10th International Stainless & Special Steel Summit September 2011, Munich, Germany

Transcription

1 10th International Stainless & Special Steel Summit September 2011, Munich, Germany Siemens Siemens AG AG All All rights reserved. ed.

2 New trends to produce stainless steel with an advanced Level 2 system using low cost charging and addition materials Walter A. Gebert 10th International Stainless & Special Steel Summit 07 th 09 th September 2011 Munich, Germany Next generation metals

3 Introduction / contents Limitations in metallic charge materials and their cost forced to search for new production routes of stainless steels and the use of alloyed pig iron and liquid hot metal has become an alternative. Different production routes for stainless steel including DeP and API. Experience gained by Siemens VAI in using oxidic alloys in AOD converters and calculations for AISI 316L with use of oxidic alloys. Content: Locations of Siemens VAI reference large-scale plants 4 Production of stainless steel with API 6 Production of stainless steel with use of De-P hot metal 9 Different process routes 12 Experience of Siemens VAI in use of oxidic alloys 16 Summary 22 Page 3

4 Siemens VAI projects in the Stainless steel industry since 1994 (12 EAF, 22 AOD, 2 VOD, 8 LF, 111 Caster & Casterrevamp) NAS 140 t EAF 150 t AOD 800,000 t/y TKL Alabama 160 t EAF 180 t AOD 180 t LT Slab Caster I,000,000 t/y Outokumpu 2x125 t AOD 750,000 t/y Outokumpu 90 t LF Slab Caster 500,000 t/y CARINOX 160 t EAF 180 t AOD 180 t LF Slab Caster 1,100,000 t/y ALZ 120 t EAF 120 t AOD Slab Caster 1,200,000 t/y ISCOR 125 t K-OBM-S 100 t VOD 600,000 t/y Outokumpu 150 t EAF 150 t AOD 150 t LF Slab Caster 850,000 t/y TKN Krefeld Plant revitalization 2x96 t AOD 1,000,000 t/y Zhangjiagang ZPSS 130 t EAF 150 t AOD Slab Caster 700,000 t/y Sandvik steel 3x75 t AOD Vessel mod. 250,000 t/y BÖHLER Uddeholm Plant Revamping 50 t AOD, 130,000 t/y Acc. di BOLZANO 55 t AOD 3 Strand Bloom Caster 100,000 t/y Viraj Profiles 55 t AOD 200,000 t/y TISCO Taiyuan 75 t K-OBM-S 350,000 t/y 3x50 t AOD Revamp TISCO Taiyuan 3x45 t AOD 450,000 t/y Xingtai 50 t AOD 210,000 t/y Tangshan 110 t AOD 600,000 t/y TISCO Taiyuan 2x160 t EAF 2x180 t AOD 2x100 t LF 2x Slab Caster 2,000,000 t/y KAW ASAKI, Chiba 2x160 t K-OBM-S/KMS-S Patent License 600,000 t/y POSCO, Pohang 85 t EAF 90 t AOD Slab Caster 500,000 t/y ACESITA S.A. 80 t AOD 420,000 t/y COLUMBUS, Middleburg 100 t EAF, 2x100 t AOD Slab Caster 600,000 t/y Jiuquan ISCO 120 t AOD 120 t LF 600,000 t/y MICROSTEEL, Durban 15 t AOD, VOD 1 Strand Billet Caster 100,000 t/y PERKASA 40 t EAF 40 t VOD 2 Strand Bloom Caster LISCO 2x155 t EAF 2x170 t AOD 2x170 t LF 170 t VOD 2,000,000 t/y Page 4

