Dynamic Basic Oxygen Steelmaking Process and Its Industry Validation

Abstract

The simulation of the basic oxygen steelmaking process was conducted, incorporating transient compositions, temperature, and weight of liquid steel and slag. The simulation utilized a 3-reactor model that considered the thermodynamics of chemical reactions and the kinetic limitations governed by mass transfer. Additionally, the kinetics of scrap dissolution were taken into account. To describe the different parts of the combined blown oxygen steelmaking converter (top and bottom), three interconnected adiabatic reactors were employed. The refining reactions of the basic oxygen steelmaking process were perceived using the macro programming facility of FactSage™ software. Based on the model, the scrap dissolution time was determined to be 510 s, 400 s, and 300 s for scrap radii of 0.25 m, 0.18 m, and 0.14 m, respectively. The model’s predictions aligned well with the plant data regarding the removal of carbon, silicon, and phosphorus with respect to blowing time.

Appendices

Appendix 1

Wt. of liquid melt = 145000 Kg

Number of openings in lance = 6

Bath Depth (H) = 1.40 m

Bottom Stirring Flow Rate (Q) = 2.5 Nm³/min

Total metal surface area ($A_{p}$) = 0.0773 m²

The density of liquid metal ($\rho_{m}$) = 7200 kg/m³

A blowing Regime is defined as the following:

If 0 < t < 135 s; Lance height (h) = 2.30 m

If 135 < t < t < 350 s; Lance Height (h) = 1.90 m

If t > 350 s; Lance Height (h) = 170 cm

Appendix 2

Scrap dissolution model

The following value is taken from [Ref: 4]

[A = 5.4, β = 0.0000062, $T^{\prime}$ = 1810–90C, 0 $\le C \le 4.27$

$T^{\prime} = 1425$, C $\ge 4.27$, $\gamma = \rho C_{p}^{{{\text{sc}}}} \beta$ and $C_{p}^{{{\text{sc}}}} = 17.49 + 24.769 \times 10^{ - 3 }$ T, (J/mol-K)

Increasing the temperature of liquid metal to interface temperature due to scrap melting is

$$ \Delta H_{{{\text{Fe}}}} = \Delta h + C_{p}^{{{\text{sc}}}} \left( {T_{m} - T^{\prime}} \right) $$

(23)

Estimation of the temperature inside scrap is

$$ T_{sc} \left( {x,t} \right) = T^{\prime} + \mathop \sum \limits_{n = 1}^{\infty } A_{n } \sin \frac{n\pi x}{{2L}} {\text{exp}}\left( { - \gamma^{2} Dt} \right) $$

(24)

The melting rate of scrap v (m/s), into liquid iron was We obtained scrap melting velocity v (m/s), by conservation of heat equation at the solid-melt interface, which is

$$ k_{h} A\left( {T_{m} - T^{\prime}} \right) = \rho A\left( { - \Delta H_{{{\text{Fe}}}} } \right)v - \gamma A\frac{{\partial T_{{{\text{sc}}}} \left( {x,t} \right)}}{\partial x} $$

(25)

The amount of scrap melting per sec is

$$ \frac{{{\text{d}}W_{{{\text{sc}}}} }}{{{\text{d}}t}} = \rho Av $$

(26)

Fe-Fe₃C (%0.51 Si, % 0.36 Mn)