2258 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
alkylethermonoamines or alkyletherdiamines. Due to their
exceptional selectivity and dose efficiency, both representa-
tives are regarded as state-of-the-art collector compositions
in the field of removal of silica from iron ores (Figure 1).
However, the chemicals sector continues to strive for
better biodegradability and lower toxicity towards aquatic
organisms for these representatives of the etheramine family.
It is well-known that the introduction of a labile bond
in the structure of surfactants can improve biodegradability
(Stjerndahl and Holmberg, 2003). Esters are typical repre-
sentatives of weak link-bearing compounds. The ester bond
easily breaks at low or high pH and hydrolyzes via enzy-
matic catalysis performed by the enzymes widely abundant
in the environment. During the last two decades new readily
biodegradable, low aqua-toxic and highly efficient/selective
surfactants containing labile ester bonds, called polyes-
ters polyquats (PEPQ), were developed for silica removal
from calcite. These compounds successfully replaced many
environmentally unfriendly quaternary ammonium com-
pounds that have been dominating the market for many
years (Figure 2).
The presence of an inherently labile bond in a surfac-
tant molecule, traditionally, was regarded as a substantial
disadvantage. However, due to the increased concern for the
environment in society, the negative attitude towards sur-
factants that contain a labile bond has changed (Kronberg,
et al., 2014).
This study focuses on the use of alkylesteramines that
are readily biodegradable with low aquatoxicity. The self-
assembly of alkylesteramines and alkylethermonoamine
are studied through molecular dynamics simulations. The
novel surfactants were used in reverse flotation of iron ore
in a comparative study with readily biodegradable PEPQ
and well-established in the field alkylethermonoamines.
EXPERIMENTAL
Materials for Flotation
Flotations were performed on iron ores containing differ-
ent amounts of silica. The following flotation chemicals
belonging to the alkyl esteramine family were synthesized:
isodecyl -6-aminohexanoate sulphate, 2-ethylhexyl-6-ami-
nohexanoate sulphate, isooctyl -6-aminohexanoate sulphate
(Venderbosch et al., 2018). As a benchmark, the following
silica collectors were used: isodecyloxyprolylamine (partly
neutralized by acetic acid – Lilaflot® 811M alkylether-
monoamine), isotridecyloxypropylamine (partly neutral-
ized by acetic acid – Lilaflot® 821M alkylethermonoamine)
and dextrin (Crystal Tex® 627M tapioca dextrin produced
by Ingredion). The polyester polyquaternary ammonium
compound used in this study was synthesized as described
in WO 2015/091308A1 Example 1 (Gorochovceva and
Klingberg, 2013).
Computer Simulations
Molecular dynamics simulations were performed using
Gromacs (version 2018.3) (Berendsen et al., 2005), the
four-side TIP4Pew water model (Horn et al., 2004) and
the General Amber force field (Wang et al., 2004) in NVT
ensemble. The simulation box had the size of 6 × 6 × 6 nm
and, for both simulations, 60 molecules were placed in the
box. The molecules were simulated in their cationic form
and to keep the net charge of the simulation box neutral,
a small number of water molecules were replaced by Cl–
ions. Prior to the production run, the simulation box was
equilibrated in a three-step process: i) energy minimization,
ii) position-restrained 100 ps NVT simulation and iii) 100
ps NPT run. The production run was performed for a time
span of 100 ns, giving enough time for the surfactant mol-
ecules to self-assemble.
Figure 2.
R
O NH2
R
O
H
N NH
2
alkylethermonoamine alkyletherdiamine
Figure 1.
alkylethermonoamines or alkyletherdiamines. Due to their
exceptional selectivity and dose efficiency, both representa-
tives are regarded as state-of-the-art collector compositions
in the field of removal of silica from iron ores (Figure 1).
However, the chemicals sector continues to strive for
better biodegradability and lower toxicity towards aquatic
organisms for these representatives of the etheramine family.
It is well-known that the introduction of a labile bond
in the structure of surfactants can improve biodegradability
(Stjerndahl and Holmberg, 2003). Esters are typical repre-
sentatives of weak link-bearing compounds. The ester bond
easily breaks at low or high pH and hydrolyzes via enzy-
matic catalysis performed by the enzymes widely abundant
in the environment. During the last two decades new readily
biodegradable, low aqua-toxic and highly efficient/selective
surfactants containing labile ester bonds, called polyes-
ters polyquats (PEPQ), were developed for silica removal
from calcite. These compounds successfully replaced many
environmentally unfriendly quaternary ammonium com-
pounds that have been dominating the market for many
years (Figure 2).
The presence of an inherently labile bond in a surfac-
tant molecule, traditionally, was regarded as a substantial
disadvantage. However, due to the increased concern for the
environment in society, the negative attitude towards sur-
factants that contain a labile bond has changed (Kronberg,
et al., 2014).
This study focuses on the use of alkylesteramines that
are readily biodegradable with low aquatoxicity. The self-
assembly of alkylesteramines and alkylethermonoamine
are studied through molecular dynamics simulations. The
novel surfactants were used in reverse flotation of iron ore
in a comparative study with readily biodegradable PEPQ
and well-established in the field alkylethermonoamines.
EXPERIMENTAL
Materials for Flotation
Flotations were performed on iron ores containing differ-
ent amounts of silica. The following flotation chemicals
belonging to the alkyl esteramine family were synthesized:
isodecyl -6-aminohexanoate sulphate, 2-ethylhexyl-6-ami-
nohexanoate sulphate, isooctyl -6-aminohexanoate sulphate
(Venderbosch et al., 2018). As a benchmark, the following
silica collectors were used: isodecyloxyprolylamine (partly
neutralized by acetic acid – Lilaflot® 811M alkylether-
monoamine), isotridecyloxypropylamine (partly neutral-
ized by acetic acid – Lilaflot® 821M alkylethermonoamine)
and dextrin (Crystal Tex® 627M tapioca dextrin produced
by Ingredion). The polyester polyquaternary ammonium
compound used in this study was synthesized as described
in WO 2015/091308A1 Example 1 (Gorochovceva and
Klingberg, 2013).
Computer Simulations
Molecular dynamics simulations were performed using
Gromacs (version 2018.3) (Berendsen et al., 2005), the
four-side TIP4Pew water model (Horn et al., 2004) and
the General Amber force field (Wang et al., 2004) in NVT
ensemble. The simulation box had the size of 6 × 6 × 6 nm
and, for both simulations, 60 molecules were placed in the
box. The molecules were simulated in their cationic form
and to keep the net charge of the simulation box neutral,
a small number of water molecules were replaced by Cl–
ions. Prior to the production run, the simulation box was
equilibrated in a three-step process: i) energy minimization,
ii) position-restrained 100 ps NVT simulation and iii) 100
ps NPT run. The production run was performed for a time
span of 100 ns, giving enough time for the surfactant mol-
ecules to self-assemble.
Figure 2.
R
O NH2
R
O
H
N NH
2
alkylethermonoamine alkyletherdiamine
Figure 1.