5 Improvement of Siemens VAI s stainless steelmaking Process know-how and market position Project Start-up Production line (SVAI supply) Heat size Annual capacity (t/y) Product Steelmaking process know-how Steelmaking process level 2 automation Yunnan 2012 AOD 120 t 800,000 Stainless flat Siemens VAI Siemens VAI TKL Alabama 2012 EAF, AOD, LS, SlabCCM 180 t 1,000,000 Stainless flat Siemens VAI Siemens VAI Viraj Stainless 2011 AOD 55 t 200,000 Stainless flat Customer Siemens VAI Xingtai Stainless 2011 AOD, LF, BilletCCM 60 t 200,000 Stainless flat Siemens VAI Siemens VAI JISCO 2010 AOD, LF, SlabCCM 110 t 600,000 Stainless flat Siemens VAI Siemens VAI LISCO EAF, AOD, LF, SlabCCM 180 t 1,000,000 Stainless flat Siemens VAI Siemens VAI Tangshan 2009 AOD, VOD 120 t 600,000 Stainless flat Siemens VAI Siemens VAI TKN Krefeld 2009 AOD 2 x 96 t 1,000,000 Stainless flat Customer Customer NAS 2008 AOD 150 t 800,000 Stainless flat Customer Siemens VAI NAS 2006 EAF 140 t 700,000 Stainless flat Customer LISCO 2006 EAF-AOD-LF/VOD-SlabCCM 180 t 1,000,000 Stainless flat Siemens VAI Siemens VAI POSCO Shagang ZPSS 2006 EAF-AOD-SlabCCM 150 t 850,000 Stainless flat Siemens VAI /customer (support) No level 2 (customer) TISCO SMP # xEAF-2xAOD-2xSlabCCM, TwLF 180 t 2,000,000 Stainless flat Siemens VAI Siemens VAI Arcelor Mittal Carinox 2005 EAF-AOD-LF-SlabCCM 180 t 1,000,000 Stainless flat Siemens VAI VAI & Customer for AOD only Siemens VAI VAI & Customer for AOD only TISCO SMP # AOD-SlabCCM 45 t 400,000 Stainless flat Siemens VAI Siemens VAI BÖHLER Edelstahl 2003 AOD 50 t 200,000 Stainless and alloyed long Siemens VAI/customer (support) Outokumpu Stainless 2002 EAF-AOD-LF-SlabCCM 150 t 850,000 Stainless flat Siemens VAI Ger/customer (AOD, LF) Siemens VAI incl. SIMETAL Vaicon Temp Ugine&Alz Genk 2002 EAF-AOD-SlabCCM 120 t 800,000 Stainless flat Siemens VAI Siemens VAI TISCO SMP # K-OBM-S 75 t 450,000 Stainless flat Siemens VAI SVAI incl. SIMETAL Vaicon Temp AvestaPolarit 2000 LF-SlabCCM 95 t 450,000 Stainless flat Siemens VAI /customer (support) Customer ACESITA 2000 AOD-SlabCCM 80 t 470,000 Stainless flat Siemens VAI /customer (support) Siemens VAI /customer (support) ACEIRIERE di Bolzano 1997 AOD-BilletCCM 45 t 250,000 Stainless and alloyed long Customer No level 2 (customer) MICROSTEEL 1997 IF-ADO-VOD-BilletCCM 25 t 100,000 Stainless billets Siemens VAI -TM none ISCOR Pretoria 1996 K-OBM-S 125 t 500,000 Stainless flat Siemens VAI UDDEHOLM (K-OBM-S) POSCO SMP # EAF-AOD-SlabCCM 90 t 600,000 Stainless flat Customer No level 2 (customer) COLUMBUS Stainless 1995 EAF-CLU-SlabCCM-Steckel Mill 100 t 700,000 Stainless flat Siemens VAI (EAF) UDDEHOLM (CLU) Customer Siemens VAI (EAF) UDDEHOLM (CLU) Total stainless steel capacity where SVAI was involved 17,520,000. Page 5

6 Production of stainless steel with alloyed pig iron (API) Delivery of alloyed pigs and storage in compartments in plant A. Charging of API into the EAF at plant A Average chemical composition of API: bulk density: approx. 4 t/m³ API size: approx. 60 x 20 x 10 cm [wt.-%] C Si P S Cr Ni A B C <4.0 ~ <0.2 ~ D <4.0 ~ <0.2 ~ E <4.0 ~ <0.2 ~2.5 >9 Page 6

7 Production of stainless steel with alloyed pig iron (API) Advantages of the API: Iron carrier, alternative to scrap Recycling of dusts from stainless steel production Ni- and Cr-units in API cheaper than in FeNi or FeCr, Fe/Cr free of charge (depending on contract) Disadvantages of API use in the EAF: Lower productivity with increased API rate in the charge Poor melting behavior because of high bulk density and large piece size of API similar to heavy scrap charge Risk of unmolten material in the EAF after tapping possible improvement due to bottom stirring in the EAF Risk of heavy boiling during superheating of the melt Page 7

8 Production of stainless steel with alloyed pig iron (API) API impact on EAF productivity [%] API [%] Tap-to-Tap Metallic yield kwh/t Vessel life Page 8

9 Production of stainless steel with use of dephosphorized liquid hot metal Special AOD practice for the production of ferritics without EAF operation Production of ferritics performed without EAFs due to low cooling effect of FeCr in the AOD The total Cr charged as charge Cr into the AOD during the decarburization stage The melt consists of DeP-hot metal and ChCr Process with use of dephosphorized hot metal for production of austenitics and ferritics is applied at four out of six steelmaking plants in China. Page 9

