Characterization of gas–liquid two-phase mixing state in pyrometallurgical process of non-ferrous metal by electrical resistance tomography

Due to the complex mixing state (i.e., highly transient characteristics and spatial inhomogeneity) in the pyrometallurgical processes for non-ferrous metals, traditional methods have been unable to realize real-time visualization and quantitative description of the gas–liquid two-phase flow structure. In this work, the gas–liquid two-phase mixing state, its dynamic changes and structural evolution were studied, with electrical resistance tomography (ERT) as the core technology, integrating experimental design, algorithmic characterization, and quantitative evaluation. Specifically, focused on precise gas–liquid mixing state characterization, this work first used an orthogonal test with key parameters, including liquid-phase temperature, gas-phase flow rate, and injection pipeline immersion depth to verify mixing state, then applied ERT to characterize its dynamic changes, combined numerical measurement with K-means to reveal evolution from disorder to order, and used centroid tracking to evaluate uniformity, which constitutes a systematic characterization strategy. Results show that the ERT can be used to effectively reconstruct the flow image, and the real-time imaging accuracy is 87.31%. The orthogonal test revealed the interaction among temperature, flow rate, and immersion depth. The temperature had a significant effect on the mixing state, while the immersion depth and air intake complemented each other and affected the mixing state together. In all working conditions, the combination of temperature of 35 °C, flow rate of 25 l/min, and immersion depth of 160 mm achieved the best mixing state. This work provides reliable data support and theoretical basis for the visual expression and the control of mixing state.