McEwen Mining Los Azules Metallurgical Update

Wed Mar 13, 2013 7:30am EDT

* Reuters is not responsible for the content in this press release.

  TORONTO, ONTARIO, Mar 13 (MARKET WIRE) --
McEwen Mining Inc. (NYSE:MUX)(TSX:MUX) is pleased to announce new
metallurgical studies that confirmed preliminary work and tested
alternative process methods at its 100% owned Los Azules Copper Project
in San Juan Province, Argentina. The work was performed by Plenge
Metallurgical Laboratory in Lima, Peru and supervised by Samuel
Engineering of Denver, Colorado. The tests produced positive results in
the three areas discussed below, all of which should improve the economic
returns associated with the project by reducing operating and capital
costs, increasing the amount of material available for processing, and
reducing export taxes.

    1) Flotation optimization

    Test results confirm that a significantly coarser grind size of 175
micrometres can be used on Los Azules mineralized material versus the 125
micrometres used in past testing. This will reduce milling costs and
should not negatively impact copper recoveries which have been estimated
at approximately 93%.

    2) Pressure oxidation on flotation concentrates

    A Preliminary Economic Assessment ("PEA") was completed on the Los Azules
project in 2010.  It contemplated that a copper concentrate would be
produced on site and then shipped to a port on the Pacific coast via a
pipeline through Chile.  The concentrate would then be sent to a smelter
for processing.  This scenario poses some logistical and financial
challenges, so testwork has been performed to determine if the
concentrate could be processed through a pressure oxidation process at
site to produce copper cathode.  Results from this testwork were positive
and very high extraction rates of copper from the concentrate were
achieved for both primary and supergene material indicating that
producing a cathode on site is possible.  The benefits of producing a
cathode on site instead of a concentrate include: i) a reduction in
export taxes (5% on cathode versus 10% on concentrate); ii) the removal
of the pipeline from the initial capital expenditures and; iii) the
removal of treatment and refining charges from the smelting process.

    3) Testing of low grade material for suitability in a heap leach

    The 2010 PEA was based on a resource that used a cut-off grade of 0.35%
copper and a mine plan that used a cut-off grade of 0.205% copper within
the resource pit shell.  All of the material above the mine plan cut-off
will be milled.  Column leach testing was performed to determine the
viability of processing mineralized material below this cut-off grade
through heap leaching.  Positive results were achieved with an expected
copper extraction rate for the run-of-mine material of approximately 63%.
These results mean that a significant portion of lower grade material
previously considered waste could potentially be processed. 

    McEwen Mining has begun work on an updated PEA which is expected to be
completed in the third quarter of this year.  The updated PEA will be
based on a significantly larger mineral resource and will evaluate the
possibility of increasing the daily throughput.  The updated PEA will
also incorporate the results of these metallurgical studies. 

    Los Azules is one of the world's largest, undeveloped, high-grade, open
pit copper projects which, contains significant growth potential and
these metallurgical results only enhance the value of the project as they
demonstrate that the deposit is amenable to proven and established
processing methods.

    About Los Azules 

    Los Azules is a large undeveloped copper porphyry system located in
western San Juan Province within a belt of porphyry copper deposits that
straddles the Chilean/Argentine border. This belt contains some of the
world's largest copper deposits, including Codelco's El Teniente and
Andina mines, Anglo American's Los Bronces mine, Antofagasta PLC's Los
Pelambres mine and Xstrata's El Pachon project, among others. Los Azules
is one of the world's largest, highest grade, undeveloped copper-porphyry
deposits not owned by a major base metal company.

    The mineral resources for Los Azules were calculated in January 2013 and
are summarized in the table below with a cut-off grade of 0.35% copper. 


                                                                            
----------------------------------------------------------------------------
Mineral Resource   Tonnes   Copper  Contained Copper     Gold       Silver  
    Category     (millions)   (%)       (MM lbs)     grams/tonne grams/tonne
----------------------------------------------------------------------------
    Indicated        310      0.65        4.45           0.07        1.8    
    Inferred        1,302     0.49        13.95          0.06        2.0    
----------------------------------------------------------------------------


    About McEwen Mining (www.mcewenmining.com) 

    The goal of McEwen Mining is to qualify for inclusion in the S&P 500 by
2015 by creating a high growth gold producer focused in the Americas.
McEwen Mining's principal assets consist of the San Jose mine in Santa
Cruz, Argentina (49% interest); the El Gallo complex in Sinaloa, Mexico;
the Gold Bar project in Nevada, US; the Los Azules project in San Juan,
Argentina and a large portfolio of exploration properties in Argentina,
Mexico and Nevada.

    McEwen Mining has 296,024,859 shares issued and outstanding. Rob McEwen,
Chairman, President and Chief Owner, owns 25% of the shares of the
Company (assuming all outstanding Exchangeable Shares are exchanged for
an equivalent amount of Common Shares). As of December 31, 2012, McEwen
Mining had cash and liquid assets of approximately US$79 million and is
debt free.

