A composite drill core sample of primary massive sulphides
from Mahab 4 with a head grade of 9.77% copper was successfully
upgraded by means of standard flotation conditions to produce
marketable concentrate grades of 20-27% copper at recoveries of
90-94% copper.
TORONTO,
April 24, 2012 /PRNewswire/ - Gentor
Resources Inc. ("Gentor") (TSX-V: GNT) (OTCQB: GNTOF) and its Omani
partner Al Fairuz Mining Company LLC are pleased to announce the
results of initial flotation testwork on its flagship Mahab 4
Cyprus-type copper discovery in Block 5.
Gentor commissioned Wardell Armstrong
International based in Cornwall UK
to provide a programme of scoping flotation testwork initially on a
composite sample of high grade massive sulphide copper
mineralisation from its recently drill evaluated Mahab 4
deposit.
Testwork Summary
Standard testwork using nominal parameters for
Oman massive sulphides was applied
as a base case to a combined massive sulphide-semi-massive sulphide
sample grading 9.77% copper, producing a copper recovery of 85% to
an acceptable 20.2% copper concentrate. Follow-up rougher tests
summarised in Figure 1 below - using the base case but varying the
initial conditions - produced a variety of higher grade
concentrates with lower recoveries. However, finer grinding applied
to allow 80% passing 40 microns released more copper tied up within
pyrite grains to give a +90% copper recovery.
Subsequent cleaner tests summarised in Figure 2
below have shown that it is possible to achieve either:
- a circa 20.0% copper grade to 94% recovery from roughing alone;
or
- a circa 27.5% copper grade to 90% recovery from roughing + one
stage of cleaning.
Dependent on the copper grade the concentrate
contained 30-50% of the sulphide ore content. The efficiency
of the cleaner process determined that regrinding options appear to
add little benefit. This test work therefore suggests that a
relatively simple process using standard techniques and reagents is
applicable for the Mahab 4 massive sulphides.
Gentor is now preparing a wider selection of ore
type core samples including stringer zone and lower grade massive
sulphides in order to determine standard testwork treatment
parameters for the range of important bulk ore types at Mahab
4.
Gentor's President & CEO Dr. Peter Ruxton commented: "Gentor is very
pleased with these encouraging initial metallurgical tests that
confirm our expectations that the high-grade massive sulphides at
Mahab 4 will be readily treatable to produce a clean economic
concentrate. We have now approved further feasibility test
work on a range of typical Mahab 4 ore types to obtain a
comprehensive understanding of flotation conditions for this
deposit."
Test Work Program
In order to maximise the efficiency of the
preliminary program the experiences and parameters of flotation
treatment of various Oman
Cyprus-type VMS deposits was
utilised and incorporated into this phase of test work to provide
initial test conditions.
In addition, a detailed mineralogical
examination of the composite sample was undertaken in order to
determine factors such as the main sulphide and gangue minerals
present, their liberation sizes and degrees of alteration. The
massive sulphide ore type at Mahab 4 has a simple mineralogy
comprising dominant early brecciated pyrite, partly replaced at all
size levels by chalcopyrite and minor sphalerite; in a silica rich
gangue.
This enabled identification of the most
appropriate grind size, for each sample prior to undertaking
additional flotation tests in order to optimise reagent conditions
including defining collector type and dosage, flotation pH, and
circuit configuration including number and length of cleaning
stages.
Resultant base case conditions established
included:
- Grinding D80: 60µm
- pH 11.5
- 200g/t Cytec A238 collector
The final program recently completed involved
ten rougher tests and five cleaner tests.
Rougher Results
FT1 the first test for the MS head assay of
9.77% Cu (0.069% Cu (sol)), 46.96% S (0.29% S
(sol)), and 0.30 mg/kg Au gave an excellent rougher
flotation response of 85% recovery to 20.2% Cu concentrate. This
provided a strong basis from which to move forward with further
testwork to investigate the effect of pH, collector dosage and
primary grind size on flotation performance and subsequently the
collector type efficiency.
