ORE SORTING
now Lake Resources is one of the latest
companies to eye up ore sorting to reduce
costs and increase productivity, with the
exploration company asking DRA Global to
collaborate with Steinert and come up with an
effective strategy for its Thompson Brothers
lithium project, in Manitoba, Canada.
The engineering firm will examine the best
laser or X-ray method to help separate out waste
material from the spodumene pegmatite at
Thompson Brothers, Snow Lake said.
Over the other side of the world Steinert is
involved in a sorting project for a rare earth asset.
Recently Northern Minerals capped off its ore
sorting project enhancement initiatives at the
Browns Range rare earths project, in northern
Western Australia, with the selection of a
Steinert ore sorter for use at its heavy rare earth
pilot plant.
Northern Minerals said it expected the system
to be installed by the middle of the year.
The company said: “The findings from initial
test work and studies indicate that the inclusion
of ore sorting at Browns Range has the potential
to double the mill feed grade potentially leading
to an increased production rate of heavy rare
earth carbonate and a potential lowering of
operating costs.”
XRT ore sorting is also being evaluated at
North Arrow Minerals’ 100% owned Naujaat
diamond project in Nunavut, Canada.
In May 2019, the Toronto-listed company
confirmed it had engaged Imilingo Mineral
Processing of Pretoria, South Africa, TOMRA, and
Microlithics Laboratories of Thunder Bay,
Ontario, to investigate modular diamond
recovery design options incorporating TOMRA’s
XRT sorting technology at the project.
The engagement is with a view to recovering
diamonds greater than 3 mm (nominally >0.5 ct)
in size from a diamond recovery plant, it said.
North Arrow is currently planning for collection
of a 10,000 t bulk sample from the Q1-4 deposit
at Naujaat and, as part of this work, has initiated
an engineering design and costing study of a
small-scale mobile diamond recovery plant.
Imilingo’s iPlant packages combine XRT
solutions from the likes of TOMRA to sort and
deliver feed material in a clean and well
classified state, Managing Director, Jaco Prinsloo,
told IM last year. Microlithics Laboratories,
meanwhile, provides several diamond-specific
services to clients in North America.
It may not be sensor-based ore sorting, but
allmineral’s alljig ® units have gained recognition
across the industry for their ability to separate
high-value ore from waste in primary and
secondary raw materials such as coal, ore,
gravel, sand and slag.
S
60 International Mining | MARCH 2020
The AKA-FLOW
functions on a
combination of an air
fluidised bed with a
specially developed
sifter
The company, in
November,
announced that
Yunnan Hualian Zinc
and Iridium Co Ltd
had awarded the
Dusseldorf-based
company with a
contract for the
supply of three advanced alljig units to the
world’s largest “multi-mineral plant”.
The order included two F/R type, single cut,
side pulsed alljig units with an enhanced shaft
system and one M(UB) type 2 cut, under pulsed
alljig unit incorporating allmineral’s poppet valve
system to significantly reduce air consumption.
The latter unit will also be fitted with the allscan ®
chamber monitoring system for enhanced
operation, it said.
alljig units fluidise feed material using
pulsating water to form layers of grains
according to their density, which subsequently
separates the heavy material from the stratified
material bed. Electronic sensors are used to
automatically monitor and control the discharge
of heavy particles contained in the feed, with the
jigging machines creating a physically stable and
individually adjustable optimal jigging stroke at
minimal energy consumption by means of air-
pulsed water, according to allmineral. These
machines provide capacities ranging from 5 t/h
up to 700 t/h, with separation and cleaning of
feed material applicable in grain sizes from 150
mm down to less than 1 mm.
Density separation is also the focus for AKW
Equipment + Process Design and its AKA-FLOW
product.
As a dry operation gravimetric sorting device
used for preliminary separation and enrichment
of materials of different densities, AKA-FLOW is
often used as a pre-treatment process ahead of
wet mechanical separation.
The company says limited availability of water
in arid areas has led to the need for additions
and amendments to wet mechanical processing
technology. “Dry gravity separation ensures,
among other advantages, eco-friendly
processing, low energy consumption as well as
potential cost reductions due to obviating
process water circuits and product and tailings
dewatering and drying processes,” it said.
The AKA-FLOW functions on a combination of
an air fluidised bed with a specially developed
sifter, with studies looking at different raw
materials showing “outstanding performance”
both in terms of throughput and classifying, the
company said. The optimum grain size ranges
from 30 µm to 2 mm, with throughput ranges,
depending on the material, of 3-6 t/h based on
units of 400 mm width of the fluidised bed, and
9-18 t/h with units of 1,200 mm width of the
fluidised bed.
According to the company, product purity and
output can be influenced by five adjustable
parameters:
n The feed mass flow: controlled via a vibro
channel, this allows an equal distribution of
the feed material over the screening surface;
n The split preparation, which has influence on
the amount of the intermediates;
n The number of strokes controlled via the rpm
of the unbalanced drives. The higher the
frequency, the faster the material transport via
the screening surface;
n The amplitude, which can be changed through
the adjustment of the weights; and
n Airflow, which is produced by a fan and passes
from below through the screening surface.
This generates the fluidised bed.
To achieve and ensure optimum sorting
results, each material has to be tested in
accordance with the process and machine
parameters above.
In its technical laboratory in Hirschau,
Germany, AKW can perform a variety of tests for
customers with all relevant processing
equipment for classifying, sorting, solid/liquid
separation, gravimetric preparation/dry
separation, thickening, dewatering and magnetic
separation, it said.
The laboratory is equipped with a small, as
well as large, AKA-FLOW test device, allowing for
pilot tests to be carried out.
And, for the dry separation machines, control
for the regulation of the solid concentration of
the heavy fraction output has been successfully
developed, it says.