TriMetals Mining Inc. Updates Preliminary Economic Assessment at Gold Springs

VANCOUVER, BRITISH COLUMBIA--(Marketwired - Aug 12, 2015) - TriMetals Mining Inc. (TSX:TMI)(TSX:TMI.B)(OTCQX:TMIAF)(OTCQX:TMIBF) (the "Company") is pleased to announce the completion of an updated Preliminary Economic Assessment ("updated PEA") for the Gold Springs gold-silver project in mining friendly Nevada and Utah, USA.

The updated PEA shows a strong, low strip, technically simple and scalable heap-leachable open-pit project using a Merrill-Crowe gold-silver recovery process.

The project requires low up-front capital, has a rapid payback, low cash costs, strong cash flows and yields a pre-tax IRR of 49.9% and an NPV5% of $137.4 million. All dollar amounts in this release are stated in US currency.

Contractor Mining Case highlights (based on $1,300/oz Au price and $21/oz Ag price):

• 15,000 TPD mine plan of 9 year with a 2:1 strip ratio.
• NPV₅% of $137.4 million (after tax $92.1 million), IRR of 49.9% (after tax 35.8%); Payback of 3.1 years.
• LOM payable production of 428 thousand ounces of gold and 4.9 million ounces of silver.
• Cash operating cost of $669 oz Au and fully-loaded cost of $863 oz Au*.
• $133 million of cumulative after-tax free cash flow.
• Pre-production capital cost of $55 million (including a $6.4 million contingency) and on-going capital cost of $24.8 million (including a $3.7 million contingency).

* Cash Operating cost per gold ounce is net of silver credit and includes mining, processing, general and administrative and operating cost contingency; Fully-loaded cost per gold ounce includes Cash Operating cost per gold ounce plus sustaining capital, federal, state and local taxes and does not include initial capital.. The portion of the project subject to the updated PEA does not have overriding royalties.

Ralph Fitch, President and CEO stated "Completing the Updated PEA is an important milestone. With last year's exploration program we continue to gain valuable technical knowledge about the project's metallurgy, geology and engineering. The result is an updated PEA that is more robust than its predecessor. Discovering and growing a mineral resource with positive economics takes time. The mineral resource at Gold Springs has consistently grown since we started exploring Gold Springs in 2010 by approximately 5,000 AuEq** ounces per drill hole. Management firmly believes there continues to be substantial upside for the discovery of additional gold and silver mineralization since both the Jumbo and Grey Eagle resource blocks remain open to expansion. These two resource areas represent just two of 26 outcropping gold targets identified on the property to date. There are also numerous buried geophysical targets which have yet to be explored. Importantly the project is scalable allowing it to be re-designed to the optimal open-pit for the deposit in the context of an expanded resource which we believe is very likely, or in response to higher or lower precious metal prices."

** Gold equivalent (AuEq) calculations reflect gross metal content using the gold/silver ratio of 57.14 used in the most recent resource estimate (2015 Resource) and in the previously reported resource estimate (2014 Resource), and have not been adjusted for metallurgical recoveries.

The project has strong leverage to rising commodity prices as well as resiliency to lower prices:

The breakeven gold and silver prices per ounce (defined as 0% before-tax IRR) are $925 and $14.94 respectively (keeping the gold/silver price ratio constant at 61.90).

* Gold Equivalent was calculated using the gold/silver price per ounce ratio of 61.90 used in the economic analysis in the PEA.

Changes from the Previous PEA

This updated PEA compared to the one issued in 2014 has increased the production rate from 10,000 tpd to 15,000 tpd and assumes a finer crush to 3/8 inch for the Grey Eagle but maintains the same one inch crush for Jumbo. Gold and silver recoveries have been lowered a few percent in recognition of results from ongoing metallurgical testing. A recovery of 73% for gold and 40% for silver was used for Jumbo and 72% and 20% respectively for Grey Eagle.

The entire Technical Report containing the updated PEA will be available under the Company's profile on SEDAR or on the Company's website at www.trimetalsmining.com.

Updated Resource Estimate

The updated PEA, prepared by Global Resource Engineering, Ltd (GRE) and Kurt Katsura, M.S., R.G. is based on an updated mineral resource estimate (the "2015 Resource") for the Jumbo Zone and the Grey Eagle Zone at the Gold Springs gold-silver project with an effective date of June 3, 2015 (See TMI News Release dated June 3, 2015).

