2100 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
ilmenite or leucoxene (approx. 58–70 wt% TiO2), natu-
ral rutile, synthetic rutile, or a titanium slag with 85 wt%
TiO2 as the basic raw materials. Based on the composition
of Brahmaputra river ilmenite, the most likely option for
processing would be via the sulphate route.
Grosz (1987) compiled the chemical specifications for
the raw materials required for the manufacture of TiO2
pigment from the sulphate digestion process. The TiO2
specification is met when only ilmenite grains (including
both homogenous and exsolved grains) are analysed. If the
titanohematite grains are included, the average TiO2 con-
tent reduces considerably to around 36% TiO2 (Table 1).
There is a need therefore to refine the beneficiation proce-
dure to separate the high-TiO2 ilmenite and from Ti-Hemss
(which could be used in a different stream that would
recover both Ti and Fe, separately) to generate a high grade
(i.e., 97 wt%) ilmenite-only concentrate with which to
accurately assess the suitability of the ilmenite concentrate
for sulphate route processing. A suggested separation testing
procedure would likely be based on low intensity magnetic
separation (LIMS). If complete separation was not achiev-
able, it is likely that the Fe-Ti concentrate would need to be
processed in a high temperature smelting (slag) process that
would generate pig iron and TiO2-enriched slag products
(Pistorius, 2008).
Garnet product
Almandine-rich garnet is the principal abrasive for indus-
trial applications because of its high melting point (~1320
°C), high specific gravity (4.3) and high hardness (Harden,
2002). Garnet is the main substitute for quartz sand which
is becoming less used for blasting because of the silicosis
risk. The average compositional data for the garnets from
the Brahmaputra river sands are almandine-rich suggest-
ing good potential for air-blasting applications. Most
commercial garnet abrasives are within the size range 180–
250 micron (Elsner, 2010) which is towards the upper limit
of the Brahmaputra river garnets based on data in Rahman
et al. (2016) and additional characterisation test work will
be required to determine the grainsize distribution in a fully
separated garnet concentrate. As well, further beneficiation
will likely be required to remove the additional quartz and
aluminosilicate gangue phases (amphibole and epidote) to
ensure the concentrate meets commercial specifications.
SUMMARY
This paper presents the results of characterisation studies
on selected product streams from a mineral sands pilot
plant processing material from the northern Brahmaputra
river. Emphasis was on the recovered TiO2-rich and garnet
components to assess their potential product applications.
The ilmenite fraction was composed of three main grain
types: homogeneous ilmenite grains exhibiting complex
exsolution of ilmenite in Ti-Hemss hosts or hematite or
Ti-Hemss exsolution in ilmenite hosts, and hematite.
Results showed here is a need to refine the beneficiation
procedure to separate these grain types to meet product
specifications for different processing routes. Compositions
determined on 100 individual garnet grains in the garnet
fraction indicated the garnets were mostly almandine-rich
with ~68% almandine component. For the garnet to be
used for commercial applications, further beneficiation is
required to remove the quartz and aluminosilicate gangue
phases (amphibole and epidote) to ensure the concentrate
meets commercial specifications.
The initial results from the Joypurhat mineral sands
pilot plant have demonstrated that it is possible to recover
VHM components such as ilmenite and garnet from the
Brahmaputra river sands but more in-depth studies are nec-
essary to develop more efficient beneficiation processes for
the VHMs. As well, additional characterisation and ben-
eficiation studies on other potentially recoverable products
such as rutile and zircon are desirable.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the assistance pro-
vided by CSIRO co-workers Nathan Webster (XRD),
Steve Peacock (XRF), Cameron Davidson (EPMA sample
preparation) and Nick Wilson (EMPA characterisation).
We acknowledge the generous support provided by the
Honourable Minister, Ministry of Science and Technology,
Bangladesh, and co-workers at BCSIR for assisting in
the collection and preparation of samples. The Director
of BCSIR is thanked for providing financial support for
Aminur Rahman to pursue a PhD in Australia and RMIT
University is acknowledged for funding the PhD project
through a University funded postgraduate scholarship.
REFERENCES
Coleman, J.M. 1969. Brahmaputra River: Channel
processes and sedimentation. Sedimentary Geology,
3:139–239.
Elsner, H. 2010. Heavy minerals of economic importance.
Bundesanstaltfür Geowissenschaften und Rohstoffe (BGR)
Assessment Manual. Hannover, Germany. 218 p.
Force, E.R. 1991. Geology of titanium-mineral deposits.
Geological Society of America, Special Paper 259.
