122nd General Meeting of the KCS

Type Poster Presentation
Area Environmental Energy
Room No. Grand Ballroom
Time 10월 18일 (목요일) 11:00~12:30
Code ENVR.P-507
Subject CFD Modeling of the Effect of Bubble Two Bubble Sizes on Bubble-Particle Interaction Rate in a Column for Deinking
Authors Allan Gomez Flores, Gukhwa Hwang, Sowon Choi, JunHyuk You, Hyunjung Kim*
Department of Resources and Energy Engineering, Chonbuk National University, Korea
Abstract Paper recycling is important due to economic and environmental reasons. Removal of ink from waster paper is necessary to obtain proper pulps for production of recycled paper. Waste paper can be paper from books, newspapers, or other printed material. Removal of ink can be achieved by froth flotation using an agitated tank or an aerated column. It has been reported that big bubble sizes are not beneficial to float fine particles. Ink particles can be agglomerated using reagents. The ink particles are hydrophobic and have a wide range of sizes, from 1-1000 µm. In this work, ink particles of diameter of 60 µm with a contact angle of 30 degrees were used in CFD modeling. The particles had a density of 2600 kg/m3, were monosized, and their concentration was 1% v/v. Two air bubble diameters of constant size were modeled, relatively large bubbles of 5 mm and small bubbles of 1 mm. The air injection was 7 l/min. Drag and turbulent dispersion forces and gravity were considered. Flotation kinetics consisted of three processes of bubble-particle interaction, which are collision, attachment and detachment. Each process was represented as probabilities and taking in account turbulence. The results showed that the number of attached particles increased as bubble size decreased. In fact, when bubbles of 5 mm diameter were used, the flotation was only 10% measured as fraction of floated particles after 320 seconds of flotation. Fine particles tend to avoid collision by following liquid streamlines around a rising bubble, especially for large bubbles. In addition, net attachment rates inside the column are higher when the bubble size is small. Therefore, flotation in aerated columns can be improved by reducing bubble size, as well as including mixing. **This research was supported by the Korea Energy and Mineral Resources Engineering Program (KEMREP).** References [1] Chaiarrekij, S., H. Dhingra, and B. V. Ramarao. "Deinking of recycled pulps using column flotation: energy and environmental benefits." Resources, conservation and recycling 28.3-4 (2000): 219-226. [2] Beneventi, D., et al. "Hydrodynamics and recovered papers deinking in an ozone flotation column." Chemical Engineering and Processing: Process Intensification 48.11-12 (2009): 1517-1526. [3] Vashisth, Subhashini, et al. "Column Flotation Deinking: State-of-the-art and opportunities." Resources, Conservation and Recycling 55.12 (2011): 1154-1177. [4] Sarhan, A. R., J. Naser, and G. Brooks. "CFD model simulation of bubble surface area flux in flotation column reactor in presence of minerals." International Journal of Mining Science and Technology (2018). [5] Sarhan, A. R., J. Naser, and G. Brooks. "CFD modeling of bubble column: Influence of physico-chemical properties of the gas/liquid phases properties on bubble formation." Separation and Purification Technology 201 (2018): 130-138.
E-mail adgfo@jbnu.ac.kr