702 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
isopropyl xanthate (SIPX) had the highest recovery. In the
median pH range, SIPX had the lowest recoveries. SEX also
achieved higher recoveries than SIBX at pH levels below
5. This implies either the mineral surface or the pH of the
system affects the collector behavior and may influence
the pattern of strength previously observed. However, a
study that compared the adsorption of PAX and SEX on
the flotation of chalcopyrite obtained results that conflicted
with those found by Goktepe (2001) (Xie et al., 2016).
According to this study, the order of strength of the collec-
tors is controlled by the collector chain length as this affects
their bonding energies. This was done by investigating the
surface coverage (Г) of the collectors on the minerals to
compare the strength of the collectors. PAX had a greater
bonding energy with respect to the cuprous-xanthate bond
that formed on the mineral surfaces. The study also investi-
gated the competitive adsorption of the collectors. PAX was
added to a solution of SEX that had previously adsorbed
on the surface of the mineral. The SEX began to reappear
as more PAX was added to the solution. It was found that
SEX was susceptible to desorption and replacement by the
PAX. This was due to the higher bonding energy that the
PAX had with the mineral surface. Taguta et al. (2017)
calculated the heat of formation of cuprousxanthate com-
plexes and the binding energy of SEX and PAX. The results
confirmed the findings of Xie et al. (2016).
Feng et al. (2012) investigated the difference in flota-
tion performance of collectors of different chain lengths on
a Jinchuan sulfide ore. In addition to varying the collec-
tor chain length, the conditioning time was changed. The
results confirmed the findings by Xie et al. (2016), with
the potassium octyl-xanthate (POX) achieving a recovery of
up to 10% higher than potassium isobutyl-xanthate (PIBX)
under the different conditions. A study by Ikotun et. al
(2017) compared the collector action of PAX, SIBX, and
SEX in the flotation of a low-grade nickel sulfide ore. PAX
obtained the lowest nickel grade, whilst SEX achieved the
highest nickel grade of above 7%. Mielczarski et. al (1998)
explained this to be due to shorter chain lengths being
more able to form insoluble metallic ionic compounds
than the longer-chained collectors. This results in higher
selectivity of the shorter chained collectors. This pattern
was also observed in another study that found although the
shorter-chained collectors were weaker than longer chains,
their lower insolubility in water increased their selectiv-
ity (Kim et al., 2000). Studies also showed the selectivity
of collectors could be altered by a change in the pH level
of the system (Goktepe, 2001). Kim et al. (2000) found
longer chained collectors were more selective in acidic
conditions due to a change in their activity. Other studies
have observed this change in activity and it was more pro-
nounced for long-chained collectors (Karlkvist, 2017). This
implies that results obtained with longer chained collectors
may be more vulnerable to change under differing flotation
conditions.
It is important to control the decomposition of xan-
thates as some of its decomposition products, e.g., carbon
disulfide is toxic and a health hazard. The pH and tempera-
ture of the pulp have the largest effect on the stability of the
collector. Other factors that have a minor effect on collec-
tor stability include the residence time and the amount of
UV-light rays going through the pulp. The rate of decom-
position of xanthates has been found to increase in acidic
conditions (Özün and Ergen, 2019). At low pH levels, the
xanthates decompose to form carbon disulfide. However,
in alkaline conditions, multiple reactions can occur lead-
ing to multiple decomposition products. Examples of these
decomposition products include dixanthogen, perxanthate
and mono/ dithio carbonates.
Xie et al. (2016) conducted a study to compare the rate
of decomposition between PAX and SEX. This was done at
different pH levels and the results obtained were the same in
each case. The rate of degradation did not significantly dif-
fer between the two collector types. Although SEX appears
to decompose slightly more than PAX, it was determined
that this difference was negligible, and the decomposition
of xanthates was independent of chain length. These stud-
ies all provided deeper insight into the patterns observed
in flotation performance when collectors of different chain
lengths were used. However, aside from pH, all these stud-
ies were under standard flotation conditions that did not
vary the water quality.
It is known that changes in water quality affect both
the pulp and froth zones, impacting flotation performance
(Muzenda, 2010). An increase in the ionic strength (IS) and
total dissolved solids (TDS) of water results in a decrease
in recoveries. This is due to ions that either coat or create
precipitates that coat mineral surfaces, preventing collector
adsorption. Ions can either activate or depress the miner-
als and gangue. Collector behavior can be affected to dif-
ferent degrees in the presence of certain ions. The froth is
stabilised by the change in IS and TDS resulting in higher
water recoveries (Sheni et. al, 2018). Many studies illustrat-
ing the behavior of collectors with different chain lengths
were conducted under normal optimum flotation condi-
tions. Goktepe (2001) and Ikotun et. al (2017) investigated
a few pH levels but some of the results were not explained
and recommended for future investigation. However, these
studies did show the vulnerability long-chained collectors
had to changes in flotation conditions. Therefore, there is
isopropyl xanthate (SIPX) had the highest recovery. In the
median pH range, SIPX had the lowest recoveries. SEX also
achieved higher recoveries than SIBX at pH levels below
5. This implies either the mineral surface or the pH of the
system affects the collector behavior and may influence
the pattern of strength previously observed. However, a
study that compared the adsorption of PAX and SEX on
the flotation of chalcopyrite obtained results that conflicted
with those found by Goktepe (2001) (Xie et al., 2016).
