Denison Reports Uranium Concentrations from Initial Core Leach Tests up to Four Times the Amount Assumed IN Pre-Feasibility Study FOR Phoenix Isr Operation
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Denison Mines Corp.
1100 – 40 University Ave
Toronto, ON M5J 1T1
www.denisonmines.com
PRESS RELEASE
DENISON REPORTS URANIUM CONCENTRATIONS FROM
INITIAL CORE LEACH TESTS UP TO FOUR TIMES THE AMOUNT
ASSUMED IN PRE-FEASIBILITY STUDY FOR PHOENIX ISR OPERATION
Toronto, ON – February 19, 2020. Denison Mines Corp. (“Denison” or the “Company”) (DML: TSX, DNN:
NYSE American) is pleased to report that initial da ta from core leach tests includes elemental uranium
(“uranium”) concentrations, after the initial test startup, in the range of 13.5 grams per litre (“g/L ”) to 39.8
g/L. This compares favourably to the previous metal lurgical test work completed to assess the use of t he
In-Situ Recovery (“ISR”) mining method at the high- grade Phoenix uranium deposit (“Phoenix”) – which
supported a uranium concentration of 10 g/L for the ISR processing plant design used in the Pre-Feasibility
Study (“PFS”) completed for the Company’s 90% owned Wheeler River Uranium Project (“Wheeler River”
or the “Project”), located in northern Saskatchewan, Canada.
David Bronkhorst, Denison’s Vice President Operations, commented, “The initial data from the core leach
test shows that uranium can be recovered from intac t core samples at a concentration that is significa ntly
higher than the levels used in the PFS. The implic ations of a higher uranium concentration coming fro m
the ISR wellfield are potentially significant – allowing the metallurgical team to explore various combinations
of lixiviant parameters to optimize operating costs, and processing plant configurations to potentially reduce
capital costs while maintaining the same level of annual uranium production.”
Background
The test work incorporated into the PFS (see press release dated September 24, 2018) included column
leach and agitated leach tests, which led to the de sign of the Phoenix processing plant in the PFS bas ed
on a minimum of 10 g/L uranium content in the uranium bearing solution expected to be recovered from the
ISR wellfield. The current metallurgical test program (“2020 Metallurgical Program”) has been designed to
build upon the laboratory test data collected as pa rt of the PFS (see news release dated December 18,
2019).
The first stage of the 2020 Metallurgical Program i nvolves completing specialized tests using intact
mineralized core samples, representative of the in- situ conditions at Phoenix. The testing apparatus used
for these tests allows for intact core samples to be mounted within a flexible sleeve with a confining pressure
applied to the exterior of the sleeve. Lixiviant (in the case of Phoenix, an acid-bearing mining solution) can
then be injected into to the intact core at one end of the sample without having a way to by-pass the intact
core. As a result, the lixiviant travels through th e core to the other end of the sample, where a uran ium
bearing solution is recovered. Denison considers th is type of specialized test of intact competent cor e
samples to be the most representative available lab oratory test of the natural leach conditions of the
host rock.
Current Core Leach Test
Over 50 days of testing has been completed, to date , on a mineralized core sample recovered from drill
hole GWR-016. The core sample was recovered from b etween 405 and 407 metres below surface within
the extent of the high-grade core of Phoenix Zone A. Various parameters for lixiviant composition (including
both acid and oxidant concentration) have been tested to date. In all cases, the lixiviant is injected into the
core continuously and only interrupted periodically if a change in the lixiviant composition is required. After
the initial test startup, uranium bearing solution recovered from the core sample has returned uranium
content in the range of 13.5 g/L to 39.8 g/L. The average uranium concentration returned over the last
20 days of testing is 29.8 g/L – which represents a uranium content that is approximately 200%
higher than (or three times) the minimum level used for the ISR process plant design in the PFS.
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The test with this core sample will continue as the Company refines the optimal lixiviant parameters for the
mineralized core within Phoenix Zone A and ultimately the optimal uranium-bearing solution parameters for
the solution that will be fed into the proposed process plant flowsheet. The initial results reported from the
testing completed, to date, reflect the uranium con centrations recovered from a single core sample.
Additional core samples are planned for core leach testing (as described below). The initial results reported
above may not be representative of results from further testing of the current core sample, or future testing
of additional core samples.
Overview of the 2020 Metallurgical Test Program
In December 2019, the Company initiated the 2020 Me tallurgical Program, which is expected to provide
important information for the purpose of completing the Environmental Assessment (“EA”) and a future
Feasibility Study for the Phoenix ISR operation (se e Denison’s news release dated December 18, 2019).
The 2020 Metallurgical Program has been designed to use the mineralized drill core recovered through the
installation of various test wells during the 2019 ISR field test program (see Denison’s news release dated
December 18, 2019) and to build upon the previous laboratory test data, which was collected as part of the
PFS process to assess the recovery of uranium. The 2020 Metallurgical Program has been planned in
stages, allowing for the initial results from each stage of testing to inform the design and criteria of the
further stages of testing.