The 2015 Resource builds on the 2014 resource estimate (see TMI News Release dated July 8, 2014) and includes the assay information from 31 additional reverse circulation (RC) drill holes and 4 diamond (Core) drill holes completed in the Jumbo and Grey Eagle zones in 2014.

Numbers have been rounded, which may lead to some numbers not adding up exactly.

* Gold equivalent (AuEq) calculations reflect gross metal content using a gold/silver ratio of 57.14 used in the most recent resource estimate (2015 Resource) and to be consistent with that used for the previously reported resource estimate (2014 Resource), and have not been adjusted for metallurgical recoveries.

** The Inferred resource is in addition to the measured and indicated resource

Preparation of the PEA and Qualified Person

The information in this news release was derived from the Technical Report Preliminary Economic Assessment Update on the Gold Springs Property, Utah/Nevada, USA dated August 12, 2015, authored by GRE and Kurt Katsura. GRE and Kurt Katsura were contracted by the Company to complete this Technical Report which has been prepared in accordance with Canadian Securities Administrators (CSA) National Instrument 43-101, and the Resources have been classified in accordance with standards as defined by the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) "CIM Definition Standards - For Mineral Resources and Mineral Reserves," prepared by the CIM Standing Committee on Reserve Definitions and adopted by CIM Council on May 10, 2014.

To create the economic model for the updated PEA, GRE first developed a series of 4 sets of pit shells, one for Grey Eagle and one for Jumbo comprising each set, within the mineral resource block model using a range of Au and Ag prices in order to establish the most profitable and robust mine plan. Mine schedules were developed for each of the resulting sets of pit shells, using production rates of 10,000 tpd for the 2 smaller pits and 15,000 tpd for the 2 larger pits. A total of thirty-two cases were identified and evaluated. The variables comprising the cases were pit shell sets (1 through 4), four different cut-off grades and owner- or contractor-operation. Capital and operating costs were developed for each case, along with sizing of mining and process equipment. Pit shell 3, which was modeled using Au and Ag prices of $1,200⁽¹⁾/oz and $21/oz, respectively, at a cut-off grade of 0.15 Au g/t and with contractor operation was selected as the base case for the economic model. Ms. Terre Lane, Principal Mining Engineer for GRE is a "qualified person", as defined in NI 43-101, is "independent" of the Company, as defined in NI 43-101, and has reviewed and approved the technical information regarding the economic analysis in this release. The NI 43-101 compliant Technical Report supporting the Updated PEA was filed on SEDAR on August 12, 2015

About TriMetals Mining Inc.

TriMetals Mining Inc. is a growth focused mineral exploration company creating value through the exploration and development of the near surface, Gold Springs gold-silver project in mining friendly Nevada and Utah in the U.S.A.; the advancement of the large scale Escalones copper-gold project in Chile, and realization of value from the expropriated Malku Khota project in Bolivia through an arbitration process.

The Company's approach to business combines the team's track record of discovery and advancement of large projects, key operational and process expertise, and a focus on community relations and sustainable development. Management has extensive experience in the global exploration and mining industry.

The Company's common shares and Class B shares are listed on the Toronto Stock Exchange under the symbols "TMI" and "TMI.B" and the common shares and Class B shares also trade on the OTCQX market under the symbol "TMIAF" and "TMIBF". Additional information related to TriMetals Mining Inc. is available at www.trimetalsmining.com and on SEDAR at www.sedar.com.

Cautionary Statement on Mineral Resources

This news release uses the term 'measured resources', 'indicated resources' and 'inferred resources' which are terms recognized and required by Canadian regulations (under National Instrument 43-101 Standards of Disclosure for Mineral Projects), however, such terms are not defined terms under SEC Industry Guide 7 and are not permitted to be used in reports and registration statements filed with the United States Securities and Exchange Commission. Investors are cautioned not to assume that any part or all of the mineral deposits in these categories will be upgraded or converted into 'reserves' as defined under NI 43-101. Mineral resources that are not mineral reserves, do not have demonstrated economic viability. In addition, 'inferred resources' have a great amount of uncertainty as to their existence, and economic and legal feasibility. It cannot be assumed that an inferred resource will be upgraded to a higher category. Under Canadian rules, estimates of inferred resources may not form the basis of feasibility or pre-feasibility studies, or economic studies except for preliminary economic assessment as defined under NI 43-101. Investors are cautioned not to assume that part or all of an inferred resource exists, or is economically or legally mineable.

