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1

Study on gas holdup characteristics of micro-bubble countercurrent contacting flotation column

Han Jikang, Wang Weizhi, Li Ran

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 4

665--675

EN

In order to explore the gas holdup distribution of the microbubble countercurrent contact flotation column in the hematite column cationic reverse flotation process, respectively using conductance method and pressure drop method for air and water as experimental medium characteristics research of flotation column, the research group carries on the gas holdup, examines the aeration quantity, the fill medium and cation collector alkyl polyamine ether (An amine collector―GE609 which consists of four elements: carbon, hydrogen, oxygen and nitrogen)within the column on the influence of the axial and radial gas holdup. The results show that the axial gas holdup from the bottom of the column to the top of the column increases with the increase of height in the range of 0.050.07dm3/s. The radial distribution of gas holdup generally shows the distribution law of “intermediate high, low on both sides”. After the filling medium is added into the column, the radial gas holdup is evenly distributed compared with the empty column, and the gas holdup is increased. Due to the high foaming performance of GE-609, the gas holdup in the column can be increased by changing the amount of aeration and the concentration of the reagent, which can exceed 60% at the maximum. Like other alcohol foaming agents, as time passes, the effect of GE-609 weakens and the gas holdup in the column gradually decreases. The addition of quantitative HCl can improve the foaming performance of GE-609, and the gas holdup in the column is significantly improved and the stability is enhanced.

2

Effect of pH and time on hydrodynamic properties of dodecylamine

Zhou X., Tan Y. H., Finch J. A.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 4

1237--1244

EN

Gas holdup and froth height in the presence of dodecylamine (DDA, pKa = 10.63) are reported at three pH values. The results revealed a strong time effect for DDA: stability was reached at pH 3; not at natural pH, for example, gas holdup declining to the water only value; and at pH 11, while stability was reached quickly gas holdup was now less than in water alone indicating coalescence. In the first two cases, the time effect is attributed to loss of amine from the system as molecular amine, observed at natural pH as precipitates on the column wall. An argument for precipitation at pH < pKa is presented. At pH 11, coalescence is attributed to the oily nature of the molecular amine present as colloidal aggregates. Noting a difference in literature steady state gas holdup data at natural pH, it is speculated that varying steady states can be reached that corresponds to different levels of amine loss.

3

Prediction of gas holdup in the three-phase fluidized bed: air/Newtonian and non-Newtonian liquid systems

Sivakumar V., Senthilkumar K., Kannadasan T.

Polish Journal of Chemical Technology

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2010

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Vol. 12, nr 4

64-71

EN

The application of the three-phase fluidization technology in wastewater treatment and other biochemical processes has been regularly addressed in the past decades. For the design and development of the threephase fluidized bed reactors, knowledge of the hydrodynamic parameter such as gas holdup is essential and hence in this paper an attempt has been made to study the effect of fundamental and operating variables on gas holdup. On the basis of the experimental results, a unified correlation has been developed to predict gas holdup in the fluidized bed using the Newtonian and the non-Newtonian liquids. The experimental results showed good agreement with those predicted according to the developed correlation.

4

Wpływ parametrów konstrukcyjnych i procesowych na wartości współczynników zatrzymania gazu w strefie opadania dla reaktorów airlift

Grzywacz R.

Inżynieria i Aparatura Chemiczna

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2009

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Nr 6

76-78

PL

W pracy przedstawiono doświadczalną metodę wyznaczania lokalnych i globalnej wartości współczynnika zatrzymania gazu w strefie opadania dla reaktora airlift z wewnętrzną rurą cyrkulacyjną. Doświadczenia przeprowadzono dla różnych średnic rur wewnętrznych oraz dla różnych natężeń przepływu fazy gazowej. Przeprowadzone hadania są szczególnie ważne dla projektowania aerobowych procesów biodegradacji, gdyż pozwalają na prowadzenie procesu tak, aby uniknąć zjawiska anoksji mikroorganizmów w tej strefie.

EN

An experimental method for determining local and global values of gas holdup coefficient in a downcomer is shown in the paper. Various internal tube diameters and different gas flow intensity were used in experiments. The carried out researches are particularly important for designing of aerobic biodegradation process in such a way that microorganisms anoxia in this region can be avoid.