These further tests showed:
- FT2 - Increasing flotation pH from 11.5 to 12.0 resulted in a
reduction in copper recovery after 10 minutes of flotation from
83.7% to 77.8%. The grade of concentrate was, however,
approximately 2% higher in the concentrate suggesting that the
increased pH was depressing chalcopyrite that was associated with
pyrite.
- FT3 - Increasing the amount of collector added from a total of
200g/t (FT1) to 300g/t resulted in an increase in copper recovery
from 84.9% to 94.2% after 10 minutes. The increase in recovery did
however result in a reduction in the grade of concentrate of
approximately 3.2% to 17.1% Cu.
- FT4 - Reducing the primary grind size from 80% passing 60µm to
80% passing 40µm resulted in an increase in copper recovery of
8.1%, when compared with FT1, to 93.1%. The results also showed
that despite the increase in recovery, there was no detrimental
effect on concentrate grade with levels of circa 20.5% Cu being
maintained.
Based on these results, it would appear that a
finer primary grind size is of more benefit for increased recovery
than increased collector dosage. Therefore the second stage of
testwork involved four rougher flotation tests using this finer
grind size to again look at the effect of pH along with alternative
copper collectors on flotation performance.
Test conditions and results are summarised as
follows;
- FT5 - Repeat of test 4 (200g/t A238 at a grind size of 80%
passing 40µm) but with initial flotation pH increased from 11.5 to
12.0. Results showed that the increase in pH increased the
maximum grade of concentrate that was achievable, however, there
was no improvement in overall recovery.
- FT6 - Repeat of test 4 but with the Cytec Aero 238 collector
substituted for SIPX. Dosage levels were maintained. The results
showed that the alternative collector provided the highest copper
recovery observed to date of 97.2%, however, the grade of
concentrate was just 12.6% Cu. When the grade of concentrate was
increased to >20% Cu, recovery fell to levels which were below
that which could be achieved using the previous selective
collector.
- FT7 - Repeat of test 6 but with collector dosage reduced to 75%
of original level. Results showed that the test achieved higher
concentrate grades than test 6 although recovery levels were
lower.
- FT8 - Repeat of test 4 but with primary grind size reduced from
80% passing 40µ to 80% passing 30µm. The results showed that the
reduction in primary grind size resulted in a circa 2% increase in
copper recovery at 'lower' grades (circa 22-23% Cu) but that as
concentrate grade increased recoveries fell to levels achieved at
coarser grind sizes.
Based on these results, it would appear that the
best conditions identified to date are those of the test 4 regime
as seen in Figure 1. Consequently, two additional tests were
performed based on this regime but with the flotation pH reduced
from 11.5 to 10.5. The first test (FT9) was performed using Aero
238 whilst the second (FT10) was performed using SIPX. Based on the
responses shown in Figure 1 it would seem that the lower pH
produces a less economical result and the Aero 238 performs much
better than the SIPX, therefore overall the test 4 conditions
appear close to optimal for this material.
Cleaner Results
A program of five cleaner tests were conducted
that confirmed minimal treatment with standard conditions and
reagents was required to produce an acceptable range of
concentrates ranging from 20-27% Cu with commensurate high copper
recoveries of 90-94%. Furthermore, given that these results show
that only one stage of cleaning is required, it was considered
unnecessary to proceed with the proposed locked cycle testwork
which might be more appropriate for subsequent evaluation of lower
grade MS ores.
A final report on this work is not yet available
however a summary of testwork results is presented in Figure 2.
This indicates that tests FC2 and FC5 appear to optimise the copper
recovery above 90% with a minimum concentrate value of 20% Cu, and
that finer grinding in FC5 provides up to 2% better recovery in
concentrates up to 27% Cu, but at higher grades does not improve
performance and is of marginal value. Therefore it is suggested no
regrind may be necessary for this high-grade material.
Locality plans of the Oman concessions including the Mahab 4 deposit
are found on the Company's
website:http://www.gentorresources.com/s/NewsReleases.asp?ReportID=517002
Qualified Person
The results disclosed in this press release have
been reviewed, verified (including sampling, analytical and test
data) and compiled by senior geologists under the direction of Dr.
