Highlights of Bravo's 2023
Maiden Mineral Resource Estimate ("MRE") at a 0.50 g/t PdEq cut-off
grade
- The maiden MRE for Luanga shows a substantial increase in
tonnes and contained metals (Pd, Pt, Rh, Au, Ni) at higher
palladium equivalent ("PdEq") grades than the previously reported
Historical Estimate (as defined below).
- Indicated Mineral Resource of 73 million
tonnes ("Mt") at 1.75 grams per tonne ("g/t") of PdEq for 4.1
million ounces ("Moz") of PdEq.
- Includes 4.6Mt at 1.43 g/t PdEq of Oxide material.
- Additional Inferred Minerals Resources of 118Mt at 1.50 g/t PdEq for a total of 5.7
Moz PdEq.
- Includes 10.0Mt at 1.30g/t PdEq of Oxide material.
- MRE includes of 89,500 tonnes of nickel in sulphides in the
Indicated category and 104,600 tonnes Inferred.
- 38% of the MRE in the Indicated category and 62% in the
Inferred category.
- Recoverable PdEq MRE grades on sulphide ("Fresh
Rock") material are calculated based on two extensive phases of
laboratory flotation testwork performed by Bravo (117 flotation tests) and three programs
of historical flotation testwork, including two historical pilot
plant tests.
- Sulphide recovery assumptions (based on these tests): Pt
88%, Pd 80%, Rh 59%, Au 56%, Ni 50%.
- Recoverable PdEq MRE grades on Oxide material are
calculated based on two programs of carbon-in-leach and gravimetric
testwork performed by Bravo, which
included 31 leaching tests.
- Oxide recovery assumptions (based on these tests): Au 94%,
Pd 73%, Rh 61%, Pt 24%
- MRE is based on commodity price assumptions using a 10-year
trailing averages.
- Relative percentages of each metal by PdEq value
contribution to the MRE are estimated at: 43% Pd, 30% Pt, 12% Rh,
12% sulphide Ni, and 3% Au.
- MRE is open at depth along the entire 8.1km of strike of the
deposit.
- MRE delineated to an average depth of 200m while drilling has demonstrated that
mineralization continues to depths of at least ~350m in those areas
tested and is still open.
- Significant potential also exists to increase oxide inventory
beyond that in the current MRE.
- Trenching program is only partially completed, with the entire
Central Sector yet to be trenched, and some trenches still to be
completed in the North and Southwest sectors.
"The delivery of our maiden mineral resource estimate after
only 15 months from our IPO is arguably Bravo's most significant milestone to date.
The resource estimate underscores Luanga's size, grade, and
potential open-pittable nature, which is supported by
straightforward metallurgy", said Luis
Azevedo, Chairman and CEO. "On top of such attributes,
Luanga has the potential to be one of the few multi-million-ounce
sources of such critical and scarce PGM and Ni metals outside
regions challenged by political instability, infrastructure
shortcomings and permitting complexities. There remains substantial
immediate growth potential to this initial MRE. The drilling
program is now following up on the encouraging results beyond the
current MRE limiting pit constraints, in addition to the
continuation of the trenching program, which has proven to be an
effective way of assessing oxide mineralization potential. Further,
we are progressing with the drilling of the recently identified
priority electromagnetic anomalies, which targets massive or
semi-massive sulphides, adding to the prospectivity for new
discoveries and deposit types at Luanga".
VANCOUVER, BC, Oct. 22,
2023 /CNW/ - Bravo Mining Corp. (TSXV: BRVO) (OTCQX:
BRVMF), ("Bravo" or
the "Company") announced that it has completed an initial
MRE for its 100% owned Luanga palladium + platinum + rhodium + gold
+ nickel project ("Luanga" or "Luanga PGM+Au+Ni
Project"), located in the Carajás Mineral Province, state of
Pará, Brazil.
Bravo's maiden and pit
constrained MRE has an effective date of October 22, 2023, and it is comprised of 73 Mt
grading 1.75 g/t PdEq for a total of 4.1 Moz of PdEq in the
Indicated category and 118 Mt grading
1.50 g/t PdEq for 5.7 Moz PdEq in the Inferred category. Table 1
shows a breakdown of the MRE by tonnage, grade and metal content
for each metal, weathering type, and resource classification
category.
