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11 July 2024
Cobra Resources
plc
("Cobra"
or the "Company")
ISR Bench Scale Study
Update
Further metallurgical success
at world leading ISR rare earth project
Cobra
(LSE: COBR), an exploration
company advancing a strategy to lower the cost of critical rare
earth production at the Boland Project in South Australia, is
pleased to announce that diagnostic tests being carried out as part
of ongoing in situ recovery ("ISR") bench scale testing of a
high-grade core sample, have produced positive preliminary
metallurgical results.
ISR is a low capital, and low
disturbance mining process that utilises unique geological
conditions to bypass traditional mining and processing methods with
low environmental risk. ISR has been used for many years
to produce uranium in South Australia from similar geological
environments.
The Australian National Scientific and Technical Organisation
("ANSTO") is undertaking mineral-recovery trials on rare earth
mineralisation recovered from Cobra's recently installed ISR
wellfield to demonstrate the value of applying ISR to Cobra's
unique ionic rare earth mineralisation. Testing has yielded low
impurity levels and low acid consumption which support a pathway
for cost-effective recovery.
For further context to the technical
information discussed in this announcement with comparative
analysis, please view the Q&A on Cobra's Investor Hub
here:
https://investors.cobraplc.com/link/6rkjLe
Highlights:
·
Strong ionic
recoveries from a high-grade sample: 41% recoveries of Rare Earths ("REEs") from a sub-sample
grading 2,688 ppm Total
Rare Earth Oxide ("TREO") magnet rare earths Nd2O3 + Pr6O11 total
532 ppm and Dy2O3 + Tb2O3
total 83 ppm at pH 3,
ambient temperature
·
Low-cost
metallurgical characteristics: Low
impurities and low acid consumption support a simple low-capital
flowsheet for purification and precipitation - favourable for
project economics
·
Low levels of
deleterious radioactive elements: in
Pregnant Liquor Solution ("PLS") of 0.24 mg/L U and <0.01 mg/L
Th, important for product transport and oxide separation
·
Ability to
increase recoveries through ISR: low
acid consumption and low levels of impurities enable optimisation
to further maximise REE recovery. This is being tested by
increasing leach time of the bench scale ISR test and making
lixiviant adjustments
Rupert Verco, CEO of Cobra,
commented:
"These initial recoveries are very pleasing. Managing
impurities and acid consumption are significant factors of rare
earth processing costs and these results provide a pathway for
cost-effective recovery - particularly when coupled with ISR
mining.
Achieving recoveries of 41% from such a high head grade of
2,688 ppm TREO in this diagnostic test is highly encouraging for
optimising recoveries from the bench scale ISR tests being
performed on a core sample exceeding 4,506 ppm TREO. There is
plenty of room to optimise these recoveries considering the low
level of impurities, low acid consumption and the minimal costs
involved in ISR mining.
Our overarching objective is to produce metals which are
critical to energy efficiency through a mining process with the
lowest environmental risk and the lowest possible cost. We aim to
demonstrate the value of this by confirming recovery via ISR and
maximising metallurgical confidence. We look forward to bringing
further metallurgy results to the market in the coming
weeks."
Next Steps
Considering these favourable
results, the following adjustments to Cobra's work programme have
been made:
1. Extended duration of ISR bench scale
study: to determine maximum recovery / impurity limits with
results anticipated over the coming weeks
2. Commencement of a second ISR bench scale ISR
study: on core from CBSC0002 to achieve repeatability and
increase the volume of pregnant liquor for flowsheet
development
3. Further diagnostic leach tests: across
installed wellfield holes to enable economic assessment of the
complete wellfield and all zones of mineralisation
4. Resource drilling: planning and design
have been completed. The commencement of resource drilling has been
delayed enabling metallurgical results to be interpreted and
evaluated against existing drilling ensuring the most desirable
areas of the palaeochannel are targets
5. Flowsheet advancement: pregnant liquor
produced from both bench scale ISR tests to be used to advance both
membrane desorption and traditional REE purification and
precipitation processes
Further information relating to
diagnostic leach test results are presented in the
appendices.
Enquiries:
|
Cobra Resources plc
Rupert Verco (Australia)
Dan Maling (UK)
|
via Vigo
Consulting
+44 (0)20
7390 0234
|
|
SI
Capital Limited (Joint Broker)
Nick Emerson
Sam Lomanto
|
+44
(0)1483 413 500
|
|
Global Investment Strategy (Joint Broker)
James Sheehan
|
+44 (0)20
7048 9437
james.sheehan@gisukltd.com
|
|
Vigo
Consulting (Financial Public Relations)
Ben Simons
Kendall Hill
|
+44 (0)20
7390 0234
cobra@vigoconsulting.com
|
The person who arranged for the
release of this announcement was Rupert Verco, Managing Director of
the Company.
