2488 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
adsorption system the bottom six layers (6L) were kept fixed
to bulk coordinate, while the top six layers (6L) were relaxed
and allowed to interact with the adsorbates. The coordina-
tion of the surfaces and their surface energies are given in
Table 1. The (100) surface had the lowest positive surface
energy value, thus most stable. This is in agreement with the
previous reports by Waterson et al. (2015) and Ntoahae et
al. (2005) for sperrylite mineral surface.
Collector Molecular Geometries
The neutral and acidic NBX, NBDTC and DTBAT col-
lector molecules are shown in Figure 3 which displays the
optimized collector geometries. The xanthate, dithiocar-
bamate and s-triazine collectors are characterised by head
group composed of –OCS2, –NHCS2 and –NHN3C3S2,
respectively. Note that we focused on the centre of reactivity
C–S group atoms of the collectors. As shown in Figure 3,
the C4–S1 possesses a double bond and the C4–S2 pos-
sesses a single bond on NBX and NBDTC. In addition
the C–S bonds of DTBAT are single bonds. Two sets of
molecular geometries were investigated, that is the neutral
(association with Na+) and acidic (association with H+)
sets. Figure 3 shows the collectors association with Na+ and
H+ for NBX, NBDTC and DTBAT.
The calculated bond lengths and bond angles for the
xanthate, dithiocarbamate and s-triazine collectors both in
neutral and acidic conditions are presented in Table 2. The
C–S bond lengths of xanthate were found shorter amongst
the collectors suggesting that these bonds were more stable,
while those on SDTBAT were longer. This implied that the
SDTBAT will be highly reactive followed by the SNBDTC
then SNBX. The C–O =1.355 Å and 1.347 Å for SNBX
and HNBX, C–N =1.354 Å and 1.351 Å for SNBDTC
and HNBDTC and C–N =1.376 Å and 1.353 Å for
SDTBAT and HDTBAT (see Table 2). The bond angles of
127.52° and 126.07° for SNBX and SNBDTC under neu-
tral condition and bond angles of 120.40° and 117.02° for
HNBX and HNBDTC under acidic condition were also
obtained.
Table 1. Relaxed surface energies, atoms coordination of bulk and (100) surface on sperrylite and platarsite minerals
Model Number of Atoms
Surface Coordination
Surface Energies (J.m−2) Pt As S
Bulk PtAs2 12 6 4 N/A N/A
PtAs2 (100) Surface 96 5 3 N/A 1.05
Bulk PtAsS 12 6 4 4 N/A
PtAsS (100) Surface 96 4,5 3 3 0.56
Figure 3. Relaxed molecular geometries of organic collectors: (a) SNBX, (b) SNBDTC and (c) SDTBAT, (d) HNBX, (e)
HNBDTC and (f) HDTBAT
adsorption system the bottom six layers (6L) were kept fixed
to bulk coordinate, while the top six layers (6L) were relaxed
and allowed to interact with the adsorbates. The coordina-
tion of the surfaces and their surface energies are given in
Table 1. The (100) surface had the lowest positive surface
energy value, thus most stable. This is in agreement with the
previous reports by Waterson et al. (2015) and Ntoahae et
al. (2005) for sperrylite mineral surface.
Collector Molecular Geometries
The neutral and acidic NBX, NBDTC and DTBAT col-
lector molecules are shown in Figure 3 which displays the
optimized collector geometries. The xanthate, dithiocar-
bamate and s-triazine collectors are characterised by head
group composed of –OCS2, –NHCS2 and –NHN3C3S2,
respectively. Note that we focused on the centre of reactivity
C–S group atoms of the collectors. As shown in Figure 3,
the C4–S1 possesses a double bond and the C4–S2 pos-
sesses a single bond on NBX and NBDTC. In addition
the C–S bonds of DTBAT are single bonds. Two sets of
molecular geometries were investigated, that is the neutral
(association with Na+) and acidic (association with H+)
sets. Figure 3 shows the collectors association with Na+ and
H+ for NBX, NBDTC and DTBAT.
The calculated bond lengths and bond angles for the
xanthate, dithiocarbamate and s-triazine collectors both in
neutral and acidic conditions are presented in Table 2. The
C–S bond lengths of xanthate were found shorter amongst
the collectors suggesting that these bonds were more stable,
while those on SDTBAT were longer. This implied that the
SDTBAT will be highly reactive followed by the SNBDTC
then SNBX. The C–O =1.355 Å and 1.347 Å for SNBX
and HNBX, C–N =1.354 Å and 1.351 Å for SNBDTC
and HNBDTC and C–N =1.376 Å and 1.353 Å for
SDTBAT and HDTBAT (see Table 2). The bond angles of
127.52° and 126.07° for SNBX and SNBDTC under neu-
tral condition and bond angles of 120.40° and 117.02° for
HNBX and HNBDTC under acidic condition were also
obtained.
Table 1. Relaxed surface energies, atoms coordination of bulk and (100) surface on sperrylite and platarsite minerals
Model Number of Atoms
Surface Coordination
Surface Energies (J.m−2) Pt As S
Bulk PtAs2 12 6 4 N/A N/A
PtAs2 (100) Surface 96 5 3 N/A 1.05
Bulk PtAsS 12 6 4 4 N/A
PtAsS (100) Surface 96 4,5 3 3 0.56
Figure 3. Relaxed molecular geometries of organic collectors: (a) SNBX, (b) SNBDTC and (c) SDTBAT, (d) HNBX, (e)
HNBDTC and (f) HDTBAT