Peter Ruxton who is a Professional
Member of the Institute of Materials, Minerals and Mining
(I.M.M.M.), the Company's President and Chief Executive Officer and
a "qualified person" (as such term is defined in Canadian National
Instrument 43-101 as promulgated by the Canadian Securities
Administrators).
Technical Report
Additional information with respect to the
Company's Omani properties is contained in the technical report
prepared by Venmyn Rand (Pty) Ltd, dated December 31, 2010 and entitled "National
Instrument 43-101 Independent Technical Report on Block 5 and Block
6 Copper Projects, Semail Ophiolite Belt, Sultanate of Oman held by Gentor Resources, Inc." A
copy of this report can be obtained from SEDAR at
www.sedar.com.
About Gentor
Gentor is a mineral exploration company whose
projects include copper and gold properties in the Sultanate of
Oman and a
molybdenum-tungsten-silver property in East Central Idaho,
U.S. The Company's strategy is to create shareholder value by
developing highly prospective mineral properties around the globe,
with current focus in the Sultanate of Oman. In Oman, Gentor is partnered with Al Fairuz
Mining Company LLC on its Block 5 exploration tenement and Al Zuhra
Mining Company LLC on Block 6.
Cautionary Notes
Forward-Looking Information: This press
release contains forward-looking information. All statements,
other than statements of historical fact, that address activities,
events or developments that the Company believes, expects or
anticipates will or may occur in the future (including, without
limitation, statements regarding metallurgical testwork and other
exploration results, potential mineral resources, potential
mineralization and the Company's exploration and development plans)
are forward-looking information. This forward-looking
information reflects the current expectations or beliefs of the
Company based on information currently available to the
Company. Forward-looking information is subject to a number
of risks and uncertainties that may cause the actual results of the
Company to differ materially from those discussed in the
forward-looking information, and even if such actual results are
realized or substantially realized, there can be no assurance that
they will have the expected consequences to, or effects on the
Company. Factors that could cause actual results or events to
differ materially from current expectations include, among other
things, copper recoveries being less than those indicated by the
metallurgical testwork carried out to date (there can be no
assurance that copper recoveries in small scale laboratory tests
will be duplicated in large tests under on-site conditions or
during production); risks related to the exploration stage of the
Company's properties, the possibility that future exploration
results will not be consistent with the Company's expectations,
changes in world copper or gold markets and equity markets,
political developments in Oman,
uncertainties relating to the availability and costs of financing
needed in the future, the uncertainties involved in interpreting
exploration results and other geological data and the other risks
involved in the mineral exploration business. Forward-looking
information speaks only as of the date on which it is provided and,
except as may be required by applicable securities laws, the
Company disclaims any intent or obligation to update any
forward-looking information, whether as a result of new
information, future events or results or otherwise. Although
the Company believes that the assumptions inherent in the
forward-looking information are reasonable, forward-looking
information is not a guarantee of future performance and
accordingly undue reliance should not be put on such information
due to the inherent uncertainty therein.
The United States Securities and Exchange
Commission (the "SEC") permits mining companies, in their filings
with the SEC, to disclose only those mineral deposits that a
company can economically and legally extract or produce. U.S.
investors are cautioned not to assume that any disclosure of
mineralization contained in this press release is economically or
legally mineable. U.S. investors are urged to closely
consider all of the disclosures in the Company's reports filed
pursuant to the United States Securities Exchange Act of 1934 which
may be secured from the Company, or from the SEC's website at
http://www.sec.gov/edgar.html.
Neither TSX Venture Exchange nor its Regulation
Services Provider (as that term is defined in the policies of the
TSX Venture Exchange) accepts responsibility for the adequacy or
accuracy of this release.
SOURCE Gentor Resources Inc.
Image with caption: "Figure 1. Summary of Rougher Testwork
Results (CNW Group/Gentor Resources Inc.)". Image available at:
http://photos.newswire.ca/images/download/20120424_C8386_PHOTO_EN_12649.jpg
Image with caption: "Figure 2. Summary of Cleaner Testwork
Results (CNW Group/Gentor Resources Inc.)". Image available at:
http://photos.newswire.ca/images/download/20120424_C8386_PHOTO_EN_12648.jpg
