2994 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
INTRODUCTION
Increase in the consumption of natural resources owing to a
rise in population and the advent of technologies like solar
and hydrogen energy, has created huge stress on the avail-
ability of raw materials like mineral ores that are essential
to build the infrastructure needed for such technologies.
Among them, sulphide ores form the source of crucial
minerals because they are the source of metals like copper,
nickel, molybdenum and gold.1 Dwindling resources on
one the hand and a rising demand on other, places extreme
stress on nature. In this context, effective extraction of met-
als from limited resources is crucial.
In a typical extraction of a mineral from its ore, the ore
is enriched with the desired mineral by removing unwanted
impurities (gangue) associated with it. Further concentra-
tion of an ore can be done in a variety of methods like,
gravity separation (based on density difference), magnetic
separation (based on magnetic nature of metal/gangue),
leaching (based on difference in solubility) and froth flo-
tation (based on surface properties of the mineral). In all
these methods, ore is finely divided in the comminution
stage and provided as feed.
Among these methods, froth flotation is particularly
suitable for sulphide ores, though it is suitable for other
ores like oxides and silicates too. In froth flotation process,
finely powdered ore is fed into a liquid medium and the
liquid is agitated with the help of a gas. Under suitable
conditions of pH and in the presence of a reagent (collec-
tor) to render the mineral surface hydrophobic, the mineral
attaches itself to the bubble and rises to the surface forming
a foam layer. The foam layer is collected, dried and pro-
cessed to obtain the concentrated ore.
Froth flotation process involves the usage of some
reagents as frothing agents, activators and collectors.
However, by appropriate control of the operating condi-
tions, collector-less flotation is also possible where the min-
eral surface inherently becomes hydrophobic and becomes
naturally floatable.
The sulphides like pyrite (Py) and arsenopyrite (Asp)
has ppm levels of gold. Considering the scarce availability
and the economic value, gold extraction is of high commer-
cial significance. However, gold is locked either physically
in the gangue or chemically in the interstitial space of the
host minerals. In the case of Pyrite (Py) and Arsenopyrite
(Asp) ores, gold is chemically locked in the lattice of Py.
According to some reports, in natural samples, Asp exhib-
its higher concentrations of gold compared to arsenic-rich
pyrite or Py in deposits where both minerals coexist.2, 3
Thus, it is commercially significant to preferentially segre-
gate As rich fraction from the ore concentrates. Asp and
Py occur together in most cases as they both share simi-
lar crystal structure, flotation behavior, oxidation behav-
ior4 and rest potential5 (in ethyl xanthate at pH 7). Since
their densities and magnetic properties are similar, flotation
can be used for concentration and/or selective separation.
However, upon crushing, Asp breaks exposing two faces
namely, FeS and AsS. This exposed FeS resembles (100)
surface of Py6 which makes their separation challenging.
While numerous studies in literature focus on the flo-
tation of Py from Asp6, 7, 8, 9 there is limited research on
the reverse scenario i.e., flotation of Asp from Py. Kydros
et al. (1993)10 reported a substantial recovery of Asp from
Py using sodium dodecylsulphonate at pH~4. Forson et
al. (2021)11 proposed a two-stage flotation mechanism for
the efficient recovery of Asp from Py, with the first stage
involving the flotation of Asp and the second stage target-
ing the flotation of Py from Asp. In a subsequent publi-
cation, Forson et al. (2022)12 presented a method for the
separation of Asp from Py in the presence of Cu ions. They
elucidated that IPETC exhibits selective affinity towards
Asp over Py during flotation processes. The study delin-
eated distinct recovery dynamics based on pH conditions.
Specifically, within the pH range of approximately 6.8–8.5,
Py demonstrated enhanced recovery rates relative to Asp.
Conversely, under alkaline conditions around pH 11, Asp
recovery surged to an impressive 90.3%, concomitantly sup-
pressing Py recovery to a mere 27.9%. This observed pH-
dependent behavior of IPETC was rationalized through its
molecular speciation. At the lower pH range, IPETC exists
predominantly in a neutral form. This neutrality facilitates
a more favorable interaction with Py, resulting in its pref-
erential recovery. In contrast, at elevated pH levels, IPETC
undergoes deprotonation, leading to a heightened electro-
static attraction and stronger chelation with Asp, thereby
promoting its selective recovery. Furthermore, the presence
and concentration of Cu2+ ions in the system introduces
an additional layer of complexity. Preliminary findings
suggested that Cu2+ concentration modulates the adsorp-
tion behavior of IPETC towards both minerals. However,
delineating the intricate interplay between IPETC’s dual
behavior across the distinct pH regimes and its interaction
dynamics in the presence of Cu2+ ions remain a challenging
endeavor. A comprehensive understanding of these multi-
faceted interactions holds significant promise for advancing
the design and optimization of flotation collectors tailored
for efficient Asp recovery.