10 Outcome of miscellaneous dephosphorization processes Different plant operators apply miscellaneous dephosphorization processes. The outcome of those processes are: C Si P T *) [wt.-%] [ C] Plant < Plant < Plant <0.020 >1250 *) Temperature after charging into down streaming process unit Page 10

11 Production of stainless steel with use of dephosphorized liquid hot metal Top lance blowing pattern Page 11

12 Applied different process routes (1/4) Plant A mainly 200 series, also 300 & 400 series API, HCFeCr HCFeMn, Mn Plant B 300 & 400 series SS/C-scrap, API, HCFeCr HCFeCr Page 12

13 Applied different process routes (2/4) Plant C Ferritic route 180 t 30 min 180 t ~60 min 135 t LD premelt ~70 min 40 min 180 t 180 t 160 t EAF premelt 180 t 40 min ~65 min Austenitic route 160 t 150 t LD premelt 75 t LD premelt 75 t LD premelt Page 13

14 Applied different process routes (3/4) HM DeP-HM, HCFeCr Plant D mainly 400 series HM Plant E - 200, 300 & 400 series DeP-HM, HCFeCr, FeNi, Mn HM Page 14

15 Applied different process routes (4/4) Plant F Ferritic route 30 min 50 t ~65 min 35 t DeP-HM ~70 min 50 t 40 t 45 t EAF premelt ~65 min API, HCFeCr Austenitic route 45 t 20 t Page 15

16 Experience of Siemens VAI in use of oxidic alloys in recent projects Advantages of oxidic alloys: Highly profitable No investment for additional equipment Causes no major operational effort Best performance when: Oxides to be charged in the first few decarburization steps Charging at low feeding rates FeSi can be used at some extend as heating and reduction agent during decarburization Alloying with oxides up to 2-4% Page 16

17 Experience of Siemens VAI in use of oxidic alloys in recent projects Chemical composition and prices of materials used for calculations Input as metallic alloy Input as oxide Element name of met. alloy [wt.-%] price/kg element [USD] name of oxide [wt.-%] price/kg element [USD] Mo FeMo MoO Ni Ni-el FeNi NiO V FeV V2O Tungsten ore/wolframite 1) W FeW Tungsten ore/scheelite 1) Tungsten trioxide 1) Page 17

18 Heat calculations for oxidic alloys Stainless steel AISI 316L Preconditions / border conditions Calculations conducted with Siemens VAI Level 2 system for AOD converters EAF premelt, 2.2% C and pre-alloyed Cr, Mo, Ni Carbon in EAF mainly from HC ferroalloys, coal/coke or pig iron 50 t AOD converter with top lance as example of calculations Alloying with both oxidic alloys and ferroalloys Lowering of build-up mass in order to maximize utilization of oxides in the AOD Minimization of iron input from ferroalloys in the AOD in order to minimize mass build-up (shifting of alloying elements into EAF) Page 18

19 Heat calculations for oxidic alloys Stainless steel AISI 316L Compositions of premelt and steel: wt.-% weight [t] C Si Mn P S Cr Ni Mo Cu Premelt EAF AISI 316L Alloy degree in EAF-premelt, alloy degree in AOD, savings, additional costs and profit: Element Alloy degree added in premelt (EAF) [wt.-%] Alloy degree added into AOD by oxide [wt.-%] Savings per kg element/t AOD liq. Steel [USD] Additional costs per kg/t AOD liq. steel [USD] Mo (MoO 3 ) Profit [USD] Ni (NiO) Page 19

20 Heat calculations for oxidic alloys Stainless steel AISI 316L $2 500 $116 Production costs and profit, US$ per MT steel $2 000 $1 500 $1 000 $500 $84 Profit Current alloying element Fluxes and other $0 FeMo MoO3 Ni + FeNi NiO Page 20

21 Heat calculations for oxidic alloys Stainless steel AISI 316L Summary for AISI 316L Slightly higher conversion costs (lime, dolomite and FeSi) Specific costs for process gases, slag deposit, premelt production in EAF constant or negligibly low and significantly influence overall costs Conversion costs with ferroalloys only about $45 per MT steel Conversion costs with oxidic alloys about $47 to $48 per MT steel Profit dependent on price difference between ferroalloy and oxidic alloy and alloying degree with oxidic alloy Profit between $84 and $116 per MT steel Page 21

