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Investigation of flocculation properties and floc structure of coal processing plant tailings in the presence of monovalent and divalent ions

Gungoren Can, Unver Ilgin Kursun, Ozdemir Orhan

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 5

747--758

EN

Low-rank coals are generally processed with wet methods including washing, flotation, etc. Fine-sized tailings of these processes are discharged to tailing ponds with a significant amount of associated water which contains a high amount of dissolved ions. These tailings should be dewatered employing coagulation/flocculation in terms of technological and environmental aspects. In this study, the coagulation/flocculation behavior of coal processing plant tailings obtained from Manisa, Turkey was investigated in the presence of monovalent (Na+, K+) and divalent (Mg2+, Ca2+) ions and an anionic flocculant (SPP-600). First, the coagulation properties of coal tailings were determined. Then, the flocculation experiments were carried out, and the turbidity values of the suspensions were measured. Moreover, the sizes of the flocs were determined using a laser diffraction particle size analyzer to analyze the strength of the flocs. The results of the coagulation experiments showed that while divalent ions were more effective at 10-1 mol/dm3, higher settling rate and lower turbidity values were obtained in the presence of monovalent ions at 1 mol/dm3 concentration. The optimum flocculant dosage was obtained as 150 g/Mg from the flocculation experiments. The floc size and strength measurements indicated that the larger flocs were obtained with Na+ than Ca2+ in the presence of the flocculant. The strongest flocs were obtained at 10-1 mol/dm3 Ca2+ + 150 g/Mg flocculant. It can be concluded from this study that the coagulation followed by the flocculation method can be employed to obtain fast flocculation behavior and low turbidity for the dewatering of coal tailings.

2

Effect of shear-induced breakage and reflocculation on the floc structure, settling, and dewatering of coal tailings

Fan Yuping, Ma Xiaomin, Song Shuai, Dong Xianshu, Chen Ruxia, Dong Yingdi

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 2

363--373

EN

Flocculation is crucial for the treatment of coal tailings in industries. In this paper, the effects of shear-induced breakage and reflocculation of the floc, settling, and dewatering of coal tailings were investigated. The results show that as shear strength increases, the settling velocity of flocculated tailings decreases. A shear rate of 200 rpm (170.6 s-1) leads to the loss of half the settling velocity. However, at high dosage cases, 200 rpm-300 rpm shear could improve the clarity of the supernatant. Small particles are flocculated preferentially, especially for particles below 10 µm. With the increase in dosage, the critical particle size for the occurrence of flocculation increases. The chaos index proposed can quantitatively reflect the degree of flocculation or reflocculation of coal tailings. At high dosage conditions, shear could enhance the dewatering performance of flocs by reconstructing the filter cake. Controlling the structure of flocs by dosage and shear strength can help obtain appropriate settling, clarifying, and dewatering performance of coal tailings.

3

Analiza komputerowa struktury nadźwiękowionych kłaczków osadów biologicznych

Fryźlewicz-Kozak B., Drabik K.

Inżynieria i Aparatura Chemiczna

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2011

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Nr 5

28-29

PL

Analizowany materiał stanowił zdjęcia nadźwiękowionego osadu czynnego, pochodzące z oczyszczalni ścieków w Olkuszu. Do obróbki zdjęć użyto specjalistycznych oprogramowań: Fraclalyse - do analizy fraktalnej oraz programu ImageJ do analizy parametrów geometrycznych. W celu dokładniejszego zilustrowania zmian zachodzących w nadżwiękowionym osadzie, posłużono się dodatkowo parametrami kształtu.

EN

Analyzed materials were images of sonicated activated sludge, from wastewater treatment plants in Olkusz. The image processing specialized software was: Fractalyse - for fractal analysis and ImageJ for the analysis of geometrical parameters. In order to illustrate more accurately the changes in sonicated sediment shape parameters were used.

4

Mechanism of behaviour of biological sludge in an ultrasonic field

Fryźlewicz-Kozak B., Tal-Figiel B.

Czasopismo Techniczne. Mechanika

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2008

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R. 105, z. 5-M

111-120

EN

This paper deals with studies of changes in structure and size of activated sludge flocs from municipalindustrial treatment plants in a function of parameters of ultrasounds (i.e. ultrasound field intensity and time of ultrasound application). Different methods of determining of fractal dimension were presented.

PL

W artykule omówiono mechanizm zachowania się osadów biologicznych i zachodzące zmiany w strukturze i w rozmiarze kłaczków osadów biologicznych w funkcji parametrów pola ultradźwiękowego (tj. natężenia pola ultradźwiękowego i czasu jego działania). Przedstawiono różne metody wyznaczania wymiaru fraktalnego.