Department of Casting and Material Working at the National University of Science and Technology MISiS, Moscow, Russia:

A. V. Koltygin, Associate Professor, Candidate of Technical Sciences, e-mail: koltygin.av@misis.ru
A. V. Pavlov, Postgraduate Student, e-mail: pavloveone@mail.ru
V. E. Bazhenov, Associate Professor, Candidate of Technical Sciences, e-mail: v.e.bagenov@gmail.com
A. A. Nikitina, Category I Trainer, e-mail: nikitina.misis@gmail.com

This paper describes some physical models with an impeller that simulate the process of blowing molten magnesium with inert gas (argon) in model media (liquid and gas) aimed at removing non-metallic inclusions from the melt. A 7% aqueous solution of NaCl and air were used as model media selected on the basis of similarity principle. A prototype impeller designed in house was tested and a transparent physical model – used. It is shown that the blowing efficiency is determined by the bulk distribution density of gas bubbles, which is associated with the impeller RPMs and gas flow rate, as well as with the geometry of the impeller. It was established that when using the developed impeller design the amount of bubbles dispersed in liquid is to a significant extent dictated by the impeller RPMs and to a lesser extent – by the gas flow rate. When the gas flow rate exceeds a certain threshold, it won’t lead to any increase in the amount of gas bubbles, nor in the volume of the blown liquid. In the course of the study and when using the proposed impeller design, the authors defined a metal treatment regime that would ensure a distribution of small gas bubbles across almost the entire volume for a cylinder-shaped crucible with the diameter of 660 mm and the height of 1,140 mm of a commercial magnesium smelter (with the impeller speed equal to 488 min^–1 at the argon flow rate of ~15.6 l/min).

1. Polmear I. J. Magnesium alloys and applications. Materials Science and Technology. 1994. Vol. 10. pp. 1–16.
2. Polmear I. J. Light alloys: from traditional alloys to nanocrystals. Elsevier, 2005. 421 р.
3. Shalomeev V. A. Improved macro- and microstructure of aircraft castings made of magnesium alloys. Vestnik dvigatelestroeniya. 2013. No. 1. pp. 127–132.
4. Ignatov M. N., Pshenichnikov A. F., Mukhina E. V., Balakhnin N. I., Kurganov A. A. et al. Removing solid oxides from magnesium alloys by purging with neutral gases. Vestnik Permskogo gosudarstvennogo tekhnicheskogo universiteta. Mekhanika i tekhnologiya materialov i konstruktsiy. 2002. No. 5. pp. 39–43.
5. Mukhina I. Yu. Casting alloys and technical processes in magnesium castings production. Liteynoe proizvodstvo. 2003. No. 4. pp. 18, 19.
6. Ghali E., Dietzel W., Kainer K.-U. General and localized corrosion of magnesium alloys: A critical review. Journal of Materials Engineering and Performance. 2004. Vol. 13. pp. 7–23.
7. Balart M., Patel J., Fan Z. Melt protection of Mg – Al based alloys. Metals. 2016. Vol. 131, Iss. 6. DOI: 10.3390/met6060131
8. Mirak A. R., Davidson C. J., Taylor J. A. Study on the early surface films formed on Mg – Y molten alloy in different atmospheres. Journal of Magnesium and Alloys. 2015. Vol. 3, Iss. 3. pp. 173–179.

9. Xiong S., Wang X. Protection behavior of fluorine-containing cover gases on molten magnesium alloys. Transactions of Nonferrous Metals Society of China. 2010. Vol. 20, Iss. 7. pp. 1228–1234.
10. Mukhina I. Yu., Duyunova V. A. Smelting of magnesium alloys in shielding media: Process fundamentals. Liteynoe proizvodstvo. 2021. No. 1. pp. 9–15.
11. Bobryshev B. L., Moiseev V. S., Aleksandrova Yu. P., Moiseev K. V., Bobryshev D. B. et al. Enhanced processing of magnesium alloys during smelting. Tekhnologiya legkikh splavov. 2021. No. 3. pp. 35–44.
12. Volkova E. F., Mukhina I. Yu. Novel magnesium-base materials and high-resource processes of making them. Tekhnologiya legkikh splavov. 2007. No. 2. pp. 28–34.
13. Bobryshev B. L., Moiseev V. S., Kipin I. A., Petrov I. A. Structure and properties of alloy ML5 under different inoculation methods. Izvestiya vuzov. Tsvetnaya metallurgiya. 2019. No. 4. pp. 23–29.
14. Bobryshev B. L., Moiseev V. S., Sidyakin V. A., Popkov D. V., Bobryshev D. B. et al. Method for flux-free melting of magnesium alloys of magnesium – aluminum – zinc – manganese system and device for its implementation. Patent RF, No. 2701248. Applied: 25.06.2018. Published: 25.09.2019.
15. Okulov A. B., Yudin V. A., Koltygin A. V., Bazhenov V. E., Nikitina A. A. et al. Device for refining liquid magnesium alloy by blowing. Patent RF, No. 2745049. Applied: 07.08.2020. Published: 18.03.2021.
16. Yakimov V. I., Kalinin A. T., Yakimov A. V. Facility to treat magnesium alloys by gases in process of flux-free preparation. Patent RF, No. 2173722. Applied: 27.07.2000. Published: 20.09.2001.
17. Liu Y., Zhang Z., Masamichi S., Zhang J., Shacy P. et al. Improvement of impeller blade structure for gas injection refining under mechanical stirring. Journal of Iron and Steel Research International. 2014. Vol. 21, Iss. 2. pp. 135–143.
18. Hernández-Hernández M., Camacho-Martínez J. L., González-Rivera C., Ramírez-Argáez M. A. Impeller design assisted by physical modeling and pilot plant trials. Journal of Materials Processing Technology. 2016. No. 236. DOI: 10.1016/j.jmatprotec.2016.04.031
19. Zhang L., Lv X., Torgerson A. T., Long M. Removal of impurity elements from molten aluminum: A review. Mineral Processing and Extractive Metallurgy Review. 2011. Vol. 32, Iss. 3. pp. 150–228.
20. Saternus M., Merder T. Physical modelling of aluminum refining process conducted in batch reactor with rotary impeller. Metals. 2018. No. 8. 726.
21. Saternus M., Merder T. Physical modeling of the impeller construction impact on the Aluminum Refining Process. Materials. 2022. No. 15. 575.