Resource
Classification
|
Weathering
|
Average Grades and
Contained Metal Estimates
|
Tonnes
|
Pd Eq
|
Pd
|
Pt
|
Rh
|
Au
|
Ni
|
Mt
|
g/t
|
Oz
|
g/t
|
Oz
|
g/t
|
Oz
|
g/t
|
Oz
|
g/t
|
Oz
|
%
|
Tonnes
|
Indicated
|
Oxide
|
4.6
|
1.43
|
212,990
|
0.91
|
135,949
|
0,54
|
79,901
|
0.07
|
10,031
|
0,08
|
11,944
|
n/a
|
n/a
|
Fresh Rock
|
68.5
|
1.77
|
3,892,313
|
0.78
|
1,705,709
|
0.53
|
1,159,078
|
0.06
|
131,248
|
0.07
|
146,263
|
0.13
|
89,539
|
Total
|
73.1
|
1.75
|
4,105,303
|
0.78
|
1,841,658
|
0.53
|
1,238,979
|
0.06
|
141,279
|
0.07
|
158,207
|
0.13
|
89,539
|
Inferred
|
Oxide
|
10.0
|
1.30
|
418,810
|
0.75
|
241,117
|
0.72
|
230,367
|
0.08
|
25,738
|
0.04
|
12,444
|
n/a
|
n/a
|
Fresh Rock
|
108.1
|
1.52
|
5,286,970
|
0.60
|
2,082,479
|
0.57
|
1,997,054
|
0.05
|
190,746
|
0.04
|
122,076
|
0.10
|
104,640
|
Total
|
118.1
|
1.50
|
5,705,780
|
0.61
|
2,323,596
|
0.59
|
2,227,421
|
0.06
|
216,484
|
0.04
|
134,520
|
0.10
|
104,640
|
Table 1: MRE
Declaration at a Cut-off of 0.5g/t
PdEq*
|
* Notes:
- The MRE has been prepared by Porfírio Cabaleiro
Rodriguez, Mining Engineer, BSc (Mine
Eng), MAIG, director of GE21 Consultoria Mineral Ltda., an
independent Qualified Person ("QP") under National Instrument
43-101 Standards of Disclosure for Mineral Projects ("NI 43-101").
The effective date of the MRE is 22 October
2023.
- Mineral resources are reported using the 2014 CIM
Definition Standards and were estimated in accordance with the CIM
2019 Best Practices Guidelines, as required by NI 43-101.
- Mineral resources that are not mineral reserves do not have
demonstrated economic viability. There is no certainty that all
mineral resources will be converted into mineral reserves.
- This MRE includes inferred mineral resources which have
had insufficient work to classify them as Indicated mineral
resources. It is uncertain but reasonably expected that inferred
mineral resources could be upgraded to indicated mineral resources
with continued exploration.
- The Mineral Resource Estimate is reported/confined within an
economic pit shell generated by Whittle software, using the
following assumptions:
Generated from work completed by Bravo and historical test work:
-
- Phase 1 and 2 Metallurgy testwork – Metallurgical
recovery in sulphide material of 80% Pd, 88% Pt, 59% Rh, 56% Au,
50% Ni to a saleable Ni-PGM concentrate.
- Phase 1 and 2 Metallurgy testwork– Metallurgical
recovery in oxide material of 73% Pd, 24% Pt, 61% Rh, 94% Au to a
saleable PGM ash residue (Ni not applicable).
- Independent Geotechnical Testwork – Overall pit slopes
of 40 degrees in oxide and 50 degrees in Fresh Rock.
- Densities are based on 26,898 relative density sample
measurements. Averages are 1.58 t/m3 oxide, 2.71
t/m3 Saprock and 2.85 t/m3 fresh
rock.
- External downstream payability has not been included, as the
base case MRE assumption considers internal downstream
processing.
- Payable royalties of 2%.
Metal Pricing:
-
- Metal price assumptions are based on 10-year trailing
averages: Pd price of US$1,380/oz, Pt
price of US$1,100/oz, Rh price
of US$6,200/oz, Au price of
US$1,500/oz, Ni price of US$15,648/t.
Palladium Equivalent ("PdEq")
Calculation:
-
- The PdEq equation is: PdEq = Pd g/t + F1 + F2 + F3 +
F4
Where: F1 =
((Ptp*PtR)/(Pdp*PdR)) x
Ptt ; F2 =
((Rhp*RhR)/(Pdp*PdR)) x
Rht ; F3 =
((Aup*AuR)/(Pdp*PdR)) x
Aut ; F4 =
((Nip*NiR)/(Pdp*PdR)) x
Nit;
being P = Metal Price and R =
Recovery
Costs are taken from comparable projects in
GE21's extensive database of mining operations in Brazil, which includes not only operating
mines, but recent actual costs from what could potentially be
similarly sized operating mines in the Carajás. Costs considered a
throughput rate of ca. 10mtpa:
-
- Mining costs: US$2.50/t oxide,
US$3.50/t Fresh Rock. Processing
costs: US$8.50/t fresh rock,
US$7.50/t oxide. US$2.50/t processed for General &
Administration. US$1.00/t processed
for grade control. US$0.50/t
processed for rehabilitation.
- Several of these considerations (metallurgical recovery,
metal price projections for example) should be regarded as
preliminary in nature, and therefore the PdEq calculations
should also be regarded as preliminary in nature. Totals may not
sum due to rounding.
- The current MRE supersedes and replaces the Historical
Estimate (as defined and described below), which should no longer
be relied upon.
