EAF burdening How can EAF burdening best utilise DRI? Rutger Gyllenram Kobolde & Partners www.kobolde.com
Disclaimer Examples given in this presentation are just examples, given in order to illustrate the role of DRI properties in burden optimization. Data and calculations are made and presented in good faith and to the best of our ability. However, since every plant and market is unique in some sense evaluations must be made, and conclusions drawn, under the local conditions. The author and Kobolde & Partners AB therefore do not take any responsibility for decisions made based on this presentation. 2
How can EAF burdening best utilise DRI? 1. What effects does partial DRI burdening have on energy consumption, tap to tap time and finished product? 2. How is EAF chemistry affected by DRI use and what is the importance of slag carry over to the ladle? 3. How does DRI analysis affect the possibility of having an MgO saturated slag and low refractory wear? I will try to cover these subjects by making a parameter study and giving examples on how DRI properties affect the result. 3
What effects does partial DRI Limiting the uncertainty in tramp elements Decreasing tramp elements Improve slag foaming Decrease Nitrogen Possibility of a one basket practice burdening have 4
Ore Transport Natural Gas Water Power Oxygen Electrodes Scrap Alloys Slag formers Coal Desox agents Manpower, overhead, capital and maintenance in DR plant and EAF Unloading System boundary Reduction to DRI Screening DRI Melting Steel Slag carry over Desoxidation Desox steel Casting DRI fines Briquetting Ore dust DRI dust CO2 Slag EAF dust Semis RAWMATMIX DRI Option
Model considerations Parameter study Aimed at increasing understanding Changing only a few parameters Basis for ViU but is NOT a ViU DRI amount 0 50 ton for 80 ton steel (desox) Aim at 0.1% C and 0.15% Cu MgO Saturation with FeO=20% and CaO=38% Model from: Selin R., The role of phosphorus, vanadium and slag forming oxides in direct reduction based steelmaking TRITA PT 87 04 ISSN 0284 3013, Stockholm 1987 Calculated with RAWMATMIX DRI option 6
C DRI / HBI data High Si Low Si Low Si+MgO FeTot 89.76 91.81 91.87 Met % 92 92 92 C 2 2 2 S 0 0.0027 0.0027 Fe 82.58 84.46 84.52 Ni 0 0.0053 0.0139 Cu 0 0.0054 0.0054 SiO 2 4.55 1.69 1.48 Al 2 O 3 0.24 0.74 0.56 FeO 9.24 9.45 9.46 MnO 0 0.21 0.14 CaO 0.93 1.05 1.09 MgO 0.23 0.13 0.35 P 2 O 5 0.03 0.08 0.09 V 2 O 5 0 0.07 0.11 TiO 2 0.04 0.07 0.1 Cr 2 O 3 0 0.025 0.012 99.84 99.9884 99.934 Calculated from commercial ore data Same C and Met% 7
Scrap data Premium High Cu Low grade C 0.05 0.05 0.4 Si 0.02 0.02 0.3 P 0.005 0.005 0.02 S 0.01 0.01 0.06 Ti 0.001 0.001 0.001 V 0.001 0.001 0.001 Cr 0.1 0.4 0.2 Mn 0.8 0.8 0.8 Fe 97.098 94.578 92.058 Ni 0.08 0.1 0.3 Cu 0.05 0.5 0.25 Mo 0.03 0.03 0.1 Sn 0.005 0.005 0.01 SiO 2 0.5 1.0 1.0 Al 2 O 3 0.25 0.5 0.5 FeO 1.0 2.0 4.0 Example scrap Focus (scrap scrap): Fe Cu Si Focus (scrap DRI): C P V 8
Prices and consumption figures Prices Materials Lime/lime stone (USD/ton) 120 Dolomitic lime/stone (USD/ton) 150 Lining (USD/ton) 1000 Energy Electricity (USD/kWh) 0.134 Coal/coke additions (USD/ton) 1342 Other Electrodes (USD/kg) 5.369 Process water (USD/m3) 0.134 Slag management (USD/ton) 25 Dust management (USD/ton) 50 Plant cost (USD/hr) 5000 Furnace / charge data Fixed Burners (kwh/charge) 5000 Oxygen (Nm3/charge) 2450 Variable Electrodes (kg/mwh) 4.38 Water (m3/min) 10 Average power on (MW) 45 Average power idle (MW) 4 Idle time (min) 4 Power off time (min) 5 9
Scrap and DRI/HBI in a 80 ton charge 100 Scrap charge aiming at 0.2% Cu 90 Scrap and DRI in charge (ton) 80 70 60 50 40 30 20 DRI Premium scrap High Cu scrap Low grade Sum Scrap Material weight 10 0 DRI amount (High Si) in 80 ton charge (ton) 10
Slag properties (20%FeO, 38%CaO) 12 Slag vs DRI use in 80 ton charge 11.0 MgO saturation vs DRI use in 80 ton charge 10 10.0 8 9.0 Slag amount 6 4 High Si Low Si Low Si + MgO MgO in slag (%) 8.0 7.0 High Si Low Si Low Si + MgO 2 6.0 0 DRI amount in 80 ton charge (ton) 5.0 DRI amount in 80 ton charge (ton) 11
Slag additions 1.40 Lime addition vs DRI use in 80 ton charge 4.00 Dolomite addition vs DRI use in 80 ton charge 1.20 3.50 1.00 3.00 Lime addition (ton) 0.80 0.60 High Si Low Si Low Si + MgO Dolomite addition (ton) 2.50 2.00 1.50 High Si Low Si Low Si + MgO 0.40 1.00 0.20 0.50 0.00 DRI amount in 80 ton charge (ton) 0.00 DRI amount in 80 ton charge (ton) 12
Material and energy costs Relative material cost vs DRI Relative energy related costs vs DRI 30 30 25 25 Material related costs (USD) 20 15 10 High Si Low Si Low Si + MgO Energy related costs (USD) 20 15 10 High Si Low Si Low Si + MgO 5 5 0 DRI amount in 80 ton charge (ton) 0 DRI amount in 80 ton charge (ton) 13
Other and total cost Relative other costs vs DRI Relative total cost vs DRI 50 50 45 45 40 40 Relative other costs (USD) 35 30 25 20 15 High Si Low Si Low Si + MgO Relative cost (USD) 35 30 25 20 15 High Si Low Si Low Si + MgO 10 10 5 5 0 DRI amount in 80 ton charge (ton) 0 DRI amount in 80 ton charge (ton) 14
Tap to tap and productivity (based on energy usage) 70 Tap to tap time (min) 0.0 Relative productivity (%) Tap to tap time (min) 65 60 55 50 45 5.0 10.0 15.0 20.0 25.0 40 High Si 51 54 57 60 63 66 Low Si 51 53 55 57 60 62 Low Si + MgO 51 53 55 57 59 61 30.0 High Si Low Si Low Si + MgO 15
Trace elements in DRI DRI = ore oxygen + additives + C Elements like V and P high affinity to Oxygen Slag carried over from furnace to ladle is reduced into the steel Example 2 Slag carry over 16
Slag carry over (50 ton DRI Low Si + MgO) 0.014 % V and %P as a function of slag carry over kg/ton 0.012 0.01 Steel analysis 0.008 0.006 %V %P 0.004 0.002 0 0 2 4 6 8 10 12 17
Conclusions 18
Conclusions It is not only about scrap and DRI It is about scrap and the right DRI (SSAB) 19