TIDMALBA
RNS Number : 5899M
Alba Mineral Resources PLC
24 May 2022
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Alba Mineral Resources plc
("Alba" or the "Company")
Clogau-St David's Waste Tip Concentrates Return Grades up to
1,000 g/t
Alba Mineral Resources (AIM: Alba) is pleased to provide an
update on progress made at its Clogau-St David's Gold Mine
("Clogau" or the "Mine") in Wales, including assay results from
gold concentrates produced from the processing of 8.76 tonnes of
fines material excavated from the Mine's historic Waste Tip. The
assay results have returned gold concentrate grades of up to 1,000
g/t, with average head grades for this material of 1.7 g/t.
Key Points
-- Gold concentrate grades of up to 1,000 g/t have been returned
following independent assaying of the 81 kg of total gold
concentrates produced at the Clogau pilot processing plant from the
five pits dug in January 2022 at the Waste Tip, with the average
grade of the final high-grade concentrates being 503 g/t.
-- An average head grade of 1.7 g/t was achieved for the
material processed through the processing plant, significantly
higher than the average of 0.95 g/t achieved from the initial
sampling of the same pits, indicating that the sampling exercise
under-represented the overall grade due to the nuggety effect of
the ore.
-- The successful completion of this Phase 2 programme,
including the significantly higher average head grades, will enable
further economic assessment of the Waste Tip to be completed.
-- A positive assessment will enable Alba to proceed with a
Mining Plan and formal planning application to commercially produce
gold from the Waste Tip's estimated 4,000 tonnes of fines
material.
Alba's Executive Chairman, George Frangeskides, commented:
"The Phase 2 programme at the Clogau Waste Tip has achieved
strong concentrate grades of up to 1,000 g/t, with an average
across the five pits of 503 g/t. What is more, the independent
assaying has confirmed that the overall head grade of the fine
material taken from the Waste Tip averages 1.7 g/t, which is a
significant upgrade on the average grade achieved from sampling the
same material prior to the processing stage. This is unsurprising
given what we know about the nuggety effect of the gold at Clogau,
and it bodes well for the commercial viability of mining the Waste
Tip."
Details
The 2,833 m (2) Waste Tip at Clogau comprises ore rock mined but
discarded and not processed for its gold content during previous
periods of mining. Following a Phase 1 sampling programme in 2021,
which returned gold grades of up to 9.89 g/t with average grades of
up to 4.37 g/t for the fine fractions and 3.80 g/t for the medium
fractions, the Company commenced a Phase 2 programme in January
2022. Undertaken over five pits, first assay results from this
second programme returned gold grades of up to 11.35 g/t (RNS 21
March 2022).
At the same time, the Company reported that 107 kg of
concentrate had been produced in its pilot processing plant from
the 8.76 tonnes of sub 20mm fines material collected. Note that
these reported figures correspond to the wet weights. The
equivalent dry weights are 81 kg of concentrate from 7.01 tonnes of
sub 20mm fines.
Subsequent to the Company's 21 March 2022 RNS, the concentrate
has been processed on-site over a Wilfley shaking table for further
gravimetric concentration of the gold. This exercise has helped
Alba to quantify gold recovery, which provides a metric of the
initial feed ore required to produce an economic operation. The
upgraded gold concentrates were then sent to an independent assay
laboratory for assaying.
As shown in Table 1, during the first stage of processing the
highest grades in the individual processing steps were consistently
found in the centrifugal concentrator material, with highly
elevated gold grades also found in the sluice box material. Average
centrifuge material grades were of 108 g/t prior to tabling, with
final average gold concentrate grades (post tabling) averaging 503
g/t, with a high of 1,000 g/t from Pit 5.
Average gold concentrate grades of 196 g/t after tabling were
also produced from the sluice box material, greatly improving the
total recovery of the processing plant. Gold grades were
significantly lower in the +0.8mm fraction, validating the decision
to screen the concentrate before treating it over the table. The
gold grades in the initial tailings produced from the processing
plant had average grades of 0.83 g/t, which demonstrates the
efficiency of the plant. The gold recovered from the shaking table
was generally fine in nature with some larger nuggets recovered, up
to 0.5mm.
