Alphamin Resources Corp. (AFM:TSXV, APH:JSE AltX, “Alphamin” or the
“Company”), a producer of 4% of the world’s mined tin1 from its
high-grade operation in the Democratic Republic of Congo, is
pleased to announce updated Mineral Resource and Mineral Reserve
estimates along with an updated life of mine schedule (LoM) for the
Mpama North Mine.
HIGHLIGHTS
-
The updated LoM
schedule shows:-
- replacement of
contained tin depleted over the past 2.5 years
- contained tin
inventory over LoM of 154.5kt at 30 June 2022 (31 Dec 2019:
154.2kt);
-
The updated Resource
shows:-
- 155.7kt (30 June
2019: 199kt) and 41.2kt (30 June 2019: 21.8kt) tin contained (which
includes mineral reserves) at 30 April 2022 in Measured/Indicated
and Inferred Resources, respectively, with an 8.0% and a 65.4%
increase in grade, respectively.
-
The updated Reserve shows:-
- 121.4kt tin
contained at 30 June 2022 (31 Dec 2019: 133.4kt) in the Proven and
Probable mineral reserve categories with 15.7% increase in grade to
4.64% Sn .
Updated Mpama North Life of Mine
Plan
An updated Mineral Resource Estimate (MRE) and
Mineral Reserve estimation have been developed for the Mpama North
Mine. These updates replace those announced in the Technical Report
of 22 April 2022 which, for Mpama North, were not updated and
remained the same as those contained in the Technical Report
effective 31 December 2019. The culmination of these Resource and
Reserve updates is the re-design and scheduling of the Mpama North
Mine into an updated Life of Mine (LoM) schedule. A comparative
summary of the previous and updated LoM schedules is presented in
Table 1.
Table 1: Mpama North
LoM Schedule
Comparison
Description |
Units |
31 December 2019LoM
Schedule |
30 June
2022LoM
Schedule |
RoM tonnes |
Mt |
3.85 |
3.23 |
Grade delivered to process plant |
% Sn |
4.00 |
4.78 |
Tin content |
kt Sn |
154.2 |
154.5 |
Cut-off grade |
% Sn |
1.60 |
1.00 |
*Note: Rounding may result in computational
discrepancies
Mining has progressed steadily at Mpama North
since the 2019 estimation of the Reserves and LoM schedule with
990,821 tonnes of ore having been extracted in the 30 months Dec
2019 – Jun 2022. A number of operational improvements and changes
resulted in actual mine performance surpassing the 2019 LoM
schedule. Run of Mine (RoM) tonnes mined for the financial years
2020 and 2021 exceeded the 2019 LoM schedule by 18.5% and 8.1%,
respectively.
In addition, the Reserve cut-off grade
calculated in the 31 December 2019 LoM schedule of 1.6% Sn, has at
an operational level consistently been reduced due to the improved
RoM output, optimised mine planning, out-performance versus
dilution assumptions, improvements in the process plant recoveries
and an increase in the tin price. These actual results have now
been captured in the updated Reserve cut-off grade and LoM schedule
which are declared at 1.0% Sn. Exploration success in the form of
strike extension of the high-grade chute in the Mpama North deeps
target plus the reduced cut-off grade valorises previously excluded
lower grade Resource Blocks, converting them into Reserve blocks,
which has further added valuable additions to the LoM schedule.
The result of these positive factors is that all
contained tin depleted since 31 December 2019 has been replaced in
the new LoM schedule. The 154.5kt contained tin in the updated LoM
versus the previous 154.2kt has also been accompanied by a valuable
grade increase of 19.6% to 4.78% Sn from 4.00% Sn previously
scheduled.
As with the previous LoM schedule of 31 December
2019, the updated LoM schedule contains a small portion of Inferred
Resources. The Inferred Resource constitutes 18.9% of all RoM
tonnes delivered to the plant. 50% of these planned Inferred
Resources are scheduled in the final three years of mining in the
deep portion of the mine and will be the subject of infill Resource
drilling to increase confidence before they are included in any
shorter term mine plans or budgets.
The annual contained tin mined target remains
~15,000 tonnes per year which, after expected processing recoveries
of 78%, results in ~12,000 tonnes per year of contained tin in
concentrate production at the Mpama North Mine.
Mpama North
Mineral Resource Estimate
The updated Mineral Resource Estimate (MRE) at
Mpama North is illustrated in Figure 1. It is based on new resource
exploration drilling on the northern deeps high-grade extensions as
well as partial mine depletions (area shaded grey) since the last
estimate effective 30 June 2019.
All resource additions have resulted from the
renewed Mpama North Mine resource exploration drilling commenced in
2021. The drilling targeted and successfully extended the known
dimensions of the highly mineralised linear plunging high-grade
chute, returning some of the best project intercepts to date (see
Appendix 2). On-going drilling continues at Mpama North with
mineralisation intercepted outside the mineral resource boundaries
declared in this update.
The updated MRE includes 9 NQ size additional
core intersections from the recent exploration drilling at the
Mpama North Mine which were completed from August 2021 to March
2022. These new intersections in addition to the original 122 NQ
size and 21 PQ size drillholes completed pre-mining between July
2012 to November 2015, form the basis for the updated MRE. The
updated MRE and previous MRE for comparison are presented in Table
2.
