Introduction
Process | Specifications | Injection Mode | Flow Rate | Liquid Steel Composition | Industrial Application Result | References |
---|---|---|---|---|---|---|
Conventional BOF | 30 t | O2–CO2 mixed injection in top blowing | 400 to 800 Nm3/h | liquid iron | average dust generation rate reduced by 12.5 pct, whereas average T-Fe generation in dust reduced by 12.7 wt pct | |
O2–CO2 mixed injection in top blowing and CO2 injection in bottom blowing | top blowing: 500 Nm3/h; bottom blowing: 80 to 160 Nm3/h | liquid iron | contents of [N] and [P] in molten steel reduced by 50 and 23.33 wt pct, respectively | |||
120 t | CO2 injection in bottom blowing | 200 to 500 Nm3/h | liquid iron | nitrogen content in finished steel reduced from 30 to 70 ppm to a level consistently lower than 40 ppm | ||
300 t | O2–CO2 mixed injection in top blowing | O2–(5 to 10 vol pct) CO2 mixed injection in top blowing | liquid iron | dephosphorization rate increased by 6.99 pct and the dust amount decreased by 2.65 pct, CO content in the furnace gas increased by 2.66 vol pct, and the converter gas volume increased by 5.24 Nm3/t steel. | ||
Dephosphorization BOF | 300 t | O2–CO2 mixed injection in top blowing and CO2 injection in bottom blowing | top blowing: 2400 to 7000 Nm3/h; bottom blowing: 800 to 3000 Nm3/h | liquid iron | end-point carbon content increased from 3.19 to 3.26 wt pct and end-point phosphorus content decreased from 0.051 to 0.044 wt pct | |
Vanadium-Extraction BOF | laboratory research | — | — | — | top-blowing style saved more carbon during the vanadium-extraction process, whereas it oxidized more vanadium to the slag phase compared with the bottom-blowing style | |
EAF | 75 t | bottom blowing CO2 gas | 80 to 100 L/min | 50 wt pct liquid iron and 50 wt pct scrap | average nitrogen content of the final molten steel with bottom-blown Ar is 55.6 × 10−6 whereas it is 46.2 × 10−6 with bottom-blown CO2 | |
LF | 60 t/200 t | bottom blowing CO2 gas | 90 to 800 L/min | Al-killed steel | induces small additional deoxidizer losses but no deterioration in the purity of the final product. | |
70 t | Ar–CO2 | total gas flow 20 to 300 L/min | 45# grade | equal yield density of inclusions decreases where there is only a slight increase in [O] and [N] contents in molten steel under CO2 blowing | ||
RH | 120 t | CO2 | 80 to 100 Nm3/h | Al-killed steel | selective oxidation of carbon and oxygen can occur between CO2 and molten steel in vacuum; CO2 can react with a small portion of [C], enhancing the RH stirring intensity | |
AOD | laboratory research | — | — | — | CO2 injection is beneficial for reducing Cr loss in molten steel, and the reaction rate of CO2 and C is slow; high proportion of CO2 injection will not only make the bath temperature too low but will also prolong the smelting cycle |
Liquid Composition | Experimental Method | Gas Phase Composition | Flow Rate and Pressure | Temperature | References |
---|---|---|---|---|---|
2 g Fe–4 wt pct C | levitated drop method | CO2 | 100 to 1200 mL·min−1 | 2053 K | |
300 g molten iron, containing Si, Cr, and Mn wC = 0.5 to 2 pct | crucible method, gas injection at 7 mm above molten pool | CO2–Ar φCO2 = 5.9 to 58.8 pct | 1700 mL·min–1 | 1873 K | |
4 to 7 g Fe–1 wt pct C | levitated drop method | CO2–Ar φCO2 = 0 to 8 pct | 262 to 305 mL·min–1 | 1803 K | |
400 g Fe–C wC = 0.02 to 0.05 pct | crucible method, gas injection at 5 mm above molten pool | CO2–Ar pCO2/pAr = 1/1, 1/4, 1/5, 1/10, 1/20, and 1/40 | 1300 mL·min–1 | 1873 K | |
Fe–C wC = 0.02 to 0.05 pct | crucible method, gas injection at 5 mm above molten pool | Ar–CO–CO2 | 1300 to 1600 mL·min–1 | 1873 K | |
Fe–4 wt pct C–0.3 wt pct S Fe–0.1 wt pct C | a horizontal furnace a vertical furnace | CO–CO2–H2 φCO2 = 2.2 to 9 pct | U = 13 to 52 cm/s | 1800 K | |
Fe–5/5.5 wt pct C Fe | high pressure levitation cell | CO–CO2 φCO2 = 1.1/2.15 pct | 40 atm | 1923 K | |
carbon-saturated liquid iron at sulfur concentrations between 0.01 and 1 wt pct | crucible method, gas injection at 3 mm above molten pool | CO2–Ar φCO2 = 0.25 to 0.5 pct | 20 L/min 1 atm | 1553 K and 1873 K | |