According to this study, the order of strength of the collec-
tors is controlled by the collector chain length as this affects
their bonding energies. This was done by investigating the
surface coverage (Г) of the collectors on the minerals to
compare the strength of the collectors. PAX had a greater
bonding energy with respect to the cuprous-xanthate bond
that formed on the mineral surfaces. The study also investi-
gated the competitive adsorption of the collectors. PAX was
added to a solution of SEX that had previously adsorbed
on the surface of the mineral. The SEX began to reappear
as more PAX was added to the solution. It was found that
SEX was susceptible to desorption and replacement by the
PAX. This was due to the higher bonding energy that the
PAX had with the mineral surface. Taguta et al. (2017)
calculated the heat of formation of cuprousxanthate com-
plexes and the binding energy of SEX and PAX. The results
confirmed the findings of Xie et al. (2016).
Feng et al. (2012) investigated the difference in flota-
tion performance of collectors of different chain lengths on
a Jinchuan sulfide ore. In addition to varying the collec-
tor chain length, the conditioning time was changed. The
results confirmed the findings by Xie et al. (2016), with
the potassium octyl-xanthate (POX) achieving a recovery of
up to 10% higher than potassium isobutyl-xanthate (PIBX)
under the different conditions. A study by Ikotun et. al
(2017) compared the collector action of PAX, SIBX, and
SEX in the flotation of a low-grade nickel sulfide ore. PAX
obtained the lowest nickel grade, whilst SEX achieved the
highest nickel grade of above 7%. Mielczarski et. al (1998)
explained this to be due to shorter chain lengths being
more able to form insoluble metallic ionic compounds
than the longer-chained collectors. This results in higher
selectivity of the shorter chained collectors. This pattern
was also observed in another study that found although the
shorter-chained collectors were weaker than longer chains,
their lower insolubility in water increased their selectiv-
ity (Kim et al., 2000). Studies also showed the selectivity
of collectors could be altered by a change in the pH level
of the system (Goktepe, 2001). Kim et al. (2000) found
longer chained collectors were more selective in acidic
conditions due to a change in their activity. Other studies
have observed this change in activity and it was more pro-
nounced for long-chained collectors (Karlkvist, 2017). This
implies that results obtained with longer chained collectors
may be more vulnerable to change under differing flotation
conditions.
It is important to control the decomposition of xan-
thates as some of its decomposition products, e.g., carbon
disulfide is toxic and a health hazard. The pH and tempera-
ture of the pulp have the largest effect on the stability of the
collector. Other factors that have a minor effect on collec-
tor stability include the residence time and the amount of
UV-light rays going through the pulp. The rate of decom-
position of xanthates has been found to increase in acidic
conditions (Özün and Ergen, 2019). At low pH levels, the
xanthates decompose to form carbon disulfide. However,
in alkaline conditions, multiple reactions can occur lead-
ing to multiple decomposition products. Examples of these
decomposition products include dixanthogen, perxanthate
and mono/ dithio carbonates.
Xie et al. (2016) conducted a study to compare the rate
of decomposition between PAX and SEX. This was done at
different pH levels and the results obtained were the same in
each case. The rate of degradation did not significantly dif-
fer between the two collector types. Although SEX appears
to decompose slightly more than PAX, it was determined
that this difference was negligible, and the decomposition
of xanthates was independent of chain length. These stud-
ies all provided deeper insight into the patterns observed
in flotation performance when collectors of different chain
lengths were used. However, aside from pH, all these stud-
ies were under standard flotation conditions that did not
vary the water quality.
It is known that changes in water quality affect both
the pulp and froth zones, impacting flotation performance
(Muzenda, 2010). An increase in the ionic strength (IS) and
total dissolved solids (TDS) of water results in a decrease
in recoveries. This is due to ions that either coat or create
precipitates that coat mineral surfaces, preventing collector
adsorption. Ions can either activate or depress the miner-
als and gangue. Collector behavior can be affected to dif-
ferent degrees in the presence of certain ions. The froth is
stabilised by the change in IS and TDS resulting in higher
water recoveries (Sheni et. al, 2018). Many studies illustrat-
ing the behavior of collectors with different chain lengths
were conducted under normal optimum flotation condi-
tions. Goktepe (2001) and Ikotun et. al (2017) investigated
a few pH levels but some of the results were not explained
and recommended for future investigation. However, these
studies did show the vulnerability long-chained collectors
had to changes in flotation conditions. Therefore, there is