- The QP is not aware of political, environmental, or
other risks that could materially affect the potential development
of the Mineral Resources.
Luanga Mineral Resource
Estimate
The Luanga deposit mineral resource database consists of 394
drillholes (Bravo + historic
drilling) inside the mineralized envelope, with 77,612 metres of
drilling between 1992 to 2023. This represents 77,493 metres of
assayed intervals at an average interval of close to 1m per assay interval. All assayed interval
lengths of core used in the mineralized domains are HQ diameter in
the oxide and NQ2 diameter in fresh rock,
diamond drill core.
All historic data used for the MRE has been validated
statistically to show no significant bias, either by twinned
drillholes, extensive re-sampling of historic drill core,
statistical comparison of historical data with Bravo drilling, and by field validation of
collar locations. In addition, the MRE included 10 trenches for a
total of 1,339 metres and 1,349 assays at an average sampling
interval close to 1m.
Nine mineralized domains were generated based on the six
different styles of mineralization as defined in geological section
below (Figure 4). The parent block model (Figures 2 & 3) is
25 m x 25
m x 5 m with 5 m x 5 m x
5 m sub-blocks, with interpolation of
elements Multiple Indicator Kriging ("MIK") for each
mineralized fresh rock domain and Ordinary Kriging ("OK")
for each oxide domain.
There are no known issues that materially affect the MRE other
than the usual risks faced by any mining project in Brazil or other jurisdictions, such as the
risks and uncertainties inherent in mineral exploration and
development, environmental, permitting, taxation, socio-economic,
marketing, political factors or any additional risks listed in the
"Forward-Looking Statements" section in this news release.
The metallurgical recovery figures achieved at laboratory scale
are based on 117 flotation tests in 2 phases, and more than 30
flotation tests undertaken by the previous owner. Continuous
mini-pilot testwork is currently ongoing. Oxide recoveries used in
the MRE calculation are based on results generated from two
programs (2022 and 2023) of carbon-in-leach and gravimetric
testwork performed for Bravo,
which included 31 leaching tests. Refer to Schedule 2 of this press
release for further details.
Metal price assumptions are derived from the 10-year trailing
price averages to smooth out volatility and price cycle movement in
each of these metals. For illustration purposes, the pie chart
below (Figure 1) shows the relative percentages of metal value
contribution to the Luanga MRE using 'grade x metallurgical
recovery x metal price' for each metal.
Based on recoveries and GE21's estimates of costs, a cut-off
grade ("COG") of 0.44 g/t PdEq was determined, which
Bravo elected to round upwards to
a 0.5 g/t COG, adding a further >10% contingency to this
calculation to allow for potential future changes in any or several
of the assumptions. Refer to Schedule 2 of this press release for
further details.
A sensitivity analysis of the COG on the MRE, from 0.1 to 1.0
g/t PdEq, in increments of 0.1 g/t is shown in Table 2.
INDICATED
|
INFERRED
|
PdEq
Cut-off
grade
|
Tonnes
|
Distribution
|
Recovered
Pd/Eq
|
PdEq
Cut-off
grade
|
Tonnes
|
Distribution
|
Recovered
Pd/Eq
|
(g/t)
|
Mt
|
( %)
|
(g/t)
|
(g/t)
|
Mt
|
( %)
|
(g/t)
|
0.1
|
81
|
100 %
|
1.58
|
0.1
|
135
|
100 %
|
1.33
|
0.2
|
81
|
99 %
|
1.60
|
0.2
|
134
|
99 %
|
1.34
|
0.3
|
79
|
98 %
|
1.62
|
0.3
|
132
|
97 %
|
1.37
|
0.4
|
77
|
94 %
|
1.68
|
0.4
|
126
|
93 %
|
1.42
|
0.5
|
73
|
90 %
|
1.75
|
0.5
|
118
|
87 %
|
1.50
|
0.6
|
69
|
85 %
|
1.82
|
0.6
|
108
|
80 %
|
1.58
|
0.7
|
64
|
79 %
|
1.91
|
0.7
|
97
|
72 %
|
1.69
|
0.8
|
59
|
73 %
|
2.01
|
0.8
|
88
|
65 %
|
1.79
|
0.9
|
55
|
68 %
|
2.10
|
0.9
|
80
|
59 %
|
1.89
|
1.0
|
51
|
63 %
|
2.18
|
1.0
|
73
|
54 %
|
1.98
|
Table
2: MRE Sensitivity (grade/tonnes/cut-off) with a
0.5g/t PdEq selected for the base case.
|
*Notes:
|
|
- See footnotes below Table 1 on Page
2.
