.

ii. Reactivity : 250 Min.

4.2 DEFINITION Nil

5 PROCESS 5.1 CALIBRATION OF LANCE

5.1.1 Charge the converter with Hot Metal.

5.1.2 Insert about 1.5 M long steel pipes in one of the nozzles of Lance.

5.1.3 Lower lance below 1.0 M from (H2) reading of Selsyn / Encoder without opening the safety shut off valve.

5.1.4 Hold the lance at that position for about half a minute.

5.1.5 Lift lance to the upper most position in lowest speed.

5.1.6 Remove pipe from lance and measure the length of

5.1.7 Pipe not dipped in metal (H1) & note the selsyn reading (H2) Calculate H3 = H1 - H2 + 80 mm/10 T of scrap

5.1.8 Calculate Working height = Encoder/Selsyn Reading + H3.

5.1.9 Lance height calibration frequency – Once in 100 heats.

5.2 BLOWING

5.2.1 Feed following information in computer

5.2.1.1 Quantity of hot metal & scrap charged.

5.2.1.2 Composition & temp of hot metal charged. (If not available, feed analysis of previous heat)

5.2.1.3 Start blow as per regime given below. For return heat or heat with retained slag or hot metal with Si > 0.8 %, bring lance to working height within 3 minutes.

5.2.2 BLOWING REGIME

Time from blow start (sec)

Lance working height (Metre)

Oxygen flow (NM3/min)



0 120 240 300 540 780 1020

2.6 2.2 1.8 1.6 1.6 1.6 1.6

450 400 400 400 350 400 450

Lance working height is the height of lance from charged surface.

5.2.2.1 COMPUTER MODE a. Put Lance control selection switch in Remote position in computer. b. Feed bath correction in computer. c. Select regime of blow on computer. d. Give command to start the blow.

5.2.2.2 MANNUAL MODE a. Keep lance selector switch in Remote mode. b. Operate lance manually.

5.2.3 Observe that Ignition takes place within 30 seconds (indicated by luminous flame at converter mouth).

5.2.4 If ignition does not take place within 30 seconds a. Lift the lance to top most position. b. Rock the converter 2-3 times. c. Again start the blow.

5.2.5 After about 30 seconds of ignition the skirt is lowered.

5.2.6 Continue blowing as per blowing regime.

5.3 FLUX & FLUIDISER

5.3.1 Decide amount of bulk materials required as per Computer. If reactivity of lime is less than specified then ensure slag formation by lance manipulation.

5.3.2 Calculate amount of lime to be added = predicated lime - half of calcined dolo to be added.

5.3.3 Add rest amount of lime within 5-6 minutes from start of blow.

5.4 TERMINATION OF BLOW

5.4.1 INTERMEDIATE STOP

5.4.1.1 Stop the blow when about 400 M3 of Oxygen is balance from predicated amount.

5.4.1.2 Take bath temperature & sample.

5.4.1.3 Finish blow as per predicted oxygen or as per instruction of Tapping In charge.

5.4.2 FLAT BLOW

Decide termination of blow jointly or singularly from following conditions:

5.4.2.1 By blowing about 400 M3 of oxygen after drop of flame through the tap hole.

5.4.2.2 Drop in skirt pressure from 15 Pascal to 10 Pascal.

5.4.2.3 By fall in CO level in flue gases to 40 % (as per gas analysis



recorder). By fall in CO level in flue gases to 40 % (as per gas analysis recorder).

5.4.3 Lift lance only after half a minute of lifting skirt.

5.5 TEMPERATURE CORRECTION

5.5.1 Carry out temperature correction if required by reblowing oxygen at a rate of 100 M3 per 8 deg C rise in temperature.

5.5.2 Carry out higher turndown temperature correction by lime/ iron ore addition as per instruction of Tapping I/c (Temp. Drop will be about 15 deg C/T of Lime and 25 deg/T of Iron ore).

5.5.3 Intimate Shift Mgr for charge balance correction, if required, for proper turndown temperature.

5.6 SLAG CONDITIONING

If slag at turndown is viscous/ insufficient, give additional lime & blow Oxygen to achieve the desired S & P level in bath before tapping.

5.7 FERRO ALLOY ADDITION

During tapping add Ferro alloys from service bunkers as per requirement depending upon the grade of steel and instruction of Tapping I/c.

6 RECORD

Feed all information in computer for each blow against designated heat no. Record lance height calibration value in the Document no. SMS-II/39. (Ref Doc. no ISO/QL/SMS-II (G)- 14/**)

7.0 ABBREVIATIONS

PPE: Personal protective equipment.

Documents

WI-07