INTRODUCTION
Increase in the consumption of natural resources owing to a
rise in population and the advent of technologies like solar
and hydrogen energy, has created huge stress on the avail-
ability of raw materials like mineral ores that are essential
to build the infrastructure needed for such technologies.
Among them, sulphide ores form the source of crucial
minerals because they are the source of metals like copper,
nickel, molybdenum and gold.1 Dwindling resources on
one the hand and a rising demand on other, places extreme
stress on nature. In this context, effective extraction of met-
als from limited resources is crucial.
In a typical extraction of a mineral from its ore, the ore
is enriched with the desired mineral by removing unwanted
impurities (gangue) associated with it. Further concentra-
tion of an ore can be done in a variety of methods like,
gravity separation (based on density difference), magnetic
separation (based on magnetic nature of metal/gangue),
leaching (based on difference in solubility) and froth flo-
tation (based on surface properties of the mineral). In all
these methods, ore is finely divided in the comminution
stage and provided as feed.
Among these methods, froth flotation is particularly
suitable for sulphide ores, though it is suitable for other
ores like oxides and silicates too. In froth flotation process,
finely powdered ore is fed into a liquid medium and the
liquid is agitated with the help of a gas. Under suitable
conditions of pH and in the presence of a reagent (collec-
tor) to render the mineral surface hydrophobic, the mineral
attaches itself to the bubble and rises to the surface forming
a foam layer. The foam layer is collected, dried and pro-
cessed to obtain the concentrated ore.
Froth flotation process involves the usage of some
reagents as frothing agents, activators and collectors.
However, by appropriate control of the operating condi-
tions, collector-less flotation is also possible where the min-
eral surface inherently becomes hydrophobic and becomes
naturally floatable.
The sulphides like pyrite (Py) and arsenopyrite (Asp)
has ppm levels of gold. Considering the scarce availability
and the economic value, gold extraction is of high commer-
cial significance. However, gold is locked either physically
in the gangue or chemically in the interstitial space of the
host minerals. In the case of Pyrite (Py) and Arsenopyrite
(Asp) ores, gold is chemically locked in the lattice of Py.
According to some reports, in natural samples, Asp exhib-
its higher concentrations of gold compared to arsenic-rich
pyrite or Py in deposits where both minerals coexist.2, 3
Thus, it is commercially significant to preferentially segre-
gate As rich fraction from the ore concentrates. Asp and
Py occur together in most cases as they both share simi-
lar crystal structure, flotation behavior, oxidation behav-
ior4 and rest potential5 (in ethyl xanthate at pH 7). Since
their densities and magnetic properties are similar, flotation
can be used for concentration and/or selective separation.
However, upon crushing, Asp breaks exposing two faces
namely, FeS and AsS. This exposed FeS resembles (100)
surface of Py6 which makes their separation challenging.
While numerous studies in literature focus on the flo-
tation of Py from Asp6, 7, 8, 9 there is limited research on
the reverse scenario i.e., flotation of Asp from Py. Kydros
et al. (1993)10 reported a substantial recovery of Asp from
Py using sodium dodecylsulphonate at pH~4. Forson et
al. (2021)11 proposed a two-stage flotation mechanism for
the efficient recovery of Asp from Py, with the first stage
involving the flotation of Asp and the second stage target-
ing the flotation of Py from Asp. In a subsequent publi-
cation, Forson et al. (2022)12 presented a method for the
separation of Asp from Py in the presence of Cu ions. They
elucidated that IPETC exhibits selective affinity towards
Asp over Py during flotation processes. The study delin-
eated distinct recovery dynamics based on pH conditions.
Specifically, within the pH range of approximately 6.8–8.5,
Py demonstrated enhanced recovery rates relative to Asp.
Conversely, under alkaline conditions around pH 11, Asp
recovery surged to an impressive 90.3%, concomitantly sup-
pressing Py recovery to a mere 27.9%. This observed pH-
dependent behavior of IPETC was rationalized through its
molecular speciation. At the lower pH range, IPETC exists
predominantly in a neutral form. This neutrality facilitates
a more favorable interaction with Py, resulting in its pref-
erential recovery. In contrast, at elevated pH levels, IPETC
undergoes deprotonation, leading to a heightened electro-
static attraction and stronger chelation with Asp, thereby
promoting its selective recovery. Furthermore, the presence
and concentration of Cu2+ ions in the system introduces
an additional layer of complexity. Preliminary findings
suggested that Cu2+ concentration modulates the adsorp-
tion behavior of IPETC towards both minerals. However,
delineating the intricate interplay between IPETC’s dual
behavior across the distinct pH regimes and its interaction
dynamics in the presence of Cu2+ ions remain a challenging
endeavor. A comprehensive understanding of these multi-
faceted interactions holds significant promise for advancing
the design and optimization of flotation collectors tailored
for efficient Asp recovery.
