1212 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Conventional dry mill techniques and hybrid techniques
using froth flotation were compared.
Feed Preparation Plant Circuit
Feed classification was performed using both rotating and
circular vibrating screens and hydro-cyclones, in line with
typical industry practices.
Primary Concentrator Plant Circuit
Gravimetric separation was performed using spiral sepa-
rators. The spiral separator test work was conducted in a
closed-circuit test rig consisting of a full-sized spiral sepa-
rator (single start), a sump, pump and full-stream deflec-
tion samplers, as shown in Figure 3. The pump discharge
reported to a distributor with a portion of the feed stream
directed to the spiral feed box and the remainder returning
to the feed sump. The test rig was started up with water and
solids added to the sump until the required test parameters
were established. The spiral feed stream flows down the spi-
ral trough with the high-density material migrating toward
the center column and the low-density material being
transported to the outer edge of the trough. Concentrate
splitters recover the high-density material to a concen-
trate channel, while intermediate density and low-density
streams are directed by further splitters into individual
product collection channels within the product collection
box. Each stream then returns to the sump via timed, full-
stream deflection samplers. Sub-samples of each stream
were then representatively extracted, using riffle splitter, for
assay purposes.
For each stage, separation performance curves (recov-
ery vs mass yield, grade vs mass yield) are then defined at
the nominal conditions, using the specified gravity spiral
model. Assuming acceptable performance is achieved, the
sample is then processed through an open circuit bulk sam-
ple processing step to generate feedstock for subsequent
evaluation. A wide range of operating conditions and or
different equipment types or models may be tested to assess
the impact on performance and assist in delineating a flow-
sheet meeting the process objectives.
As illustrated in Figure 4, the procedure is repeated suc-
cessively through steps of closed-circuit performance tests
followed by open circuit bulk sample processing until the
final heavy mineral concentrate grade is produced.
MSP Circuit
Dry magnetic test work was conducted on a single-stage
Reading laboratory-scale high intensity permanent Rare
Earth Drum (RED) or Rare Earth Roll (RER) magnetic
separator. A non-magnetics retreat configuration was
typically selected. For subsequent stages the feed rate was
reduced according to the weight split and the selected frac-
tion re-treated to simulate a three-stage production unit.
Electrostatic separation tests were performed using a
single-stage, laboratory-scale Carrara High Tension Roll
(HTR) separator. Feed material was pre-heated to 100°C
and passed over the separator operating at the required feed
rate, roll speed and electrode voltage to generate conductor,
middling and non-conductor fractions. A middling retreat
configuration was typically selected. For subsequent stages
the feed rate was reduced according to the weight split and
the selected fraction re-treated to simulate a three-stage
production unit.
The wet shaking table employed was a laboratory-scale
Wilfley No13 model. Dry feed was introduced at a constant
rate into the feed box and dilution water was added. The
products were collected into buckets with the aid of manu-
ally positioned splitters. Products were then dewatered and
Figure 3. Spiral test rig set-up
Conventional dry mill techniques and hybrid techniques
using froth flotation were compared.
Feed Preparation Plant Circuit
Feed classification was performed using both rotating and
circular vibrating screens and hydro-cyclones, in line with
typical industry practices.
Primary Concentrator Plant Circuit
Gravimetric separation was performed using spiral sepa-
rators. The spiral separator test work was conducted in a
closed-circuit test rig consisting of a full-sized spiral sepa-
rator (single start), a sump, pump and full-stream deflec-
tion samplers, as shown in Figure 3. The pump discharge
reported to a distributor with a portion of the feed stream
directed to the spiral feed box and the remainder returning
to the feed sump. The test rig was started up with water and
solids added to the sump until the required test parameters
were established. The spiral feed stream flows down the spi-
ral trough with the high-density material migrating toward
the center column and the low-density material being
transported to the outer edge of the trough. Concentrate
splitters recover the high-density material to a concen-
trate channel, while intermediate density and low-density
streams are directed by further splitters into individual
product collection channels within the product collection
box. Each stream then returns to the sump via timed, full-
stream deflection samplers. Sub-samples of each stream
were then representatively extracted, using riffle splitter, for
assay purposes.
For each stage, separation performance curves (recov-
ery vs mass yield, grade vs mass yield) are then defined at
the nominal conditions, using the specified gravity spiral
model. Assuming acceptable performance is achieved, the
sample is then processed through an open circuit bulk sam-
ple processing step to generate feedstock for subsequent
evaluation. A wide range of operating conditions and or
different equipment types or models may be tested to assess
the impact on performance and assist in delineating a flow-
sheet meeting the process objectives.
As illustrated in Figure 4, the procedure is repeated suc-
cessively through steps of closed-circuit performance tests
followed by open circuit bulk sample processing until the
final heavy mineral concentrate grade is produced.
MSP Circuit
Dry magnetic test work was conducted on a single-stage
Reading laboratory-scale high intensity permanent Rare
Earth Drum (RED) or Rare Earth Roll (RER) magnetic
separator. A non-magnetics retreat configuration was
typically selected. For subsequent stages the feed rate was
reduced according to the weight split and the selected frac-
tion re-treated to simulate a three-stage production unit.
Electrostatic separation tests were performed using a
single-stage, laboratory-scale Carrara High Tension Roll
(HTR) separator. Feed material was pre-heated to 100°C
and passed over the separator operating at the required feed
rate, roll speed and electrode voltage to generate conductor,
middling and non-conductor fractions. A middling retreat
configuration was typically selected. For subsequent stages
the feed rate was reduced according to the weight split and
the selected fraction re-treated to simulate a three-stage
production unit.
The wet shaking table employed was a laboratory-scale
Wilfley No13 model. Dry feed was introduced at a constant
rate into the feed box and dilution water was added. The
products were collected into buckets with the aid of manu-
ally positioned splitters. Products were then dewatered and
Figure 3. Spiral test rig set-up