Information in this announcement
relates to exploration results that have been reported in the
following announcements:
·
Wudinna Project Update: "ISR bench scale update - Exceptional head grades
revealed", dated 18 June 2024
·
Wudinna Project Update: "Re-Assay Results Confirm High Grades Over Exceptional Scale at
Boland", dated 26 April 2024
·
Wudinna Project Update: "Drilling results from
Boland Prospect", dated 25 March 2024
·
Wudinna Project Update: "Historical Drillhole
Re-Assay Results", dated 27 February 2024
·
Wudinna Project Update: "Ionic Rare Earth
Mineralisation at Boland Prospect", dated 11 September
2023
·
Wudinna Project Update: "Exceptional REE Results
Defined at Boland", dated 20 June 2023
Competent Persons Statement
The information in this report that
relates to metallurgical results is based on information compiled
by Cobra Resources and reviewed by Mr. James Davidson who is the
Director of Process Engineering at Wallbridge Gilbert Aztec and a
Fellow of the Australian Institute of Mining and Metallurgy (F
AusIMM). Mr. Davidson has sufficient experience that is relevant to
the metallurgical testing which was undertaken to qualify as a
Competent Person as defined in the 2012 edition of the
"Australasian Code for Reporting of Exploration Results, Mineral
Resources and Ore Reserves". Mr. Davidson consents to the inclusion
in this report of the matters based on this information in the form
and context in which it appears.
Information in this announcement has
been assessed by Mr Rupert Verco, a Fellow of the Australasian
Institute of Mining and Metallurgy. Mr Verco is an employee of
Cobra and has more than 16 years' industry experience which is
relevant to the style of mineralisation, deposit type, and activity
which he is undertaking to qualify as a Competent Person as defined
in the 2012 Edition of the Australasian Code for Reporting
Exploration Results, Mineral Resources and Ore Reserves of JORC.
This includes 12 years of Mining, Resource Estimation and
Exploration.
About Cobra
In 2023, Cobra discovered a rare
earth deposit with the potential to re-define the cost of rare
earth production. The highly scalable Boland ionic rare earth
discovery at Cobra's Wudinna Project in South Australia's Gawler
Craton is Australia's only rare earth project amenable for in situ
recovery (ISR) mining - a low cost, low disturbance method. Cobra
is focused on de-risking the investment value of the discovery by
proving ISR as the preferred mining method which would eliminate
challenges associated with processing clays and provide Cobra with
the opportunity to define a low-cost pathway to
production.
Cobra's Wudinna tenements also
contain extensive orogenic gold mineralisation, including a 279,000
Oz gold JORC Mineral Resource Estimate, characterised by
potentially open-pitable, high-grade gold
intersections.
Regional map showing Cobra's tenements in the heart of the
Gawler Craton
Follow us on social media:
LinkedIn: https://www.linkedin.com/company/cobraresourcesplc
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https://twitter.com/Cobra_Resources
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https://investors.cobraplc.com/auth/signup
Appendix 1: Diagnostic leach
results
Preliminary metallurgical testing
being performed by the Australian Nuclear Science and Technology
Organisation ("ANSTO") aimed at demonstrating the suitability for
ISR mining - a low cost, low-disturbance method - has yielded low
impurity levels and low acid consumption with robust recoveries
providing scope for further optimisation. The objectives of
metallurgical testing are outlined below:
Diagnostic tests are aimed
to:
i.
Confirm the quantity of recoverable ionic REE
mineralisation
ii.
Determine the quantity of acid consumed
iii.
Measure the anticipated level of impurities
iv.
Enable optimising adjustments to parallel bench scale ISR
tests
The parameters of the diagnostic
leach test were:
·
Reagent: 0.5M Ammonium Sulphate
·
Sulphuric Acid addition to maintain pH3
·
Ambient Temperature
·
Duration: 24 Hours
The results reported in this
announcement are derived from the diagnostic test
The composite sample subject to the
diagnostic leach test was from CBSC003 (26.7m to 27.2m) the
sub-sample calculated head grade and subsequent recoveries are
presented in table 1 below:
Table 1:
Diagnostic leach sample head grade and subsequent
recoveries
|
|
Pr6O11
ppm
|
Nd2O3
ppm
|
Tb2O3
ppm
|
Dy2O3
ppm
|
MREO %
|
HREO %
|
TREO ppm
|
|
Sub-sample (80g) Grade
|
114
|
417
|
11.3
|
71.6
|
23%
|
29%
|
2,688
|
|
Recovery
|
41%
|
39%
|
31%
|
30%
|
38%
|
37%
|
41%
|
A favourable characteristic of ionic
mineralisation is the low level of impurities and radioactive
deleterious elements that are recovered.
Desorption at benign acidities
between pH 3-4 reduces the leaching of key impurities such as
aluminium, iron and silica. A key metric to measure the level of
impurities is the apparent ratio of rare earths to impurities
within a pregnant solution. When the ratio of REEs to impurities in
solution is low, the metallurgical process for purification become
complex, and the rate of REE recovery through purification
decreases.
Diagnostic leach results demonstrate
that the level of REEs in solution far exceed the level of
impurities, supporting a low-cost, low-temperature single-step for
impurity removal.
