XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2097
The Fe-Ti oxide phases exhibited a variety of textures
ranging from homogeneous hematite, titanohematite and
ilmenite grains through to an abundance of grains exhibit-
ing complex exsolution textures involving either ilmenite
in Ti-Hemss hosts, or hematite or Ti-Hemss exsolution in
ilmenite hosts. Similar observations were made by Rahman
et al. (2020). As discussed by Rahman et al. (2019) at tem-
peratures above 800 °C there is complete miscibility (solid
solution) between ilmenite and hematite, however during
crystallisation and cooling, hematite and ilmenite become
segregated forming titanohematite which is characterised
by lamellae of hematite in varying amounts intercalated
with ilmenite.
Results from EPMA mapping are provided in Figure 3
which provides a visual representation of the major phases
present (at levels of 1% by area). The results confirm the
main impurities in the ilmenite fraction included amphi-
bole, mica, feldspar, and quartz. These were typically pres-
ent as discrete grains indicating that further separation may
be possible to generate a purer/cleaner ilmenite concen-
trate. The results also show that the current beneficiation
procedure leads to a mixed Fe- and Fe-Ti oxide concen-
trate that has low TiO2 and high Fe2O3 (reflecting the high
proportion of hematite and complex Ti-Hemss particles).
There is a need therefore to refine the beneficiation proce-
dure, if possible, to separate hematite from ilmenite and
from Ti-Hemss (which could be used in a different stream
that would recover both Ti and Fe, separately). If complete
separation was not achievable, it is likely that the Fe-Ti con-
centrate would need to be processed in a high temperature
smelting (slag) process that would generate pig iron and
TiO2-enriched slag products (Pistorius, 2008).
Mag Mix and Non-Mags Fractions
Quantitative XRD analysis of the Mag. Mix fraction indi-
cated the sample mineralogy was dominated by amphibole
(28 wt%), epidote (15 wt%), garnet (27 wt%), quartz
(14 wt%) and feldspar (5 wt%). Minor phases included
ilmenite (2 wt%), titanite (3 wt%), mica (3 wt%), and
pyroxene (3 wt%). The QXRD analysis of the Non-mags
fraction indicated 22 wt% quartz, 16 wt% epidote, 14 wt%
amphibole, 12 wt% garnet, 8 wt% titanite, 7% apatite,
6 wt% feldspar and 5 wt% zircon. Minor to trace pyroxene
(3 wt%), rutile (3 wt%) and mica (1 wt%) were also present.
Figure 3. EPMA map results for the ilmenite fraction showing the distribution of major phases
at levels 1% by area. Note that the XRD results indicated hematite as a separate phase however
in this sample the bulk of the hematite is present as Titanohematite (i.e., Ti-Hem
ss )particles
The Fe-Ti oxide phases exhibited a variety of textures
ranging from homogeneous hematite, titanohematite and
ilmenite grains through to an abundance of grains exhibit-
ing complex exsolution textures involving either ilmenite
in Ti-Hemss hosts, or hematite or Ti-Hemss exsolution in
ilmenite hosts. Similar observations were made by Rahman
et al. (2020). As discussed by Rahman et al. (2019) at tem-
peratures above 800 °C there is complete miscibility (solid
solution) between ilmenite and hematite, however during
crystallisation and cooling, hematite and ilmenite become
segregated forming titanohematite which is characterised
by lamellae of hematite in varying amounts intercalated
with ilmenite.
Results from EPMA mapping are provided in Figure 3
which provides a visual representation of the major phases
present (at levels of 1% by area). The results confirm the
main impurities in the ilmenite fraction included amphi-
bole, mica, feldspar, and quartz. These were typically pres-
ent as discrete grains indicating that further separation may
be possible to generate a purer/cleaner ilmenite concen-
trate. The results also show that the current beneficiation
procedure leads to a mixed Fe- and Fe-Ti oxide concen-
trate that has low TiO2 and high Fe2O3 (reflecting the high
proportion of hematite and complex Ti-Hemss particles).
There is a need therefore to refine the beneficiation proce-
dure, if possible, to separate hematite from ilmenite and
from Ti-Hemss (which could be used in a different stream
that would recover both Ti and Fe, separately). If complete
separation was not achievable, it is likely that the Fe-Ti con-
centrate would need to be processed in a high temperature
smelting (slag) process that would generate pig iron and
TiO2-enriched slag products (Pistorius, 2008).
Mag Mix and Non-Mags Fractions
Quantitative XRD analysis of the Mag. Mix fraction indi-
cated the sample mineralogy was dominated by amphibole
(28 wt%), epidote (15 wt%), garnet (27 wt%), quartz
(14 wt%) and feldspar (5 wt%). Minor phases included
ilmenite (2 wt%), titanite (3 wt%), mica (3 wt%), and
pyroxene (3 wt%). The QXRD analysis of the Non-mags
fraction indicated 22 wt% quartz, 16 wt% epidote, 14 wt%
amphibole, 12 wt% garnet, 8 wt% titanite, 7% apatite,
6 wt% feldspar and 5 wt% zircon. Minor to trace pyroxene
(3 wt%), rutile (3 wt%) and mica (1 wt%) were also present.
Figure 3. EPMA map results for the ilmenite fraction showing the distribution of major phases
at levels 1% by area. Note that the XRD results indicated hematite as a separate phase however
in this sample the bulk of the hematite is present as Titanohematite (i.e., Ti-Hem
ss )particles