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1

Study on bubble characteristics of flotation column in hematite reverse cationic flotation process

Wang Weizhi, Han Jikang

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 1

64--75

EN

In the self-designed flotation column simulation system, the foaming characteristics of the micro-bubble countercurrent contact flotation column used in the hematite cation column flotation process are systematically studied. The objective of this study is to investigate the bubble generation by a bubble generator in the flotation column. The bubble image was obtained by the high-speed camera recorder, and the bubble diameter was calculated and analyzed by image processing software. The distribution characteristics of the bubble size under different aeration conditions and with different reagent concentrations were investigated. The results show that as the aeration increases, the average diameter bubbles increases, the bubble size distribution changes from narrow to wide, and the number of small bubbles decreases. The cationic collector GE-609 can change the bubble shape. As the concentration increases, the bubble shape gradually changes from an irregular shape to a standard spherical shape. When the concentration of GE-609 exceeds 2.5 mg/dm3, the average circularity C of the bubbles in the bubble group stabilizes at 1, and the increase in concentration no longer changes the bubble shape. GE-609 also has an efficient foaming effect, as the concentration increases, the bubble diameter distribution changes significantly, the proportion of small bubbles increases, and the proportion of large bubbles decreases significantly. When the critical concentration is exceeded, the bubble diameter distribution probability density peak width no longer changes significantly. Compared with the two types of alcohol foaming agents, GE-609 produces a bubble Sauter diameter close to that of 2-octanol and slightly lower than terpineol.

2

Modelling and measurement of bubble formation and growth in electroflotation processes

Sarkar S. K., Machniewski P.M., Evans G.M.

Chemical and Process Engineering

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2013

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Vol. 34, nr 3

327--336

EN

Electroflotation is used in the water treatment industry for the recovery of suspended particles. In this study the bubble formation and release of hydrogen bubbles generated electrolytically from a platinum cathode was investigated. Previously, it was found that both the growth rate and detachment diameter increased with increasing wire diameter. Conversely, current density had little effect on the released bubble size. It was also found that the detached bubbles rapidly increased in volume as they rose through the liquid as a result of decreasing hydrostatic pressure and high levels of dissolved hydrogen gas in the surrounding liquid. The experimental system was computationally modelled using a Lagrangian-Eulerian Discrete Particle approach. It was revealed that desorption of gaseous solutes from the electrolyte solution, other than hydrogen, may have a significant impact on the diameter variation of the formed bubbles. The simulation confirmed that liquid circulation, either forced or induced by the rising bubble plume, influences both the hydrogen supersaturation (concentration) in the neighbourhood of the electrode and the size of the resulting bubbles.

3

Confined fluidised bed porosity in the light of bubbling-bed models

Zabierowski P.

Chemical and Process Engineering

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2012

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Vol. 33, nr 3

431-444

EN

Based on hydrodynamic data, Kato-Wen and Kunii-Levenspiel bubbling-bed model parameters, supplemented with assumptions characteristic for tested confined fluidised bed, were analysed. The calculated bubble diameters and the bed composition proved essential influence of inter-particle space of packed compacted component onto fluidisation character. The usability of the conducted model analysis was also confirmed. Finally, it can be concluded that Kunii-Levenspiel and Kato-Wen models with characteristic assumptions (for the tested bed) can be applied for calculation of the confined fluidised bed layer porosity. Discrepancies of [epsilon]f value, determined on the basis of the above mentioned bubbling-bed models do not exceed 8% of the error. The model parameters obtained from the matching the model relations to experimental data[epsilon]f = f(uo) allow an analysis of the fluidisation character as well as gas velocity regime and the fluidised bed structural composition identification. A description of the regime of the process in which confined fluidised bed is characterised with an increase of mass and heat transfer rate is also possible using relation (17) derived in the present study.

4

Powierzchnia miedzyfazowa gaz - ciecz w roztworach białka serwatkowego napowietrzanych we współprądowej kolumnie barbotażowej

Hołowacz I., Kawalec-Pietrenko B., Kucharska K.

Inżynieria i Aparatura Chemiczna

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2009

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Nr 6

83-84

PL

Badano własności zawiesiny komórek drożdży Saccharomyces cerevi-siae poddanych dezintegracji w młynie perełkowym. Stopień dezintegracji komórek wyznaczono na podstawie stężenia uwolnionego białka. Własności reologiczne zawiesiny mierzono cylindrycznym re-ometrem rotacyjnym z podwójną szczeliną. Wykazano wpływ energii kinetycznej wypełnienia młyna na nieliniowość przebiegu procesu i zmiany lepkości pozornej zawiesiny.

EN

Properties of suspension of yeast Saccharomyces cerevisiae cells disintegrated in a bead mill were investigated. A degree of cell disintegration was determined on grounds of released protein concentration. Rheological properties of suspension were measured using a cylindrical rotary double-gap rheometer. An influence of mill packing kinetic energy on process non-linearity and changes of suspension apparent viscosity was proved.