Table 2:
Diagnostic leach impurity ratios and levels of radioactive
deleterious elements in solution
|
TREY:Al
|
TREY:Fe
|
TREY:Si
|
U mg/L
|
Th mg/L
|
|
13
|
9.7
|
>7.9
|
0.24
|
<0.01
|
TREY =
La+Ce+Pr+Nd+Sm+Eu+Gd+Tb+Dy+Ho+Er+Tm+Yb+Lu+Y
Al - Aluminium
Fe - Iron
Si - Silica
U - Uranium
Th - Thorium
Appendix 2: ISR bench scale
test CBSC003 26.7m - 27.2m
The diagnostic leach sample is a
sub-sample of CBSC003 26.7m - 27.2m, a length of core that is
currently subject to bench scale ISR tests. The head grade of the
sample is 4,506 ppm TREO calculated from the sample composites
presented in Table 3
Table 3:
Sample composites of the sample subject to the bench scale ISR
test
|
Depth from (m)
|
Depth to (m)
|
Pr6O11
|
Nd2O3
|
Tb2O3
|
Dy2O3
|
MREO %
|
HREO
|
HREO %
|
TREO
|
|
26.7
|
26.8
|
317
|
1,277
|
35
|
207
|
24%
|
2,286
|
29%
|
7,764
|
|
26.8
|
26.9
|
290
|
1,144
|
30
|
177
|
23%
|
1,990
|
28%
|
7,187
|
|
26.9
|
27
|
206
|
710
|
18
|
105
|
21%
|
1,129
|
23%
|
4,869
|
|
27
|
27.1
|
84
|
328
|
9
|
56
|
22%
|
610
|
28%
|
2,144
|
|
27.1
|
27.2
|
53
|
211
|
6
|
36
|
22%
|
401
|
29%
|
1,371
|
|
26.7
|
27.2
|
183
|
708
|
19
|
112
|
23%
|
1,239
|
28%
|
4,506
|
MREO = Pr6O11+ Nd2O3+
Tb2O3+ Dy2O3
HREO = Sm2O3+ Eu2O3+
Gd2O3+ Tb2O3+
Dy2O3+Ho2O3+Er2O3+Tm2O3
+Yb2O3+Lu2O3+Y2O3
Bench scale ISR test is designed to
emulate the ISR process to determine:
i.
The rate in which the lixiviant can percolate through the pore
space of the mineralised sample
ii.
The subsequent time required to adjust sample pH
iii.
The rate and quantity in which rare earths are liberated to
solution
The results of the initial
bench scale ISR study are expected over the coming
weeks
Appendix 3: Interpretation of
results
·
Strong
un-optimised recoveries from a high-grade sample:
38% recoveries of Magnet Rare Earths ("MREO") from
a sample grading 2,688 ppm
Total Rare Earth Oxide ("TREO") magnet rare earths Nd2O3 + Pr6O11
total 528 ppm and Dy2O3 +
Tb2O3 total 83
ppm
·
Low-cost
metallurgical characteristics: acid consumption:
over 24 hours total sulphuric acid
(H2SO4) consumption of 8.8 kg/t - equivalent
to ~A$2/t (£1.06/t)1
·
Low levels of
impurity: TREY:Al ratio of 13:1,
TREY:Fe ratio of 9.7:1
TREY:Si ratio of 7.9:1 -
these results are considered very favourable for low-cost
purification via a low temperature single step impurity
removal
·
Low levels of
deleterious radioactive elements: in
Pregnant Liquor Solution ("PLS") of 0.24 mg/L U and <0.01 mg/L
Th, an important aspect for product transport and oxide
separation
·
Un-optimised
recoveries with upside: owing to the
low level of impurities and the low acid consumption, the ability
to increase REE recoveries is being evaluated by increasing the
length of the bench scale ISR study and making adjustments to the
lixiviant. These results are expected in the coming
weeks.
Figure 1: Aerial photograph of
the Boland Project wellfield with significant
intersections
*Partially assayed
#Stored for metallurgical
testing, pending assay
Appendix 4: Cobra's Boland rare
earth discovery
·
Ionic clay-hosted rare earths present as a
low-capital, low operating cost source of heavy and magnet rare
earth metals
·
Processing of clay ores induces several operating
challenges, including productivity loss, material handling,
dewatering, reagent use and reclamation
·
Ionic rare earth mineralisation at Boland exists
in permeable geology in an environment that permits ISR, thus
bypassing the challenges associated with processing of clay
ores
·
ISR is the preferred method of recovery used in
the uranium industry, where1:
o Global ISR production accounted for ~60% of mined uranium in
2022
o Capital expenditure for ISR is 1-15% of conventional
mines
o Operating costs of ISR is generally 30-40% lower than
traditional mines
o Environmental impact and rehabilitation cost is significantly
lower than traditional mines
·
South Australia is home to Australia's only three
operating ISR uranium mines and has a regulatory framework that
supports ISR mining
·
Bench-scale leach studies under ISR conditions are
currently underway at ANSTO, a first for ionic REE projects outside
of China
·
Cobra has installed a wellfield to rapidly advance
the project towards an infield pilot study
·
Cobra aims to demonstrate that the cost of
production at Boland can be materially reduced via ISR, providing
operating resilience to volatile rare earth markets which has
stalled the commencement of many rare earth projects
·
Re-assaying of historic uranium focused drilling
is being used to confirm the scale of rare earth mineralisation.