Figure
1: Updated
Mpama North Resource
Grade Block model
(0.5% Sn
cut-off)
Table
2: Bisie Mpama North
Mineral Resource at 0.50% Sn Cut-Off Grade (30
June 2022)
Category |
QuantityMt |
Grade% Sn |
Tin Contentkt |
06/2019 |
04/2022 |
06/2019 |
04/2022 |
06/2019 |
04/2022 |
Measured |
0.33 |
0.04 |
4.75 |
2.16 |
15.6 |
0.9 |
Indicated |
3.99 |
3.09 |
4.59 |
5.02 |
183.4 |
154.9 |
Total Measured and Indicated |
4.32 |
3.13 |
4.61 |
4.98 |
199.0 |
155.7 |
Total Inferred |
0.48 |
0.55 |
4.57 |
7.56 |
21.8 |
41.2 |
Notes:
- All tabulated data have been
rounded and as a result minor computational errors may occur.
- Mineral Resources which are not
Mineral Reserves and have no demonstrated economic viability.
- Mineral Resources are reported
inclusive of Mineral Reserves.
- Alphamin has an 84.1 percent
interest in ABM. The Government of the Democratic Republic of Congo
(GDRC) has a non-dilutive, 5% share in ABM. The Gross Mineral
Resource for the Project is reported.
- The 2022 MRE is effective 30 April
2022 and has been depleted by mining from mine surveys as at 30
April 2022 and an estimate of the extent of artisanal mining to 725
mamsl.
- The 2019 MRE is effective 30 June
2019 and is depleted by mining from mine surveys as at 30 June 2019
and an estimate of the extent of artisanal mining to 725
mamsl.
Differences between the previous MRE and updated
MRE are a decrease in Measured and Indicated Resources contained
tin content of 43.3kt Sn with an increase in grade of 8.0% to 4.98%
Sn. An increase in Inferred Resources contained tin content of
19.4kt and an increase in grade of 65.4% to 7.56% Sn is also
observed for Inferred Resources.
In addition to any resource growth in the
northern depths high-grade zone, promising additional resource
growth potential is likely at Mpama North Mine in the shallow
northern strike extension as well as in the down-dip eastern dip
extension, both of which are currently undergoing exploration
drilling.
The full Mineral Resource checklist of
assessment and reporting criteria are presented in Appendix 3. The
Mineral Resource estimate has been completed by Mr. J.C. Witley
(BSc Hons, MSc (Eng.)) who is a geologist with 33 years’ experience
in base and precious metals exploration and mining as well as
Mineral Resource evaluation and reporting. He is a Principal
Resource Consultant for The MSA Group (an independent consulting
company), is registered with the South African Council for Natural
Scientific Professions (SACNASP) and is a Fellow of the Geological
Society of South Africa (GSSA). Mr. Witley has the appropriate
relevant qualifications and experience to be considered a
“Qualified Person” for the style and type of mineralisation and
activity being undertaken as defined in National Instrument 43-101
Standards of Disclosure of Mineral Projects.
Mpama North
Mineral Reserve
Estimate
An updated Mineral Reserve estimation was
completed subsequent to the updated MRE. Modifying factors in the
updated Reserve estimate are largely based on:-
- Actual performance statistics and
site-specific experience and reconciliation data to support revised
modifying factors (mining recovery, dilution, pillar loss
etc.),
- More detailed
geotechnical data from mining allowing the mine to be divided into
geotechnical domains with different stope design parameters per
domain,
- Increased mining
levels per mining echelon for stoping, resulting in a reduction in
the pillar losses and an increased extraction ratio,
- A reduced
cut-off grade based on updated calculations from actual operating
costs, increased tin prices and the impact from higher processing
recoveries, and
- Recent additions
to Mineral Resources from 2021/2022 exploration activities.
The updated Reserve estimate and previous
estimate for comparison are presented in Table 3.
Table 3: Bisie Mpama North Mineral
Reserve at 1.0% Sn Cut-Off Grade (30 June
2022)
Category |
QuantityMt |
Grade% Sn |
Tin Contentkt |
2019 |
2022 |
2019 |
2022 |
2019 |
2022 |
Proven Mineral Reserve |
0.05 |
0.00 |
3.77 |
1.38 |
1.9 |
0.0 |
Probable Mineral Reserve |
3.28 |
2.62 |
4.01 |
4.64 |
131.5 |
121.3 |
Total Proven and Probable
Mineral Reserves |
3.33 |
2.62 |
4.01 |
4.64 |
133.4 |
121.4 |
Notes:
- The Mineral Reserve has been
reported in accordance with the requirements and guidelines of
NI43-101 and are 100% attributable to ABM.
- Apparent computational errors due
to rounding and are not considered significant.
- The Mineral Reserves are reported
with appropriate modifying factors of dilution and recovery.
- The Mineral Reserves are reported
at the head grade and at delivery to Plant.
- Although stated separately, the
Mineral Resources are inclusive of the Mineral Reserves.
- No Inferred Mineral Resources have
been included in the Mineral Reserve estimate.
- Quantities are reported in metric
tonnes.
