3650
Parallel Testing of a Non-Mercury, Non-Cyanide
Pilot Plant and a Traditional Small-Scale Gold Processing Plant
in the Philippines
Franco Danilo Luistro, Herman Mendoza, Djoan Kate Tungpalan, Hanna Czarise Regidor
Department of Mining, Metallurgical and Materials Engineering University of the Philippines–Diliman
ABSTRACT: A non-mercury, non-cyanide method of recovering gold applicable to small-scale mining
operations was developed to introduce an alternative gold processing technique to target small-scale mining
communities in the Philippines. To showcase its process capabilities, a parallel processing of ore was done
alongside a traditional gold processing plant located on a small-scale mining community in Itogon, Benguet.
Results from the parallel testing indicated that the alternative method recovered 86.11% of the gold from the
ore while the traditional small-scale process only yielded 82.80%. Other factors like processing time, operating
expenses and tailings treatment were also considered for the comparison of the two processes. Overall, the
alternative method performed faster than the traditional small-scale process at lower operating expense per gram
of gold recovered, this also included the treatment of tailings in which the traditional small-scale process lacked.
Keywords: Gold Processing, Small-scale mining, Alternative method for gold extraction
INTRODUCTION
Mercury has been used by the small-scale mining industry
to recover gold via amalgamation. It is mixed in with the
ore through various stages of the small-scale mining activity
to form amalgams with gold (Viega, Maxson and Hylander,
2006). As countries start to ban the use of mercury, some
small-scale miners have shifted to the use of cyanide for the
recovery of gold (Verbrugge, et al., 2021).
In the Philippine setting, an estimate of around
300,000 small-scale miners operates throughout 30 of
its mineral-rich provinces (Mendoza, et al., 2013). These
small-scale miners mainly use cyanidation as their means to
recover gold from the ore.
While both the use of mercury and cyanide prove to be
effective methods in recovering gold from its ores, uncon-
trolled and unregulated use, as well as the lack of proper
waste handling can lead to severe health and environmental
impacts (World Health Organization 2017, Eisler and
Weimeyer, 2004).
To address the issues posed by amalgamation and cya-
nidation, several studies that aim to improve gold recov-
ery and provide environmentally friendly alternatives have
been conducted. One such alternative being introduced by
researchers from the University of the Philippines–Diliman,
is a process that involves recovery of gold via gravity con-
centration and leaching of gold bearing flotation concen-
trates using alkaline hypochlorite solutions (Regidor, et
al., 2022). To demonstrate the process to the small-scale
mining community, several pilot-scale runs have been con-
ducted, as well as a parallel run to compare the performance
of the process against the traditional method being utilized
by the small-scale miners.
The parallel testing of both processing plants is a col-
laborative effort from a small-scale mining community in
Itogon, Benguet, and the researchers from the University
Parallel Testing of a Non-Mercury, Non-Cyanide
Pilot Plant and a Traditional Small-Scale Gold Processing Plant
in the Philippines
Franco Danilo Luistro, Herman Mendoza, Djoan Kate Tungpalan, Hanna Czarise Regidor
Department of Mining, Metallurgical and Materials Engineering University of the Philippines–Diliman
ABSTRACT: A non-mercury, non-cyanide method of recovering gold applicable to small-scale mining
operations was developed to introduce an alternative gold processing technique to target small-scale mining
communities in the Philippines. To showcase its process capabilities, a parallel processing of ore was done
alongside a traditional gold processing plant located on a small-scale mining community in Itogon, Benguet.
Results from the parallel testing indicated that the alternative method recovered 86.11% of the gold from the
ore while the traditional small-scale process only yielded 82.80%. Other factors like processing time, operating
expenses and tailings treatment were also considered for the comparison of the two processes. Overall, the
alternative method performed faster than the traditional small-scale process at lower operating expense per gram
of gold recovered, this also included the treatment of tailings in which the traditional small-scale process lacked.
Keywords: Gold Processing, Small-scale mining, Alternative method for gold extraction
INTRODUCTION
Mercury has been used by the small-scale mining industry
to recover gold via amalgamation. It is mixed in with the
ore through various stages of the small-scale mining activity
to form amalgams with gold (Viega, Maxson and Hylander,
2006). As countries start to ban the use of mercury, some
small-scale miners have shifted to the use of cyanide for the
recovery of gold (Verbrugge, et al., 2021).
In the Philippine setting, an estimate of around
300,000 small-scale miners operates throughout 30 of
its mineral-rich provinces (Mendoza, et al., 2013). These
small-scale miners mainly use cyanidation as their means to
recover gold from the ore.
While both the use of mercury and cyanide prove to be
effective methods in recovering gold from its ores, uncon-
trolled and unregulated use, as well as the lack of proper
waste handling can lead to severe health and environmental
impacts (World Health Organization 2017, Eisler and
Weimeyer, 2004).
To address the issues posed by amalgamation and cya-
nidation, several studies that aim to improve gold recov-
ery and provide environmentally friendly alternatives have
been conducted. One such alternative being introduced by
researchers from the University of the Philippines–Diliman,
is a process that involves recovery of gold via gravity con-
centration and leaching of gold bearing flotation concen-
trates using alkaline hypochlorite solutions (Regidor, et
al., 2022). To demonstrate the process to the small-scale
mining community, several pilot-scale runs have been con-
ducted, as well as a parallel run to compare the performance
of the process against the traditional method being utilized
by the small-scale miners.
The parallel testing of both processing plants is a col-
laborative effort from a small-scale mining community in
Itogon, Benguet, and the researchers from the University