These results confirm the presence of rare earth mineralisation
over a strike of 12 km, where mineralisation is open in most
directions. Follow-up drilling will aim to infill these results to
support a maiden Mineral Resource Estimate ("MRE") at
Boland
Appendix 5: Further information
relating to the Boland Project and reported results
·
In February 2024, Cobra drilled five sonic core
holes and installed screened and cased wells to advance ISR mining
of ionic rare earths
·
On 25 March 2024, the Company announced the assay
results of three of the five holes drilled, revealing three
consistent zones of mineralisation
·
Core from two holes were preserved and transported
to ANSTO for metallurgical testing. Samples have been kept
air-tight and refrigerated to prevent changes in oxidation and
therefore sampling and assaying can only occur directly before the
commencement of metallurgical testing
·
Zone three represents the deepest and
highest-grade zone of mineralisation. The wellfield has been
designed and installed to pilot test ISR from zone three
·
Further core from CBSC0003 and CBSC0002 is being
prepared for further metallurgical testwork to support flow sheet
optimisation
·
Drilling results have been reported via a
four-acid digest method, which is a partial digest that represents
the ionic / leachable portion of REE mineralisation. Samples
prepared for and subject to metallurgical testing have been assayed
via lithium borate fusion; a complete digest of REE-bearing
minerals. Results from Boland are 10-15% higher when reported via
lithium borate fusion
·
Recoveries reported in this announcement have been
reported against head grades calculated via lithium borate fusion
assays and are therefore a reflection of the recoverable quantity
of the total rare earth oxide grade
Appendix 6: JORC Code, 2012
Edition - Table 1
Section 1 Sampling Techniques and Data
|
Criteria
|
JORC Code explanation
|
Commentary
|
|
Sampling
techniques
|
·
Nature and
quality of sampling (eg cut channels, random chips, or specific
specialised industry standard measurement tools appropriate to the
minerals under investigation, such as down hole gamma sondes, or
handheld XRF instruments, etc). These examples should not be taken
as limiting the broad meaning of sampling.
·
Include
reference to measures taken to ensure sample representivity and the
appropriate calibration of any measurement tools or systems
used.
·
Aspects of the
determination of mineralisation that are Material to the Public
Report.
·
In cases where
'industry standard' work has been done this would be relatively
simple (eg 'reverse circulation drilling was used to obtain 1 m
samples from which 3 kg was pulverised to produce a 30 g charge for
fire assay'). In other cases more explanation may be required, such
as where there is coarse gold that has inherent sampling problems.
Unusual commodities or mineralisation types (eg submarine nodules)
may warrant disclosure of detailed information.
|
2023
RC
· Samples were collected via a Metzke cone splitter mounted to
the cyclone. 1m samples were managed through chute and butterfly
valve to produce a 2-4 kg sample. Samples were taken from the point
of collar, but only samples from the commencement of saprolite were
selected for analysis.
· Samples submitted to Bureau Veritas Laboratories, Adelaide,
and pulverised to produce the 50 g fire assay charge and 4 acid
digest sample.
AC
· A
combination of 2m and 3 m samples were collected in green bags via
a rig mounted cyclone. An PVC spear was used to collect a 2-4 kg
sub sample from each green bag. Samples were taken from the point
of collar.
· Samples submitted to Bureau Veritas Laboratories, Adelaide,
and pulverised to produce the 50 g fire assay charge and 4 acid
digest sample.
2024
SONIC
· Core
was scanned by a SciAps X555 pXRF to determine sample intervals.
Intervals through mineralized zones were taken at 10cm. Through
waste, sample intervals were lengthened to 50cm. Core was halved by
knife cutting. XRF scan locations were taken on an inner surface of
the core to ensure readings were taken on fresh sample
faces.
· Samples were submitted to Bureau Veritas for 4 acid digest ICP
analysis.
|
|
Drilling
techniques
|
·
Drill type (eg
core, reverse circulation, open-hole hammer, rotary air blast,
auger, Bangka, sonic, etc) and details (eg core diameter, triple or
standard tube, depth of diamond tails, face-sampling bit or other
type, whether core is oriented and if so, by what method,
etc).
|
2023
· Drilling completed by Bullion Drilling Pty Ltd using 5 ¾"
reverse circulation drilling techniques from a Schramm T685WS rig
with an auxiliary compressor.
· Drilling completed by McLeod Drilling Pty Ltd using 75.7 mm NQ
air core drilling techniques from an ALMET Aircore rig mounted on a
Toyota Landcruiser 6x6 and a 200psi, 400cfm Sullair
compressor.
2024
· Sonic
Core drilling completed Star Drilling using 4" core with a SDR12
drill rig. Holes were reamed to 6" or 8" to enable casing and
screens to be installed
|
|
Drill sample
recovery
|
·
Method of
recording and assessing core and chip sample recoveries and results
assessed.
·
Measures taken
to maximise sample recovery and ensure representative nature of the
samples.
·
Whether a
relationship exists between sample recovery and grade and whether
sample bias may have occurred due to preferential loss/gain of
fine/coarse material.
|
Aircore & RC
· Sample
recovery was generally good. All samples were recorded for sample
type, quality and contamination potential and entered within a
sample log.
· In
general, sample recoveries were good with 10 kg for each 1 m
interval being recovered from AC drilling.
· No
relationships between sample recovery and grade have been
identified.
· RC drilling
completed by Bullion Drilling Pty Ltd using 5 ¾" reverse
circulation drilling techniques from a Schramm T685WS rig with an
auxiliary compressor
· Sample
recovery for RC was
generally good. All samples were recorded for sample type, quality
and contamination potential and entered within a sample
log.
· In
general, RC sample
recoveries were good with 35-50 kg for each 1 m interval being
recovered.
· No
relationships between sample recovery and grade have been
identified.
Sonic Core
· Sample
recovery is considered excellent.
|
|
Logging
|
·
Whether core and
chip samples have been geologically and geotechnically logged to a
level of detail to support appropriate Mineral Resource estimation,
mining studies and metallurgical studies.