- The input studies are to the
prescribed level of accuracy.
- The Mineral Reserve estimates
contained herein may be subject to legal, political, environmental
or other risks that could materially affect the potential
exploitation of such Mineral Reserves
The Mineral Reserve assessment and reporting
criteria are presented in Appendix 4. The Mineral Reserve estimate
has been prepared by Mr. Clive Brown, Pr. Eng., B.Sc. Engineering
(Mining), is a qualified person (QP) as defined in National
Instrument 43-101 and has reviewed and approved the scientific and
technical information contained in this news release. He is a
Principal Consultant and Director of Bara Consulting Pty Limited,
an independent technical consultant to the Company.
____________________________________________________________________________
FOR MORE INFORMATION, PLEASE
CONTACT:
Maritz
Smith CEO Alphamin
Resources
Corp. Tel:
+230 269 4166E-mail:
msmith@alphaminresources.com____________________________________________________________________________
CAUTION REGARDING FORWARD LOOKING
STATEMENTS
Information in this news release that is not a
statement of historical fact constitutes forward-looking
information. Forward-looking statements contained herein include,
without limitation, statements relating to the updated LoM schedule
for Mpama North, and planned future exploration activities and
anticipated outcomes. Forward-looking statements are based on
assumptions management believes to be reasonable at the time such
statements are made. There can be no assurance that such statements
will prove to be accurate, as actual results and future events
could differ materially from those anticipated in such statements.
Accordingly, readers should not place undue reliance on
forward-looking statements. Although Alphamin has attempted to
identify important factors that could cause actual results to
differ materially from those contained in forward-looking
statements, there may be other factors that cause results not to be
as anticipated, estimated or intended. Factors that may cause
actual results to differ materially from expected results described
in forward-looking statements include, but are not limited to:
uncertainty of future exploration and assay results and consistency
with past results and expectations;; uncertainties inherent in
estimates of Mineral Resources and Mineral Reserves; global
geopolitical and economic uncertainties; volatility of metal
prices; uncertainties with respect to social, community and
environmental impacts; uninterrupted access to required
infrastructure; adverse political events; impacts of the global
Covid-19 pandemic as well as those risk factors set out in the
Company’s Management Discussion and Analysis and other disclosure
documents available under the Company’s profile at www.sedar.com.
Forward-looking statements contained herein are made as of the date
of this news release and Alphamin disclaims any obligation to
update any forward-looking statements, whether as a result of new
information, future events or results or otherwise, except as
required by applicable securities laws.
Neither the 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 news release.
Appendix 1: SAMPLE PREPARATION, ANALYSES
AND QUALITY CONTROL AND QUALITY ASSURANCE (QAQC)
For sample preparation, analyses and quality
control and quality assurance, see the Company’s news release dated
07 March 2022 entitled “ALPHAMIN ANNOUNCES MAIDEN MINERAL RESOURCE
ESTIMATE AND POSITIVE PRELIMINARY ECONOMIC ASSESSMENT FOR MPAMA
SOUTH”
Appendix
2: SIGNIFICANT INTERCEPTS
FROM RECENT DRILLING AT MPAMA NORTH. EARLIER DRILLING
INTERCEPTS ARE REPORTED IN THE TECHNICAL REPORT DATED 22 APRIL 2022
FILED ON SEDAR.COM (0.5% Sn lower
threshold)
Hole |
Easting |
Northing |
RLm |
Azi (°) |
Dip (°) |
From |
To |
Sn % |
Width |
Sample Position |
GPS |
GPS |
(m)1 |
mid_x |
mid_y |
mid_z |
MND001 |
No significant intercepts |
MND002 |
No significant intercepts |
MND003 |
No significant intercepts |
MND004 |
583392 |
9886283 |
682 |
270 |
-52 |
524.8 |
525.1 |
0.67 |
0.30 |
582,994 |
9,886,250 |
347.0 |
MND005 |
No significant intercepts |
MND006 |
No significant intercepts |
MND007 |
583100 |
9886210 |
726 |
270 |
-75 |
402.0 |
402.5 |
0.58 |
0.45 |
582,987 |
9,886,211 |
340.5 |
MND009 |
582881 |
9886200 |
752 |
270 |
-65 |
96.4 |
96.8 |
2.28 |
0.40 |
582,842 |
9,886,200 |
667.3 |
MND010 |
No significant intercepts |
MND011 |
583103 |
9886211 |
726 |
270 |
-83 |
419.3 |
428.0 |
21.85 |
8.74 |
583,021 |
9,886,194 |
312.7 |
430.6 |
438.9 |
17.52 |
8.30 |
583,018 |
9,886,193 |
302.0 |
MND012 |
582950 |
9886140 |
765 |
270 |
-60 |
64.7 |
65.4 |
12.20 |
0.65 |
582,916 |
9,886,142 |
699.8 |
MND013 |
582945 |