Fe–C–S wC = 2.48 pct/0.92 pct wS = 0.027 to 0.148 pct | levitation drop method | CO2–CO φCO2 = 0.25 to 0.5 pct | 1000 mL/min | 1973 K | |
Fe–Csat liquid alloys containing S, P, Sn, and Pb | crucible method, gas injection at 10 mm above molten pool | 10 pct CO2–Ar | 10 L/min | 1873 K | |
20 g carbon-saturated Fe–0.2 wt pct S | crucible method, gas injection at 10 mm above molten pool | Ar–CO2–H2O | 4 to 16 L/min | 1773 K | |
0.8 g Fe–C alloys containing S, P, and Cr | levitation drop method | CO2–N2–CO | 0.002 to 0.01 m3/min | 1723 K | |
0.8 g Fe–C–S alloys wC = 3.4 pct | levitation drop method | O2–CO2–H2O–H2O–He φCO2 = 10 to 16 vol pct | 1 atm 0.01 m3/min | 1723 K | |
80 to 110 g Fe–C–Si wSi = 0.08 to 0.71 pct | crucible method, electric resistance furnace | CO2 CO2–Ar | 10 mL/min | 1573 K | |
90 g Fe–C–S alloys wC = 3.77 to 4.60 pct, wSi =0.14 to 2.78 pct | vertical SiC electric resistance furnace, jets were inserted in the furnace | CO2–O2 | 10 to 12 mL/min | 1573 K | |
800 g Fe–4 wt pct C or commercial type metal | induction melting, lance tip was kept at about 40 mm above the bath surface | CO2–O2–CO–Ar–N2 | 4 to 14 L/min | 1723 K | |
6 kg high-purity electrolytic iron | vacuum induction furnace | Ar–CO2 | 0.4 bar 0.1 L/min | 1873 K | |
25 g Fe–Cr–C alloy in a horizontal furnace 1 kg Fe–Cr–C alloy in an induction furnace thermogravimetric analysis | O2–CO2 | 1670 mL/min | 1873 K | ||
0.7 g Fe–Cr–Csat 10, 17, and 20 wt pct Cr | electromagnetic levitation method | 30 vol pct CO2–Ar | 100, 1000, 3000, and 12,200 mL/min | 1873 K | |
Fe–C melts wC = 1 to 4 pct | isotope tracing method crucible method, 1 to 2 cm of gas injection height | 13CO2–18O2–Ar | 30 to 60 mL/min | 1873 K | |
Fe–C melts wC = 0 to 2 to 8 pct | isotope tracing method crucible method, 2 cm of gas injection height | O2–CO2 13CO2–18O2 | 40150 mL/min | 1873 K |
Theoretical Calculation
Process Description
Modeling Assumptions
Model Setup
Phase | Material | Standard State | Gibbs Free Energy of Standard Molar Formation \(\Delta {{}_{f}G}_{m}^{\theta }\) J/mol | Reaction Equation | Equation Order |
---|---|---|---|---|---|
Gas Phase | O2 | pure substance in gas phase | 0 | — | — |
CO | pure substance in gas phase | –117,934.9 – 84.01 × T | C(graphite) + 0.5O2 = CO | [10] | |
CO2 | pure substance in gas phase | –396,476.3 – 0.045 × T | C(graphite) + O2 = CO2 | [11] | |
Metal Phase | C | 1 wt pct Henrian activity | 22,590 – 42.26 × T | C(graphite) = [C] | [12] |
O | –117,150 – 2.89 × T | 0.5O2 = [O] | [13] | ||
Fe | pure substance in liquid phase | 13,762 – 7.6 × T | Fe (s) = Fe (l) | [14] | |
Slag Phase | FeO | pure substance in liquid phase | –229,114.5 + 42.996 × T | Fe (s) + 0.5O2 = FeO (l) | [15] |
Calculating Results and Analysis
Reaction Process of CO2 Continuously Injected into the Fe–C Melt with Medium Carbon Content
Temperature (K) | Metal Phase Mass (g) | Initial Carbon Content (Wt Pct) | Initial Oxygen Content (Wt Pct) | CO2 Flow Rate (mL min–1) | Time (min) |
---|---|---|---|---|---|
1873 | 1000 | 2 | 0.0012 | 1000 | 60 |
Reaction Process of CO2 Continuously Injected into the Fe–C Melt with Extremely Low Carbon Content
Temperature (K) | Metal Phase (mass/g) | Initial Carbon Content (Wt Pct) | Initial Oxygen Content (Wt Pct) | CO2 Flow Rate (mL min–1) | Time (min) |
---|---|---|---|---|---|
1873 | 1000 | 0 | 0 | 100 | 60 |
Experiments and Discussion
Item | Mass (g) | Initial Carbon Content (Wt Pct) | Temperature (K) | CO2 Flow Rate (mL·min–1) | Injection Intensity (mL·min–1·g–1) |
---|---|---|---|---|---|
1 | 600 | 0.048 | 1873 | 100 | 0.1667 |
2 | 600 | 0.039 | 1873 | 100 | 0.1667 |
3 | 600 | 0.029 | 1873 | 100 | 0.1667 |
4 | 600 | 0.01 | 1873 | 100 | 0.1667 |
5 | 600 | 0.0056 | 1873 | 100 | 0.1667 |
6 | 600 | 0.0042 | 1873 | 100 | 0.1667 |
Experimental Apparatus and Process
Elements | C | Si | Mn | P | S | O |
---|---|---|---|---|---|---|
ppm | 4 | < 5 | 4 | 3 | 4 | 60 |