·
Whether logging
is qualitative or quantitative in nature. Core (or costean,
channel, etc) photography.
·
The total length
and percentage of the relevant intersections
logged.
|
Aircore & RC
· All
drill samples were logged by an experienced geologist at the time
of drilling. Lithology, colour, weathering and moisture were
documented.
· Logging is generally qualitative in nature.
· All
drill metres have been geologically logged on sample intervals (1-3 m).
Sonic Core
· Logging was carried out in detail, determining lithology and
clay/ sand content. Logging intervals were lithology based with
variable interval lengths.
· All
core drilled has been lithologically logged.
|
|
Sub-sampling techniques and
sample preparation
|
·
If core, whether
cut or sawn and whether quarter, half or all core
taken.
·
If non-core,
whether riffled, tube sampled, rotary split, etc and whether
sampled wet or dry.
·
For all sample
types, the nature, quality and appropriateness of the sample
preparation technique.
·
Quality control
procedures adopted for all sub-sampling stages to maximise
representivity of samples.
·
Measures taken
to ensure that the sampling is representative of the in situ
material collected, including for instance results for field
duplicate/second-half sampling.
·
Whether sample
sizes are appropriate to the grain size of the material being
sampled.
|
2021-onward
· The
use of an aluminum scoop or PVC spear to collect the required 2-4
kg of sub-sample from each AC sample length controlled the sample
volume submitted to the laboratory.
· Additional sub-sampling was performed through the preparation
and processing of samples according to the lab internal
protocols.
· Duplicate AC samples were collected from the green bags using
an aluminium scoop or PVC spear at a 1 in 25 sample
frequency.
· Sample
sizes were appropriate for the material being sampled.
· Assessment of duplicate results indicated this sub-sample
method provided good repeatability for rare earth
elements.
· RC
drill samples were sub-sampled using a cyclone rig mounted splitter
with recoveries monitored using a field spring scale.
· Manual
re-splitting of RC samples through a riffle splitter was undertaken
where sample sizes exceeded 4 kg.
· RC
field duplicate samples were taken nominally every 1 in 25 samples.
These samples showed good repeatability for REE.
Sonic Drilling
· Field
duplicate samples were taken nominally every 1 in 25 samples where
the sampled interval was quartered.
· Blanks
and Standards were submitted every 25 samples
· Half
core samples were taken where lab geochemistry sample were
taken.
· In
holes where column leach test samples have been submitted, full
core samples have been submitted over the test areas.
|
|
Quality of assay data and
laboratory tests
|
·
The nature,
quality and appropriateness of the assaying and laboratory
procedures used and whether the technique is considered partial or
total.
·
For geophysical
tools, spectrometers, handheld XRF instruments, etc, the parameters
used in determining the analysis including instrument make and
model, reading times, calibrations factors applied and their
derivation, etc.
·
Nature of
quality control procedures adopted (eg standards, blanks,
duplicates, external laboratory checks) and whether acceptable
levels of accuracy (ie lack of bias) and precision have been
established.
|
· Samples were submitted to Bureau Veritas Laboratories,
Adelaide for preparation and analysis.
· Multi
element geochemistry were digested by four acid ICP-MS and analysed
for Ag, Ce, Cu, Dy, Er, Eu, Gd, Ho, La, Lu, Mg, Na, Nd, P, Pr, Sc,
Sm, Tb, Th, Tm, U, Y and Yb.
· For
the sonic samples Ag was removed from the analytical suite and V
was included
· Field
gold blanks and rare earth standards were submitted at a frequency
of 1 in 25 samples.
· Field
duplicate samples were submitted at a frequency of 1 in 25
samples
· Reported assays are to acceptable levels of accuracy and
precision.
· Internal laboratory blanks, standards and repeats for rare
earths indicated acceptable assay accuracy.
· Samples retained for metallurgical analysis were immediately
vacuum packed and refrigerated.
· These
samples were refrigerated throughout transport.
Metallurgical Test Work performed by
the Australian Nuclear Science and Technology Organisation
(ANSTO).
ANSTO laboratories prepared a 80g
sample from the homogenized core section CBSC003 26.7-27.2m. The
sample was
· Standard desorption conditions:
· 0.5M
(NH4)2SO4 as lixiviant
· pH
3
· 30
minutes, 2 hrs, 6 hrs, 12 hrs & 24 hours
· Ambient temperature of 22°C; and
· 4 wt%
solids density
·
Prior to commencing the test work, a bulk 0.5 M
(NH4)2SO4 solution was prepared as the synthetic lixiviant and the
pH adjusted to 3 using H2SO4.
·
Each of the leach tests was conducted on 80 g of
dry, un-pulverised sample and 1920 g of the lixiviant in a 2 L
titanium/ stainless steel baffled leach vessel equipped with an
overhead stirrer.
·
Addition of solid to the lixiviant at the test pH
will start the test. 1 M H2SO4 was utilised to maintain the test pH
for the duration of the test, if necessary. The acid addition was
measured.
·
At the completion of each test, the final pH was
measured, the slurry was vacuum filtered to separate the primary
filtrate.
·
The primary filtrate was analysed as follows: •
ICP-MS for Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Mn, Nd, Pb, Pr, Sc, Sm,
Tb, Th, Tm, U, Y, Yb (ALS, Brisbane); • ICP-OES for Al, Ca, Fe, K,
Mg, Mn, Na, Si (in-house, ANSTO);
·
The water wash was stored but not
analysed.
|
|
Verification of sampling and
assaying
|
·
The verification
of significant intersections by either independent or alternative
company personnel.
