XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3299
processes, the matte is refined using established hydromet-
allurgical techniques, such as pressure or oxidative leaching,
and then impurity removal, hydrogen reduction, and/or
electrowinning (Meshram and Pandey 2018). Conversely,
considerable amounts of nickel are lost during flotation
and in the smelting slag, and managing some impure ele-
ments in the concentrates, such magnesium and arsenic,
can present challenges. The literature has addressed a
number of unconventional hydrometallurgical methods
for the processing nickel sulfide concentrates (Crundwell,
Moats, and Ramachandran 2011). These methods typi-
cally involve fine grinding the concentrate and then oxida-
tive pressure leaching the sulphide to provide sulfuric acid
for the leach process. There have also been descriptions
of biological treatments for nickel sulfides, which involve
bacterially assisted leaching, solution purification, metal
separation, and nickel electrowinning (Juanqin et al. 2010
Mbaya, Ramakokovhu, and Thubakgale 2013 Meshram
and Pandey 2018 Xie, Xu, Yan, and Yang 2005 Xu et
al. 2022 Xu, Xie, Yan, and Yang 2005 Yang et al. 2011).
Conversely, due to disadvantages such slow leaching kinet-
ics, high energy costs, expensive neutralizing chemicals, and
excessive waste generation, these procedures have not been
industrially established or found practical use (Meshram
and Pandey 2018 Xu et al. 2022 Crundwell, Moats, and
Ramachandran 2011 Hosseini, Raygan, Rezaei, and Jafari
2017 Rabbani and Ahmadi 2020).
In recent years, the use of ferric chloride to process
such sulfidic ores in large-scale mineral processing has
received significant consideration. This is because, theoreti-
cally, the ferric ions serve as the essential oxidative catalyst
in the oxidation of sulfides accessible in addition to the
potential complexation of the Cl− ions with oxidized metal
ions to enhances metal recovery (Karppinen, Seisko, and
Lundström 2024). The primary by-product of the oxida-
tion potential of the ferric chloride leaching system is ele-
mental sulfur. Elemental sulfur is considered less harmful to
the environment than sulfur dioxide from pyrometallurgy
or sulfurate from high pressure leaching (Meshram and
Pandey 2018). It is worth mentioning that the introduction
of modern building materials including titanium, fiber-
reinforced plastic, polypropylene, and butyl rubber, averts
concerns reading the corrosive nature of ferric chloride (Fan
et al. 2021 Fan et al. 2011). However, the technique is
associated with high production cost and extensive waste
management requirements due to the potential for ferric
to cause acid mine drainage (Issifu-Amponsah, Adam, and
Ofori-Sarpong 2016 Ofori-Sarpong, Adam, Asamoah, and
Amankwah 2020 Afriyie–Debrah 2014).
In the current study, the application of activated car-
bon as a cheaper and environmentally friendly alternative
is proposed. Compared to other carbonaceous materials,
activated carbon has a larger porosity (Owusu, Mends,
and Acquah 2022), specific surface area (Kove, Buah, and
Dankwa 2021), and degree of surface reactivity (Amara,
Mends, and Ofori-Sarpong Owusu, Mends, and Acquah
2022 Méndez et al. 2022), which has led to its widespread
use as an effective catalyst in the many electrochemical
industries (Rabbani et al. 2024). In mining applications,
activated carbon is used extensively in the gold cyanide
recovery (Amara, Mends, and Ofori-Sarpong), and to
study the passivation of certain minerals (Owusu, Mensah,
Ackah, and Amankwah 2021 Owusu et al. 2023). In recent
times, it has been demonstrated that carbon-based materi-
als have the chemical ability to accept, transfer or donate
electrons to and from the neighboring environments (Gao,
Yue, Gao, and Li 2020). In this sense, it is likely that carbo-
naceous materials like activated carbon, having high elec-
tronic conductivity and porosity have the capability to act
as an oxidant, and facilitate the electron transfer and redox
reactions (Ndagijimana et al. 2023). The main objective of
this research was accordingly to investigate the potential
application of commercial coconut shell-based activated
carbon as a catalyst for the recovery of valuable metals from
sulfide ores. Leaching experiments were performed using
ferric chloride as a baseline. The leaching variables were
optimized by response surface methodology (RSM) based
central composite design design (CCD), to generate an
optimal solution for the maximum leaching of nickel.
EXPERIMENTAL
Materials
The rougher flotation tailing sample utilized in this study
was prepared to 80% passing 75 microns by grinding a rep-
resentative portion in a laboratory-size ball mill at about 80
rev/min for 10 min. The ground sample was consequently
used for the leaching experiments and characterization stud-
ies. Sulfuric acid and ferric chloride used in the study were
analytically pure reagents, purchased from ThermoFisher
Scientific ™. The granular activated carbon was procured
from Delta Adsorbents.
