MINERAL SEPARATION
uantum Design’s Superconducting High-Gradient Magnetic Separation (SHGMS) system
offers high processing capacity in a compact, modular design with fully cryogen-free
operation, according to the company.
The self-contained, automated system integrates into processing streams and can operate
continuously, requiring only electrical power, compressed air, raw material and water. “Multiple
systems can be operated in parallel for increased processing capacity and minimal loss in
throughput during maintenance,” Dr Paul Beharrell, Senior Scientist in charge of the SHGMS, said.
The Quantum Design SHGMS system provides:
n Easy-to-use, fully-automated operation;
n Touch screen interface;
n Average magnetic field of 5 Tesla over processing volume;
n A compact, self-contained system with high processing capacity;
n Ten million kg/y clay processing throughput;
n Instantly changeable processing parameters;
n A modular design allowing for processing capacity to grow and maintenance of single unit while
others continue processing.
SHGMS can be applied to a myriad of processes in many different industries. Some examples
include purification of kaolin to increase its brightness and thereby significantly increase its value;
concentration of valuable minerals such as rare earths and precious metals; extraction and
concentration of very small particles of weakly magnetic materials; extraction of valuable minerals
from mine tailings and mine waste dumps.
The extraction and concentration of these materials is particularly applicable to uranium, gold,
platinum, titanium and rare earth minerals, according to the company.
Q
requiring separation are expected, Wei said.
Technology advances in material and
manufacturing have enabled the industry to build
magnetic separators tailored to specific
applications, Wei said. “If the magnets have been
correctly engineered, these powerful separators
can remove almost any ferrous material that
dares to pass through their magnetic fields.”
He added: “As technology and research
advances, conveyor belts become wider (>2,400
mm) and operate at much faster speeds (>5.7
m/s) which, in turn, means the belts are required
to handle a much greater capacity (7,200 t/hr).
“This puts more stress on magnetic separators
to keep up with the increased trends in width,
speed and overall bulk material handling capacity.”
Magnetic separation
High intensity magnetic separators can be used
as an effective tool for producing high-grade
concentrates or products, with magnets often
finding their way into the process flowsheet at
feldspar and silica sand operations – to separate
magnetically susceptible materials from the
targeted minerals – or when processing coltan to
extract tantalum for use in the manufacture of
batteries.
Bunting Magnetics is a leading designer and
Magnetic protection
Separation technologies are not only useful for
the recovery of economic amounts of minerals or
metals; they also provide protection for
downstream equipment.
Peter Wei, Project Engineer for Kinder Australia,
in a paper titled, Magnetic Separation for the
Protection of Crushing Equipment in the
Quarrying, Recycling and Mining Industries spelt
this out.
“A magnetic separator is industrial equipment
which creates a powerful magnetic flux. They are
to remove fine metals such as iron flakes, pins
and bits of wire.
In recent years, in order to satisfy the
changing needs and requirements of the mining
industry, new and improved magnetic separators
have been developed.
“Depending on the type of mineral being
mined, the size of tramp irons occurring will
vary,” Wei said. “Hence, magnetic separators
require varying degrees of magnetic flux power.
These are separated into electro magnets and
used to protect vital process equipment
downstream from damage while it produces a
clean separated final product,” he said.
The type of equipment Wei is thinking of permanent magnets.”
Electro magnets require rectifiers and are
more commonly used in suspended applications.
A rectifier changes alternating current to a direct
current, with the two-coiled magnetic creating a
includes primary jaw crushers, cone crushers,
hammer mills and other tertiary crushers.
At the same time, magnets can effectively
prevent long sharp metal shards from cutting, powerful magnetic field that can be effectively
used to remove tramp iron from conveyor belts,
according to Wei.
Permanent magnetic separators are used on
ripping or tearing conveyor belts, he said.
The type and style of magnets used in industry
depends on the location within the process.
Larger materials and deeper burden depth
require larger magnets to be operational, while conveyor belts where only small levels of tramp
ferrous material is expected, with plant operators
monitoring the amount of ferrous metals
captured and determining when the magnet
requires cleaning – a process that involves a non-
magnets suspended over a conveyor belt are
typically designed to remove large ferrous
material such as hand-held tools, iron scrap and metallic stainless-steel tray scraper.
There is a third self-cleaning magnet option,
which is based on existing and improved
technology of the two variations above, but only
machinery tips.
Rare earth magnets, meanwhile, are employed
20 International Mining | MAY 2019
used if large volumes of metallic materials
manufacturer of magnetic separators and metal
detectors for the recycling, quarrying and mining
industries. Its range of metal separation and
detection equipment is manufactured at their
Master Magnets facility in Redditch, just outside
Birmingham, UK.
There are three basic types of magnetism used
in industrial magnetic separation technology,
according to Bunting:
n Paramagnetic – minerals that are only slightly
affected by an applied magnetic field. They
move towards concentration in lines of
magnetic flux (eg hematite, ilmenite, and
chromite);
n Ferromagnetism – minerals capable of
achieving a high degree of magnetic alignment
(eg magnetite), and;
n Diamagnetism – a mineral (eg silica) very
weakly repelled by the pole of a strong
magnet. When a magnetic field is applied, a
diamagnetic mineral will develop a magnetic
moment through induction but in the opposite
direction and is therefore repelled.
Bunting said: “Magnetic separation of mineral
deposits is based on a three-way competition
between magnetic forces, other external forces
such as gravitational or inertial forces, and inter-
particle attractive and repulsive forces.
“The combination of these forces determines
the outcome of any given magnetic separation
and is much affected by the nature of the feed
such as size distribution, magnetic susceptibility
and other physical and chemical characteristics.”