·
The use of
twinned holes.
·
Documentation of
primary data, data entry procedures, data verification, data
storage (physical and electronic) protocols.
·
Discuss any
adjustment to assay data.
|
· Sampling data was recorded in field books, checked upon
digitising and transferred to database.
· Geological logging was undertaken digitally via the MX Deposit
logging interface and synchronised to the database at least daily
during the drill programme.
· Compositing of assays was undertaken and reviewed by Cobra
Resources staff.
· Original copies of laboratory assay data are retained
digitally on the Cobra Resources server for future
reference.
· Samples have been spatially verified through the use of
Datamine and Leapfrog geological software for pre 2021 and post
2021 samples and assays.
· Twinned drillholes from pre 2021 and post 2021 drill
programmes showed acceptable spatial and grade
repeatability.
· Physical copies of field sampling books are retained by Cobra
Resources for future reference.
· Elevated pXRF grades were checked and re-tested where
anomalous. pXRF grades are semi quantitative.
|
|
Location of data
points
|
·
Accuracy and
quality of surveys used to locate drill holes (collar and down-hole
surveys), trenches, mine workings and other locations used in
Mineral Resource estimation.
·
Specification of
the grid system used.
·
Quality and
adequacy of topographic control.
|
Pre 2021
· Collar
locations were pegged using DGPS to an accuracy of +/-0.5
m.
· Downhole surveys have been completed for deeper RC and diamond
drillholes
· Collars have been picked up in a variety of coordinate systems
but have all been converted to MGA 94 Zone 53. Collars have been
spatially verified in the field.
· Collar
elevations were historically projected to a geophysical survey DTM.
This survey has been adjusted to AHD using a Leica CS20 GNSS base
and rover survey with a 0.05 cm accuracy. Collar points have been
re-projected to the AHD adjusted topographical surface.
2021-onward
· Collar
locations were initially surveyed using a mobile phone utilising
the Avenza Map app. Collar points recorded with a GPS horizontal
accuracy within 5 m.
· RC
Collar locations were picked up using a Leica CS20 base and Rover
with an instrument precision of 0.05 cm accuracy.
· Locations are recorded in geodetic datum GDA 94 zone
53.
· No
downhole surveying was undertaken on AC holes. All holes were set
up vertically and are assumed vertical.
· RC
holes have been down hole surveyed using a Reflex TN-14 true north
seeking downhole survey tool or Reflex multishot
· Downhole surveys were assessed for quality prior to export of
data. Poor quality surveys were downgraded in the database to be
excluded from export.
· All
surveys are corrected to MGA 94 Zone 53 within the MX Deposit
database.
· Cased
collars of sonic drilling shall be surveyed before a mineral
resource estimate
|
|
Data spacing and
distribution
|
·
Data spacing for
reporting of Exploration Results.
·
Whether the data
spacing and distribution is sufficient to establish the degree of
geological and grade continuity appropriate for the Mineral
Resource and Ore Reserve estimation procedure(s) and
classifications applied.
·
Whether sample
compositing has been applied.
|
·
Drillhole spacing was designed on transects 50-80
m apart. Drillholes generally 50-60 m apart on these transects but
up to 70 m apart.
·
Additional scouting holes were drilled
opportunistically on existing tracks at spacings 25-150 m from
previous drillholes.
·
Regional scouting holes are drilled at variable
spacings designed to test structural concepts
·
Data spacing is considered adequate for a
saprolite hosted rare earth Mineral Resource estimation.
·
No sample compositing has been applied
·
Sonic core holes were drilled at ~20m spacings in
a wellfield configuration based on assumed permeability potential
of the intersected geology.
|
|
Orientation of data in
relation to geological structure
|
·
Whether the
orientation of sampling achieves unbiased sampling of possible
structures and the extent to which this is known, considering the
deposit type.
·
If the
relationship between the drilling orientation and the orientation
of key mineralised structures is considered to have introduced a
sampling bias, this should be assessed and reported if
material.
|
·
RC drillholes have been drilled between -60 and
-75 degrees at orientations interpreted to appropriately intersect
gold mineralisation
·
Aircore and Sonic drill holes are
vertical.
|
|
Sample
security
|
·
The measures
taken to ensure sample security.
|
Pre 2021
·
Company staff collected or supervised the
collection of all laboratory samples. Samples were transported by a
local freight contractor
·
No suspicion of historic samples being tampered
with at any stage.
·
Pulp samples were collected from Challenger
Geological Services and submitted to Intertek Genalysis by Cobra
Resources' employees.
2021-onward
·
Transport of samples to Adelaide was undertaken by
a competent independent contractor. Samples were packaged in zip
tied polyweave bags in bundles of 5 samples at the drill rig and
transported in larger bulka bags by batch while being
transported.
·
There is no suspicion of tampering of
samples.
|
|
Audits or
reviews
|
·
The results of
any audits or reviews of sampling techniques and
data.
|
·
No laboratory audit or review has been
undertaken.