9886142 |
759 |
270 |
-50 |
142.7 |
143.0 |
10.05 |
0.28 |
582,852 |
9,886,146 |
651.2 |
177.0 |
178.0 |
1.02 |
1.00 |
582,829 |
9,886,146 |
625.5 |
MND014 |
No significant intercepts |
MND015a |
582950 |
9886140 |
755 |
270 |
-70 |
172.3 |
172.7 |
6.34 |
0.36 |
582,887 |
9,886,144 |
594.8 |
MND016 |
583063 |
9886162 |
741 |
270 |
-50 |
249.4 |
253.0 |
0.62 |
3.58 |
582,895 |
9,886,161 |
554.1 |
MND017 |
583195 |
9886171 |
744 |
270 |
-50 |
385.0 |
386.0 |
1.02 |
1.00 |
582,947 |
9,886,165 |
450.1 |
MND018 |
583063 |
9886162 |
740 |
270 |
-60 |
284.7 |
285.0 |
11.70 |
0.30 |
582,912 |
9,886,160 |
498.4 |
MND019 |
583196 |
9886171 |
744 |
270 |
-64 |
432.2 |
444.0 |
25.94 |
11.76 |
582,992 |
9,886,162 |
357.3 |
445.0 |
445.6 |
15.30 |
0.55 |
582,988 |
9,886,162 |
351.2 |
MND020 |
583196 |
9886171 |
744 |
270 |
-72 |
484.9 |
492.3 |
7.08 |
7.36 |
583,024 |
9,886,160 |
288.3 |
495.0 |
499.3 |
7.50 |
4.25 |
583,020 |
9,886,159 |
280.6 |
MND021 |
583195 |
9886171 |
744 |
270 |
-57 |
425.3 |
425.6 |
10.50 |
0.30 |
582,962 |
9,886,178 |
388.9 |
MND022a |
583244 |
9886211 |
741 |
270 |
-73 |
547.0 |
558.3 |
7.62 |
11.30 |
583,060 |
9,886,205 |
220.5 |
559.0 |
565.9 |
16.37 |
6.85 |
583,056 |
9,886,205 |
211.4 |
567.7 |
569.5 |
1.31 |
1.83 |
583,054 |
9,886,205 |
205.7 |
MND023 |
583204 |
9886236 |
738 |
270 |
-75 |
511.6 |
524.7 |
21.27 |
13.10 |
583,038 |
9,886,208 |
249.3 |
527.0 |
528.4 |
2.35 |
1.42 |
583,033 |
9,886,207 |
240.8 |
1. Apparent widths, not true thickness |
Appendix 3: Mineral
Resource Checklist of Assessment
and Reporting Criteria
Drilling techniques |
A total of 195 exploration drillholes have been completed at Mpama
North. All drillholes were diamond drill cored and drilled from
surface (mostly NQ) at angles of between -60° and -75°. The
drillholes were drilled from east to west along section lines
spaced between approximately 25 m and 50 m apart.21 PQ sized holes
from a metallurgical drilling campaign were also included that were
drilled in three clusters approximately 25 m apart. |
Logging |
All of the drillholes were geologically logged by qualified
geologists. The logging is of an appropriate standard for grade
estimation. |
Drill sample recovery |
Core recovery in the mineralised zones was observed to be very good
and is on average greater than 95%. Five of the shallow drillholes
intersected artisanal workings and so recovery of the high-grade
mineralisation was poor and therefore the data from these holes
were not used for grade estimation. |
Sampling methods |
Half core samples were collected continuously through the
mineralised zones after being cut longitudinally in half using a
diamond saw. Drillhole samples were taken at nominal 1 m intervals,
which were adjusted to smaller intervals in order to target the
vein zones. Lithological contacts were honoured during the
sampling. MSA’s observations indicated that the routine sampling
was performed to a reasonable standard and is suitable for
evaluation purposes. |
Quality of assay data and laboratory tests |
2012-2015 DrillingThe assays were conducted at ALS Chemex in
Johannesburg where samples were analysed for tin using fused disc
ME-XRF05 with 10% precision and an upper limit of 10 000 ppm.
This was reduced to 5,000 ppm from 2014 onwards. Over limit samples
were sent to Vancouver for ME-XRF10 which uses a Lithium Borate
50:50 flux with an upper detection limit of 60% and precision of
5%. ME-ICP61, HF, HNO3, HCL04 and HCL leach with ICP-AES finish was
used for 33 elements including base metals. ME-OG62, a four-acid
digestion, was used on ore grade samples for Pb, Zn, Cu & Ag.
External quality assurance of the laboratory assays for the
Alphamin samples was monitored. Blank samples, certified reference
materials and duplicate samples were inserted with the field
samples accounting for approximately 10% of the total sample
set.The QAQC measures used by Alphamin revealed the following:
- The high-grade CRM (31.42% Sn) assays
by ALS prior to 2015 returned values approximately 8% higher than
the certified mean value. 98 pulp rejects from this period of
between 1.5% and 60% Sn were re-assayed by ALS in 2016 together
with the high-grade CRM. The 2016 assays correlated well with those
prior to 2015 and the high-grade CRM returned values within
tolerance. Therefore, the pre-2015 assays were accepted for
estimation without modification.
- The lower grade CRM assays (<2% Sn)
indicated that the Sn and Cu assays were accurate and unbiased,
consistently returning values within two standard deviations of the
accepted CRM value.
- The field duplicates confirmed the nuggetty nature of the tin
mineralisation. The majority of the duplicate assays were within
20% of the field sample.
