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Dominion Diamond Announces Results of Fox Deep Preliminary Economic Assessment


Dominion Diamond Corporation (TSX:DDC, NYSE:DDC) (the "Company" or
"Dominion") is pleased to report the results of a preliminary economic
assessment ("PEA") on the development of an underground operation below
the mined out Fox open pit at the Ekati Diamond Mine ("Ekati mine") in
the Northwest Territories of Canada. The Fox kimberlite pipe is located
in the Core Zone Joint Venture in which the Company has an 88.9%
participating interest. Unless otherwise indicated, all amounts are
presented on a 100% basis, and all financial information is presented in
US dollars.


  • Preliminary economic assessment on Fox Deep project based on
    underground incline caving mining method, with incremental post-tax
    net present value at 7% discount rate of $187 million (Dominion's
    share) and internal rate of return of 23%
  • PEA based on processing of 31.3 million tonnes and recovery of 11.0
    million carats from Fox Deep
  • Fox Deep would extend the mine life at Ekati to fiscal 2042 from
    fiscal 2035, which reflects inclusion of the recently-approved Misery
    Deep project
  • Initial capital development of $628 million, sustaining capital of
    $192 million, and total operating expenses of $1.4 billion or $51 per
    dry metric tonne processed
  • Base case diamond price of $232 per carat based on the Company's July
    2017 Price Book, increased at 2.5% per annum during the life of the
  • Pre-feasibility study ("PFS") on Fox Deep underway and on track for
    completion in late fiscal 2018

Fox Deep Project – Preliminary Economic

The Fox pipe was in production as an open pit operation from 2005 to
2014, and produced more than 8.7 million carats. The Fox Deep PEA
evaluated the underground development of the Fox pipe, using an incline
cave mining method, as an incremental development opportunity to the
existing mine plan. The net present value (NPV) calculation for Fox Deep
represents the Company's share of the incremental NPV. This analysis
assumes production at Fox Deep from fiscal 2033 to fiscal 2042, which
would extend the Ekati life of mine plan by seven years.

On February 22, 2017, the Company announced the results from a reverse
circulation ("RC") drilling campaign at Fox Deep in the winter/spring of
2016. The resource model, updated with new data from the 2016 drilling
campaign, confirmed the continuity of the resource at depth and
identified a deep higher-grade zone. As disclosed on April 12, 2017, the
indicated mineral resource increased substantially to 45.6 million
tonnes and 16.5 million carats as at January 31, 2017, from the previous
estimates of 35.2 million tonnes and 11.6 million carats, respectively.

A PEA and PFS on the project were initiated in spring 2017, based on an
incline caving method. Incline caving has been used successfully at the
Koala underground operation at the Ekati mine. This method has been
identified as the most appropriate one to achieve increased height of
draw, a lower extraction level, and access to the higher-grade zone
identified at depth in the 2016 drill program. The incline cave design
is expected to have improved geotechnical stability compared to block
caving, and a potentially higher production rate due to a larger number
of drawpoints. A trade-off study between shaft and ramp access to Fox
Deep was completed during the PEA and concluded that ramp access is
preferable both economically and technically.

The PEA is based on the mining of Fox Deep from calendar 2032 to
calendar 2041. This would defer the reclamation and closure of the main
Ekati site by 7 years, to calendar 2042. The mine plan includes the
extraction of 31.3 million tonnes of kimberlite on five underground
production levels, using an incline caving method similar to that
currently employed at the Koala pipe. A total of 11.0 million carats are
expected to be recovered from Fox Deep.

The area surrounding the Fox pipe is currently under a surface lease,
which provides tenure for operational infrastructure. Development of an
underground mine below the existing open pit would likely require an
amendment of the Ekati Water Licence to include the project scope, and a
new Land Use Permit, but will largely rely on existing regulatory
instruments. The permitting process for the Fox Deep project is expected
to be similar to that of the Misery Deep project, which was initiated in
August 2017.