Experimental Design
The response surface methodology is an empirical statis-
tical technique that establishes the regression model and
optimum operating conditions by utilizing the functional
relationship between factors and responses (Lou, Tang, Liu,
and Zhang 2023 Li et al. 2022). In this study, a 25-factorial
design was adopted, and sixty-two experiments were carried
processes, the matte is refined using established hydromet-
allurgical techniques, such as pressure or oxidative leaching,
and then impurity removal, hydrogen reduction, and/or
electrowinning (Meshram and Pandey 2018). Conversely,
considerable amounts of nickel are lost during flotation
and in the smelting slag, and managing some impure ele-
ments in the concentrates, such magnesium and arsenic,
can present challenges. The literature has addressed a
number of unconventional hydrometallurgical methods
for the processing nickel sulfide concentrates (Crundwell,
Moats, and Ramachandran 2011). These methods typi-
cally involve fine grinding the concentrate and then oxida-
tive pressure leaching the sulphide to provide sulfuric acid
for the leach process. There have also been descriptions
of biological treatments for nickel sulfides, which involve
bacterially assisted leaching, solution purification, metal
separation, and nickel electrowinning (Juanqin et al. 2010
Mbaya, Ramakokovhu, and Thubakgale 2013 Meshram
and Pandey 2018 Xie, Xu, Yan, and Yang 2005 Xu et
al. 2022 Xu, Xie, Yan, and Yang 2005 Yang et al. 2011).
Conversely, due to disadvantages such slow leaching kinet-
ics, high energy costs, expensive neutralizing chemicals, and
excessive waste generation, these procedures have not been
industrially established or found practical use (Meshram
and Pandey 2018 Xu et al. 2022 Crundwell, Moats, and
Ramachandran 2011 Hosseini, Raygan, Rezaei, and Jafari
2017 Rabbani and Ahmadi 2020).
In recent years, the use of ferric chloride to process
such sulfidic ores in large-scale mineral processing has
received significant consideration. This is because, theoreti-
cally, the ferric ions serve as the essential oxidative catalyst
in the oxidation of sulfides accessible in addition to the
potential complexation of the Cl− ions with oxidized metal
ions to enhances metal recovery (Karppinen, Seisko, and
Lundström 2024). The primary by-product of the oxida-
tion potential of the ferric chloride leaching system is ele-
mental sulfur. Elemental sulfur is considered less harmful to
the environment than sulfur dioxide from pyrometallurgy
or sulfurate from high pressure leaching (Meshram and
Pandey 2018). It is worth mentioning that the introduction
of modern building materials including titanium, fiber-
reinforced plastic, polypropylene, and butyl rubber, averts
concerns reading the corrosive nature of ferric chloride (Fan
et al. 2021 Fan et al. 2011). However, the technique is
associated with high production cost and extensive waste
management requirements due to the potential for ferric
to cause acid mine drainage (Issifu-Amponsah, Adam, and
Ofori-Sarpong 2016 Ofori-Sarpong, Adam, Asamoah, and
Amankwah 2020 Afriyie–Debrah 2014).
In the current study, the application of activated car-
bon as a cheaper and environmentally friendly alternative
is proposed. Compared to other carbonaceous materials,
activated carbon has a larger porosity (Owusu, Mends,
and Acquah 2022), specific surface area (Kove, Buah, and
Dankwa 2021), and degree of surface reactivity (Amara,
Mends, and Ofori-Sarpong Owusu, Mends, and Acquah
2022 Méndez et al. 2022), which has led to its widespread
use as an effective catalyst in the many electrochemical
industries (Rabbani et al. 2024). In mining applications,
activated carbon is used extensively in the gold cyanide
recovery (Amara, Mends, and Ofori-Sarpong), and to
study the passivation of certain minerals (Owusu, Mensah,
Ackah, and Amankwah 2021 Owusu et al. 2023). In recent
times, it has been demonstrated that carbon-based materi-
als have the chemical ability to accept, transfer or donate
electrons to and from the neighboring environments (Gao,
Yue, Gao, and Li 2020). In this sense, it is likely that carbo-
naceous materials like activated carbon, having high elec-
tronic conductivity and porosity have the capability to act
as an oxidant, and facilitate the electron transfer and redox
reactions (Ndagijimana et al. 2023). The main objective of
this research was accordingly to investigate the potential
application of commercial coconut shell-based activated
carbon as a catalyst for the recovery of valuable metals from
sulfide ores. Leaching experiments were performed using
ferric chloride as a baseline. The leaching variables were
optimized by response surface methodology (RSM) based
central composite design design (CCD), to generate an
optimal solution for the maximum leaching of nickel.
EXPERIMENTAL
Materials
The rougher flotation tailing sample utilized in this study
was prepared to 80% passing 75 microns by grinding a rep-
resentative portion in a laboratory-size ball mill at about 80
rev/min for 10 min. The ground sample was consequently
used for the leaching experiments and characterization stud-
ies. Sulfuric acid and ferric chloride used in the study were
analytically pure reagents, purchased from ThermoFisher
Scientific ™. The granular activated carbon was procured
from Delta Adsorbents.
Experimental Design
The response surface methodology is an empirical statis-
tical technique that establishes the regression model and
optimum operating conditions by utilizing the functional
relationship between factors and responses (Lou, Tang, Liu,
and Zhang 2023 Li et al. 2022). In this study, a 25-factorial
design was adopted, and sixty-two experiments were carried
