Coating powder beds with liquids and foams based on viscous formulations using a twin screw mixer: A continuous process study (Open Access)--颗粒学报PARTICUOLOGY

Manga, M. S., Kontziampasis, D., Al-Maqdad, M., Clifford, S., Bakalis, S., & York, D. W. (2024). Coating powder beds with liquids and foams based on viscous formulations using a twin screw mixer: A continuous process study. Particuology, 93, 364-376. https://doi.org/10.1016/j.partic.2024.07.012

Coating powder beds with liquids and foams based on viscous formulations using a twin screw mixer: A continuous process study (Open Access)

Mohamed S. Manga^{a 1 *}, Dimitrios Kontziampasis^{a b c d 1 *}, Mustafa Al-Maqdad^a, Sean Clifford^{e f}, Serafim Bakalis^{f g}, David W. York^a

a School of Chemical and Process Engineering, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, LS2 9JT, UK
b School of Mechanical Engineering, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, LS2 9JT, UK
c School of Science and Engineering, University of Dundee, DD1 4HN, Dundee, Scotland, UK
d Dundee International Institute of Central South University, Tongzipo Road, Central South University, Changsha, Hunan, 410013, China
e Department of Chemical Engineering, School of Engineering, University of Newcastle, Newcastle, NE1 7RU, UK
f School of Chemical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
g Department of Chemical Engineering, Faculty of Engineering, University of Nottingham, NG7 2RD, UK

10.1016/j.partic.2024.07.012

Volume 93, October 2024, Pages 364-376

Received 19 March 2024, Revised 15 July 2024, Accepted 18 July 2024, Available online 31 July 2024, Version of Record 6 August 2024.

E-mail: mohamedsmanga@gmail.com; dkontziampasis001@dundee.ac.uk; d.kontziampasis@gmail.com

Highlights

• Novel method for continuous coating of powders using foam.

• New continuous powder coating assessment method for foams and liquids.

• Image analysis proves coating quality is optimal when using foam.

• Scaling up has minor effect on coating quality.

• Coating quality depends on rheological properties of the coating liquid.

Abstract

Coating with viscous formulations has been essential in numerous industries as it can be a means for providing functionalization, additional properties, as well as other benefits. However, there have been scarce studies that have investigated and proposed methodologies in literature. Continuous coating of powders with viscous liquids poses as a promising technology, which has been mentioned in some studies, but has not yet been thoroughly investigated. This paper employs the use of image processing and analysis, in combination with statistical analysis of particles to evaluate the effectiveness of foams and liquids as a means of coating powder beds. Two different sizes of twin screw mixers that are working in continuous operation are employed, and a new continuous foaming device is fabricated and used for the experiments of coating. The effect of materials and process parameters (as for example rotational speed, and flowrate) on the quality of coating are investigated. Image analysis is used to assess the coating quality. The results clearly showcase the potential of using twin screw mixers for coating purposes and not only for mixing. The hypothesis that using large bubble foams to improve the coating of viscous liquids on particles is proven correct, as they provide higher quality coatings compared to their equivalent liquids, when used in the twin screw mixer. Surprisingly, using a larger scale twin screw mixer, does not show a substantial effect on the mixing, regarding quality, however there is still a requirement for mix optimization for achieving scale-up of this process. These results provide a new pathway for coating powders with viscous formulations in industrial applications, requiring less energy and effort in this process, and can pave the way towards introducing more sustainable industrial methodologies for coating.

Graphical abstract

Keywords

Powder coating; Continuous processing; Viscous liquid; Foam; Image analysis; Positron emission particle traking (PEPT)

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