·
Genalysis Intertek and BV Laboratories Adelaide
are NATA (National Association of Testing Authorities) accredited
laboratory, recognition of their analytical competence.
|
Appendix 5: Section 2 Reporting of
Exploration Results
|
Criteria
|
JORC Code explanation
|
Commentary
|
|
Mineral tenement and land
tenure status
|
·
Type, reference
name/number, location and ownership including agreements or
material issues with third parties such as joint ventures,
partnerships, overriding royalties, native title interests,
historical sites, wilderness or national park and environmental
settings.
·
The security of
the tenure held at the time of reporting along with any known
impediments to obtaining a licence to operate in the
area.
|
·
RC drilling occurred on EL 6131, currently owned
100% by Peninsula Resources limited, a wholly owned subsidiary of
Andromeda Metals Limited.
·
Alcrest Royalties Australia Pty Ltd retains a 1.5%
NSR royalty over future mineral production from licenses EL6001,
EL5953, EL6131, EL6317 and EL6489.
·
Baggy Green, Clarke, Laker and the IOCG targets
are located within Pinkawillinnie Conservation Park. Native Title
Agreement has been negotiated with the NT Claimant and has been
registered with the SA Government.
·
Aboriginal heritage surveys have been completed
over the Baggy Green Prospect area, with no sites located in the
immediate vicinity.
·
A Native Title Agreement is in place with the
relevant Native Title party.
|
|
Exploration done by other
parties
|
·
Acknowledgment
and appraisal of exploration by other parties.
|
·
On-ground exploration completed prior to Andromeda
Metals' work was limited to 400 m spaced soil geochemistry
completed by Newcrest Mining Limited over the Barns
prospect.
·
Other than the flying of regional airborne
geophysics and coarse spaced ground gravity, there has been no
recorded exploration in the vicinity of the Baggy Green deposit
prior to Andromeda Metals' work.
·
Paleochannel uranium exploration was undertaken by
various parties in the 1980s and the 2010s around the Boland
Prospect. Drilling was primarily rotary mud with downhole
geophysical logging the primary interpretation method.
|
|
Geology
|
·
Deposit type,
geological setting and style of mineralisation.
|
·
The gold and REE deposits are considered to be
related to the structurally controlled basement weathering of
epidote- pyrite alteration related to the 1590 Ma Hiltaba/GRV
tectonothermal event.
·
Mineralisation has a spatial association with
mafic intrusions/granodiorite alteration and is associated with
metasomatic alteration of host rocks. Epidote alteration associated
with gold mineralisation is REE enriched and believed to be the
primary source.
·
Rare earth minerals occur within the saprolite
horizon. XRD analysis by the CSIRO identifies kaolin and
montmorillonite as the primary clay phases.
·
SEM analysis identified REE bearing mineral phases
in hard rock:
· Zircon, titanite, apatite, andradite and epidote.
·
SEM analyses identifies the following secondary
mineral phases in saprock:
· Monazite, bastanite, allanite and rutile.
·
Elevated phosphates at the base of saprock do not
correlate to rare earth grade peaks.
·
Upper saprolite zones do not contain identifiable
REE mineral phases, supporting that the REEs are adsorbed to clay
particles.
·
Acidity testing by Cobra Resources supports that
pH chemistry may act as a catalyst for Ionic and Colloidal
adsorption.
·
REE mineral phase change with varying saprolite
acidity and REE abundances support that a component of REE bursary
is adsorbed to clays.
·
Palaeo drainage has been interpreted from historic
drilling and re-interpretation of EM data that has generated a top
of basement model.
·
Ionic REE mineralisation is confirmed through
metallurgical desorption testing where high recoveries are achieved
at benign acidities (pH4-3) at ambient temperature.
·
Ionic REE mineralisation occurs in reduced clay
intervals that contact both saprolite and permeable sand units.
Mineralisation contains variable sand quantities that is
expected
|
|
Drillhole
Information
|
·
A summary of all
information material to the understanding of the exploration
results including a tabulation of the following information for all
Material drill holes:
o easting and northing of the
drill hole collar
o elevation or RL (Reduced
Level - elevation above sea level in metres) of the drill hole
collar
o dip and azimuth of the
hole
o down hole length and
interception depth
o hole
length.
·
If the exclusion
of this information is justified on the basis that the information
is not Material and this exclusion does not detract from the
understanding of the report, the Competent Person should clearly
explain why this is the case.
|
·
Exploration results are not being reported as part
of the Mineral Resource area.
|
|
Data aggregation
methods
|
·
In reporting
Exploration Results, weighting averaging techniques, maximum and/or
minimum grade truncations (eg cutting of high grades) and cut-off
grades are usually Material and should be stated.
·
Where aggregate
intercepts incorporate short lengths of high grade results and
longer lengths of low grade results, the procedure used for such
aggregation should be stated and some typical examples of such
aggregations should be shown in detail.
·
The assumptions
used for any reporting of metal equivalent values should be clearly
stated.
|
·
Reported summary intercepts are weighted averages
based on length.
·
No maximum/ minimum grade cuts have been
applied.
·
No metal equivalent values have been
calculated.
·
Gold results are reported to a 0.3 g/t cut-off
with a maximum of 2m internal dilution with a minimum grade of 0.1
g/t Au.