- Blank samples indicated that no significant contamination
occurred.
2021-2022 DrillingAt the on-site ABM laboratory (overseen by
Anchem), samples were first checked off against the submission list
supplied and then weighed and oven dried for 2 hours at 105 degrees
Celsius. The dried samples were crushed by jaw crusher to 75%
passing 2 mm, from which a 250 g riffle split was taken. This 250 g
split was pulverised in ring mills to 90% passing 75 μm from which
a sample for analysis was taken. Samples were homogenised using a
corner-to-corner methodology and two samples were taken from each
pulp, one of 10 g for on-site laboratory assaying and another 150 g
sample for export and independent accredited 3rd party laboratory
assaying.Received samples at ALS Johannesburg were checked off
against the list of samples supplied and logged in the system.
Quality Control is performed by way of sieve tests every 50 samples
and should a sample fail, the preceding 50 samples are ground in a
ring mill pulveriser using a carbon steel ring set to 85 % passing
75μm. Samples are analysed for tin using method code ME-XRF05
conducted on a pressed pellet with 10% precision and an upper limit
of 5,000ppm. The over-limit tin samples are analysed as fused disks
according to method ME-XRF15c, which makes use of pre-oxidation and
decomposition by fusion with 12:22 lithium borate flux containing
20% Sodium Nitrate as an oxidizing agent, with an upper detection
limit of 79% Sn.ME-ICP61, HF, HNO3, HCL04 and HCL leach with
ICP-AES finish was used for 33 elements including base metals.
ME-OG62, a four-acid digestion, was used on high-grade samples for
Pb, Zn, Cu & Ag.The Mpama North samples were assayed in batches
together with the Mpama South samples. External quality assurance
of the laboratory assays for the Alphamin samples was monitored.
Blank samples (299), certified reference materials (434) and
duplicate samples (357) were inserted with the field samples
accounting for approximately 11% of the total sample set.The QAQC
measures used by Alphamin revealed the following:
- Blank samples
indicated that no significant contamination occurred overall. Low
levels of contamination (mostly <200 ppm Sn) mostly occurred,
however 12 values between 229 ppm and 1,285 ppm were returned.
Given the high grades at Bisie, the levels of contamination are not
significant.
- Five different CRMs
were used with expected values between 0.18% and 31.42% Sn. The
lower grade CRMs were prepared by Ore Research and Exploration
(OREAS) and the two high grade CRMs (4.19% and 31.42% Sn) by the
Bureau of Analysed Samples Ltd (BCS). In general, ALS returned
values within the tolerance limits (three standard deviations) for
the OREAS CRMs, although slightly lower than the expected values.
Assays of the highest grade BCS CRM were mostly outside of the
three standard deviation limits but within ±4%of the expected
value. For the 5.07% Sn BCS CRM, assays were consistently lower
than the expected value by as much as 7%. Overall, the CRMs results
indicate a slight negative bias for the ALS assays.
- Coarse duplicates
show mostly excellent correlation, indicating minimal error in the
process and a high degree of repeatability.
|
Verification of sampling and assaying |
A selection of cores representative of the 2012-2015 drilling
programme at Mpama North were visually verified during three site
visits by the QP (July 2013, May 2014 and August 2015). The QP
observed the mineralisation in the cores and compared it with the
assay results. It was found that the assays generally agreed with
the observations made on the core The QP took ten quarter core
field duplicates for independent check assay in 2013, which
confirmed the original sample assays within reasonable limits for
this style of mineralisation150 pulp duplicates were sent to SGS
(Johannesburg) in 2013 for confirmation assay and a further 173
were assayed in 2015. In 2015, 99 pulp duplicates were sent to
Setpoint (Johannesburg) for confirmation assays.
- The pulp duplicates
assayed by SGS in 2013 showed excellent correlation with the ALS
assays at both high- and low-grade ranges.
- SGS assays were
lower than ALS for grades above 20% for the 2014 data checked in
2015. SGS under-reported the grade of all the CRMs that were
inserted. The high-grade CRM was under assayed by approximately
5%.
- Setpoint assays were
lower than ALS for grades above 10% for the 2014 data checked in
2015. ALS tended to under-report the grades of the CRMs.
Since the 2012 to 2015 drilling took place, the QP has visited the
Bisie site on two occasions. From 10 to 12 March 2020 the Mpama
North underground workings were visited, and the on-site laboratory
was inspected. From 11 to 18 August 2021 the available Mpama South
cores, current Mpama North sites and drilling were inspected as
well as upgrades to the on-site laboratory.Core photos from the
drilling programme have regularly been provided to the QP for
inspection. |
Location of data points |
All except two of the Bisie surface drillhole collars used in the
Mineral Resource estimate were surveyed by D.GPS. All collar
elevations were validated against a LiDAR topographic
survey.Down-hole surveys were completed for all the holes drilled
at Mpama North. From 2012 to 2015 these were mostly by standard
multishot techniques and therefore the accuracy of the survey was
impacted by natural magnetism. The latest drillhole surveys have
been competed using a north seeking gyro. |
Tonnage factors (in situ bulk densities) |
For the 2012-2015 drilling, specific gravity determinations were
made for 2,698 drillhole samples using a laboratory gas pycnometer.