The first stage of the 2020 Metallurgical Program i s expected to continue throughout the first half of 2020
using core samples representative of the various or e types and grade ranges (~1% U 3O8 to up to
60% U3O8) contained within Phoenix. The goal of the first stage of the program is to determine the optimal
lixiviant parameters for various grade ranges withi n Phoenix, which will involve the testing of severa l
representative core samples. The uranium recovery results from the first 50 days of testing of the first core
sample will allow refinement of the test program fo r the next core samples planned for future intact c ore
leach tests, and for the final planning and design of the second stage of the 2020 Metallurgical Progr am –
which involves the completion of various column leach tests.
The column leach tests planned in the second stage of the program involve the crushing and packing of
mineralized core samples into test columns, which a re then expected to utilize the same lixiviant
composition as the core leach tests to provide addi tional data on the recovery of uranium, and any oth er
metals, from the various ore types and grade ranges associated with the Phoenix deposit. The purpose of
the column leach tests is to correlate data from th e specialized core leach tests to the traditional I SR
laboratory testing methods used during the PFS. Additionally, the column leach tests are able to generate
uranium bearing solutions in larger quantities for further laboratory testing of the process plant flowsheet –
which is planned as the third stage of the 2020 Met allurgical Program, and is expected to involve benc h-
scale testing of the unit operations of the proposed process plant flowsheet with uranium-bearing solutions
produced during the leach tests. The third stage of the program is in the planning stage and will be refined
pending the results of the leach tests.
The laboratory work for the first stage and second stage of the 2020 Metallurgical Program is being carried
out at the Saskatchewan Research Council ("SRC") Mineral Processing and Geoanalytical Laboratories, in
Saskatoon, under the supervision of Mr. Chuck Edwards (P.Eng., FCIM).
About Wheeler River
Wheeler River is the largest undeveloped uranium pr oject in the infrastructure rich eastern portion of the
Athabasca Basin region, in northern Saskatchewan – including combined Indicated Mineral Resources of
132.1 million pounds U 3O8 (1,809,000 tonnes at an average grade of 3.3% U 3O8), plus combined Inferred
Mineral Resources of 3.0 million pounds U 3O8 (82,000 tonnes at an average grade of 1.7% U 3O8). The
project is host to the high-grade Phoenix and Gryph on uranium deposits, discovered by Denison in 2008
and 2014, respectively, and is a joint venture betw een Denison (90% and operator) and JCU (Canada)
Exploration Company Limited (10%).
A PFS was completed for Wheeler River in late 2018, considering the potential economic merit of
developing the Phoenix deposit as an ISR operation and the Gryphon deposit as a conventional
underground mining operation. Taken together, the project is estimated to have mine production of 109 .4
million pounds U 3O8 over a 14-year mine life, with a base case pre-tax NPV of $1.31 billion (8% discount
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rate), Internal Rate of Return ("IRR") of 38.7%, an d initial pre-production capital expenditures of $3 22.5
million. The Phoenix ISR operation is estimated to have a stand-alone base case pre-tax NPV of $930.4
million (8% discount rate), IRR of 43.3%, initial p re-production capital expenditures of $322.5 millio n, and
industry leading average operating costs of US$3.33 /lb U 3O8. The PFS is prepared on a project (100%
ownership) and pre-tax basis, as each of the partne rs to the Wheeler River Joint Venture are subject t o
different tax and other obligations.
Further details regarding the PFS, including additional scientific and technical information, as well as after-
tax results attributable to Denison's ownership int erest, are described in greater detail in the NI 43 -101
Technical Report titled "Pre-feasibility Study for the Wheeler River Uranium Project, Saskatchewan,
Canada" dated October 30, 2018 with an effective da te of September 24, 2018. A copy of this report is
available on Denison's website and under its profil e on SEDAR at www.sedar.com and on EDGAR at
www.sec.gov/edgar.shtml.
About Denison
Denison is a uranium exploration and development company with interests focused in the Athabasca Basin
region of northern Saskatchewan, Canada. In additio n to the Wheeler River project, Denison’s Athabasca
Basin exploration portfolio consists of numerous pr ojects covering approximately 280,000 hectares.
Denison’s interests in the Athabasca Basin also include a 22.5% ownership interest in the McClean Lake
joint venture (“MLJV”), which includes several uranium deposits and the McClean Lake uranium mill, which
is currently processing ore from the Cigar Lake mine under a toll milling agreement, plus a 25.17% interest
in the Midwest and Midwest A deposits, and a 66.57% interest in the J Zone and Huskie deposits on the
Waterbury Lake property. Each of Midwest, Midwest A, J Zone and Huskie are located within 20 kilometres
of the McClean Lake mill.
Denison is also engaged in mine decommissioning and environmental services through its Denison
Environmental Services division and is the manager of Uranium Participation Corp., a publicly traded
company which invests in uranium oxide and uranium hexafluoride.
