XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 711
of flocculation plays a pivotal role in the efficient recovery
and reuse of water resources, thereby mitigating environ-
mental impacts associated with mining activities and con-
tributing significantly to sustainable water management
in the mining industry. Flocculant performance in in the
dewatering of fine phosphate slurries could be affected by a
multitude of inter-connected process parameters or factors.
The main affecting parameters are the polymer type and
dosage (Sworska et al., 2000 Wu et al., 2020), pH (Sworska
et al., 2000), solid content (Wu et al., 2020), water chem-
istry and dissolved salts (Boshrouyeh Ghandashtani et al.,
2022 Castillo et al., 2023 Sworska et al., 2000), tempera-
ture (Niu et al., 2022) and mixing conditions (Ardaman
&Associates, 1985 Ofori et al., 2012 OruÇ &Sabah,
2006).
The effectiveness of flocculation is also significantly
influenced by intrinsic properties of flocculants, including
their chemistry, architectural structure (linear vs. branched),
molecular weight (MW) and charge density (Boshrouyeh
Ghandashtani et al., 2022). Changes in polymer properties
are expected to influence not just the conformation of poly-
mer molecules within a solution but also the adsorption of
polymers onto the surface of minerals. In particular, higher
molecular weights (MWs) typically result in larger hydro-
dynamic sizes of polymer chains in solution. As the MW
increases, the formation of loops and, notably, extended
tails become more pronounced. These tails play a pivotal
role in facilitating bridging of particles, thereby contribut-
ing to the formation of larger aggregates or flocs (Costine
et al., 2018). In the context of efficient dewatering and
solid-liquid separation through sedimentation, attaining
high settling rates, minimizing supernatant turbidity, and
optimizing water recovery are generally imperative goals.
However, it is widely recognized that striking the appro-
priate balance between achieving minimal water turbidity,
maximizing water recovery, and enhancing the settling rate
of flocculated particles poses a significant challenge. Hence,
the delicate task of optimizing and enhancing separation
efficiency involves finding a compromise among these key
performance indicators. In this study, response surface
methodology (RSM) is utilized as the experimental design
approach.
The main aim of this study is to investigate the physical,
chemical, mineralogical, and electrophoretic characteristics
of the FPTs. Additionally, the investigation entails assess-
ing the flocculation efficiency of different anionic poly-
acrylamides and ultimately determining the most suitable
flocculant through the application of technical analysis cri-
teria. To achieve this goal, a part of the study employed the
response surface methodology (RSM). RSM is a graphical
statistical approach used to identify operational condi-
tions that optimally fulfil process specifications. This tech-
nique proves convenient for analysing processes in which
a response or multiple responses of interest are influenced
by multiple variables (Cutright &Meza, 2007 Musa et al.,
2020). It plays a crucial role in optimizing mine tailings
dewatering and provides a systematic approach to fine-tune
the conditions of key factors and evaluate their impacts on
the observed responses. The RSM serves as a valuable tool
to investigate the individual effects of each factor on floc-
culation and sedimentation Key Performance Indicators
(KPIs) and explore the interactions between these factors
(Bezerra et al., 2008).
MATERIALS, METHODS, AND
EXPERIMENTAL PROCEDURE
Materials
The fine phosphate slurry sample used in the experiments
was taken from the input of a thickener in the phosphate
processing plant of Youssoufia, in Morocco. The represen-
tative sample was transferred to the laboratory in barrels of
30 litters then stirred to obtain a homogeneous slurry. The
sample was then dried in a room temperature at 25°C. Prior
to flocculation tests, a mixture was prepared according to
the feed solid content used in the processing plant. The
FPTs were initially dried to preserve the characteristics of
their particles. However, when stored as a slurry, their char-
acteristics undergo changes, particularly since the sample
is rich in montmorillonite, a clay known for its capacity to
swell and absorb water, resulting in a significant increase in
volume, especially over prolonged durations.
Four polyacrylamide-based polymers (2 cationic and
2 anionic) with different molecular weights and charge
densities supplied from BASF and Solenis were used in the
flocculation and sedimentation experiments. The detailed
characteristics of each polymer are shown in Table 1. Prior
to flocculation tests, a homogeneous stock solution of 0.2
g/L (0.02% wt) of polymer was prepared using deion-
ised water with a pH of 5.8 and a conductivity of 3.6 µS/
cm. The selection of the flocculant preparation was made
through preliminary tests, with the aim of identifying the
optimal flocculant preparation that ensures enhanced floc-
culation and sedimentation efficiency. It is worth noting
that flocculation-sedimentation experiments were con-
ducted at the natural pH of approximately 8.6, although
this was not explicitly mentioned.
