|
International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 12, No. 1, 2015, pp. 173-182
|
Bioline Code: st15015
Full paper language: English
Document type: Research Article
Document available free of charge
|
|
International Journal of Environment Science and Technology, Vol. 12, No. 1, 2015, pp. 173-182
en |
Jet loop reactor application for mine water treatment using fly ash, lime and aluminium hydroxide
Madzivire, G.; Gitari, W.M.; Vadapalli, V.R.K. & Petrik, L.F.
Abstract
Recent studies have shown that a combination
of coal fly ash (FA) and Al(OH)3 can be used to
treat neutral mine drainage (NMD) and reduce sulphate
concentration to within South African drinking water
quality levels, Class II (400–600 mg/L). The shortcomings
of this method were the large amounts of FA
required to raise the pH to greater than 11 (3:1 liquidto-
solid ratio) so that Al(OH)3 can be added to facilitate
removal of sulphate ions through ettringite precipitation.
This requires large silos to store FA, making upscaling
of this treatment technology using normal
mixing methods to be unrealistic. In the current study, a
jet loop reactor was used to reduce the amount of FA
needed to increase the pH to greater than 11. The pH
was raised to greater than 11 by mixing 0.25 % of lime
(w/v ratio) and 13 kg of coal FA with 80 L of NMD in
a jet loop reactor. After the pH of the mixture was
above 11, amorphous Al(OH)3 (83.2 g) was added to
the mixture. This resulted in the sulphate concentration
decreasing to less than 500 mg/L. Bench-scale studies
using 0.25 % (w/v) of lime and 6:1 coal mine water to
FA ratio could not reduce the sulphate concentration to
below 500 mg/L. Therefore, the impingement and cavitation
mixing techniques that happen in a jet loop
reactor played an important role in enhancing sulphate
removal.
Keywords
Sulphate; Neutral mine drainage; Ettringite; Impingement; Cavitation
|
|
© Copyright 2015 - International Journal of Environment Science and Technology Alternative site location: http://www.ijest.org
|
|