Global
In November 2013, the pre-feasibility
optimisation study was commissioned
with the purpose of developing a single,
preferred business case to a pre-feasibility
study level of definition. WorleyParsons
RSA was appointed by the WGJV as
the pre-feasibility optimisation study
consultants. Before starting to work on
the pre-feasibility optimisation study,
WorleyParsons used the StepWise
methodology to develop, assess, and
shortlist preferred options. The StepWise
process, developed by WorleyParsons’
strategic and advisory arm Advisian,
provides solid data to enable prospective
funders to make strategic investment
decisions, with a focus on maximising
returns, while minimising and managing
exposure to risk.
Bailie says that by following
the StepWise process, WGJV and
WorleyParsons RSA were able to
reframe a new business case for
the Wafi-Golpu Project by looking
at a small-scale build-up and
programme of ongoing work that led
to the feasibility study, and later the
Feasibility Study Update.
Initially, fourteen conceptual mining
options were developed and assessed
with the associated technical and
business case, which was narrowed
down to three preferred options to
carry forward into the pre-feasibility
optimisation study. WorleyParsons
RSA completed the pre-feasibility
optimisation study in 2014, which
recommended a staged development
approach involving the mass mining
method, block caving, and commencing
with the development of a smaller
lower-cost start-up mine (Stage 1
Project). The Stage 2 Project focused on
a life of mine plan as a follow-on from
the Stage 1 Project, with the objective
of identifying and evaluating options
to maximise and enhance the value of
the Golpu ore body through optimising
access and the exploitation of the ore
body above the 4100mRL target area.
Updated feasibility study
In 2016, the feasibility study was
subjected to a competent independent
review process, which identified no
fatal flaws but made recommendations
for additional work to be undertaken.
New legislation pertaining to changes
in the fiscal and taxation regime had
adversely impacted the economics of
the project, while tailings management
developments, data from deep geotech
drilling, and concerns regarding
power generation all necessitated
the reconsideration of the initial
pre-feasibility and feasibility studies.
Based on the ore body dataset
improvement achieved in 2016, the
feasibility study update intended to
validate, optimise, and improve upon
the 2015 Stage 2 Golpu Pre-Feasibility
and Feasibility Study findings and
recommendations. The FSU incorporates
a much larger mine than previously
anticipated, and mining throughput will
be increased from three to 16.84 million
tonnes per annum (Mtpa) at BC44, six
to 16.84Mtpa at BC42 and BC40 at
PFS level. This increase in throughput
required the redesign of the underground
material handling system, process plant,
associated infrastructure, and overland
concentrate and tailings transport
pipelines.
Utilising technology
In setting out the updated business
case for the FSU, WorleyParsons
RSA drew on SmartPlant design
technology that uses rapid prototyping,
and other innovative processes such
as Building Information Modelling
(BIM), to create a sophisticated digital
project design platform and prepare
for project execution as efficiently and
cost-effectively as possible.
“By utilising our intelligent design
tools, we were able to incorporate all the
consu ltants and role players involved in
the project into one user-friendly digital
model,” says Niell McEwan, senior
project manager at WorleyParsons
RSA. SmartPlant is a portfolio of
design and data management solutions
that captures integrated engineering
knowledge. It includes BIM that
augments the three primary spatial
dimensions of width, height, and depth
with 3-D, 4-D, and 5-D technology,
allowing the entire project team to
visualise project objectives as never
before, greatly improving operational
efficiency in a dynamic time and
cost-saving environment.
Leigh Cox, general manager for
Engineering and Construction for
WGJV, says that making use of the
WorleyParsons RSA rapid prototyping,
and other innovative processes such as
BIM, underpinned efficient engineering
and design delivery, with the added benefit
of having higher confidence in the design,
design integration, and cost estimation
and planning. “We were impressed with
WorleyParsons RSA’s use of BIM for
the FSU, as it showed us how quickly
different components and disciplines
can be merged together to help evaluate
design, optimise resource utilisation, and
identify design risks upfront and on an
ongoing basis,” says Cox.
The findings of the FSU provide
greater clarity around the infrastructure
that will be associated with the
development of the Wafi-Golpu Project
and proposes a modular-designed power
plant to ensure a reliable base load power
supply; new port facilities created within
the Port of Lae; a new northern access
road and two new community roads;
and puts forward three types of tailings
management options for consideration.
The largest mine in PNG
If developed, the Wafi-Golpu Project
will be the largest, deepest, and most
complex underground mine in Papua
New Guinea (PNG), with a mine life of
28 years. In addition to this significant
injection into the PNG economy, the
project will create economic benefits
across the country, including about 2 500
direct jobs during construction, about
850 ongoing operations jobs, and further
indirect jobs created in the region.
Wafi-Golpu is 400m above sea level
in moderately hilly terrain. Furthermore,
the proposed mine is located near the
Watut River, 30km upstream from its
confluence with the Markham River. In
February 2016, the WGJV participants
completed feasibility and pre-feasibility
studies for the Wafi-Golpu copper-gold
project and declared updated resources
and reserves for the project. Both studies
confirmed a robust investment case.
In August 2016, an application for
a special mining lease was lodged,
supported by a proposal for development.
Subsequent to the completion of these
studies and after further geotechnical
drilling, certain technical challenges
were identified, including seismicity
impacting the preferred location of the
terrestrial tailings storage facility, and
limitations on the capacity of identified
potential terrestrial storage sites in the
vicinity of the mine, to accommodate the
projected life of mine volume of mine
tailings. Deep-sea tailings placement was
seen as a potential alternative tailings
management strategy, as there are
excellent geographical conditions around
PNG for the deep-sea placement of
tailings with a number of other mines in
the area using this method. b
JULY 2018 MINING MIRROR
[7]