22 Summary (1/2) Due to the requirement to reduce metallic charge material costs and the limitations in their availability, the use of alloyed pig iron and liquid hot metal has become more popular for the production of stainless steel In all large-scale stainless steel reference plants of Siemens VAI, either alloyed pig iron or liquid hot metal is used For austenitic production, the liquid hot metal is charged into the EAF together with scrap and alloys and subsequently into the AOD For the production of ferritics, a special AOD process technology has been developed and introduced that allows for operation without an EAF, based on De-P hot metal and HCFeCr only For this operation, a special AOD blowing practice and specially designed top blowing lance will be adopted Page 22

23 Summary (2/2) Oxides used as substitutes for ferroalloys of elements such as nickel, molybdenum, vanadium and tungsten Siemens VAI has developed experience how to process oxidic alloys in the stainless and special steel Industry and to increase the profitability of the production. No major investment required (with the exception of extra material bunkers where required) for oxidic alloys Profit between $25 and $425 per MT of steel, depending on the steel grade and the required amount and type of oxidic alloy, including already higher conversion costs when oxides are implemented Page 23

24 Thank you for your attention! Walter A. Gebert Senior Vice President Metallurgical Plants Turmstrasse Linz Phone: +43 (732) Fax: +43 (732) Page 24

25 Back-Up Page 25

26 Production of stainless steel with alloyed pig iron (API) API share in metallic charge for EAF up 75% Impacts of a high API share: High silicon input by HCFeCr and API reason for high slag volume and therefore increased costs for power, O 2, slag formers, refractory and deposit Increase of tap-to-tap time and kwh/t Decrease of metallic yield and vessel life Restrictions of API: Phosphorus content Common stainless steel grades have a P limit of % in final product but the limit can go up to 0.040% and beyond that Special charging and melting procedures to remove P up to 20% Increased process time in the AOD due to higher C-input by HC FeCr and API No use of API for production of Ni-free ferritic stainless steel grades Page 26

27 Production of stainless steel with use of dephosphorized liquid hot metal Gas blowing pattern while AOD operation with hot metal: The use of De-P hot metal can cause high C input and a high starting C content of the melt in the AOD In the high C range from 3.5% C down to approx. 0.3% C relatively soft top blowing with lance and high O 2 flow rates to avoid splashing and to ensure required high decarburization speed In the low C range a hard-blowing low O 2 flow rate operation is required for metallurgical reasons Double-lance operation was introduced and after refining in the high C range the lance be will changed to a hard-blowing single-hole low-flow lance Page 27

28 Arrangement of top lance device Lance with Tip #1: High flow Soft blow Lance with Tip #2: Low flow Hard blow Page 28

29 Heat calculations for oxidic alloys Tool steel AISI H42 Preconditions / border conditions: Calculations done with Siemens VAI Level 2 system for stainless steel converters EAF premelt, 2.2% C and pre-alloyed Cr, Mo, W Carbon in EAF mainly from HC ferroalloys, coal/coke or pig iron 50 t AOD converter with top lance as an example of calculations Alloying residual Mo and W and all V in AOD converter (better V yield in AOD than in EAF) Alloying with both oxidic alloys and ferroalloys Lowering of build-up mass in order to maximize the use of oxides in AOD Minimization of iron input from ferro-alloys in the AOD in order to minimize mass build-up (shifting of alloying elements into the EAF) Page 29

30 Heat calculations for oxidic alloys Tool steel AISI H42 Compositions of premelt and steel: wt.-% Weight [t] C Si Mn P S Cr Mo V W Premelt EAF H42 steel Alloy degree in EAF-premelt, alloy degree in AOD, savings, additional costs and profit: Element Alloy degree added in premelt (EAF) [wt.-%] Alloy degree added into AOD by oxide [wt.-%] Savings per kg element/t AOD liq. steel [USD] Additional costs per kg/t AOD liq. steel [USD] Profit [USD] Mo V (wolframite) W (scheelite) (trioxide) Page 30

31 Heat calculations for oxidic alloys Tool steel AISI H42 $2 500 Conversion costs and profit, US$ per MT steel $2 000 $1 500 $1 000 $500 $185 $25 $333 $294 $425 Profit Current alloying element Fluxes and other $0 Page 31

32 Heat calculations for oxidic alloys Tool steel AISI H42 Summary for AISI H42 Higher conversion costs (lime, dolomite and 2/3 of costs increase by FeSi) Specific costs for process gases, slag deposit, premelt production in EAF constant or negligibly low and significantly influence overall costs Conversion costs with ferroalloys only about $27 to $28 per MT steel Conversion costs with oxidic alloys about $51 to $52 per MT steel Profit dependent on price difference between ferroalloy and oxidic alloy and alloying degree with oxidic alloy Profit between $25 and $425 per MT steel Page 32