·
Rare earth element analyses were originally
reported in elemental form and have been converted to relevant
oxide concentrations in line with industry standards. Conversion
factors tabulated below:
|
Element
|
Oxide
|
Factor
|
|
Cerium
|
CeO2
|
1.2284
|
|
Dysprosium
|
Dy2O3
|
1.1477
|
|
Erbium
|
Er2O3
|
1.1435
|
|
Europium
|
Eu2O3
|
1.1579
|
|
Gadolinium
|
Gd2O3
|
1.1526
|
|
Holmium
|
Ho2O3
|
1.1455
|
|
Lanthanum
|
La2O3
|
1.1728
|
|
Lutetium
|
Lu2O3
|
1.1371
|
|
Neodymium
|
Nd2O3
|
1.1664
|
|
Praseodymium
|
Pr6O11
|
1.2082
|
|
Scandium
|
Sc2O3
|
1.5338
|
|
Samarium
|
Sm2O3
|
1.1596
|
|
Terbium
|
Tb4O7
|
1.1762
|
|
Thulium
|
Tm2O3
|
1.1421
|
|
Yttrium
|
Y2O3
|
1.2699
|
|
Ytterbium
|
Yb2O3
|
1.1387
|
·
The reporting of REE oxides is done so in
accordance with industry standards with the following calculations
applied:
· TREO =
La2O3 + CeO2 +
Pr6O11 + Nd2O3 +
Sm2O3 + Eu2O3 +
Gd2O3 + Tb4O7 +
Dy2O3 + Ho2O3 +
Er2O3 + Tm2O3 +
Yb2O3 + Lu2O3 +
Y2O3
· CREO =
Nd2O3 + Eu2O3 +
Tb4O7 + Dy2O3 +
Y2O3
· LREO =
La2O3 + CeO2 +
Pr6O11 +
Nd2O3
· HREO =
Sm2O3 + Eu2O3 +
Gd2O3 + Tb4O7 +
Dy2O3 + Ho2O3 +
Er2O3 + Tm2O3 +
Yb2O3 + Lu2O3 +
Y2O3
· NdPr =
Nd2O3 +
Pr6O11
· TREO-Ce = TREO - CeO2
· % Nd =
Nd2O3/ TREO
· % Pr =
Pr6O11/TREO
· % Dy =
Dy2O3/TREO
· % HREO
= HREO/TREO
· % LREO
= LREO/TREO
· XRF
results are used as an indication of potential grade only. Due to
detection limits only a combined content of Ce, La, Nd, Pr & Y
has been used. XRF grades have not been converted to
oxide.
|
|
Relationship between
mineralisation widths and intercept lengths
|
·
These
relationships are particularly important in the reporting of
Exploration Results.
·
If the geometry
of the mineralisation with respect to the drill hole angle is
known, its nature should be reported.
·
If it is not
known and only the down hole lengths are reported, there should be
a clear statement to this effect (eg 'down hole length, true width
not known').
|
·
All reported intercepts at Boland are vertical and
reflect true width intercepts.
·
Exploration results are not being reported for the
Mineral Resource area.
|
|
Diagrams
|
·
Appropriate maps
and sections (with scales) and tabulations of intercepts should be
included for any significant discovery being reported These should
include, but not be limited to a plan view of drill hole collar
locations and appropriate sectional views.
|
·
Relevant diagrams have been included in the
announcement.
·
Exploration results are not being reported for the
Mineral Resources area.
|
|
Balanced
reporting
|
·
Where
comprehensive reporting of all Exploration Results is not
practicable, representative reporting of both low and high grades
and/or widths should be practiced to avoid misleading reporting of
Exploration Results.
|
·
Not applicable - Mineral Resource and Exploration
Target are defined.
·
Exploration results are not being reported for the
Mineral Resource area.
|
|
Other substantive exploration
data
|
·
Other
exploration data, if meaningful and material, should be reported
including (but not limited to): geological observations;
geophysical survey results; geochemical survey results; bulk
samples - size and method of treatment; metallurgical test results;
bulk density, groundwater, geotechnical and rock characteristics;
potential deleterious or contaminating
substances.
|
·
Refer to previous announcements listed in RNS for
reporting of REE results and metallurgical testing
|
|
Further
work
|
·
The nature and
scale of planned further work (eg tests for lateral extensions or
depth extensions or large-scale step-out
drilling).
·
Diagrams clearly
highlighting the areas of possible extensions, including the main
geological interpretations and future drilling areas, provided this
information is not commercially sensitive.
|
·
The metallurgical testing reported in this
announcement represents the first phase of bench scale studies to
test the extraction of ionic REEs via ISR processes.
·
Hydrology, permeability and mineralogy studies are
being performed on core samples.
·
Installed wells are being used to capture
hydrology base line data to support a future infield pilot
study.
·
Trace line tests shall be performed to emulate
bench scale pore volumes.
|
Appendix 6: Drillhole
coordinates
|
Prospect
|
Hole number
|
Grid
|
Northing
|
Easting
|
Elevation
|
|
Boland
|
CBSC0001
|
GDA94 /
MGA zone 53
|
6365543
|
534567
|
102.9
|
|
Boland
|
CBSC0002
|
GDA94 /
MGA zone 53
|
6365510
|
534580
|
104.1
|
|
Boland
|
CBSC0003
|
GDA94 /
MGA zone 53
|
6365521
|
534554
|
102.7
|
|
Boland
|
CBSC0004
|
GDA94 /
MGA zone 53
|
6365537
|
534590
|
105
|
|
Boland
|
CBSC0005
|
GDA94 /
MGA zone 53
|
6365528
|
534573
|
103.2
|