For more information, please contact
David Cates (416) 979-1991 ext 362
President and Chief Executive Officer
Sophia Shane (604) 689-7842
Investor Relations
Follow Denison on Twitter @DenisonMinesCo
Qualified Persons
Description of the metallurgical test program and data contained in this release was reviewed by Mr. Chuck
Edwards, P. Eng., FCIM, Principal at Chuck Edwards Extractive Metallurgy Consulting, an independent
Qualified Person in accordance with the requirements of NI 43-101.
The other technical information contained in this r elease has been reviewed and approved by Mr. Dale
Verran, MSc, P.Geo, Pr.Sci.Nat., Denison's Vice President, Exploration, a Qualified Person in accordance
with the requirements of NI 43-101.
Cautionary Statement Regarding Forward-Looking Statements
Certain information contained in this news release constitutes ‘forward-looking information’, within the meaning of the applicable United
States and Canadian legislation concerning the business, operations and financial performance and condition of Denison.
Generally, these forward-looking statements can be identified by the use of forward-looking terminolog y such as ‘plans’, ‘expects’,
‘budget’, ‘scheduled’, ‘estimates’, ‘forecasts’, ‘intends’, ‘anticipates’, or ‘believes’, or the negatives and/or variations of such words and
phrases, or state that certain actions, events or r esults ‘may’, ‘could’, ‘would’, ‘might’ or ‘will be taken’, ‘occur’, ‘be achieved’ or ‘has
the potential to’.
In particular, this news release contains forward-l ooking information pertaining to the following: the 2020 Metallurgical Program,
including its intended scope and timing, objectives and evaluation interpretations; the current and co ntinued use and availability of
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third party technologies for testing; the results o f the PFS and expectations with respect thereto; de velopment and expansion plans
and objectives, including plans for a feasibility study; and expectations regarding its joint venture ownership interests and the continuity
of its agreements with its partners.
Forward looking statements are based on the opinions and estimates of management as of the date such statements are made, and
they are subject to known and unknown risks, uncert ainties and other factors that may cause the actual results, level of activity,
performance or achievements of Denison to be materi ally different from those expressed or implied by s uch forward-looking
statements. For example, the initial results of the 2020 Metallurgical Program discussed herein may no t be maintained after further
testing or be representative of actual conditions within the Phoenix deposit. In addition, Denison may decide or otherwise be required
to discontinue the 2020 Metallurgical Program or ot her testing, evaluation and development work at Whe eler River if it is unable to
maintain or otherwise secure the necessary resources (such as testing facilities, capital funding, regulatory approvals, etc.). Denison
believes that the expectations reflected in this forward-looking information are reasonable but no assurance can be given that these
expectations will prove to be accurate and results may differ materially from those anticipated in this forward-looking information. For
a discussion in respect of risks and other factors that could influence forward-looking events, please refer to the factors discussed in
Denison’s Annual Information Form dated March 12, 2019 under the heading ‘Risk Factors’. These factors are not, and should not be
construed as being exhaustive.
Accordingly, readers should not place undue relianc e on forward-looking statements. The forward-lookin g information contained in
this news release is expressly qualified by this cautionary statement. Any forward-looking information and the assumptions made with
respect thereto speaks only as of the date of this news release. Denison does not undertake any obligation to publicly update or revise
any forward-looking information after the date of t his news release to conform such information to act ual results or to changes in
Denison's expectations except as otherwise required by applicable legislation.
Cautionary Note to United States Investors Concerni ng Estimates of Measured, Indicated and Inferred Mi neral Resources
and Probable Mineral Reserves: This news release may use the terms 'measured', 'i ndicated' and 'inferred' mineral resources.
United States investors are advised that while such terms have been prepared in accordance with the definition standards on mineral
reserves of the Canadian Institute of Mining, Metal lurgy and Petroleum referred to in Canadian Nationa l Instrument 43-101 Mineral
Disclosure Standards ("NI 43-101") and are recogniz ed and required by Canadian regulations, the United States Securities and
Exchange Commission ("SEC") does not recognize them. 'Inferred mineral resources' have a great amount of uncertainty as to their
existence, and as to their economic and legal feasibility. It cannot be assumed that all or any part of an inferred mineral resource will
ever be upgraded to a higher category. Under Canadi an rules, estimates of inferred mineral resources m ay not form the basis of
feasibility or other economic studies. United States investors are cautioned not to assume that all or any part of measured or
indicated mineral resources will ever be converted into mineral reserves. United States investors are also cautioned not to
assume that all or any part of an inferred mineral resource exists, or is economically or legally mine able. The estimates of
mineral reserves in this news release have been prepared in accordance with NI 43-101. The definition of probable mineral reserves
used in NI 43-101 differs from the definition used by the SEC in the SEC's Industry Guide 7. Under th e requirements of the SEC,
mineralization may not be classified as a "reserve" unless the determination has been made, pursuant to a "final" feasibility study that
the mineralization could be economically and legall y produced or extracted at the time the reserve det ermination is made. Denison
has not prepared a feasibility study for the purpos es of NI 43-101 or the requirements of the SEC. Ac cordingly, Denison's probable
mineral reserves disclosure may not be comparable t o information from U.S. companies subject to the re porting and disclosure
requirements of the SEC.