    Technical Information:

    Richard S. Kunter, FAusIMM, CP, QP, Chief Process Engineer, Mining and
Metals, Samuel Engineering, Inc., who is a Qualified Person and
independent of McEwen Mining, as defined by National Instrument 43-101
("NI 43-101") has reviewed and approved the technical content of this
news release.

    For additional information about the Los Azules project see the Technical
Report titled "Los Azules Porphyry Copper Project, San Juan Province,
Argentina" dated August 1, 2012, with an effective date of June 15, 2012,
prepared by D. Ernest Winkler, P.Eng., Robert Sim, P.Geo., Bruce Davis,
PhD, FAusIMM and James K. Duff, P.Geo., all of whom are qualified persons
and all of whom are independent of McEwen Mining, each as defined by NI
43-101.  The foregoing report is available under the Corporation's
profile on SEDAR (www.sedar.com).

    The mineral resource estimate referenced in this news release was
prepared in January 2013 by Robert Sim, P.Geo. And Bruce Davis, PhD,
FAusIMM, each a qualified person and independent of McEwen Mining, each
as defined by NI 43-101 and disclosed in the Corporation's news release
dated February 5, 2013 titled "McEwen Mining Continues to Expand Los
Azules' Large, High-Grade, Mineral Resource.

    Cautionary Note to U.S. Investors:

    McEwen Mining reports its resource estimates in accordance with standards
of the Canadian Institute of Mining, Metallurgy and Petroleum referred to
in Canadian National Instrument 43-101 ("NI 43-101"). These standards are
different from the standards generally permitted in reports filed with
the SEC. Under NI 43-101, McEwen Mining reports measured, indicated and
inferred resources, measurements which are generally not permitted in
filings made with the SEC. According to Canadian NI 43-101 criteria, the
estimation of measured resources and indicated resources involve greater
uncertainty as to their economic feasibility than the estimation of
proven and probable reserves. Under SEC Industry Guide 7 criteria,
measured, indicated and inferred resources are considered Mineralized
Material. The SEC considers that in addition to greater uncertainty as to
the economic feasibility of Mineralized Material compared to proven and
probable reserves, there is also greater uncertainty as to the existence
of Mineralized Material. U.S. investors are cautioned not to assume that
measured or indicated resources will be converted into economically
mineable reserves. The estimation of inferred resources involves far
greater uncertainty as to their existence and economic viability than the
estimation of other categories of resources.

    Caution Concerning Forward-Looking Statements 

    This press release contains certain forward-looking statements and
information, including "forward-looking statements" within the meaning of
the Private Securities Litigation Reform Act of 1995. The forward-looking
statements and information expressed, as at the date of this press
release, McEwen Mining Inc.'s (the "Company") estimates, forecasts,
projections, expectations or beliefs as to future events and results.
Forward-looking statements and information are necessarily based upon a
number of estimates and assumptions that, while considered reasonable by
management, are inherently subject to significant business, economic,
political and competitive uncertainties, risks and contingencies, and
there can be no assurance that such statements and information will prove
to be accurate. Therefore, actual results and future events could differ
materially from those anticipated in such statements and information.
Risks and uncertainties that could cause results or future events to
differ materially from current expectations expressed or implied by the
forward-looking statements and information include, but are not limited
to, risks related to the cost of transferring or otherwise allocating
funds between operating jurisdictions, factors associated with
fluctuations in the market price of precious metals, mining industry
risks, political, economic, social and security risks associated with
foreign operations, risks associated with the construction and permitting
of mining operations and commencement of production and the projected
costs thereof, risks related to litigation, property title, the state of
the capital markets, environmental risks and hazards, uncertainty as to
calculation of mineral resources and reserves and other risks. Readers
should not place undue reliance on forward-looking statements or
information included herein, which speak only as of the date hereof. The
Company undertakes no obligation to reissue or update forward-looking
statements or information as a result of new information or events after
the date hereof except as may be required by law. See McEwen Mining's
Annual Report on Form 10-K for the fiscal year ended December 31, 2012
and other filings with the Securities and Exchange Commission, under the
caption "Risk Factors", for additional information on risks,
uncertainties and other factors relating to the forward-looking
statements and information regarding the Company. All forward-looking
statements and information made in this news release are qualified by
this cautionary statement. 

    The NYSE and TSX have not reviewed and do not accept responsibility for
the adequacy or accuracy of the contents of this news release, which has
been prepared by management of McEwen Mining Inc.

Contacts:
McEwen Mining Inc.
Jenya Meshcheryakova
Investor Relations
(647) 258-0395 ext 410 or Toll Free: (866) 441-0690
(647) 258-0408 (FAX)

McEwen Mining Inc.
Mailing Address
181 Bay Street Suite 4750
Toronto, ON M5J 2T3, PO box 792
info@mcewenmining.com
www.mcewenmining.com

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