- The PdEq calculation (as defined by the
formula in the footnotes below Table 1) includes metallurgical
recovery for each metal. Therefore, the PdEq grade is one that has
a reasonable expectation of what can be recovered after allowing
for mining and processing costs and recoveries.
|
|
Comparison with the Previously
Published Historical Estimate
A historical estimate (the "Historical Estimate")
prepared internally in 2017 by the prior owner of Luanga indicated
a total of "124Mt grading 1.24g/t
Pd+Pt+Au and 0.11% Ni using a COG of 0.5g/t PGM+Au" as reported in
a technical report prepared for Bravo and titled "Independent Technical Report
for the Luanga PGM+Au+Ni Project, Pará State, Brazil" with an effective date of March 28, 2023. Information such as individual
metal grades or category was not made available to Bravo, therefore a direct comparison between
the Historical Estimate and the current MRE is not possible;
nevertheless, it is notable that there has been a significant
increase in both the tonnage and grade in the overall current MRE
vs the Historical Estimate. This comparison is noted to illustrate
the impact on the tonnage and grade in respect of the work
completed by Bravo since the
Historical Estimate was completed. The Company notes that Rh was
not part of the Historical Estimate, and in addition, while Ni
grades in the current MRE are almost identical to the Historic
Estimate, Bravo's Ni assays
represent sulphide Ni that is potentially recoverable, whereas the
Ni grades in the Historical Estimate are total Ni, which includes
unrecoverable Ni in silicates.
Mineral Resource growth
potential
The Company believes that there is excellent potential to
increase this initial MRE at Luanga, as follows:
- The mineralization is open at depth along the entire 8.1km of
strike.
- Outside of the Central Sector, the current MRE generally
extends to depths that align with the depths of the Phase 1
drilling, typically around 200 metres in the Southwest and North
Sectors. This can be seen in Figure 2, where there are few drill
holes that extend below the constraining pit shell. Drilling in the
Phase 1 (completed) program targeted the depth extent of historical
drilling (typically up to ~150m), while the ongoing Phase 2 and 3
programs aim to test the extensions of mineralization to 300+m
below surface. To date, only the Central Sector drilling reached
depths of ~300m below surface (Figure 4). The cross-section in
Figure 5 (Southwest Sector) shows how the lack of data at depth is
restricting the MRE. Similarly, in Figure 3, the interpreted
continuation of mineralization at depth (unclassified, coloured
grey) demonstrates where deeper drilling is required.
- Several deeper Phase 2 drill holes completed by Bravo in the Central Sector have intersected
wider and higher-grade mineralization intervals than typical of the
MRE, such as hole DDH23LU175 which reported 54.2m at 3.33g/t PGM+Au, 0.22% Ni from
280.5m, including 32.5m at 4.99g/t PGM+Au, 0.30% Ni from
300.2m (see News Release 15 August 2023). This could indicate potential
for higher grades and greater widths of mineralization below the
limit of the current MRE, with potential for additional
tonnage.
- Bravo's trenching program is
only partially complete, with the entire Central Sector yet to be
trenched and some trenches still to be completed in the North and
Southwest Sectors. Nevertheless, where completed, trenching
indicates a potential for greater aerial extent and typically
higher grades (see News Releases 08 May
2023 and 26 September 2023) of
oxide mineralization (likely due to supergene enrichment and more
extensive surface dispersion). As a result, the current MRE shows a
limited extent and lower grades in oxides in areas where no
trenching has been completed versus those areas where trenching has
been completed. Bravo plans to
complete trenching over the entire strike length of the Luanga
deposit over the next 6 months and, if recent trends continue,
Bravo could expect to see
increased tonnes and grade in the oxides versus those within the
current MRE. Additionally, trenching to date has identified the
presence of high-grade zones within the oxide, which could be
studied in later phases as well.
- Some of Bravo's deeper
drilling has intersected several mineralized horizons
stratigraphically above or below the main mineralized horizon,
which is known as the Main Sulphide Zone ("MSZ"). However,
many historic holes and several of Bravo's earlier drill holes did not extend
deep enough to adequately test these horizons (Figure 5). As a
result, they are relatively minor contributors to the current MRE.
As Bravo continues its deeper
drilling and re-enters earlier holes to deepen them, these poorly
defined mineralized zones may develop into more significant
contributors to future MRE growth.
About Bravo Mining
Corp.
Bravo is a Canadian and
Brazil-based mineral exploration
and development company focused on advancing its Luanga PGM+Au+Ni
Project in the world-class Carajás Mineral Province of Brazil.
The Luanga Project benefits from being in a location close to
operating mines, with excellent access and proximity to existing
infrastructure, including road, rail, and clean and renewable hydro
grid power. A fully funded 63,000m
infill, step out and exploration drilling is currently underway.
Bravo's current Environmental,
Social and Governance activities includes replanting trees in the
region, hiring and contracting locally, and ensuring protection of
the environment during its exploration activities.
Technical Disclosure and Qualified
Persons
Porfírio Cabaleiro Rodriguez, Mining Engineer, BSc (Mine Eng), MAIG, director of GE21 Consultoria
Mineral Ltda., is an Independent QP as defined in NI 43-101 and is
responsible for the MRE.
An independent peer review was carried out by Anderson Candido
FAusIMM (Fellow Australia Institute of Mining and Metallurgy). Mr.
