XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2115
characterized by minerals including rhodocrosite, kutnaho-
rite, illites, kaolinites, pyrites, quartz, apatite, and siegenite.
Super Absorbent Polymer -SAP
Superabsorbent polymers are sodium polyacrylates that
form a partially cross-linked network of high molecular
weight. They can absorb up to several hundred times their
own weight in water (Srikakulapu et al., 2020). They are a
special case of hydrogels. The most well-known are acrylic
hydrogels, cross-linked copolymers of acrylic acid and
sodium acrylate (Hanane, Hafida 2019).
The physicochemical characteristics determine the
behavior of these molecules. A complete characteriza-
tion of these properties is interesting to optimize their use
according to the desired applications and performances.
For example, they have electric charges of different natures.
There are neutral, ionic, ampholytic, and zwitterionic
polymers. Their morphology is also a determining prop-
erty. The main morphologies of commercialized products
are semi-crystalline, crystalline, amorphous, fibrous, and
macro-porous (Venkatachalam, Kaliappa 2021). This mor-
phology is also related to the cross-linking of the molecule,
which also controls water absorption (Guimaraes, Araujo,
Gotelip Barbosa 2018). Chemically, most SAPs are derived
from synthetic water-soluble acrylic monomers (Dayal, et
al., 1999). These molecules are subsequently modified to
obtain the properties of an SAP (good absorption capac-
ity, formation of an interpenetrating network, etc.). It is
the molecular structure and chemical composition that will
control the mechanisms of water absorption and release and
the associated kinetics (Venkatachalam, Kaliappa 2021).
Water Absorption by SAPs Theory and Its
Associated Kinetics
The network structure of polymers experiences growth
upon contact with water, primarily driven by two funda-
mental forces. The swelling phenomenon is orchestrated
by osmosis mechanisms, concurrently accompanied by a
reduction in enthalpy value. This process is pivotal for the
expansion of the polymer network. Conversely, the elastic
contractile force inherent in the network counteracts this
growth, compelling it to contract. The delicate interplay
between these two forces facilitates the attainment of equi-
librium in the swelling process (Pradhan, Pradhan 2023,
Achilleos, et al., 2000).
The intricate dynamics of polymer swelling have been
modeled, leading to the proposition of a mobile boundary
model demarcating a non-solvated segment from the “gel”
region. This boundary is not static but evolves dynamically
over time, reflecting the nuanced and evolving nature of
polymer interactions with water (Venkatachalam, Kaliappa
2021).
The swelling process is regulated by absorption kinet-
ics. The typical model applied to Superabsorbent Polymers
(SAPs) adheres to a straightforward second-order kinetics,
characterized as follows (Masaro, Zhu 1999):
St =Se (1 – e–t/r)
where, St is the absorption degree per gram over a given
time [gram of water/g of SAP], Se is the maximum absorp-
tion degree [gram of water/g of SAP], t is the absorption
time [s] and r is a constant [s].
The maximum absorption degree, Se, decreases over suc-
cessive water absorption/desorption cycles (Venkatachalam,
Kaliappa 2021). When SAP particles are incorporated with
ore, the maximum capacity is determined by estimating it
through calculations derived from laboratory-based experi-
mental data. In the laboratory setting, each SAP particle is
surrounded by an excess of water available for absorption.
However, in industrial conditions characterized by superfi-
cially moist ore, the attainment of this maximum capacity
is limited to only a fraction.
Studies on the incorporation of SAP with iron ore
emphasize the pivotal role of particle size distribution of
SAP as a crucial factor impacting absorption kinetics. The
research does not consider chemical composition influences.
Analysis of the employed polymers exposes a clear hierar-
chical sizing order, affirming the sequence’s validity within
the absorption kinetics framework. Notably, finer products
exhibit an enhanced absorption rate. Contrariwise, the
absorption efficacy of SAP fades when milled polymer is
applied (Srikakulapu et al., 2020).
Screen Efficiency
In its elemental configuration, a screen is conceptualized as
a planar structure with multiple apertures or perforations,
possessing uniform dimensions. Upon interaction with
the screen surface, particles undergo either permeation or
retention, contingent upon whether their sizes are smaller
or larger than the governing dimensions of the apertures.
The screening efficiency is quantified by the degree of mate-
rial segregation into size fractions exceeding and/or falling
below the aperture size (Wills, Finch 2016). Typically,
the focus is on the fine product amount, with efficiency
gauged by the recovery of the finished product (material
smaller than the cut-size) into the fine (undersize) amount,
denoted as Eu.
