Complex Multiphase Coupling Mechanisms in the Multi-lance Top-Blown Copper Converting Furnace

The multi-lance top-blown converting furnace is pivotal in the converting process of molten white matte (copper content nearly 75 pct) in continuous copper smelting technology. The complex multiphase hydrodynamics and phase interaction mechanisms inherent in this furnace significantly influence converting efficiency of blister copper. This study numerically explores the intricate gas–melt flow hydrodynamics and stirring dynamics in the multi-lance top-blown converting furnace based on the OpenFOAM platform. Following model validation, this study elucidates various aspects of bath dynamics in the furnace. The findings reveal that the arrangement of multiple lances along the longitudinal axis introduces an offset effect on longitudinal momentum transfer and a superposition effect on transverse momentum transfer, unlike the single-lance blowing configuration. A linear empirical relationship between jet momentum number and length group under multi-lance top blowing is established, with a determined constant value of 3.65 for turbulent gas jet. Additionally, a strong correlation between dimensionless cavity shape index and the kinetic energy of molten slag is observed, leading to the formulation of a functional relationship equation demonstrating exponential growth: E_b = exp(− 2.81011–0.79077 \({I}_{\text{cm}}\) $I_{\text{cm}}$ + 0.13479 \({{I}_{\text{cm}}}^{2}\) ${I_{\text{cm}}}^2$ ). Moreover, both the internal flow of molten bath and the shear stress on the furnace wall exhibit a step-like periodic oscillation mode. Notably, based on the similarity observed in the main frequency peaks, a robust correlation between the two phenomena is inferred. Under conditions of small lance spacing and diameter, an increase in the cavity aspect ratio enhances momentum transfer efficiency and stirring performance of bath, but it also exacerbates erosion of the lances and the furnace. This study elucidates the multiphase mixing characteristics, phase interaction mechanisms, and furnace wall erosion patterns in a multi-lance top-blown converting furnace, providing a crucial theoretical foundation for the design, operation, and optimization of such systems.