Candido is a full-time employee of independent consultancy RPM
Global and is an Independent QP as defined in NI 43-101 and was
responsible for the independent peer review over the complete MRE
process.
Technical assurance was carried out by Professor Mark Noppé
MAICD, FAusIMM (CP). Prof. Noppé is the Director of the WH Bryan
Mining Geology Research Centre at The University of Queensland, is an Independent QP as
defined in NI 43-101 and was responsible for technical assurance
and peer review over the complete MRE process.
Each of Mr. Cabaleiro, Mr. Candido and Prof. Noppé has reviewed
and approved the scientific and technical information related to
the MRE contained in this news release.
Technical information in this news release has also been
reviewed and approved by Simon
Mottram, FAusIMM, President of Bravo Mining Corp. who serves
as the Company's QP as defined in NI 43-101. Mr. Mottram has
verified the technical data and opinions contained in this news
release.
Details of the MRE will be provided in a technical report with
an effective date of October 22,
2023, prepared in accordance with NI 43-101, which will be
filed under the Company's SEDAR+ profile within 45 days of this
news release.
Forward Looking
Statements
This news release contains forward-looking information which
is not comprised of historical facts. Forward-looking information
is characterized by words or sentences such as "potential",
"potentially", "prospective", "assume", "assumptions",
"preliminary", "if", "generally", "expect", "expected", "reasonable
expectation", "indicate", "believe", "anticipate", "probable",
"probability", "plans" variants of these words and other similar
words, phrases, or statements that certain events or conditions
"could", "may", "should" or "will" occur. This news release
contains forward-looking information pertaining to the Company's
maiden MRE; the potential for future MRE growth from deeper
drilling, and/or additional zones and/or drilling of geophysical
targets; potential repeatability and improvements to the economic
assumptions and/or to metallurgical recoveries used in the MRE; and
the Company's plans in respect thereof. Forward-looking information
involves risks, uncertainties and other factors that could cause
actual events, results, and opportunities to differ materially from
those expressed or implied by such forward-looking information.
Factors that could cause actual results to differ materially from
such forward-looking information include, but are not limited to,
unexpected results from exploration programs, changes in the state
of equity and debt markets, fluctuations in commodity prices,
delays in obtaining required regulatory or governmental approvals,
environmental risks, limitations on insurance coverage; and
other risks and uncertainties involved in the mineral exploration
and development industry. Forward-looking information in this news
release is based on the opinions and assumptions of management
considered reasonable as of the date hereof, including, but not
limited to, the assumption that the assay results confirm that the
interpreted mineralization contains significant values of nickel,
PGMs and Au; that the mineralization remains open to depth; that Ni
grades are improving to depth; that future drill and assay results
will be in line with management's expectations; that exploration
and other business activities will not be adversely disrupted or
impeded by regulatory, political, community, economic,
environmental and/or healthy and safety risks; that the Luanga
project will not be materially affected by potential supply chain
disruptions; and general business and economic conditions will not
change in a materially adverse manner. Although the Company
believes that the assumptions and factors used in preparing the
forward-looking information in this news release are reasonable,
undue reliance should not be placed on such information. The
Company disclaims any intention or obligation to update or revise
any forward-looking information, other than as required by
applicable securities laws.
Historical Estimate
This press release contains information relating to the
Historical Estimate. No qualified person (as defined in NI 43-101)
has done sufficient work to classify the Historical Estimate as
current mineral resources or mineral reserves under NI 43-101 and
Bravo is not treating the
Historical Estimate as current mineral resources or mineral
reserves. The Historical Estimate is superseded by the current MRE,
and it should no longer be relied upon.
Cautionary Note for U.S. Investors
Concerning Mineral Resources
This news release has been prepared in accordance with the
requirements of the securities laws in effect in Canada, which differ from the requirements of
United States securities laws. The
terms "mineral resource", "indicated mineral resource" and
"inferred mineral resource" are defined in and required to be
disclosed by NI 43-101; however, these terms are not defined terms
under the U.S. Securities and Exchange Commission ("SEC")
modernization rules, known as "S-K 1300", and are normally not
permitted to be used in reports and registration statements filed
with the SEC. Investors are cautioned not to assume that all or any
part of an "indicated mineral resource" or "inferred mineral
resource" will ever be upgraded to a higher category or converted
into mineral reserves in accordance with S-K 1300. "Inferred
mineral resources" have a great amount of uncertainty as to their
existence, and great uncertainty as to their economic and legal
feasibility. Under Canadian rules, estimates of inferred mineral
resources may not form the basis of feasibility or pre-feasibility
studies, except in rare cases. Investors are cautioned not to
assume that all or any part of an inferred mineral resource exists
or is economically or legally mineable. Disclosure of "contained
ounces" in a mineral resource is permitted disclosure under
Canadian regulations; however, the SEC normally only permits
issuers to report mineralization that does not constitute
"reserves" by SEC S-K 1300 standards as in place tonnage and grade
without reference to unit measures. Accordingly, information
contained in this News Release contain descriptions of the
Company's mineral deposits that may not be comparable to similar
information made public by U.S. companies subject to the reporting
and disclosure requirements under the
United States federal securities laws and the rules and
regulations thereunder.