The PEA was conducted by SRK Consulting (Canada) Inc. which designed the
conceptual mine development layout, prepared schedules for development
and production, and developed capital and operating cost estimates. The
Company contributed sections of the report in alignment with the authors
of the study. The chart below summarizes the incremental production, and
capital and operating costs as estimated in the PEA:

Fox Deep Preliminary Economic Assessment Key Operating and Financial

Mining Method       Incline block caving (underground)
Mined Kimberlite 31.3 million tonnes
Recovered Carats 11.0 million carats
Recovered Grade 0.4 carats per tonne1
Diamond Recovery 99%2
Initial Development Capital $628 million3
Sustaining Capital $192 million3
Total Unit Operating Cost $51 per tonne processed3
Base Case Diamond Price $232 per carat4
First Production Date Fiscal 2033
Mine Operational Life 10 years
Post-tax NPV (incremental) $187 million5
Real Discount Rate 7%6
Post-tax IRR (incremental)       23%5

Note: All dollar figures refer to real 2017 dollars and, except for NPV
and IRR, are on a 100% basis. Tonnes refer to dry metric tonnes.

    (1)   The recovered grade is at 1.0 mm cut-off and includes contribution
of additional carats from the fines dense media separation ("Fines
DMS") unit in the Ekati processing plant.
(2) Recovery relative to mineral resource reported at +0.5 mm cut-off
(based upon diamonds that would be recovered by the Ekati bulk
sample plant using 0.5 mm width slot de-grit screens).
(3) Assumes an exchange rate of 1.33 CAD/USD in calendar 2017 and
thereafter. An exchange rate of 1.25 CAD/USD and 1.41 CAD/USD would
result in a post-tax NPV of $169 million and $205 million,
respectively (Dominion's share). Initial development capital
includes a $126 million or 25% contingency. Total unit operating
cost refers to average unit cost per dry metric tonne processed,
including direct and indirect mining costs, processing costs,
general and administrative costs, and marketing costs.
(4) Based on the Company's July 2017 Price Book. The rough diamond price
forecasts for the Fox Deep PEA include 2.5% per annum real price
growth during the life of the mine; real price growth of nil and
3.5% would result in a post-tax NPV of ($37) million and $307
million, respectively (Dominion's share).
(5) Company's share of unlevered NPV and project IRR are after taxes and
royalties. The PEA is based on indicated mineral resources, and
mineral resources that are not mineral reserves do not have
demonstrated economic viability.
(6) A discount rate of 5% and 10% would result in a post-tax NPV of $299
million and $91 million, respectively (Dominion's share).

Diamond Price Assumptions

The base case diamond price is approximately $232 per carat (in 2017
dollars) in the Fox Deep PEA. Pricing is based on the July 2017 Price
Book and 99% recovery relative to the mineral resource. The rough
diamond price forecasts include 2.5% per annum real price growth during
the life of the mine; real price growth of nil and 3.5% would result in
a post-tax NPV of ($37) million and $307 million, respectively
(Dominion's share). The Fox Deep PEA includes additional diamond
recovery in the lower value smaller size categories as a result of the
Company's Fines DMS unit in the Ekati processing plant, which lowers the
average recovered price, but increases total project revenue. The PEA
assumes the Fines DMS is fully operational for the life of the project.

Capital Expenditure Assumptions

The Fox Deep project will require the addition of incremental site
infrastructure such as ramp portals, fan installations, dewatering
lines, 28 kilometres of new underground development, construction of
underground infrastructure, an ore conveyor, purchase of new underground
mining equipment, and owner's costs to support project development and
execution. The PEA assumes that project development would be timed such
that the start of production at Fox Deep would coincide with the end of
operations at the Jay open pit. The following chart sets out the
estimated initial development capital expenditures by fiscal year for
the Fox Deep project:

Fiscal Year   2028   2029   2030   2031   2032   2033   2034   Total
Initial Development Capital ($ Millions) 11 23 92 73 79 196 155 628

Incremental sustaining capital is estimated to total $192 million during
the operational life of the project. This comprises $55 million from
fiscal year 2035 to 2042, for mine development, rebuilds and other
project-specific capital expenditures, and $137 million during the same
period, to extend the life of the Ekati process plant, power plant and
other existing infrastructure.

Production Assumptions

The Fox Deep PEA indicates that the incline caving method can support a
peak production rate of 4.35 million dry metric tonnes per year from 104
drawpoints on five levels; this rate matches the projected capacity of
the Ekati process plant after completion of the upgrades described in
the most recent technical report for the Ekati mine entitled "Ekati
Diamond Mine, Northwest Territories, Canada, NI 43-101 Technical Report"
which has an effective date of July 31, 2016. The PEA is based on the
following production assumptions:

Fiscal Year   2033   2034   2035   2036   2037   2038   2039   2040   2041   2042
Tonnes Processed (Millions) 0.1 1.9 4.2 4.3 4.3 4.4
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