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Flotation as a separation technique in the coal gold agglomeration process
Author(s)
Moses, Lucian Benedict
Date Issued
2000
Type
Thesis
Publisher
Cape Technikon
Abstract
Internationally, there is an increase in the need for safer environmental
processes that can be applied to mining operations, especially on a small
scale, where mercury amalgamation is the main process used for the
recovery of free gold. An alternative, more environmentally acceptable,
process called the Coal Gold Agglomeration (CGA) process has been
investigated at the Cape Technikon. This paper explains the application of
flotation as a means of separation for the CGA process.
The CGA process is based on the recovery of hydrophobic gold particles
from ore slurries into agglomerates formed from coal and oil. The
agglomerates are separated from the slurry through scraping, screening,
flotation or a combination of the aforementioned. They are then ashed to
release the gold particles, after which it is smelted to form gold bullion. All components were contacted for fifty minutes after which a frother was
added and after three minutes of conditioning, air, at a rate of one I/min
per cell volume was introduced into the system. The addition of a collector
(Potassium Amyl Xanthate) at the start of each run significantly improved
gold recoveries. Preliminary experiments indicated that the use of baffles
decreased the gold recoveries, which was concluded to be due to
agglomerate breakage. The system was also found to be frother-selective
and hence only DOW-200 was used in subsequent experiments. A
significant increase or decrease in the air addition rate both had a negative
effect on the recoveries; therefore, the air addition rate was not altered
during further tests. The use of tap water as opposed to distilled water
decreased the attainable recoveries by less than five per cent. This was a
very encouraging result, in terms of the practical implementation of the
CGA process.
processes that can be applied to mining operations, especially on a small
scale, where mercury amalgamation is the main process used for the
recovery of free gold. An alternative, more environmentally acceptable,
process called the Coal Gold Agglomeration (CGA) process has been
investigated at the Cape Technikon. This paper explains the application of
flotation as a means of separation for the CGA process.
The CGA process is based on the recovery of hydrophobic gold particles
from ore slurries into agglomerates formed from coal and oil. The
agglomerates are separated from the slurry through scraping, screening,
flotation or a combination of the aforementioned. They are then ashed to
release the gold particles, after which it is smelted to form gold bullion. All components were contacted for fifty minutes after which a frother was
added and after three minutes of conditioning, air, at a rate of one I/min
per cell volume was introduced into the system. The addition of a collector
(Potassium Amyl Xanthate) at the start of each run significantly improved
gold recoveries. Preliminary experiments indicated that the use of baffles
decreased the gold recoveries, which was concluded to be due to
agglomerate breakage. The system was also found to be frother-selective
and hence only DOW-200 was used in subsequent experiments. A
significant increase or decrease in the air addition rate both had a negative
effect on the recoveries; therefore, the air addition rate was not altered
during further tests. The use of tap water as opposed to distilled water
decreased the attainable recoveries by less than five per cent. This was a
very encouraging result, in terms of the practical implementation of the
CGA process.
Additional information
Thesis (MTech (Chemical Engineering))--Cape Technikon, 2000.
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