A regression formula of tin grade against specific gravity was
developed that was applied to the samples that did not have direct
SG measurements. The assigned specific gravity was interpolated
into the block model using ordinary kriging. The laboratory
pycnometry readings compared well with a number of SG measurements
completed using the Archimedes principle of weight in air versus
weight in water.For the 2021-2022 drilling, 1,154 relative density
measurements were made on mineralised and unmineralised samples
using the weight in air versus weight in water method. |
Data density and distribution |
The holes were drilled from east to west along section lines spaced
approximately 50 m to 60 m apart with infill drilling on 25 m
to 30 m spaced sections in a portion of the shallower area. Along
the section lines, the drillholes intersected the mineralisation
between approximately 25 m and 50 m apart in most of the Mineral
Resource area.21 PQ sized holes from a metallurgical drilling
campaign were included that were drilled in three clusters
approximately 25 m apart. Within the clusters, the PQ holes were
drilled approximately 5 m apart.In the Mineral Resource area, 131
NQ drillholes were used for the grade estimate. Several holes did
not intersect the mineralised zone or intersected low-grade
mineralisation outside of the area currently defined as a Mineral
Resource, and five of the shallow drillholes intersected artisanal
workings. The data from these holes were not used for grade
estimation. |
Database integrity |
Data are stored in an Access database. MSA completed spot checks on
the database and is confident that the Alphamin database is a
reasonably accurate representation of the original data
collected. |
Dimensions |
The area defined as a Mineral Resource extends approximately 750 m
in the down plunge direction. It extends for a width of
approximately 300 m in the plane of mineralisation perpendicular to
the plunge. The main zone of the Mineral Resource, which accounts
for 97% of the Mineral Resource, is on average approximately 9 m
thick, although is narrower (less than 1 m) at the margins and up
to 20 m thick in the central areas.The minor zones that occur
several metres above and below the main zone are considerably
narrower than the main zone and cover areas of between 100 m and
200 m in the dip and strike directions. |
Geological interpretation |
The mineralised intersections in drill core are clearly
discernible. The Mineral Resource is interpreted to occur as
irregular tabular mineralised zones, dipping 65° to the east,
containing several narrow veins, blocks and disseminations of
cassiterite. The mineralised zones are hosted in chlorite schist
that is the result of intense alteration and may originally have
been a distinct stratigraphic interval or structure.The main zone
of the Mineral Resource is almost continuous for approximately 750
m although it has been affected by a number of faults causing local
displacement. Several faults with throws in excess of 10 m have
been modelled.
- The Main Vein
mineralisation consists of a number of uncorrelated cassiterite
veins within pervasively chloritised schist. This zone generally
occurs over thicknesses of between 2 m and 22 m with an average
thickness of approximately 9 m. The Main Vein zone is generally the
highest grade and most consistent overall.
- Hanging Wall Vein
mineralisation occurs within partly chloritised schist and
micaceous schist between 4 m and 20 m above the Main Vein. This
zone of mineralisation is generally between 0.5 m and 4 m wide and
occurs in the central area of the deposit and tapers out
northwards. The middling between the Hanging Wall Vein and the Main
Vein decreases in areas and it is possible that this vein merges
into the Main Vein in some parts of the deposit.
- Footwall Vein (FW
Vein) mineralisation occurs within the micaceous schist and
amphibolite schist between 2 m and 12 m below the Main Vein. This
zone is restricted to the southern areas, is very narrow (<50
cm) and high-grade in its most northern occurrences but thickens to
the south to several metres. It is possible that this vein merges
into the Main Vein in some parts of the deposit.
A three-dimensional wireframe model was created for the three zones
of mineralisation based on a grade threshold of 0.35% Sn. The main
zone is the most consistent zone and occurs within a persistent
chlorite schist. Narrower less continuous zones occur above and
below the main zone within chlorite-mica schists. |
Domains |
The mineralisation was modelled as three tabular zones containing
irregular vein style mineralisation. A hard boundary was used to
select data for estimation in order to honour the sharp nature of
vein boundaries. |
Compositing |
Sample lengths were composited to 1 m. Composites of less than 1 m
occurred in the narrow vein areas, which were retained.
Accumulations of Sn%-density-composite length were calculated for
grade estimation so that narrow high-grade composites did not
excessively influence the estimate. |
Statistics and variography |
Two populations of Sn mineralisation occur, a high-grade population
of cassiterite veins and a lower grade population containing
disseminated cassiterite as vein fragments and blebs. The data were
separated into the two statistical populations, which resulted in
the coefficient of variation for the Sn accumulation composites in
the high-grade population being 0.5 and for the lower grade
population being 1.6. The histograms are positively skewed.Normal
Scores variograms were calculated in the plane of the
mineralisation, down-hole and across strike. Variogram ranges for
the Sn accumulation in the main zone were modelled with ranges in
the order of 75 m in the longest direction of continuity and 60 m
in the second direction. Reliable variograms could not be produced
for either the hangingwall or footwall zones and the main zone
variogram was used to estimate these areas. |
Top or bottom cuts for grades |
Top caps were applied to outlier values by examination of
histograms and cumulative probability plots. Top caps were applied
to the accumulation value for tin, which affected 2.5% of the
data. |
Data clustering |
21 PQ sized holes from a metallurgical drilling campaign were
included that were drilled in three close clusters approximately 25
m apart. Within the clusters the PQ holes were drilled
approximately 5 m apart. Outside of the metallurgical sampling area
the grid is approximately regular. |
Block size |
20 mN by 2 mE by 10 mRL three-dimensional block models were used.
