| • |
An
integrated approach to breakage characterisation and representation
for comminution (pendulum, drop-weight tester, t-curves). |
| • |
The
mathematical modelling of breakage and classification
processes with robust, useful and accessible models of
crushers, rod mills, AG/SAG mills, ball mills, screens,
hydrocyclones and, more recently, impact crushing and
other comminution devices. |
| • |
A
complete methodology for process design and optimisation
of comminution and classification processes by computer
simulation. |
| • |
Models
for predicting the power draw of a range of crushers,
AG/SAG mills, ball and rod mills (in the range 7-20,000
kW). |
| • |
A
prototype methodology for design and optimisation of flotation
circuits using kinetic models by computer simulation. |
| • |
A
much improved understanding of the dense medium process,
including models of drums, cyclones and drain and rinse
screens, and guidelines for minimising medium loss. |
| • |
A
general methodology for process analysis, modelling and
simulation. |
| • |
A
series of computer products for use by practising engineers:
JKSimMet, JKSimFloat, JKSimDM, JKMBal, etc. (generally
developed by JKTech). |
The
process of collecting reliable data from production scale
operations has resulted in one of P9's major and most enduring
achievements: its databases, particularly in comminution and
dense medium separation, which are probably the best and most
comprehensive available. These have proved vital in calibrating
the mathematical models, testing their validity, and providing
a reliable yardstick for process design. With the new approach
to flotation modelling currently underway in P9, a comprehensive
database of flotation operations is now established and growing
rapidly.
In addition to the long-term advances in know-how and technology,
and the collection of data into large reliable databases,
short-term benefits have been delivered to sponsors in over
120 major case studies within the program. As far as possible,
each site study is designed to address a particular local
problem, whilst at the same time contributing another element
to the greater body of knowledge. Some recent examples include
the following:
| • |
Increase
in throughput of up to 25% in the Hellyer AG mill through
modifications to operating conditions and closed circuiting. |
| • |
Rapid
commissioning of Red Dome comminution circuits through
on-site optimisation by simulation. |
| • |
Extensive
post-mortem of the WMC Leinster AG mill commissioning,
leading to a significant improvement in throughput. |
| • |
Improved
throughput at Teck Cominco Red Dog Operation following
comprehensive studies of SAG, ball and tower mill circuits. |
| • |
Improved
throughput at Alcoa's Wagerup operation through the retro-fitting
of twin-chamber pulp lifters (August 1999). |
| • |
Use
by several sponsors of the new techniques of flotation
cell hydrodynamic characterisation to evaluate flotation
cell performance and new equipment purchases. |
| • |
Installation
of scavenger froth crowders in the Xstrata (MIM) copper
concentrator to improve froth zone recovery. |
| • |
Use
of the new flotation circuit modelling technique to review
the WMC Mt Keith flotation circuit design. |
| • |
Many
site studies of dense medium separation plants, leading
to reduction of ferrosilicon costs. |
| • |
Adoption
by BHP Iron Ore and Hamersley Iron of a new dense medium
cyclone design, evaluated by the project. |
Finally,
the use of postgraduate students to carry out the site related
research activities has produced over 100 skilled, industrially-literate
graduates with Masters and PhD training. A vast majority of
these have subsequently worked within the mining industry,
particularly at sponsors' sites, some at senior levels. These
graduates, together with the professionals who worked in the
project within their company's sponsorship of the work, have
had a significant influence on the practice of minerals processing
as they have moved about the industry, disseminating the project's
mature know-how. The training of postgraduate students in
this manner is rapidly dwindling and should be a cause of
concern to industry.
Specific
areas of research in the P9M extension were comminution, flotation
and gravity concentration. This section summarises, by module,
the aims of the P9M extension.
To
access the full details of what has been achieved please click
here.
Comminution, Classification and Liberation
Comminution research in P9M built largely on the foundations
of previous work and, in many cases, focused on process problems
identified during earlier studies. It covered topics in crushing,
milling, classification and liberation. Autogenous and semi-autogenous
milling remain the major topics of interest, though for the
first time in many years crushing and fine grinding were included
in response to sponsor demand. The program contained four
broad foci:
| • |
to
develop further the understanding of a range of comminution
sub-processes and to determine what conditions, from a
design and operation viewpoint, will lead to the best
machine and circuit performance possible, |
| • |
to
improve the ability to correctly size comminution circuits, |
| • |
to increase the useful breadth and level of detail that
our process models can predict, |
| • |
to
develop innovative solutions to equipment/process shortcomings. |
The
program was divided into a number of tasks, as follows:
| • |
incorporate/improve
lifter design, speed and filling effects in AG/SAG and
ball mill models |
| • |
model slurry flow in square and low aspect ratio mills
|
| • |
model
coarse solids flow through pebble ports |
| • |
validate
scale-up/modelling procedure for tower mills and stirred
mills |
| • |
validate
HPGR modelling/scale-up procedure |
| • |
develop
a generic model of crushers that covered primary crusher
operation and simple liner configurations |
| • |
further
develop the 3-product cyclone - model and implement/evaluate
in the field |
| • |
relate
acoustic emissions to load in AG and SAG mills |
| • |
validate
liberation model |
| • |
refine
and validate procedure for predicting steel wear in mills |
Flotation
The
main deliverable of the flotation work in P9M was a comprehensive
methodology for modelling industrial flotation cells and circuits,
incorporating both true flotation and entrainment, using the
models developed in projects P9K and P9L. To this end, the
work was broken up into a number of tasks, as follows:
| • |
develop
a comprehensive methodology for flotation cell and circuit
modelling |
| • |
confirm
the validity of the P9 models of flotation, and the assumptions
contained in them |
| • |
establish
a database of industrial mechanical flotation cell characteristics
in terms of key hydrodynamic, gas dispersion and solids
suspension parameters |
| • |
further
develop and refine the Sb (bubble surface area flux) predictor
model |
| • |
further investigate the effect of particle size, liberation
and mineralogy on P (ore floatability) |
| • |
determine
the effect of regrinding on P values |
| • |
develop
models of Rf (froth zone recovery) and entrainment for
large industrial scale flotation cells |
| • |
develop
a water recovery model dependent on ore and pulp characteristics |
| • |
investigate
the effects of power input and turbulence on the flotation
of fines |
| • |
carry
out flow visualisation and CFD studies on mechanical flotation
cells |
Gravity Concentration
The
gravity concentration module was a modest research program
aimed at developing an improved understanding of a range of
gravity separation processes not investigated in previous
JKMRC research. The objectives were:
| • |
to develop an improved understanding of the principles
of separation in key generic technologies (eg enhanced
(centrifugal) gravity concentration). |
| • |
to
develop simulation tools for the engineer to undertake
process design, equipment selection and process optimisation. |
| • |
to
achieve process improvements in selected cases. |
| • |
to provide sponsors with a window on the range of gravity
separation technologies, and access to other JKMRC work
in the field. |
The
work was divided into three tasks:
| • |
develop
a general model of enhanced gravity concentration in a
form that will allow calibration to specific machine types. |
| • |
improve
the performance of fine mineral jigs |
| • |
enhance
the performance of gravity separation processes using
novel measurement and control systems |
Final Reports from previous P9 extensions are available to any
AMIRA members after the confidentiality period is passed.
Reports from the P9K and P9L Projects are available at the following
costs.
P9K A$200 for each Volume (2 Volumes, Flotation and Comminution).
P9L A$500 for each Volume (2 Volumes, Flotation and Comminution).
The P9M Reports are currently confidential until December 2005. |
