XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3095
around 150 mV-SHE or –47 mV-Ag/AgCl. These potential
figures gradually decrease with increasing silver grade until
a very low potential value (–30 mV -SHE, –227 mV-Ag/
AgCl) is reached for pure silver (Leppinen, 1991). In prac-
tice however, varying the type of the reagents employed is
not realistic, therefore optimal blending of the ores to keep
the mineralogy of the feed relatively constant is the pre-
ferred choice.
WORK OBJECTIVES
The objective of the work was to evaluate the response of
the electrum in the ore against a series of commercially
available flotation reagents, with an ultimate aim to replace
the current Aerofroth ®238 used as promoter at the plant.
As a secondary aim, fine tuning of the dosage rates for the
best performing reagents and investigating the reasons
for precious metals losses still accountable in tailings was
undertaken.
A previous study on Krumovgrad ore (Demeusy, 2023)
showed a correlation between electrum recovery and Au/Ag
ratio, notably by detecting a higher ratio of gold in the elec-
trum grains in the concentrate, implying a negative effect
from the increased presence of silver. In light of these find-
ings, the current work scope is to confirm the role of the
Au/Ag ratio and its implication for metallurgical results.
As a rule, optimal floatability of gold is achieved when
the redox potential is close to that of di-xanthogen for-
mation. However for the case of the Ag-rich electrum in
Krumovgrad tailings, the formation of Ag-xanthate com-
plex occurs at lower potential (–20 mV) than the one
between xanthogen and pure gold. Hence, evaluating the
flotation performance of Au-rich- and Ag-rich-electrum at
various pulp potential presents another goal of the work.
MATERIALS AND METHODS
Ore
The sample used in this study was a crushed run-of-mine
ore sourced at the Krumovgrad mine with a P80 of 125 mm.
It presents a blend of ore collected from the Wall zone and
the Upper zone. In total 40 flotation tests have been com-
pleted (all in duplicate). The initially supplied batch of ore
was sufficient to complete 24 tests, while for the remaining
16 tests a second batch of ore was supplied however with
lower precious metals content. Table 1 gives the mean Au,
Figure 1. Colloform-banded macro-texture in hand specimens from high-angle veins Ada Tepe deposit
(Marinova, 2013)
around 150 mV-SHE or –47 mV-Ag/AgCl. These potential
figures gradually decrease with increasing silver grade until
a very low potential value (–30 mV -SHE, –227 mV-Ag/
AgCl) is reached for pure silver (Leppinen, 1991). In prac-
tice however, varying the type of the reagents employed is
not realistic, therefore optimal blending of the ores to keep
the mineralogy of the feed relatively constant is the pre-
ferred choice.
WORK OBJECTIVES
The objective of the work was to evaluate the response of
the electrum in the ore against a series of commercially
available flotation reagents, with an ultimate aim to replace
the current Aerofroth ®238 used as promoter at the plant.
As a secondary aim, fine tuning of the dosage rates for the
best performing reagents and investigating the reasons
for precious metals losses still accountable in tailings was
undertaken.
A previous study on Krumovgrad ore (Demeusy, 2023)
showed a correlation between electrum recovery and Au/Ag
ratio, notably by detecting a higher ratio of gold in the elec-
trum grains in the concentrate, implying a negative effect
from the increased presence of silver. In light of these find-
ings, the current work scope is to confirm the role of the
Au/Ag ratio and its implication for metallurgical results.
As a rule, optimal floatability of gold is achieved when
the redox potential is close to that of di-xanthogen for-
mation. However for the case of the Ag-rich electrum in
Krumovgrad tailings, the formation of Ag-xanthate com-
plex occurs at lower potential (–20 mV) than the one
between xanthogen and pure gold. Hence, evaluating the
flotation performance of Au-rich- and Ag-rich-electrum at
various pulp potential presents another goal of the work.
MATERIALS AND METHODS
Ore
The sample used in this study was a crushed run-of-mine
ore sourced at the Krumovgrad mine with a P80 of 125 mm.
It presents a blend of ore collected from the Wall zone and
the Upper zone. In total 40 flotation tests have been com-
pleted (all in duplicate). The initially supplied batch of ore
was sufficient to complete 24 tests, while for the remaining
16 tests a second batch of ore was supplied however with
lower precious metals content. Table 1 gives the mean Au,
Figure 1. Colloform-banded macro-texture in hand specimens from high-angle veins Ada Tepe deposit
(Marinova, 2013)