2484 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
INTRODUCTION
The separation of valuable minerals from the gangue min-
erals is still a challenge, in particular the extraction of arse-
nides platinum group minerals (PGMs). Sperrylite (PtAs2)
and platarsite (PtAsS) are predominantly found in the
Platreef Bushveld complex in South Africa which is one of
the leading countries with highest percentages of platinum
group minerals (Schouwstra, Kinloch and Lee, 2000). The
mineralogy of the ore and their stability plays an impor-
tant role in understanding the floatability of these minerals.
Platinum (Pt) is usually found in different mineralogy and
this is dependent on the geological area. More than 75% of
platinum and 35% of palladium (Pd) in the world are pro-
duced in South Africa and they have originated in the ore
bodies (Shaik and Petersen, 2017). There are about 21%
of arsenides and 19% sulphides of PGMs in the Platreef,
which are mainly composed of Pt and Pd (Viljoen and
Schurmann, 1998) and it is clear that the arsenides host
the largest amounts of precious minerals. The PGMs are
extracted from ores but, because of their high value, they
are also recovered from industrial residues of variable com-
position. Most interestingly, the development of new tech-
nology for the extraction, recovery and separation of the
PGMs is therefore of special interest.
The PGMs are the most important source of platinum
and palladium (Vaughan and Craig, 1978), with platinum
extremely resistant to physical and chemical degradation and
having exceptional catalytic properties. These properties have
led to extensive utilization in jewellery, high temperature
industrial and automobile markets. The PGEs are present
as discrete in PGMs attached to the sulphides and arsenides
or in solid solution (Osbahr et al., 2013). In addition, the
sulphur and arsenide mixed system platarsite as one of the
platinum bearing mineral, possesses properties that makes it
relevant in the extraction of platinum and is of great impor-
tance to the mining industry (Gronvold and Rost, 1956).
Sperrylite is one of the most common platinum
group mineral (PGM) recovered by froth flotation and is
abundant in the Platreef Bushveld complex (Schouwstra,
Kinloch and Lee, 2000). It is relatively slow floating com-
pared to other PGM minerals (Shackleton, Malysiak, and
O’Connor, 2007). It has been reported that the flotation of
PGMs resulted in low recovery when using traditional xan-
thates (O’Connor and Shackleton, 2013). This was owed to
the report that the arsenides PGMs are not amiable to flota-
tion, and therefore new collectors are required (O’Connor
and Shackleton, 2013), (Maier, Barnes and Groves, 2013),
(Sefako, Sibanda and Sekgarametso, 2019). The triazine
collectors are promising reagents for mineral flotation and
have not been given much attention in minerals processing.
This is due to the high cost of synthetic materials in the
experimental laboratory. However, computational model-
ling has the ability to screen potential collector molecules
using minimal time and resources prior to beginning full
laboratory testing (Chen, Lan and Chen, 2013). The novel
collectors may show promise in order to improve the recov-
ery of slow floating arsenide minerals. Other factors such
as pH are crucial in impacting the floatability of minerals
and such are seldom ignored due to costs in such processes
for PGMs in industry. Hence, improving the recovery of
sperrylite and platarsite minerals will be of great economic
value to the South African PGMs industry.
McFadzean et al. (2018) have previously used compu-
tational and experimental microcalorimetry to investigate
the affinity of xanthates on pyrite surface. It was found
that there is a good agreement between the computational
and microcalorimetry binding energies trend. In addition,
Mkhonto et al. (2018) also used the same method of com-
parison for 2-mercaptobenzothiazole (MBT), 2-mercapto-
benzoxazole (MBO) and 2-mercaptobenzimidazole (MBI)
collectors on pyrite mineral surfaces and there was a good
agreement between the computational and microcalorim-
etry approach. Mkhonto et al. (2023) investigated the
adsorption of NBX, NBDTC and DTBAT collectors on
pyrite surface and there was a good agreement between the
computational and experimental techniques.
In this current study a computational and experimen-
tal approaches were used to design and synthesise a novel
s-triazine collector and investigate the adsorption perfor-
mance in comparison with xanthate and dithiocarbamate
collectors on dry and hydrated at neutral and acidic con-
ditions on sperrylite and platarsite mineral (100) surfaces.
These were accompanied by microflotation tests at different
pH conditions to determine their flotation performance on
sperrylite and platarsite minerals.
MATERIALS AND METHODOLOGY
Computational Methods
Calculations were carried out using density functional the-
ory (DFT) (Hohenberg and Kohn, 1964) with dispersion
correction (DFT-D3) to study the performance of NBX,
NBDTC and DTBAT collectors on dry and hydrated sper-
rylite and platarsite surfaces under neutral and acidic con-
ditions and as such two codes were utilized. The Vienna
Ab-initio Simulation Package (VASP) code (Kresse and
FurthermUller, 1996) was adopted for dry surface adsorp-
tion, while the Cambridge Serial Total Energy Package
(CASTEP) code (Clark et al., 2005) was employed for
hydrated surface adsorptions. This was due to VASP code
not being able to handle the large systems as compared to
INTRODUCTION
The separation of valuable minerals from the gangue min-
erals is still a challenge, in particular the extraction of arse-
nides platinum group minerals (PGMs). Sperrylite (PtAs2)
and platarsite (PtAsS) are predominantly found in the
Platreef Bushveld complex in South Africa which is one of
the leading countries with highest percentages of platinum
group minerals (Schouwstra, Kinloch and Lee, 2000). The
mineralogy of the ore and their stability plays an impor-
tant role in understanding the floatability of these minerals.