Readers are also cautioned that the PEA is preliminary in nature and includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves and there is no certainty that the results indicated in the PEA will be realized. Mineral resources that are not mineral reserves do not have economic viability.

Forward-Looking Statements

The PEA was prepared to broadly quantify the Gold Springs project's capital and operating cost parameters and to provide guidance on the type and scale of future project engineering and development work that will be needed to ultimately define the project's likelihood of a positive feasibility determination and optimal production rate. It was not prepared to be used as a valuation of the project nor should it be considered to be a final feasibility study on which a commercial production decision could be made. The capital and operating cost estimates which were used have been developed only to an approximate order of magnitude based on generally understood capital cost to production level relationships, and although they are based on engineering studies, these are preliminary so the ultimate costs may vary widely from the amounts set out in the PEA. This could materially adversely impact the projected economics of the project. As is normal at this stage of a project, data in some areas was incomplete and estimates were developed based solely on the expertise of the Company's employees and consultants. At this stage of development for Gold Springs the criteria, methods and estimates are preliminary and result in a high level of subjective judgment being employed. There can be no assurance that the potential results contained in the PEA will be realized.

Certain statements contained herein constitute "forward-looking statements". These forward looking statements include, but are not limited to, statements regarding estimated mineral resources and the potential for delineation of additional resources through further exploration at the Gold Springs, as well as statements regarding estimated net present values, internal rates of return, daily and annual production, costs, recovery rates, metal prices, and statements regarding the Company's development plan for Gold Springs. These forward- looking statements are based on current expectations and entail various risks and uncertainties. Actual results may materially differ from expectations if known and unknown risks or uncertainties affect our business or if our estimates or assumptions prove inaccurate. Factors that could cause results or events to differ materially from current expectations expressed or implied by the forward-looking statements, include, but are not limited to, risks of the mineral exploration industry which may affect the advancement of the Gold Springs project, including possible variations in mineral resources, grade, recovery rates, metal prices, capital and operating costs, and the application of taxes; availability of sufficient financing to fund planned or further required work in a timely manner and on acceptable terms; timely receipt of required permits, availability of equipment and qualified personnel, failure of equipment or processes to operate as anticipated, changes in project parameters as plans continue to be refined; failure of equipment or processes to operate as anticipated; regulatory, environmental and other risks of the mining industry more fully described in the Company's Annual Information Form and continuous disclosure documents, which are available on SEDAR at www.sedar.com. The assumptions made in developing the forward-looking statements include: the accuracy of current resource estimates and the interpretation of drill, metallurgical testing and other exploration results; the timely receipt of required permits for the Gold Springs project; the continuing support for mining by local governments in Nevada and Utah; the availability of equipment and qualified personnel to advance the Gold Springs project; execution of the Company's existing plans and further exploration and development programs for Gold Spring, which may change due to changes in the views of the Company or if new information arises which makes it prudent to change such plans or programs; and the assumptions and estimates disclosed in the Preliminary Economic Assessment on the Gold Springs Property, Utah/Nevada, USA dated August 12, 2015, authored by GRE and Kurt Katsura.

Readers are cautioned not to place undue reliance on the forward-looking statements contained in this press release. Except as required by law, TMI assumes no obligation to update or revise any forward-looking statement, whether as a result of new information, future events or any other reason. Unless otherwise indicated, forward-looking statements in this press release describe the Company's expectations as of August 12, 2015.

⁽¹⁾ This is the Au price used to model the mine pit and should not be confused with the Au price used to calculate project economics in the economic analysis section in the PEA.

Contact

TriMetals Mining Inc.
Ralph Fitch
President & CEO
303.584.0606
ralphfitch@trimetalsmining.com
TriMetals Mining Inc.
Matias Herrero
Chief Financial Officer
303.584.0606
mherrero@trimetalsmining.com