Schedule 1: Schedule: Key Assumptions and Methods Used for
the Mineral Resource Estimate
Variography and
Interpolations
Grade estimation for sulphide material was completed using the
MIK technique, for each element and for each domain. Ten grade
increments levels were used to define indicators for each element.
Variography and MIK were performed using Isatis.neo software
and reported for each respective domain. No grade variables were
capped. Grade estimation for oxide material was completed
using the OK technique, for each element and for each domain.
Cut-off Grade
The PdEq COG of 0.5 g/t was calculated by taking the all-in cost
(oxide and fresh rock) and dividing them by the value of one gram
of Pd multiplied by metallurgical recovery. From this a global
average (rounded up from the calculated value of 0.44g/t) of
0.5 g/t PdEq has been chosen as the COG. Rounding to 0.5g/t adds a
further >10% contingency to the calculation process to
accommodate potential future changes in any, or several of, the
assumptions.
COG
(PdEq)
|
Oxide
|
Units
|
Costs
|
14.0
|
US$/t
|
DGV1
|
31.95
|
US$/g
|
Cut-Off
|
0.43
|
PdEq/ g/t
|
Fresh
|
Units
|
Costs
|
16.0
|
US$/t
|
DGV1
|
35.5
|
US$/g
|
Cut-Off
|
0.44
|
PdEq/ g/t
|
Avg
Cut-off
|
0.5
|
PdEq/
g/t
|
|
1 Deposit
Grade Value ("DGV") = (P-Pd/31.1035) * R-Pd
|
|
Where: P-Pd = Palladium
Price in US$/oz,
|
|
R-Pd = Palladium
Metallurgical Recovery
|
Classification of Mineral
Resource
To classify mineral resources, a study of spatial continuity for
PdEq was conducted using variography followed by ordinary kriging
interpolation. This study established a continuity zone suitable
for considering as "Indicated Mineral Resources", with a drilling
grid of approximately 75m x
75m, extending both along the strike
and dip directions, and requiring a minimum of two drill holes.
Subsequently, manual post-processing was undertaken to construct
wireframes representing the volumes categorized as Indicated, while
considering the blocks within the resource pit shell. Any remaining
blocks within the resource-limiting pit were classified as
"Inferred Mineral Resources".
Reasonable Prospect for
Eventual Economic Extraction
The reported MRE is pit constrained using Whittle software to
create a pit shell that has reasonable prospects for eventual
economic extraction. Relevant parameters used in the mineral
resource estimate are shown below the MRE table and include
commodity prices used, metallurgical recoveries, geotechnical
assumptions, and cost structures. Further, there are no known
environmental or community matters that are likely to constrain the
future extraction of the reported MRE.
Schedule 2: Preliminary
Metallurgical Analysis
Metallurgical recoveries used in the MRE calculation are as
follows:
- Sulphide (Fresh rock) recovery inputs: Pt 88%, Pd 80%, Rh
59%, Au 56%, Ni 50%
- Oxide recovery inputs: Au 94%, Pd 73%, Rh 61%, Pt
24%.
Fresh rock recoveries used in the MRE calculation are based on
results generated from two extensive phases of laboratory flotation
testwork performed by Bravo (117
flotation tests) and three programs of historical flotation
testwork, including two historical pilot plant tests. Results
indicate that Luanga mineralization has the metallurgical character
to potentially produce saleable PGM (Platinum Group Metal) +
sulphide Ni concentrates at grades in line with grades achieved for
PGM operators in established jurisdictions around the world,
including concentrate grades of +80 g/t PGM, 5-10% Ni + Cu and S of
20–30% at the feed grade range of 1-2 g/t PGM. Bravo testwork considered geospatially
representative samples with feed grades ranging from 0.9 – 7.0 g/t
PdEq. Final concentrate grades produced in the Bravo test work ranged from 37–475 g/t PGM,
with a weighted average grade of 134 g/t PGM.
Bravo sample test results
demonstrate significant improvement over historical metallurgical
results driven by the following key factors:
- Identification and application of fines flotation regimes
demonstrating a material improvement of +6% on rougher recoveries
while maintaining concentrate grade. Further cleaner improvement is
anticipated from planned testing.
- Optimization of flowsheet and reagent suite, resulting in
significant selectivity and recovery improvement at the rougher
stage, and the production of high-grade concentrates, which
provides potential for blending and concentrate quality
optimization.
Oxide recoveries used in the MRE calculation are based on
results generated from two programs (2022 and 2023) of
carbon-in-leach and gravimetric testwork performed for Bravo, which included 31 leaching tests.
