Water atomisation of molten metals: a mathematical model for a water spray

ABSTRACT

In water atomization, a molten metal stream is fragmented by high-pressure water sprays by means of momentum transfer. In this work, a flat fan water spray is considered as a two-phase flow: water and a surrounding gas. An existing mathematical model for predicting the velocities of water droplets and entrained gas in a flat fan spray is improved. The total momentum flux of a spray is calculated for different spray travel distances, spray pressures and spray spreading angles, addressing the dependence of spray momentum flux on these parameters. A new quantity, the ‘effective momentum flux’, is introduced which also accounts for the effect of apex angle.

Finally, based on the results of lab-scale water atomization experiments, a correlation is proposed for the powder mass median size versus the effective momentum flux of the water spray, consolidating the influence of spray parameters including pressure, travel distance, spreading angle and apex angle.

KEYWORDS:

• Water atomization
• metal powder
• powder size
• flat fan spray
• momentum flux, metal additive manufacturing

Acknowledgements

The authors thank the Natural Sciences and Engineering Research Council of Canada (NSERC) and the University of Toronto Dean’s Catalyst Professorship for funding this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 Spray travel distance is also a function of apex angle, $L=S/sin\left(\alpha \right)$.

Additional information

Funding

This work was supported by Natural Sciences and Engineering Research Council of Canada (NSERC) [Grant Number PGSD3 - 518811 - 2018]; University of Toronto Dean’s Catalyst Professorship.

Notes on contributors

Ali Asgarian

Ali Asgarian is a postdoctoral research fellow at the University of Toronto (UofT), Canada, where he investigates metal powder production processes through simulations and experiments. He actively collaborates with Rio Tinto Metal Powders (RTMP) to implement his research findings in their large-scale plant, and with metal additive manufacturing labs to optimize the metal powder characteristics for additive manufacturing. Ali received his PhD from UofT, where he built a lab-scale water atomizer and studied the water atomization of molten metals. Prior to his PhD, he worked as a senior mechanical engineer at Hatch Ltd., a global consulting engineering firm. He is an active licensed professional engineer in Ontario, Canada with over 10 years of experience in the field of mining and mineral processing, power plants, and process plants. He is also the recipient of several national and international awards including a Postgraduate (Doctoral) Scholarship from the Natural Sciences and Engineering Research Council (NSERC) of Canada, an AIST Foundation’s Steel Scholarship (Smith Graduate), a 1-year Ontario Graduate Scholarship (OGS), a U.S. Steel Canada Fellowship, two ‘Merit a Poster’ awards from POWDERMET international conference, and a gold quality award from Hatch ltd.

Rodolfo Morales

Rodolfo Morales graduated from The University of Tokyo with a PhD degree. He is currently working as Professor at the Department of Materials Science and Engineering-ESIQIE, Instituto Politecnico Nacional, Mexico City. His fields of research are fluid flow dynamics applied to steelmaking and continuous casting, thermodynamics and kinetic of refining processes. Dr Morales has 200 publications in the most acknowledged journals in the field, and has supervised many PhD and MSc students. Dr Morales actively provides consulting to the Mexican and American steelmaking companies. In 2018–2019, he was a visiting Professor at The University of Toronto, Department of Materials Science & Engineering.

Markus Bussmann

Markus Bussmann is a Professor and Chair of the Department of Mechanical & Industrial Engineering at the University of Toronto. For many years he has been involved with modelling the flow, heat transfer and phase change associated with various industrial and materials processes including aspects of kraft chemical recovery, the melting and dissolution of metals and alloys, oil sands processing, and various spray and atomization processes.

Kinnor Chattopadhyay

Kinnor Chattopadhyay is an Associate Professor and Dean’s Catalyst Professor at the Department of Materials Science & Engineering at the University of Toronto. He is an AIST Foundation Steel Professor and the President of Canadian Association of Recycling of Lithium Ion Batteries – CARLIB. For many years he has been involved in improving process metallurgy, especially iron and steel processing, powder metallurgy, and AI/Machine learning in metals.