Eu =Uu /Ff
characterized by minerals including rhodocrosite, kutnaho-
rite, illites, kaolinites, pyrites, quartz, apatite, and siegenite.
Super Absorbent Polymer -SAP
Superabsorbent polymers are sodium polyacrylates that
form a partially cross-linked network of high molecular
weight. They can absorb up to several hundred times their
own weight in water (Srikakulapu et al., 2020). They are a
special case of hydrogels. The most well-known are acrylic
hydrogels, cross-linked copolymers of acrylic acid and
sodium acrylate (Hanane, Hafida 2019).
The physicochemical characteristics determine the
behavior of these molecules. A complete characteriza-
tion of these properties is interesting to optimize their use
according to the desired applications and performances.
For example, they have electric charges of different natures.
There are neutral, ionic, ampholytic, and zwitterionic
polymers. Their morphology is also a determining prop-
erty. The main morphologies of commercialized products
are semi-crystalline, crystalline, amorphous, fibrous, and
macro-porous (Venkatachalam, Kaliappa 2021). This mor-
phology is also related to the cross-linking of the molecule,
which also controls water absorption (Guimaraes, Araujo,
Gotelip Barbosa 2018). Chemically, most SAPs are derived
from synthetic water-soluble acrylic monomers (Dayal, et
al., 1999). These molecules are subsequently modified to
obtain the properties of an SAP (good absorption capac-
ity, formation of an interpenetrating network, etc.). It is
the molecular structure and chemical composition that will
control the mechanisms of water absorption and release and
the associated kinetics (Venkatachalam, Kaliappa 2021).
Water Absorption by SAPs Theory and Its
Associated Kinetics
The network structure of polymers experiences growth
upon contact with water, primarily driven by two funda-
mental forces. The swelling phenomenon is orchestrated
by osmosis mechanisms, concurrently accompanied by a
reduction in enthalpy value. This process is pivotal for the
expansion of the polymer network. Conversely, the elastic
contractile force inherent in the network counteracts this
growth, compelling it to contract. The delicate interplay
between these two forces facilitates the attainment of equi-
librium in the swelling process (Pradhan, Pradhan 2023,
Achilleos, et al., 2000).
The intricate dynamics of polymer swelling have been
modeled, leading to the proposition of a mobile boundary
model demarcating a non-solvated segment from the “gel”
region. This boundary is not static but evolves dynamically
over time, reflecting the nuanced and evolving nature of
polymer interactions with water (Venkatachalam, Kaliappa
2021).
The swelling process is regulated by absorption kinet-
ics. The typical model applied to Superabsorbent Polymers
(SAPs) adheres to a straightforward second-order kinetics,
characterized as follows (Masaro, Zhu 1999):
St =Se (1 – e–t/r)
where, St is the absorption degree per gram over a given
time [gram of water/g of SAP], Se is the maximum absorp-
tion degree [gram of water/g of SAP], t is the absorption
time [s] and r is a constant [s].
The maximum absorption degree, Se, decreases over suc-
cessive water absorption/desorption cycles (Venkatachalam,
Kaliappa 2021). When SAP particles are incorporated with
ore, the maximum capacity is determined by estimating it
through calculations derived from laboratory-based experi-
mental data. In the laboratory setting, each SAP particle is
surrounded by an excess of water available for absorption.
However, in industrial conditions characterized by superfi-
cially moist ore, the attainment of this maximum capacity
is limited to only a fraction.
Studies on the incorporation of SAP with iron ore
emphasize the pivotal role of particle size distribution of
SAP as a crucial factor impacting absorption kinetics. The
research does not consider chemical composition influences.
Analysis of the employed polymers exposes a clear hierar-
chical sizing order, affirming the sequence’s validity within
the absorption kinetics framework. Notably, finer products
exhibit an enhanced absorption rate. Contrariwise, the
absorption efficacy of SAP fades when milled polymer is
applied (Srikakulapu et al., 2020).
Screen Efficiency
In its elemental configuration, a screen is conceptualized as
a planar structure with multiple apertures or perforations,
possessing uniform dimensions. Upon interaction with
the screen surface, particles undergo either permeation or
retention, contingent upon whether their sizes are smaller
or larger than the governing dimensions of the apertures.
The screening efficiency is quantified by the degree of mate-
rial segregation into size fractions exceeding and/or falling
below the aperture size (Wills, Finch 2016). Typically,
the focus is on the fine product amount, with efficiency
gauged by the recovery of the finished product (material
smaller than the cut-size) into the fine (undersize) amount,
denoted as Eu.
Eu =Uu /Ff