The conceptual oxide processing flowsheet has been validated at
each processing stage through testwork, including: PGM solubility
in the presence of cyanide at ambient temperature/pressure and
within reasonable reagent dosage conditions; PGM adsorption onto
carbon; Final product generation as saleable high grade PGM ash
residue ("ashing" or "ashed" is the burning of the loaded carbon
for final mass reduction to an ultra-high grade ash residue) with
an assayed average grade of 119,100g/t PGM (or 11.91% PGM).
Bravo's current data demonstrates
a high probability for economic recovery of PGM from oxide material
at Luanga through conventional cyanide leaching, carbon-in-leach
extraction, and ultra-high grade 'ashed' residue production. The
recommendations for oxide metallurgical input into the MRE are
based on laboratory-generated factual data for each stage of
processing to a final product, from the Luanga 2022 and 2023
programs. Key factors that have contributed to successful recovery
of PGM from oxide material include:
- Intense host rock weathering in oxide and a high degree of
naturally liberated PGM, contributing to lower mining and
comminution costs.
- High degree of solubility in cyanide, particularly for Au, Pd
and Rh.
- High PGM absorption kinetics and recovery for PGM onto
carbon.
Details of the 2022 and 2023 metallurgical programs and their
results will be documented in the Technical Report (effective date
of October 22, 2023) prepared in
accordance with NI 43-101, which will be filed under the Company's
SEDAR profile within 45 days of this news release.
Schedule 3: Geological
Interpretation
Luanga is a layered mafic-ultramafic complex consisting of a 6km
across (on surface) and up to 3.5km wide ovoid-shaped intrusion,
which hosts 8.1km (strike length) of mineralization. Today, the
Ultramafic Zone ("UZ") overlies the Transition Zone ("TZ"), which
overlies the Mafic Zone ("MZ"), suggesting that the sequence is
tectonically overturned. These zones are based on the different
type and/or proportion of cumulus minerals. The estimated thickness
of the layered sequence is 3,500m, as
indicated by the extensive drilling in the entral portion of the
Complex, which is likely to represent the axial portion of the
original magma chamber.
The UZ is up to 800m thick and
consists of harzburgites with lesser dunites and lenses of
orthopyroxenite in the upper portions (facing criteria, considering
the overturned sequence). The lower contact of the UZ with the
Xingu Complex and Grão Pará Group is poorly exposed and was mapped
mainly by soil sample assays of the geochemistry surveys and
ground/aero magnetic data. The contact with the stratigraphically
overlying TZ is gradational and characterized by a 5-10m thick sequence of interlayered
orthopyroxenite and harzburgite. Typically, harzburgites in the
basal UZ consist of variable altered ultramafic rocks with abundant
olivine + orthopyroxenite and/or their alteration products. Domains
with primary magmatic textures are locally preserved and consist of
medium-to coarse-grained harzburgite.
The TZ is up to 1,000m thick,
comprised of interlayered ultramafic and mafic cumulate rocks.
Interlayering of different rock types in different scales (from
centimetres to dozens of metres) is a distinctive feature of the
TZ. Cumulate rocks have variable textures, from adcumulate to
orthocumulate, and variable assemblages of cumulus and intercumulus
minerals. The most common rock types are orthopyroxenite locally
with chromite-rich zones/chromitite layers and minor
norite/harzburgite layers. Orthopyroxenite is a medium to
coarse-grained orthopyroxene cumulate. The texture varies from
adcumulate to mesocumulate and orthocumulate with plagioclase as
the predominant intercumulus mineral. Primary textures and minerals
are variably altered to fine-grained aggregates. Chromitite layers
with variable thickness and textures occur mainly in the upper
portions of the TZ and the lowermost portion of the MZ. The
thickest chromitite-rich layer is up to 60cm, located at the
contact between the upper harzburgite and orthopyroxenite layers of
the TZ.
The MZ is up to 3,000m thick,
comprised of mostly monotonous norites. The norite consists of
medium-grained orthopyroxene + plagioclase cumulates. Primary
textures and minerals are variably altered to fine-grained
aggregates. Minor interlayered ultramafic rocks in the MZ consist
mainly of orthopyroxenites.
The Luanga mineralized envelope follows the arc-shaped structure
of the mafic-ultramafic complex along a strike of approximately 8.1
km, which is then subdivided into three mineralized sectors named
North, Central and Southwest. The TZ at Luanga hosts several PGM
mineralized units, including the Main Sulphide Zone ("MSZ") which
hosts the bulk of the Luanga PGM mineral resources. Other
mineralized layers are identified within the UZ, and within the
TZ.
The proposed genetic model for PGM mineralization considers: (i)
the magmatic evolution of the complex; (ii) the petrographic and
geochemical differences of mineralization styles; (iii) the PGM
assemblages. The mineralization stages are summarized as
follows:
- Stage 1 – Early segregation and precipitation of the
High PGM low Rh (Pd-Pt), and High Ni-Rh sulphide zones during
the crystallization of olivine cumulates in the UZ.
