XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1235
• Two stage crushing and HPGR processing to pro-
duce a minus 3 mm fine crushed product without
generating excessive fines
• Primary grinding (type is dependent on annualised
capacity) to a P80 grind size of 250 to 300 microns,
closed with hydrocyclones
• Three stage WHIMS to reject over 70% of initial
feed mass, predominantly feldspars and silica.
• Desliming of WHIMS magnetics to remove the
majority of the minus 20 microns fraction. Underflow
is filtered and dried and the slimes are sent forward
to the flotation circuit.
• Dried underflow solids are subjected to primary
HTR separation, producing a high REO grade non-
conductor product, whilst middlings are subjected
to two stages of counter-current cleaning to recover
additional REE values. Collective rejects, the iron-
rich conductors. are set to final tailings along with
WHIMS magnetics.
• Enriched non-conductors containing the REEs are
combined with slimes and subjected to flotation to
further reduce concentrate mass and acid consuming
gangue minerals.
• Flotation concentrate is thickened ahead of hydro-
metallurgical treatment, with atmospheric sulphuric
acid tank leaching currently favoured.
• Combined tailings are thickened and pumped to the
tailings storage facility.
The use of HTR separators to provide early rejection of
hastingsite ahead of downstream co-enrichment processes
is highly desirable. However, the capacity of HTRs is lim-
ited to at best 7 dry t/h, so unless the processing rate is
very modest, it is impractical to employ HTRs as the pri-
mary separation method. Therefore, HTRs are used in this
flowsheet to upgrade WHIMS magnetics in order to reduce
the solids bulk that needs to be treated. The HTR feed is
deslimed first to remove the troublesome fine fraction, pro-
viding a deslimed product that is easy to dewater and dry.
A schematic of the proposed flowsheet is presented as
Figure 14. Each unit operation adopted is supported by
testwork (grinding, WHIMS, flotation, HTR and thick-
ening) or experience with similar ores (HPGRs, filtration)
but have been rearranged somewhat into the current for-
mat. Further testing is needed to derive overall performance
data, particularly mass yields, concentrate REE grade and
recovery.
CONCLUSION
QEMSCAN analysis indicates the target REE bearing
mineral allanite is largely free at moderately coarse grind
Figure 14. Proposed Beneficiation Flowsheet for Halleck
Creek Ore
• Two stage crushing and HPGR processing to pro-
duce a minus 3 mm fine crushed product without
generating excessive fines
• Primary grinding (type is dependent on annualised
capacity) to a P80 grind size of 250 to 300 microns,
closed with hydrocyclones
• Three stage WHIMS to reject over 70% of initial
feed mass, predominantly feldspars and silica.
• Desliming of WHIMS magnetics to remove the
majority of the minus 20 microns fraction. Underflow
is filtered and dried and the slimes are sent forward
to the flotation circuit.
• Dried underflow solids are subjected to primary
HTR separation, producing a high REO grade non-
conductor product, whilst middlings are subjected
to two stages of counter-current cleaning to recover
additional REE values. Collective rejects, the iron-
rich conductors. are set to final tailings along with
WHIMS magnetics.
• Enriched non-conductors containing the REEs are
combined with slimes and subjected to flotation to
further reduce concentrate mass and acid consuming
gangue minerals.
• Flotation concentrate is thickened ahead of hydro-
metallurgical treatment, with atmospheric sulphuric
acid tank leaching currently favoured.
• Combined tailings are thickened and pumped to the
tailings storage facility.
The use of HTR separators to provide early rejection of
hastingsite ahead of downstream co-enrichment processes
is highly desirable. However, the capacity of HTRs is lim-
ited to at best 7 dry t/h, so unless the processing rate is
very modest, it is impractical to employ HTRs as the pri-
mary separation method. Therefore, HTRs are used in this
flowsheet to upgrade WHIMS magnetics in order to reduce
the solids bulk that needs to be treated. The HTR feed is
deslimed first to remove the troublesome fine fraction, pro-
viding a deslimed product that is easy to dewater and dry.
A schematic of the proposed flowsheet is presented as
Figure 14. Each unit operation adopted is supported by
testwork (grinding, WHIMS, flotation, HTR and thick-
ening) or experience with similar ores (HPGRs, filtration)
but have been rearranged somewhat into the current for-
mat. Further testing is needed to derive overall performance
data, particularly mass yields, concentrate REE grade and
recovery.
CONCLUSION
QEMSCAN analysis indicates the target REE bearing
mineral allanite is largely free at moderately coarse grind
Figure 14. Proposed Beneficiation Flowsheet for Halleck
Creek Ore