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Comstock Mining Reports that Recent Metallurgical Column Tests Exceed High Yield Expectations

Comstock Mining Inc. reported today that recent metallurgical column tests on mineralized material from the Dayton Resource Area have exceeded already high yield expectations and contribute to the advancement of a full feasibility assessment for the mine, updating prior metallurgical test work and the technical resource report published in January 2013.

Photos accompanying this announcement are available at

Over the past several months, the technical staff has been conducting column tests of both cyanide and non-cyanide solutions. They established four, full metallurgical column tests, two cyanide and two non-cyanide, running parallel, that supports and advances the feasibility study for establishing proven and probable reserves at the Dayton. The samples were crushed, agglomerated and loaded into four ten-foot columns for leach simulation.   These simulations were conducted on-site, in the Company’s metallurgical labs, and are coordinated through Cycladex Inc., (“Cycladex”) a strategic investee, and funded by U.S. National Science Foundation grants.

The Cyanide columns leached exceptionally high and fast for gold, higher than prior tests and expectations.

Corrado De Gasperis, Executive Chairman and CEO of the Company stated, “Our expectations for the cyanide columns started high, at about 80%, so the 82-85% result in just 25 days was exceptional and much faster than any previous test.  Cycladex yields exceeded expectations for both gold and silver and tracked exceptionally well against the cyanide parallel columns. Although still in the early stages, we are pleased with the Cycladex yields and speed and look forward to assessing the specific consumption and cost efficiency in the next few phases.”

Mr. De Gasperis, continued, “Perhaps the most surprisingly positive outcome was that the Cycladex exceeded cyanide in these first tests for yields on silver, where we had very low starting expectations. We stopped that test at 67 days with nearly a 50% yield, far better than expected for silver.”

The technical staff has already designed and established new column tests for the primary purpose of assessing the specific consumption of the new materials and material cost for processing.  This is important for assessing ultimate economic feasibility of these solutions.  These simulations will also be conducted on-site, in the Company’s metallurgical labs, and are still funded by U.S. National Science Foundation research grants.

This updated metallurgical testing compliments extensive metallurgical testing for Dayton completed and published in 2011.  The Company is advancing the Dayton Resource Area to full feasibility, with expectations for a production ready mine plan within the next two years.

In-house Dayton engineering and mine planning have resulted in profiling various economic pit shells with multiple cutoff grade scenarios.  Multiple layout plans for the mine and corresponding processing facilities have been conceptually developed and located on lands 100% privately held by the Company, thus simplifying and shortening the critical permitting chain. We performed due diligence assisted by SRK Consulting that resulted in confirmation of the scoping level mine plans and the associated feasibility assessments.

The Company is also in the final stages of two joint ventures that can enhance liquidity, accelerate mining activities and enhance and validate the value of our mineral resources and properties.  We expect to announce these ventures as soon as they are completed, likely during the second quarter reporting process.


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