Grosz, A.E. 1987. Nature and distribution of potential
heavy-mineral resources offshore of the Atlantic coast
of the United States. Marine Mining. 6:339–357.
ilmenite or leucoxene (approx. 58–70 wt% TiO2), natu-
ral rutile, synthetic rutile, or a titanium slag with 85 wt%
TiO2 as the basic raw materials. Based on the composition
of Brahmaputra river ilmenite, the most likely option for
processing would be via the sulphate route.
Grosz (1987) compiled the chemical specifications for
the raw materials required for the manufacture of TiO2
pigment from the sulphate digestion process. The TiO2
specification is met when only ilmenite grains (including
both homogenous and exsolved grains) are analysed. If the
titanohematite grains are included, the average TiO2 con-
tent reduces considerably to around 36% TiO2 (Table 1).
There is a need therefore to refine the beneficiation proce-
dure to separate the high-TiO2 ilmenite and from Ti-Hemss
(which could be used in a different stream that would
recover both Ti and Fe, separately) to generate a high grade
(i.e., 97 wt%) ilmenite-only concentrate with which to
accurately assess the suitability of the ilmenite concentrate
for sulphate route processing. A suggested separation testing
procedure would likely be based on low intensity magnetic
separation (LIMS). If complete separation was not achiev-
able, it is likely that the Fe-Ti concentrate would need to be
processed in a high temperature smelting (slag) process that
would generate pig iron and TiO2-enriched slag products
(Pistorius, 2008).
Garnet product
Almandine-rich garnet is the principal abrasive for indus-
trial applications because of its high melting point (~1320
°C), high specific gravity (4.3) and high hardness (Harden,
2002). Garnet is the main substitute for quartz sand which
is becoming less used for blasting because of the silicosis
risk. The average compositional data for the garnets from
the Brahmaputra river sands are almandine-rich suggest-
ing good potential for air-blasting applications. Most
commercial garnet abrasives are within the size range 180–
250 micron (Elsner, 2010) which is towards the upper limit
of the Brahmaputra river garnets based on data in Rahman
et al. (2016) and additional characterisation test work will
be required to determine the grainsize distribution in a fully
separated garnet concentrate. As well, further beneficiation
will likely be required to remove the additional quartz and
aluminosilicate gangue phases (amphibole and epidote) to
ensure the concentrate meets commercial specifications.
SUMMARY
This paper presents the results of characterisation studies
on selected product streams from a mineral sands pilot
plant processing material from the northern Brahmaputra
river. Emphasis was on the recovered TiO2-rich and garnet
components to assess their potential product applications.
The ilmenite fraction was composed of three main grain
types: homogeneous ilmenite grains exhibiting complex
exsolution of ilmenite in Ti-Hemss hosts or hematite or
Ti-Hemss exsolution in ilmenite hosts, and hematite.
Results showed here is a need to refine the beneficiation
procedure to separate these grain types to meet product
specifications for different processing routes. Compositions
determined on 100 individual garnet grains in the garnet
fraction indicated the garnets were mostly almandine-rich
with ~68% almandine component. For the garnet to be
used for commercial applications, further beneficiation is
required to remove the quartz and aluminosilicate gangue
phases (amphibole and epidote) to ensure the concentrate
meets commercial specifications.
The initial results from the Joypurhat mineral sands
pilot plant have demonstrated that it is possible to recover
VHM components such as ilmenite and garnet from the
Brahmaputra river sands but more in-depth studies are nec-
essary to develop more efficient beneficiation processes for
the VHMs. As well, additional characterisation and ben-
eficiation studies on other potentially recoverable products
such as rutile and zircon are desirable.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the assistance pro-
vided by CSIRO co-workers Nathan Webster (XRD),
Steve Peacock (XRF), Cameron Davidson (EPMA sample
preparation) and Nick Wilson (EMPA characterisation).
We acknowledge the generous support provided by the
Honourable Minister, Ministry of Science and Technology,
Bangladesh, and co-workers at BCSIR for assisting in
the collection and preparation of samples. The Director
of BCSIR is thanked for providing financial support for
Aminur Rahman to pursue a PhD in Australia and RMIT
University is acknowledged for funding the PhD project
through a University funded postgraduate scholarship.
REFERENCES
Coleman, J.M. 1969. Brahmaputra River: Channel
processes and sedimentation. Sedimentary Geology,
3:139–239.
Elsner, H. 2010. Heavy minerals of economic importance.
Bundesanstaltfür Geowissenschaften und Rohstoffe (BGR)
Assessment Manual. Hannover, Germany. 218 p.
Force, E.R. 1991. Geology of titanium-mineral deposits.
Geological Society of America, Special Paper 259.
Grosz, A.E. 1987. Nature and distribution of potential
heavy-mineral resources offshore of the Atlantic coast
of the United States. Marine Mining. 6:339–357.