Estimation of Flow Properties and Process Simulation on Multiphase Melts

Abstract

In the process of steelmaking refining, slag used in the preliminary treatment of molten iron or the converter is a multiphase melt. It contains solid particles that cannot dissolve entirely from the raw materials and gas bubbles generated through reactions, thus making it a multiphase molten material with dispersed components. The flow characteristics of the suspensions, foams, and emulsions significantly affect the separation of iron particles in the slag and the behavior of slag discharge. Multiphase melts typically behave as non-Newtonian fluids, so the evaluation, focusing on viscosity, is crucial to understanding their flow characteristics. This report reviews recent advances in slag visualization techniques for understanding the flow of multiphase molten materials. The results are as follows:

Through studies of viscosity measurements of multiphase melts using rotational viscometers, falling-ball methods, and dam break methods in cold experiments with simulated slag and high-temperature experiments with slag compositions close to practical operation, it has been shown that the apparent viscosity increases with an increase in the volume fraction of solid particles and bubbles. The complex behaviors of the viscosity measurement values could have been reproduced with high precision using predictive models based on recent developments in machine learning. In terms of process evaluation, the application of mesh and mesh-free methods is advancing as methods of computational fluid dynamics (CFD) that take non-Newtonian behavior into account, providing valuable insights into evaluating slag discharge properties and more.