The particle size distribution of the sample was deter-
mined using the Malvern Mastersizer 3000 particle size
analyser. For chemical analysis of the FPTs sample, an
X-ray Fluorescence (XRF) spectrometer (ZSX Primus IV,
of flocculation plays a pivotal role in the efficient recovery
and reuse of water resources, thereby mitigating environ-
mental impacts associated with mining activities and con-
tributing significantly to sustainable water management
in the mining industry. Flocculant performance in in the
dewatering of fine phosphate slurries could be affected by a
multitude of inter-connected process parameters or factors.
The main affecting parameters are the polymer type and
dosage (Sworska et al., 2000 Wu et al., 2020), pH (Sworska
et al., 2000), solid content (Wu et al., 2020), water chem-
istry and dissolved salts (Boshrouyeh Ghandashtani et al.,
2022 Castillo et al., 2023 Sworska et al., 2000), tempera-
ture (Niu et al., 2022) and mixing conditions (Ardaman
&Associates, 1985 Ofori et al., 2012 OruÇ &Sabah,
2006).
The effectiveness of flocculation is also significantly
influenced by intrinsic properties of flocculants, including
their chemistry, architectural structure (linear vs. branched),
molecular weight (MW) and charge density (Boshrouyeh
Ghandashtani et al., 2022). Changes in polymer properties
are expected to influence not just the conformation of poly-
mer molecules within a solution but also the adsorption of
polymers onto the surface of minerals. In particular, higher
molecular weights (MWs) typically result in larger hydro-
dynamic sizes of polymer chains in solution. As the MW
increases, the formation of loops and, notably, extended
tails become more pronounced. These tails play a pivotal
role in facilitating bridging of particles, thereby contribut-
ing to the formation of larger aggregates or flocs (Costine
et al., 2018). In the context of efficient dewatering and
solid-liquid separation through sedimentation, attaining
high settling rates, minimizing supernatant turbidity, and
optimizing water recovery are generally imperative goals.
However, it is widely recognized that striking the appro-
priate balance between achieving minimal water turbidity,
maximizing water recovery, and enhancing the settling rate
of flocculated particles poses a significant challenge. Hence,
the delicate task of optimizing and enhancing separation
efficiency involves finding a compromise among these key
performance indicators. In this study, response surface
methodology (RSM) is utilized as the experimental design
approach.
The main aim of this study is to investigate the physical,
chemical, mineralogical, and electrophoretic characteristics
of the FPTs. Additionally, the investigation entails assess-
ing the flocculation efficiency of different anionic poly-
acrylamides and ultimately determining the most suitable
flocculant through the application of technical analysis cri-
teria. To achieve this goal, a part of the study employed the
response surface methodology (RSM). RSM is a graphical
statistical approach used to identify operational condi-
tions that optimally fulfil process specifications. This tech-
nique proves convenient for analysing processes in which
a response or multiple responses of interest are influenced
by multiple variables (Cutright &Meza, 2007 Musa et al.,
2020). It plays a crucial role in optimizing mine tailings
dewatering and provides a systematic approach to fine-tune
the conditions of key factors and evaluate their impacts on
the observed responses. The RSM serves as a valuable tool
to investigate the individual effects of each factor on floc-
culation and sedimentation Key Performance Indicators
(KPIs) and explore the interactions between these factors
(Bezerra et al., 2008).
MATERIALS, METHODS, AND
EXPERIMENTAL PROCEDURE
Materials
The fine phosphate slurry sample used in the experiments
was taken from the input of a thickener in the phosphate
processing plant of Youssoufia, in Morocco. The represen-
tative sample was transferred to the laboratory in barrels of
30 litters then stirred to obtain a homogeneous slurry. The
sample was then dried in a room temperature at 25°C. Prior
to flocculation tests, a mixture was prepared according to
the feed solid content used in the processing plant. The
FPTs were initially dried to preserve the characteristics of
their particles. However, when stored as a slurry, their char-
acteristics undergo changes, particularly since the sample
is rich in montmorillonite, a clay known for its capacity to
swell and absorb water, resulting in a significant increase in
volume, especially over prolonged durations.
Four polyacrylamide-based polymers (2 cationic and
2 anionic) with different molecular weights and charge
densities supplied from BASF and Solenis were used in the
flocculation and sedimentation experiments. The detailed
characteristics of each polymer are shown in Table 1. Prior
to flocculation tests, a homogeneous stock solution of 0.2
g/L (0.02% wt) of polymer was prepared using deion-
ised water with a pH of 5.8 and a conductivity of 3.6 µS/
cm. The selection of the flocculant preparation was made
through preliminary tests, with the aim of identifying the
optimal flocculant preparation that ensures enhanced floc-
culation and sedimentation efficiency. It is worth noting
that flocculation-sedimentation experiments were con-
ducted at the natural pH of approximately 8.6, although
this was not explicitly mentioned.
The particle size distribution of the sample was deter-
mined using the Malvern Mastersizer 3000 particle size
analyser. For chemical analysis of the FPTs sample, an
X-ray Fluorescence (XRF) spectrometer (ZSX Primus IV,