XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1231
WHIMS magnetics was subjected to 12 passes through the
Falcon unit (the initial ore feed and 11 tails) to generate
a mass yield-recovery-grade relationship. Unfortunately,
no upgrade of REE values was observed, nor downgrad-
ing of Fe values, with a strong relationship of cumulative
mass yield and recovery occurring. This is thought to be
due to the lack of fluidising water in the unit, however,
using a fluidising bowl with limited concentrate catchment
is impractical in this application at industrial scale due to
the high mass yields required (20 to 30% versus 0.05% for
high value commodities such as coarse gold).
On the basis of these results, WHIMS was retained as
the primary separation method, with flotation for further
enrichment of magnetics, discussed next.
Flotation
Ore Flotation
Extensive flotation on ore feed sample, both with reverse
silica flotation and direct REO flotation, using 1 kg charges
was undertaken in parallel with WHIMS to assess as an
alternative processing route and also to screen collectors for
eventual WHIMS magnetics flotation. Results of sighter
testing are presented in Figure 10 as terminal recovery-
grade values against a notional response curve.
Only one test extended beyond this curve, which used
the Solvay reagent Aero 6494, an alkyl hydroxamate col-
lector, for recovery of allanite. Sodium silicate was used
to disperse gangue. The result reflects rougher and clean-
ing of concentrate without regrinding beyond the primary
grind size of 80% passing 38 µm. Achieving a high upgrade
was hampered by co-recovery of hastingsite which also
responded well to rare earth collectors. Starch, normally
effective for depressing hematite, depressed hastingsite but
also depressed allanite since the two minerals are chemically
very similar.
Reverse flotation (rejecting gangue minerals to concen-
trate) testing was also undertaken. This style of flotation
is applied extensively in the iron ore industry in Brazil to
remove residual silica with encapsulated iron ore fines from
the magnetic product. It is also used for “pre-flotation” of
Figure 10. Terminal recovery-grade results for whole ore direct flotation tests
WHIMS magnetics was subjected to 12 passes through the
Falcon unit (the initial ore feed and 11 tails) to generate
a mass yield-recovery-grade relationship. Unfortunately,
no upgrade of REE values was observed, nor downgrad-
ing of Fe values, with a strong relationship of cumulative
mass yield and recovery occurring. This is thought to be
due to the lack of fluidising water in the unit, however,
using a fluidising bowl with limited concentrate catchment
is impractical in this application at industrial scale due to
the high mass yields required (20 to 30% versus 0.05% for
high value commodities such as coarse gold).
On the basis of these results, WHIMS was retained as
the primary separation method, with flotation for further
enrichment of magnetics, discussed next.
Flotation
Ore Flotation
Extensive flotation on ore feed sample, both with reverse
silica flotation and direct REO flotation, using 1 kg charges
was undertaken in parallel with WHIMS to assess as an
alternative processing route and also to screen collectors for
eventual WHIMS magnetics flotation. Results of sighter
testing are presented in Figure 10 as terminal recovery-
grade values against a notional response curve.
Only one test extended beyond this curve, which used
the Solvay reagent Aero 6494, an alkyl hydroxamate col-
lector, for recovery of allanite. Sodium silicate was used
to disperse gangue. The result reflects rougher and clean-
ing of concentrate without regrinding beyond the primary
grind size of 80% passing 38 µm. Achieving a high upgrade
was hampered by co-recovery of hastingsite which also
responded well to rare earth collectors. Starch, normally
effective for depressing hematite, depressed hastingsite but
also depressed allanite since the two minerals are chemically
very similar.
Reverse flotation (rejecting gangue minerals to concen-
trate) testing was also undertaken. This style of flotation
is applied extensively in the iron ore industry in Brazil to
remove residual silica with encapsulated iron ore fines from
the magnetic product. It is also used for “pre-flotation” of
Figure 10. Terminal recovery-grade results for whole ore direct flotation tests