Inclusion interactions during flotation in liquid metals – FLOTINC

The production of high performance metallic materials is a strategic challenge for the European metallurgy with the aim of efficiently competing with emerging market economies.
In this respect, inclusion cleanliness is a major challenge, since it strongly influences the mechanical performance of metallic alloys, and can reduce the weight of metallic parts.

Ladle treatment of liquid metal by gas injection has been pointed out for a long time as the processing stage mainly responsible for the inclusion cleanliness of steels, aluminium alloys and speciality steels. In these reactors, inclusions are recovered by the combination of settling and flotation. Such processes aim at both, depleting the population of inclusions and controlling the size of the biggest remaining inclusions. The first objective benefits from inclusion aggregation because bigger aggregates are more easily eliminated by sedimentation and flotation, but the need to limit the inclusion size imposes a strict upper bound to this process. Optimizing operating conditions to provide well balanced aggregation kinetics is a key issue to guarantee process efficiency and cleanliness of the cast liquid.

In spite of their critical impact on industrial operations, aggregation mechanisms of inclusions in liquid metal are still not fully understood, nor adequately captured by correlations that could be used in process modeling and design due to their inherent complexity.
This lack of knowledge furthermore results from the complexity of experiments with liquid metals, as well as from the multi-scale nature of the problem which makes it impossible for state-of-the-art simulations to capture all the physics at once.

FLOTINC addresses these two bottlenecks by an innovative multi-scale concept dedicated to the fundamental aspects of the aggregation dynamics of inclusions during flotation. It combines the two decisive scales, the scale of bubbles and bubble groups on one hand and the scale of inclusions and inclusion interactions on the other hand. This is made possible by four teams joining forces, two teams of experimentalists and two teams of simulation specialists, each employing recent cutting-edge technologies developed by the respective researchers.
At the small scale, collaborative experiments and simulations are conducted, and the same is done on the large scale.
The link between inclusion aggregation and bubbly flow conditions is mainly established by the simulations. They allow local properties of the larger scales to be used as input for the smaller scales,
while resolution of the processes on the small scales provides sub-models for the large scales.
In this way, the wide spectrum of coupled physical mechanisms at different scales can be captured as a whole.

Physical analyses will provide new and valuable information on aggregation and flotation in metallurgical processes and on strategies for their control.
The experimental and numerical results will be expressed in the form of statistical kernels, that will provide industries and further research with quantitative aggregation models.
These will be applicable to a wide variety of metallurgical processes and substantially improve the predictive capacity of simulations on the industrial scale.

Addressing the industrial challenge of inclusion cleanliness, this project perfectly matches the axis “Matériaux et Procédés” of the challenge “Stimuler le renouveau industriel”