The blocks were divided into sub-cells to better represent the
interpreted mineralisation extents. The blocks were rotated into
the plane of mineralisation prior to estimation. |
Grade estimation |
The accumulation of tin grade, density and composite length were
estimated using ordinary kriging. Copper, lead, zinc, silver,
arsenic and sulphur grades were also estimated.The
Sn%-density-composite length accumulations were divided into a
high-grade population (>80 %t/m) and a lower grade population
(<80 %t/m). The probability of a block containing values above
and below this threshold was estimated by indicator kriging.
Outside of the indicator variogram range, estimates did not use the
extreme high grades (>80 %tm) in order to reduce the influence
of these values on estimates further away from them. The high- and
low-grade populations were estimated separately using ordinary
kriging and the block model grade was then assigned based on the
estimated grade of the high and low grade and their proportion in
each block.A minimum number of 4 and a maximum of 10 one metre
composites were required for the high-grade Sn-accumulation
population. A minimum number of 8 and a maximum of 24 one metre
composites were required for the lower grade Sn-accumulation
population and other variables. Search distances and orientations
were aligned with the variogram range and mineralised
trends.Estimates were extrapolated for a maximum distance of 20 m
up- or down-plunge from the nearest drillhole intersection.
Extrapolation is minimal over most of the Mineral Resource as the
up-and down dip limits have been well defined by the drilling,
except in a portion on the down-plunge area that is open at
depth. |
Resource classification |
Measured Mineral Resources were declared where the drillhole
spacing is approximately 25 m and where the geological model has
low variability. The mineralisation was classified as Indicated
Mineral Resources if block estimates occur within the 50 m drilling
grid, so that all Indicated estimates are informed by samples
within the variogram range. The remainder of the interpreted model
within the sparser drilled area was classified as Inferred Mineral
Resources with a maximum extrapolation from a drillhole of 20 m
along plunge. The up-plunge extremity is separated from the main
area by a fault and the structural interpretation in this area is
tenuous and it does not contain sufficient data to classify them as
Indicated Mineral Resources. Consequently, this area was classified
as Inferred Mineral Resources.The high-grade mineralisation of
reasonable tonnage leads no doubts as to reasonable potential for
economic extraction, it being one of the highest-grade tin deposits
in the world. Mpama North is currently a profitable mine. |
Mining cuts |
The thickness of the mineralisation was honoured in the estimate
and as a result some areas will be more sensitive to dilution than
others. The thickness, grade and steep dip implies that the Mineral
Resource can be extracted using established underground mining
methods. |
Metallurgical factors or assumptions |
The tin mineralisation occurs as cassiterite, an oxide of tin
(SnO2). The Cu, Zn and Pb mineralisation occurs as sulphides. Each
of these minerals is amenable to standard processing techniques for
each metal. At the Mpama North Mine, gravity separation is used to
create a saleable tin concentrate and the sulphide minerals are
removed from the tin concentrate as they represent impurities. |
Legal aspects and tenure |
Alphamin through its wholly owned DRC subsidiary, Alphamin Mining
Bisie SA, has a Mining License PE 13155 which includes the Bisie
Tin Mine. Alphamin has an 80.75 percent interest in ABM. The
Government of the Democratic Republic of Congo (GDRC) has a
non-dilutive, 5% share in ABM. |
Audits, reviews and site inspection |
The following review work was completed by MSA:
- Inspection of approximately 25% of the
Alphamin cores used in the Mineral Resource estimate
- Database spot check
- Inspection of drill sites
- Independent check
sampling
- Inspection of the
on-site sample preparation laboratory.
|
Appendix
4: Mineral
Reserve and Mine Schedule Modifying
factors
Modifying Factors
TABLE
4.1
MODIFYING FACTORS APPLIED |
Modifying factor |
Value |
Comment |
Mining recoveryDevelopment and slypingLong hole
stopesSill pillars (other) |
98%98%61% |
Based on historical performance reported |
DilutionDevelopment and slypingLong hole
stopesSill pillars |
8%10%18% |
Based on historical performance reported |
A cut-off grade calculation was performed based on the metal
price provided by Alphamin of US$32,000 per tonne and costs as per
the 2022 mine budget, provided by Alphamin and reviewed by Bara.
The breakeven grade calculation is shown in the table below. This
breakeven grade of 1.5% Sn was applied to determine the limits of
mining while the marginal cut-off grade of 1.0% was applied to
select stopes for inclusion in the mine schedule and Mineral
Reserve.
