Searchlight Minerals Corp. Announces Significant Technical
Achievement in Gold and Iron Recovery at Its Clarkdale Slag Project
HENDERSON, NV--(Marketwired - May 9, 2014) - Searchlight
Minerals Corp. (OTCBB: SRCH) ("Searchlight" or the "Company") today
announced significant technical achievements in gold and iron
recovery at its Clarkdale Slag Project.
These achievements include, but are not limited to:
- The determination of precise nature of the gold contained
in the slag material.
- The addition of a high temperature pre-treatment step that
aids in the recovery of the gold and provides a saleable
iron byproduct.
- Up to a 60% extraction of metallic gold from fire assay of
ion exchange resin.
Based on the achievements above, the Company believes that the
project is commercially viable, if repeatable, at current
results.
Significant technical results achieved in Gold recovery
As previously reported, the Company has been working to
demonstrate economic feasibility of its Clarkdale Slag Project by
successfully operating four major steps of the production process:
crushing and grinding, leaching, continuous process operation, and
extraction of gold from solution. The current work program has
focused primarily on extraction of gold from solution as the
Company believes the first three steps have shown to be
successfully completed.
As noted in the Company's recently filed annual report (Form
10-K), in order to both increase gold recovery and improve the
overall production process, the Company has been performing tests
whereby the slag material is pretreated prior to processing it in
the autoclave. Recent test work indicates that pretreatment, by
melting the slag at high temperature, aids in the recovery of the
gold from solution derived from the autoclave. The Company believes
that the high temperature process aids in breaking down the
refractory coating on the gold particles that are subsequently put
into solution after the autoclaving of the slag material and also
separates out the iron that makes up approximately one third of the
untreated slag material.
The heat treated slag material, after the removal of the iron
is, for ease of reference, hereinafter referred to as glass. This
processed glass material contains the gold and, because of the heat
treatment process, is now easily and readily assayed by standard
fire assay techniques. It is anticipated that incorporating this
additional step into the Company's flow chart renders process
optimization testing much easier and will allow this phase of the
development program to be concluded more quickly.
Technical achievements considered to be a major breakthrough
In the past few months the precise nature of the gold contained
in the Clarkdale slag has been determined. Test work done with high
resolution microscopes -- a Scanning Electron Microscope ("SEM")
and a Transmission Electron Microscope ("TEM") -- have photographed
and measured the gold contained within sulfides and further
encapsulated by a highly refractory silicate very resistant to
thermal and chemical attack. This explains the difficulty in fire
assaying the gold or using ambient temperature strong reagent
leaching. Further, the gold is present as colloids (very small
particles) less than 100 nm in size which is 1,000 times less than
the width of a human hair. [This microscopic size is in the range
of most of the gold contained within the Carlin Trend in Nevada --
one of North America's richest gold deposits that went undetected
for decades due to the small "invisible" gold particles. The Carlin
Trend material was also very difficult to assay and process until
the true nature and deportment of the gold was determined.] The
temperature required to break the silicate coating of the Clarkdale
slag material exceeds standard fire assay temperature which is why
the gold is not captured in the lead collector used in a standard
fire assay. Specialized grinding using High Pressure Grinding Rolls
("HPGR") and high temperature leaching used in the current proposed
process flow diagram aid in breaking this coating, oxidizing the
sulfide, and converting the gold from a colloid to a charged ionic
form in solution.
Jim Murray, the Company's Project Manager, noted that "This
recent discovery of the true nature of the gold explains the
difficulty thus far in analyzing the slag material as well as
liberating and capturing the gold contained. Most common technology
used to capture gold from solution, including electro-winning and
ion exchange resin has had only limited success up to this point,
because the only gold that was being captured was the quantity of
gold that had been converted into a charged ionic form, leaving the
remainder of the colloid gold behind. The additional high
temperature pre-treatment, bench scale test work, which is
underway, suggests that the gold in solution exiting the autoclave
will be much easier to capture and convert to metallic gold." Mr.
Murray also indicated that "The conditions described above, which
tend to mask gold content and show only ionic gold, may understate
the true quantity of gold present in the Clarkdale slag
material."
Testing using this process thus far has verified the prior test
results achieved and reported by the Company of goldgrades between
0.4 to 0.6 ounces per ton (average). The processed material being
derived from the heat treated slag is also much easier to be
analyzed using standard analytical techniques. Small autoclave
tests conducted on the glass from the heat treatment have produced
up to an 85% extraction of gold into the pregnant leach solution
("PLS") solution.
The PLS solutions have been treated with ion exchange resin to
remove the gold from solution. Fire assays of the gold impregnated
resin indicate up to a 60% extraction of the gold from the PLS into
gold fire assay beads (gold in hand). While not yet optimized, this
is a significant improvement over previous attempts to capture the
gold as metal by ion exchange resin.
