6　EAF Steelmaking

6.1　Process Design

6.1.1　A new UHP EAF shall be provided with the following technologies:

1　EBT and liquid steel and slag heel operation；

2　Tubular water cooled furnace panel and water cooled furnace roof；

3　Water-cooled composite copper-steel or aluminum alloy electrode arm；

4　CoJet oxygen lance and carbon lance at furnace wall；

5　Foamed slag submerged-arc operation；

6　Mechanical charging system for EAF and ladle；

7　Computer based automatic control technology；

8　Stationary dynamic reactive compensation device；

9　Mechanical furnace dismantling and repair facility；

10　EAF waste heat recycling technology.

Notes:1　With reference to EAF for production of stainless steel，the mentioned item 1 and item 4 shall be selected as required；

2　The adoption of item 8 shall be depended on the flicker value of electrical calculation.

6.1.2　A new UHP EAF may be provided with the following technologies in addition to the items mentioned in 6.1.1:

1　Manipulator for oxygen and carbon lance at furnace door；

2　Oxy-fuel burner；

3　Automatic temperature measurement and sampling device；

4　Continuous fume composition measurement device；

5　Automatic taphole repair device；

6　Furnace mouth slag remover；

7　Weighing device for liquid steel in EAF.

6.1.3　The design of EAF shop shall be in accordance with the following provisions:

1　For a new EAF，the specific power level of transformer for per ton steel should be 600kV·A/t-1200kV·A/t；for a furnace adopting scrap preheating with fume，or a furnace with hot metal hot charging process，the specific power level close to the lower limit may be selected.

2　In downstream of EAF，ladle furnace shall be equipped and also other refining facility like vacuum treatment unit shall be provided according to the quality requirement of steel grades.

3　For a new/modified EAF steelmaking shop in the metallurgical industry，a full continuous casting process shall be adopted.In other machine foundry industries，steel casting process should be determined according to the requirement.

6.1.4　In the type selection and design of furnace，the following technologies shall be adopted depending on the condition:

1　AC high-impedance or DC power supply technology；

2　Technology of scrap preheating with hot fume；

3　Post combustion technology for CO in fume and energy saving technology like replacing electric energy with chemical energy；

4　Hot metal hot charging technology.

6.1.5　The nominal volume of furnace shall be the average tapping and the maximum tapping shall be 1.05times-1.2times of the nominal volume.The heel level after tapping is 0-50% of the nominal volume depending on types of EAF.Under the precondition of meeting the requirement for annual production，the number of furnace in a shop shall be minimized，which should not be more than 3 sets in a shop，and also the furnace shall be provided with high power and capacity.

6.1.6　The average tap-to-tap time of a heat shall be defined according to type of furnace，specific power of transformer and material condition.The annual capacity of EAF shall be calculated based on the following formula:

Where　Q——Qualified liquid steel production of a furnace（t/a）；

G——Average tapping of a heat in campaign period of EAF（t/heat）；

T——Average tap-to-tap time of a heat（min/heat）；

N——Annual effective operating time（d/a）；

n1——Annual furnace repair time（d/a）；

n2——Annual routine maintenance time scheduled（d/a）；

n3——Annual centralized maintenance time of shop（d/a）；

n4——Annual lost production time（d/a）.

6.1.7　Rational composition of EAF shop shall be defined according to production capacity，process flow，site condition，internal and external coordination condition of plant and material supply condition and may be chosen in the following general composition:

1　The main production system includes main shop，scrap proportioning shop，slag shop and fume cooling and cleaning facilities.

2　The auxiliary production system includes ferroalloy storage facility，material bin and belt conveyor corridor（used when using DRI as main furnace charge），quick analysis room，compressed air station，shop substation，water treatment facility and domestic and welfare facilities.

3　The oxygen，nitrogen，argon and fuel supply facilities，refractory storage，spare part storage，miscellaneous material storage and mechanical，electrical and vehicle maintenance facilities shall be arranged by the plant generally.

6.1.8　The noise-isolating measures shall be taken for operation rooms and shop buildings for an UHP EAF that is not provided with doghouse.

6.1.9　The energy consumption of process steps in EAF steelmaking shall be in accordance with the current relevant national standard.

6.1.10　The slag，scrap，waste electrode，waste brick and dust from EAF operation shall be recycled.

6.1.11　The gas media，fuel and cooling water as well as the pipelines provided for EAF shop shall be in accordance with the following provisions:

1　The supply capacity of oxygen，argon，nitrogen，steam，compressed air and fuel shall be calculated based on the consumption per ton steel and the hourly productivity of EAF.However，the capacity of pipelines shall be determined based on the maximum instantaneous flow rate of the shop.

2　The capacity of gas storage tank shall meet the requirement for consumption peak of shop and shall be adaptive for fluctuation of consumption.Moreover，the capacity shall meet the requirement for operation of 1 heat at least in case of gas supply failure.

3　The parameters of cooling water shall be defined according to the pressure and flow rate required by the users.

4　The operating parameters of media at connecting points of users shall be ensured to be in conformity with the requirement.

5　The emergency water supply capacity for not less than 30min shall be provided for the process equipment operating at high temperature.

6　If a shop is built by phases，the construction of main pipelines for media shall be completed according to the final scale.For the related utilities，the general layout may be made reservation for the space of expansion in the future，or the shop building may be made reservation for the condition of additional unit，depending on the actual condition.

6.1.12　The main techno-economic indices of EAF should be defined according to Table 6.1.12.