Hydrodynamic Simulation of Gas - Particle Injection Into Molten Lead

Abstract

A multiphase-hydrodynamic model was solved with the phase field method and the Cahn-Hilliard equation to simulate the behavior of particle injection with nitrogen as conveying gas through a submerged lance into a lead bath in two dimensions. The residence and mixing time were obtained for different operating parameters like gas flow rate, lance depth, and different kettle and lance dimensions. The residence and mixing time decreased when the injection rate and the lance diameter increased. Therefore, the particle will have less opportunity to react with the liquid bath decreasing the refining metal processes efficiency. When the lance height and kettle dimensions were increased, the residence and mixing time also increased. In order to have an efficient disengagement of the particles from the carrier gas within molten lead, the operating parameters must take into account the residence and mixing times. The Cahn-Hilliard equation represents adequately the hydrodynamic behavior in the lance-kettle system studied.

Experimental assessment of the gray cast iron production by inoculant injection

“…Particles were considered to be spherical in shape. Detailed information about the mathematical model and numerical issues can be found in [18,22], where the same methodology was used to study the flow patterns (at lab scale) obtained during the lead and aluminum refining processes by silver and magnesium particle injection, respectively. The numerical simulation was carried out in two dimensions and the lance was located at the centerline of the furnace crucible, as can be seen in Figure 3 where the boundary conditions are also shown.…”

“…They found high effectiveness and stability, based on the silicon composition changes after performing the inoculation through pneumatic injection of the powdered inoculant by argon as a carrier gas into the liquid. Other works related to the powder injection technique are focused on the lead refining process [18][19][20]. The injection efficiency depends mainly on the flow patterns.…”

“…However, particle trajectories are very important as they establish the residence time, which represents the time required for the particles leaving the lance tip until they reach the liquid surface. As residence time increases, the injected particles will have more opportunity to react with the metal bath, and higher efficiencies are achieved [18,19]. The basic requirement for heterogeneous nucleation lies in the ability of the molten iron to wet the inoculant particles.…”