Platinum (Pt) is usually found in different mineralogy and
this is dependent on the geological area. More than 75% of
platinum and 35% of palladium (Pd) in the world are pro-
duced in South Africa and they have originated in the ore
bodies (Shaik and Petersen, 2017). There are about 21%
of arsenides and 19% sulphides of PGMs in the Platreef,
which are mainly composed of Pt and Pd (Viljoen and
Schurmann, 1998) and it is clear that the arsenides host
the largest amounts of precious minerals. The PGMs are
extracted from ores but, because of their high value, they
are also recovered from industrial residues of variable com-
position. Most interestingly, the development of new tech-
nology for the extraction, recovery and separation of the
PGMs is therefore of special interest.
The PGMs are the most important source of platinum
and palladium (Vaughan and Craig, 1978), with platinum
extremely resistant to physical and chemical degradation and
having exceptional catalytic properties. These properties have
led to extensive utilization in jewellery, high temperature
industrial and automobile markets. The PGEs are present
as discrete in PGMs attached to the sulphides and arsenides
or in solid solution (Osbahr et al., 2013). In addition, the
sulphur and arsenide mixed system platarsite as one of the
platinum bearing mineral, possesses properties that makes it
relevant in the extraction of platinum and is of great impor-
tance to the mining industry (Gronvold and Rost, 1956).
Sperrylite is one of the most common platinum
group mineral (PGM) recovered by froth flotation and is
abundant in the Platreef Bushveld complex (Schouwstra,
Kinloch and Lee, 2000). It is relatively slow floating com-
pared to other PGM minerals (Shackleton, Malysiak, and
O’Connor, 2007). It has been reported that the flotation of
PGMs resulted in low recovery when using traditional xan-
thates (O’Connor and Shackleton, 2013). This was owed to
the report that the arsenides PGMs are not amiable to flota-
tion, and therefore new collectors are required (O’Connor
and Shackleton, 2013), (Maier, Barnes and Groves, 2013),
(Sefako, Sibanda and Sekgarametso, 2019). The triazine
collectors are promising reagents for mineral flotation and
have not been given much attention in minerals processing.
This is due to the high cost of synthetic materials in the
experimental laboratory. However, computational model-
ling has the ability to screen potential collector molecules
using minimal time and resources prior to beginning full
laboratory testing (Chen, Lan and Chen, 2013). The novel
collectors may show promise in order to improve the recov-
ery of slow floating arsenide minerals. Other factors such
as pH are crucial in impacting the floatability of minerals
and such are seldom ignored due to costs in such processes
for PGMs in industry. Hence, improving the recovery of
sperrylite and platarsite minerals will be of great economic
value to the South African PGMs industry.
McFadzean et al. (2018) have previously used compu-
tational and experimental microcalorimetry to investigate
the affinity of xanthates on pyrite surface. It was found
that there is a good agreement between the computational
and microcalorimetry binding energies trend. In addition,
Mkhonto et al. (2018) also used the same method of com-
parison for 2-mercaptobenzothiazole (MBT), 2-mercapto-
benzoxazole (MBO) and 2-mercaptobenzimidazole (MBI)
collectors on pyrite mineral surfaces and there was a good
agreement between the computational and microcalorim-
etry approach. Mkhonto et al. (2023) investigated the
adsorption of NBX, NBDTC and DTBAT collectors on
pyrite surface and there was a good agreement between the
computational and experimental techniques.
In this current study a computational and experimen-
tal approaches were used to design and synthesise a novel
s-triazine collector and investigate the adsorption perfor-
mance in comparison with xanthate and dithiocarbamate
collectors on dry and hydrated at neutral and acidic con-
ditions on sperrylite and platarsite mineral (100) surfaces.
These were accompanied by microflotation tests at different
pH conditions to determine their flotation performance on
sperrylite and platarsite minerals.
MATERIALS AND METHODOLOGY
Computational Methods
Calculations were carried out using density functional the-
ory (DFT) (Hohenberg and Kohn, 1964) with dispersion
correction (DFT-D3) to study the performance of NBX,
NBDTC and DTBAT collectors on dry and hydrated sper-
rylite and platarsite surfaces under neutral and acidic con-
ditions and as such two codes were utilized. The Vienna
Ab-initio Simulation Package (VASP) code (Kresse and
FurthermUller, 1996) was adopted for dry surface adsorp-
tion, while the Cambridge Serial Total Energy Package
(CASTEP) code (Clark et al., 2005) was employed for
hydrated surface adsorptions. This was due to VASP code
not being able to handle the large systems as compared to