TABLE
4.2
BISIE TIN PROJECT CUT OFF GRADE ESTIMATE - JUNE
2022 |
|
|
Breakeven cut-off
grade |
Marginal
cut-off grade |
Item |
Unit |
Value |
Value |
Tin price |
US$/tonne |
32,000 |
|
32,000 |
|
Operating costs |
|
|
|
On mine costs |
US$/t RoM |
196 |
|
86 |
|
Off mine costs (fixed) |
US$/t RoM |
168 |
|
168 |
|
Total cost |
US$/t milled |
364 |
|
254 |
|
Breakeven recovered grade |
% |
1.14 |
|
0.79 |
|
Plant recovery |
% |
78 |
% |
78 |
% |
Breakeven RoM grade |
% |
1.5 |
|
1.0 |
|
The stoping and development productivities to be used in the
life of mine plan were discussed and agreed with mine management.
The scheduling rates included consideration of:
- Performance over the year to date
- Changes to shift arrangements to CONOPS
- Maintenance and services installation requirements
- Equipment availability.
Table 4.3 below summarises the advance rates used in the mine
schedule.
TABLE
4.3
SCHEDULING ADVANCE PER MONTH PER END TYPE |
|
Unit |
Decline |
FW Drive |
Ore Drive |
Shifts per day |
Unit |
2 |
|
2 |
|
2 |
|
Days per month |
Unit |
26 |
|
26 |
|
26 |
|
Blast hole length |
metres |
3.2 |
|
3.2 |
|
3.2 |
|
Effective advance |
metres |
2.8 |
|
2.8 |
|
2.8 |
|
Time to drill and blast (shifts) |
Unit |
1 |
|
1 |
|
1 |
|
Time to muck and support (shifts) |
Unit |
1 |
|
1 |
|
2 |
|
Blasts per day |
Unit |
1 |
|
1 |
|
0.7 |
|
Advance pr day |
metres |
2.8 |
|
2.8 |
|
1.9 |
|
Blast efficiency |
% |
80 |
% |
80 |
% |
80 |
% |
Advance per month |
Metres/month |
58 |
|
58 |
|
39 |
|
Advance used in schedule |
Metres/month |
60 |
|
40 |
|
40 |
|
There are currently three development jumbos available on site
and they are planned at a maximum of 240 metres per month. These
drill rigs are allocated in the mine schedule as follows:
- One to the ramp (Decline) and ancillary excavations off of the
ramp.
- One to lateral waste development
- One to ore development and slyping.
The long hole drilling capacity of the long hole production
drill rig limited the long hole stoping production to a maximum of
27,000 tonnes per month.
The mining schedule targets RoM tin content delivered to plant
of minimum 15,000 tonnes tin per year. The processing plant has
capacity to process a maximum of 40,000 tonnes per month. This
processing constraint was used as a constraint in the mining
schedule. The Rom tonnage on a monthly basis based on the grade in
order to achieve the required tin production within the processing
and mining constraints.
The targeted production rate of an average of 1500 t contained
Sn per month can be maintained for 99 months (Eight years and three
months). The mining schedule includes 18.9% made up of inferred
resources which are considered too speculative geologically to have
the economic considerations applied to them that would enable them
to be categorized as mineral reserves.
Ore reserve statement
Only Measured and Indicated Mineral Resources are converted to
Mineral Reserves. The total life of mine schedule included 18.9 %
of the scheduled production from Inferred Mineral Resources, which
was not included in the Mineral Reserves. This Mineral Reserve
estimate is based on a depletion date of 30 June 2022. It followed
an assessment of the economic viability of the Mineral Resources
that were scheduled for depletion before confirming them as Mineral
Reserves.
Summary of Reserves for Bisie Tin
at 30 June
2022 |
Classification |
Quantity |
Tin Grade |
Tin Content |
(Mt) |
(%) |
(kt) |
2022 |
2019 |
2022 |
2019 |
2022 |
2019 |
Proven Mineral Reserve |
0.00 |
0.05 |
1.38 |
3.77 |
0.0 |
1.9 |
Probable Mineral Resource |
2.62 |
3.28 |
4.64 |
4.01 |
121.3 |
131.5 |
Total Mineral Reserves |
2.62 |
3.33 |
4.64 |
4.01 |
121.4 |
133.4 |
Source: Bara (2022)Notes:
- The Mineral Reserve has been reported in accordance with the
requirements and guidelines of NI43-101 and are 100% attributable
to ABM.
- Apparent computational errors due to rounding and are not
considered significant.
- The Mineral Reserves are reported with appropriate modifying
factors of dilution and recovery.
- The Mineral Reserves are reported at the head grade and at
delivery to Plant.
- The Mineral Reserves are stated at a price of US32,000/t Sn as
at 30 June 2022.
- Although stated separately, the Mineral Resources are inclusive
of the Mineral Reserves.
- No Inferred Mineral Resources have been included in the Mineral
Reserve estimate.
- Quantities are reported in metric tonnes.
- The input studies are to the prescribed level of accuracy of a
minimum pre-feasibility study level.
- The Mineral Reserve estimates contained herein may be subject
to legal, political, environmental or other risks that could
materially affect the potential exploitation of such Mineral
Reserves.
The Qualified Person for Mineral Reserves has satisfied himself
that the methodology used for estimating and presenting Mineral
Reserves herein conform to the requirements and guidelines of NI
43-101 and therefore supports this Mineral Reserve estimate as
stated above.
1 Data obtained from International Tin Association Tin Industry
Review Update 2021
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