COMMINUTION
F
loLevel Technologies has more than 40 years’ experience in developing and manufacturing
process automation solutions for the mining industry and has recently added the CyclonFLO
system to its product range.
CyclonFLO uses high powered acoustic signals to measure solids concentration percentages
by monitoring acoustic impedance changes. The main advantage in using acoustics is that they
are not affected by changes in ore characteristics (like background radiation) in the reading,
according to FloLevel.
These acoustic arrays are available in several transducer sizes to provide a solution to all
operating process temperature ranges (ball mill outfeed, SAG mill outfeed) and sample time
speeds.
The company said: “The simplicity of design provides for easy installation, minimal
maintenance support and a long service life, when compared to concentrate sample analysers.”
FloLevel said monitoring the out¬flow of the SAG mill is generally undertaken by a particle
analyser, which measures particle size and solids concentration. Smaller mining operations may
carry out both applications manually, according to FloLevel, but its CyclonFLO Array 8 measures
suspended solids concentration on a real time sample rate, to provide control information for
water addition/dilution for the SAG mill infeed, based on the measured solids concentration.
“The CyclonFLO range is designed to operate in difficult wear rate applications and will work
in pulp/slurry that is not homogenised mixed,” FloLevel said. Comparing the infeed feed rate
with the outfeed solids concentration will indicate whether the water addition at the infeed is
correct. This is extremely important as it will change the outfl¬ow solids density and has a major
infl¬uence on the slurry rheology, according to the company.
FloLevel concluded: “As grinding (SAG mill) has the highest energy costs in the concentrator,
the low cost CyclonFLO is an absolute measurement requirement to keep grinding costs down,
by providing feedback information for the DCS Water.”
The Array 8 also has solids control monitoring applications in the ball mill outflow and surge
tank pump box, while CyclonFlo Array 3 and 8 could be used in the cyclone overflow within a
comminution circuit, according to FloLevel.
FloLevel said: “Monitoring the overflow (correct particle size for rougher flotation) is very
important as it provides feedback to the control system that the correct solids density is
presenting to the cyclone infeed and the cyclone is producing the correct range of solids
concentration from the over¬flow.
“The over¬flow solids concentration is then pumped to the rougher circuit tank for
distribution. The concentration from the cyclone overflow should be held just above the
maximum solids concentration for presenting to multiple rougher flotation circuits. A solids
concentration of around 45% solids should be available at the first flotation cell for each rougher
circuit to obtain maximum recovery efficiency.
“The CyclonFLO Array 3, or the CyclonFLO Array 8, are used in this application, depending on
how homogenised the solids are mixed and the size of the cyclone system.”
And, for the cyclone underfl¬ow, FloLevel said: “Monitoring the underfl¬ow of the cyclone
(oversize particles being returned to the ball mill) is very important in monitoring the return
solids particle volume to the ball mill for controlling the required water addition at the infeed.
“It is also useful in determining the operating efficiency of the cyclone based on infeed solids
concentration, overflow solids concentration and underflow solids concentration in determining
correct separation efficiency in the cyclone.
For this application, the CyclonFLO Array 8 is always used, FloLevel said.
of work between comminution stages, he said.
“We also come across several other
bottlenecks to comminution sections causing
operations to fall short of their potential, eg
insufficient beneficiation and downstream de-
watering capacity,” he said. An insufficient level time to investigate before process changes can
be implemented.
“We feel the best results can be achieved with
of ore property knowledge – in terms of
comminution response – and a lack of
instrumentation to provide feedback to operators
and metallurgists were also regularly seen.
He concluded: “Some of the issues can be sustainable process improvements.”
Carrying out these checks will, not only, have
an impact on energy and water use; they will
also positively affect mining companies’ bottom
line, potentially providing them with more of
resolved by (mining companies) changing how
they operate their equipment, whereas some
may need significant financial investment and/or the required cash flow to invest in new
technology that can further improve their
carbon footprints.
72 International Mining | APRIL 2019
long-term service contracts, where we
collaborate with customers to attain increased
equipment availability and continuous and
New technology
Recent advances in the comminution field
include better comminution efficiency through
upstream ore sorting and downstream coarser
grinding steps, as well as HPR/HRC, improved
data collection and analysis, efficient
comminution technologies such as HPGR, and
novel/hybrid configurations, CEEC said.
Mine-to-mill optimisation continues to deliver
tangible results and can optimise existing sites
or demonstrate impact of combined changes
such as these, CEEC said. Hatch’s Duffy said each
mine-to-mill process optimisation project needed
to be tailored to the specific operation for the
best results.
“Successful mine-to-process optimisation of
both brownfield and new projects (greenfield
design) requires a detailed understanding of the
ore types and all processes, mine to plant. This is
based on extensive ore characterisation, data
collection and analysis, modelling and
simulation, which is combined with extensive
industrial experience,” she said.
Metso’s Global Consulting and Laboratories
Manager, Suzy Lynch-Watson, said the
introduction of HPGR/HRC technology to replace
SAG mills in many metalliferous ore operations
was gaining traction and bringing down energy
consumption in the comminution circuit.
“Ten years ago, the adaptation of the HPGR to
hard-rock operations was still left up to the few
brave pioneers – Boddington, Cerro Verde, etc –
but these days there have been many to adopt
similar or identical flowsheets for similar ores
and applications,” she said.
“The issues of performance and wear are
becoming more manageable with various
innovations, including Metso’s HRC – with
features such as the flanged roll and hinged
mechanism for holding the rolls straight – sure to
be a game-changer once it takes more of a hold
in the marketplace,” she said.
Tenova TAKRAF will be highlighting its own
HPGR technology expertise at this month’s
Bauma fair in Munich, Germany. The event will
give the company an opportunity to show off its
new range of roller presses.
And, there are other comminution equipment
developments coming from within the industry,
such as thyssenkrupp’s so-called eccentric roll
crusher type ERC25-25, which, the company said,
achieves a quantum leap in primary crushing
through a particularly flat and robust design and
high throughputs of up to 3,000 t/h.
As IM recently showed in its ore sorting focus
(IM March 2019), ore sorting is also starting to be
more widely accepted, moving on from
applications in commodities such as phosphate,
diamonds and gold, to bulk materials such as
copper and iron ore.
Özer said of ore sorting: “Improved sensors