The paper is based on analysis of data od around 200 EAFs of different design: conventional, DC, twin shell, with scrap preheating in conveyor or shaft, etc.. Included in the survey are furnaces charging mostly scrap, and others charging (partially) hot metal, pig iron, HBI, or cold / hot DRI. The assessment includes power, oxygen natural gas and carbon consumption; tap-to-tap time, power-on time and power-off time, as well as hourly production. With the collected data, the influence of metallics (and their thermal state at charging), and furnace design, on specific consumptions and productivity are discussed.

1. INFLUENCE OF METALLICS AND EAF TYPE ON SPECIFIC CONSUMPTIONS
AND PRODUCTIVITY
Jorge Madias – metallon, San Nicolas, Argentina
Andrea Bilancieri - TenarisSiderca, Campana, Argentina
Sara Hornby – Global Strategic Solutions, Charlotte, USA
05/10/2017

2.  Introduction
 Survey
 Power consumption
 Other factors
 Oxygen consumption
 Electrodes
 Productivity
 Conclusions
Content

3.  metallon
 Consulting & training company based in San Nicolas, Argentina
 TenarisSiderca
 Seamless pipe producer located in Campana, Argentina
 DRI plant, EAFs, LFs, Round billet/bloom casters, continuous rolling
mills, drawing plant, heat treament facility, production of couples
 Global Strategic Solutions
 Consulting company based in Charlotte, SC, USA
Introduction

4.  Large variation in scrap quality and alternative iron sources and utilization,
depending on country /region
 Variety of furnace designs available
 A look at influence of metallics and EAF design on specific consumptions
and productivity
 Based on survey of published figures of EAFs around the world
 Data base from public sources 2010 - Feb 2017
 Not included
 EAFs for steel castings, forgings and steel powder
 EAFs producing exclusively stainless and tool steels
 EAFs with heat capacity lower than 30 t
 190 furnaces worldwide
Introduction

5. Introduction
 Charge types include
 100% scrap
 Up to 40% pig iron
 Up to 60% hot metal
 Up to 100% DRI/HBI
 Up to 100% hot DRI
 Products
 Merchant long products
 SBQ
 Flat products (coil and plate)
 Seamless pipes

6. Introduction
 Transformer power vs. heat capacity

7. Survey
 Specific consumption in terms of metric tons of liquid steel in the ladle
 Data included
 Company / group; plant name; country
 EAF type, heat capacity; transformer power; electrode diameter
 Productivity; tap to tap time; power on time
 Power; oxygen; injected carbon; natural gas; electrodes
consumption
 Metallic yield; charge type; product type; reference
 Published data corresponds usually to a specific operation period (start-
ups, continuous improvement)
 Consumption figures and productivity-related times change depending
on demand and other
factors that may vary over time

8. Power consumption
 Depends upon metallics, and their thermal state at
charging
 <300 kWh/t
 Nine of the top charge >20% hot metal
 Energy consumed in the blast furnace
 EAF CO2 emissions larger than usual
 300 – 400 kWh/t
 Best scrap-based EAFs
 Charge of >20% pig iron
 400 – 450 kWh/t
 Intermediate scrap-based EAFs
 Charge of >90% hot DRI
 >450 kWh/t
 Worst scrap-based EAFs
 Charge of >50% cold DRI/HBI

9. Influence of metallics and their thermal state

10. Power consumption
Country
Heat
cap. (t)
Curr
ent Type
Transform
er (MVA)
TtT
(min)
Power cons.
(kWh/tls) O2 (Nm3/tls)
Metallics other
than scrap (%) Product
China 50 AC Standard 67 132 54 HM LS
China 100 DC Standard 90 44 177 47 57.5 HM LS
China 110 AC Standard 80 33 220 33 30 HM LS
Russia 175 AC Standard 150 45 223 34 22 HM LC
Taiwan 155 AC Twin Shell 120 44 225 37 35 HM LC
China 110 AC Standard 80 35 240 33 30 HM SP
China 110 AC Standard 80 35 240 33 30 HM SP
Brazil 110 AC Standard 48 43 265 30 HM LC
Brazil 80 AC Standard 75 295 31 25 HM/5PI LC
Singapore 80 AC Shaft 48 295 0 LC
Turkey 195 AC Standard 47 300 38,5 0 LC
South Afr. 170 AC Conarc 115 57,5 310 43 50 HM/ 50 cDRI FC
India 180 AC Conarc 137 57,5 310 50 HM/50 cDRI FC
Korea 120 AC Shaft 49 314 31 not known LC
Vietnam 63 AC Consteel 33 54 328 10 HM LC
Mexico 110 AC Standard 85 90 330 7 cDRI LC
Italy 95 AC Standard 100 42 340 20 10 PI SP
Brazil 50 AC Standard 36 343 60 30 PI LC
Brazil 50 AC Standard 48 343 60 30 PI LC
Mexico 56 AC Standard 55 55 345 7 cDRI LC

11. Power consumption
 Influence of furnace type
 Only EAFs charging >80% scrap

12. Oxygen consumption
 Distribution

13. Oxygen consumption
 Advances in chemical energy
utilization, through high capacity
injectors
 Influence of metallics
 >20% hot metal: 36.3 Nm3/t
 >20% pig iron: 43.3 Nm3/t
 >20% DRI/HBI: 31.7 Nm3/t
 >80% scrap: 31.7 Nm3/t

14. Electrodes
 Many furnaces using 610 mm (24”) electrodes, tapping 70 to 200 t per heat
 DC furnaces (1 or 2 electrodes) present the larger diameter, for a given heat
capacity

15. Electrodes
 Electrode consumption vs. power consumption

16. Hourly productivity
 Linked to furnace size
 EAF feeding slab casters are the most productive

17. Power-on time
 Top 20 EAFs have a varied heat size (35 to 220 t)
 17 of them dedicated to merchant long products
 EAFs linked to billet casters equipped with metering nozzle and oil
lubrication
 Higher casting speed
 Longer sequences

18. Power-on time

19. Conclusions
 There are four ranges of power consumption associated with the metallic
charge
 <300 kWh/t for EAFs charging more than 20% hot metal
 300 - 400 kWh/t for the more efficient scrap-based EAFs and those
charging more than 20% pig iron
 400 - 450 kWh/t for intermediate efficiency scrap-based EAFs, and
those charging hot DRI
 >450 kWh/t for low efficiency scrap-based EAFs and those high
quantities of cold DRI/HBI
 Favorable influence of scrap preheating, with transporter, shaft or twin shell
 DC EAFs do not differ much on power consumption, but are in the lower
range of electrode consumption

20. Thank you!