All of these tests thus far have been limited to a small 6 liter
test autoclave. To provide more definitive process results, the
Company has purchased (and expects delivery within 2 weeks) a much
larger heat treating unit, to produce sufficient treated slag to
allow running the larger 900 liter pilot autoclave. This will
provide a sufficient volume of PLS for a final determination of
recoverable gold by ion exchange resin, as well as, allowing the
testing of other methods of gold removal from solution to determine
the method allowing optimal recovery of gold from solution.
Other positive developments
In addition to the breakthrough discussed above, as a byproduct
of this new process, the high temperatures produce a high quality
iron product grading 75 to 85% iron content in a pelletized form.
The high quality of the iron and its pellet size form make it a
readily marketable product for sale to the China, Korea, or India
markets. The Company believes that further optimization testing
will result in greater than 90% iron as achievable and will secure
a premium price selling either into the scrap iron or pig iron
market. Test work is underway to maximize iron content while
maintaining gold recovery.
The existing railroad spur on the Clarkdale Project Site
connects to a major railroad for low cost transportation to a
seaport or domestic market. It is believed that this pre-treatment
process may pay for itself or provide a net cash flow from the sale
of the iron. To examine the efficacy of this concept, Searchlight
has engaged Samuel Engineering of Denver, Colorado to perform a
preliminary assessment and marketing study. This study has just
been concluded and suggests that a marketable higher grade iron
product could be made and sold as a byproduct to generate net cash
flow or reduce the overall costs of producing gold. Toward this end
the Company has commenced contacting commercial iron producers for
expressions of interest.
This pilot scale test work should provide sufficient process
definition for a project feasibility study to be completed,
allowing management to seek the financing to move forward to
commercialization of the Clarkdale Project.
Martin Oring, Searchlight Minerals CEO, stated "This latest
breakthrough has moved the project much closer to commercialization
as well as potentially providing extra unanticipated revenue
through the sale of iron." Mr. Oring went on to state "The gold
results set forth in the release have not yet been optimized,
however, since the Company has been able to remove the iron as a
saleable byproduct through the additional step discussed, even at
the current results, if repeatable, the project would be
commercial. We are looking forward to final definition of the
process flow diagram and moving ahead to the bankable study to
allow the project to move to a commercial status."
About Searchlight Minerals Corp.
Searchlight is an exploration stage company engaged in the
acquisition and exploration of mineral properties and slag
reprocessing projects. The Company holds interests in two mineral
projects: (i) the Clarkdale Slag Project, located in Clarkdale,
Arizona, which is a reclamation project to recover precious and
base metals from the reprocessing of slag produced from the
smelting of copper ore mined at the United Verde Copper Mine in
Jerome, Arizona; and (ii) the Searchlight Gold Project, which
involves exploration for precious metals on mining claims near
Searchlight, Nevada. The Clarkdale Slag Project is the more
advanced of two ongoing projects that the Company is pursuing. The
Searchlight Gold Project is an early-stage gold exploration
endeavor on 3,200 acres located approximately 50 miles south of Las
Vegas, Nevada.
Searchlight is headquartered in Henderson, Nevada, and its
common stock is listed on the OTC Bulletin Board under the symbol
"SRCH." Additional information is available on the Company's
website at www.searchlightminerals.com and in the Company's filings
with the U.S. Securities and Exchange Commission.
Forward-Looking Statements
This Press Release may contain, in addition to historical
information, forward-looking statements. Statements in this Press
Release that are forward-looking statements are subject to various
risks and uncertainties concerning the specific factors disclosed
under the heading "Risk Factors" in the Company's periodic filings
with the Commission. When used in this Press Release in discussing
the recent developments on the Company's mineral projects,
including, without limitation, the resolution of certain issues
relating to the operation of production modules, the words such as
"believe," "could," "may," "expect" and similar expressions are
forward-looking statements. The risk factors that could cause
actual results to differ from these forward-looking statements
include, but are not restricted to technical issues with the
mineral projects that may affect production modules and primary
process components, challenges in moving from pilot plant scale to
production scale, the risk that actual recoveries of base and
precious metals or other minerals re-processed from the slag
material at the Clarkdale site will not be economically feasible,
uncertainty of estimates of mineralized material, operational risk,
the Company's limited operating history, uncertainties about the
availability of additional financing, geological or mechanical
difficulties affecting the Company's planned mineral recovery
programs, the risk that actual capital costs, operating costs and
economic returns may differ significantly from the Company's
estimates and uncertainty whether the results from the Company's
feasibility studies are sufficiently positive for the Company to
proceed with the construction of its processing facility,
operational risk, the impact of governmental and environmental
regulation, financial risk, currency risk volatility in the prices
of precious metals and other statements that are not historical
facts as disclosed under the heading "Risk Factors" in the
Company's periodic filings with securities regulators in the United
States. Consequently, risk factors including, but not limited to
the aforementioned, may result in significant delays to the
projected or anticipated production target dates.
Contact Information: RJ Falkner & Company, Inc. Investor
Relations Counsel (800) 377-9893 Email
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