- Stage 2 – The crystallization of olivine cumulates in
the UZ with minor crystallization of sulphide minerals
progressively upgrading the sulphur content of the residual magma.
The TZ marks an abrupt change in the dynamics of the magma chamber,
characterized by cyclic units. Sulphur saturation is triggered, and
the MSZ PGM-rich layer is precipitated.
- Stage 3 – Periodic magma influxes with continuous segregation
from the base metal sulphide liquid and precipitation of Low
Sulphide – High PGM zone, in similar conditions to the MSZ.
- Stage 4 – Alteration promotes sulphur loss and PGMs are
combined with other elements (As, Sb, Te, Sn and Bi) and form PGM
Low Sulphur mineralization. Precipitation of the Massive Sulphide
Zone ("MASU") as a product of a late hydrothermal-magmatic event
controlled by local shear zones.
Based on the magmatic evolution of the complex and mineral
assemblages, supported by petrographic/chemistry studies, six
different styles of mineralization have been identified within
Luanga to date, described as follows:
|
|
(i)
|
High Pd-Pt, low
Rh-Au-Ni mineralization.
|
|
|
(ii)
|
High Ni-Rh, low
Pd-Pt-Au mineralization.
|
|
|
(iii)
|
High Pd>Pt, +/-
Rh-Au-Ni mineralization (the MSZ, which represents the substantial
majority of the tonnage contained in the MRE).
|
|
|
(iv)
|
High Pt>Pd, low
Rh-Au-Ni mineralization associated with sulphide-poor
layers.
|
|
|
(v)
|
High Pt-Rh, +/- Pd,
with low Ni mineralization related to chromitite-rich
layers.
|
|
|
(vi)
|
High Pd>Pt + high
Ni-Cu, low Rh-Au mineralization associated with massive sulphide
layers or zones.
|
The known mineralized system being evaluated by Bravo is represented by magmatic layers
enriched in palladium plus platinum with minor rhodium, gold, and
nickel, which together are referred to as "PGM+Au+Ni". The
mineralization is associated with fine-to-medium disseminated
sulphides, coarse intercumulus and semi-to-massive sulphides.
Pyrrhotite is the most abundant sulphide, followed by pentlandite
and locally minor chalcopyrite.
Schedule 4: Assay Methodologies
and Quality Assurance/Quality Control ("QAQC")
Samples follow a chain of custody between collection,
processing, and delivery to the SGS laboratory in Parauapebas,
state of Pará, Brazil. The drill
core is delivered to the core shack at Bravo's Luanga site facilities and processed
by geologists who insert certified reference materials, blanks, and
duplicates into the sampling sequence. Drill core is half cut and
placed in secured polyurethane bags, then in security-sealed sacks
before being delivered directly from the Luanga site facilities to
the Parauapebas SGS laboratory (ALS laboratory initially) by
Bravo staff. Additional
information about the methodology can be found on the SGS or ALS
global websites (SGS, ALS) in their analytical guides. Both
laboratories are ISO-accredited and independent of Bravo. Historical drilling used a similar QAQC
procedures, and as described in the section "Luanga Mineral
Resource Estimate" data generated by this work has been validated
statistically to show no significant bias, prior to inclusion.
QAQC is maintained internally at the laboratory through rigorous
use of internal certified reference materials ("CRM"), blanks, and
duplicates. An additional QAQC program is administered by
Bravo using certified reference
materials, duplicate samples and blank samples that are blindly
inserted into the sample batch. If a QAQC sample returns an
unacceptable value an investigation into the results is triggered
and when deemed necessary, the samples that were tested in the
batch with the failed QAQC sample are re-tested.
Bravo SGS
Geosol
|
|
|
Preparation
|
Method
|
Method
|
Method
|
Method
|
|
|
For All
Elements
|
Pt, Pd,
Au
|
Rh
|
Sulphide Ni,
u
|
Trace
Elements
|
|
|
PRPCLI
(85% at 200#)
|
FAI515
|
FAI30V
|
AA04B
|
ICP40B
|
|
|
Bravo
ALS
|
|
|
Preparation
|
Method
|
Method
|
Method
|
Method
|
|
|
|
|
For All
Elements
|
Pt, Pd,
Au
|
Rh
|
Ni-Sulphide
|
Trace
Elements
|
|
|
PREP-31B
|
PGM-P27
|
Rh-S25
|
Ni-ICP05
|
ME-ICP61
|
|
|
Historic Drill
Assaying SGS Geosol
|
|
|
Preparation
|
Method
|
Method
|
Method
|
Method
|
|
|
|
|
For All
Elements
|
Pt, Pd,
Au
|
Rh
|
TOTAL
Ni
|
Trace
Elements
|
|
|
Crushed to <200
mesh
|
FA30A
|
FA30B
|
ICP-117
|
ICP-117
|
|
|
SOURCE Bravo Mining Corp.