Table 1: Assay Grades from Gold Concentrates (the figures in
bold and italics represent the final gold concentrates achieved
from both the centrifugal concentrator and the sluice box, in each
case post tabling. NS (Not Sampled) relates to the samples
compromised in transit to the independent laboratory)
Centrifugal Concentrator (g/t) Sluice Box (g/t) Tailings
----
Pit Before +0.8mm Tailings Concentrate Before +0.8mm Tailings Concentrate (g/t)
ID Tabling Fraction (<0.8mm) (<0.8mm) Tabling Fraction (<0.8mm) (<0.8mm)
--------- ---------- ---------- ------------ --------- ---------- ---------- ------------ ---------
1 108.5 49.1 2.07 263 18.4 2.73 1.3 105 0.63
--------- ---------- ---------- ------------ --------- ---------- ---------- ------------ ---------
2 71.5 0.37 2.05 137 8.84 0.24 0.24 55.7 0.32
--------- ---------- ---------- ------------ --------- ---------- ---------- ------------ ---------
3 153 0.38 3.99 633 68.2 0.25 0.76 281 1.54
--------- ---------- ---------- ------------ --------- ---------- ---------- ------------ ---------
4 59.3 46.8 1.72 483 25.1 0.75 NS 222 0.83
--------- ---------- ---------- ------------ --------- ---------- ---------- ------------ ---------
5 146 1.33 NS 1000 23.7 NS 3.27 315 NS
--------- ---------- ---------- ------------ --------- ---------- ---------- ------------ ---------
Av. 108 19.6 2.46 503 28.8 0.99 1.39 196 0.83
--------- ---------- ---------- ------------ --------- ---------- ---------- ------------ ---------
Figure 1: Gravity gold recovery flowsheet used at Alba's pilot
processing plant, showing gold grades for Pit 3 material for each
processing step.
Figure 2: Pit layout with corresponding centrifuge concentrate grades.
Table 2 shows the gold recovery percentage and ratio of
concentration of Alba's pilot processing plant. Recovery percentage
represents the ratio of the weight of gold recovered in the
centrifuge and sluice box to the weight of the gold in the
feedstock to the process, expressed as a percentage, with
recoveries varying from 27-74% with an average of 52%. Ratio of
concentration refers to the number of tonnes of feed required to
produce 1 tonne of centrifuge concentrate.
This shows that on average the processing plant will require 173
tonnes of raw ore to produce 1 tonne of centrifuge concentrate at
108 g/t and 0.86 tonnes of sluice concentrate at 28.8 g/t (for
these grades, see the final row in Table 1, denoted "Av." for
averages). The assay grades and masses reported in Table 2 are used
to calculate the total mass of gold recovered in each of the
centrifuge, sluice and tailings portions and thus accurately
calculate the head grade of the material processed.
Table 2: Gold recovery and ratio of concentration of the pilot
processing plant (Recoveries and Head Grades for Pit 5 could not be
calculated as the tailings sample was compromised during
transit)
Total Centrifuge Sluice Tailings Recovery Ratio of Head
Pit % Au (centrifuge Concentration Grades
+ sluice) (g/t)
----
Pit Mass Mass Assay Mass Assay Mass Assay
ID (kg) (kg) (g/t) (kg) (g/t) (kg) (g/t)
-------- ------ ------- ------ ------- ------ -------
1 2064 22.5 108.5 10.7 18.4 2031 0.63 67 92 1.90
-------- ------ ------- ------ ------- ------ ------- ------------------ --------------- --------
2 562.8 6.6 71.5 4.5 8.84 551.7 0.32 74 85 1.22
-------- ------ ------- ------ ------- ------ ------- ------------------ --------------- --------
3 1186 5.1 153 6.6 68.2 1174 1.54 40 233 2.56
-------- ------ ------- ------ ------- ------ ------- ------------------ --------------- --------
4 1790 6.4 59.3 6.4 25.1 1777 0.83 27 280 1.13
-------- ------ ------- ------ ------- ------ ------- ------------------ --------------- --------
Ave. 52 173 1.70
------- ------------------ --------------- --------
Table 3 shows how the calculated head grades of material
processed from each pit compare with the average grades reported
from the Phase 1 and 2 bulk sampling. With the exception of Pit 1,
the head grades calculated following the processing of all the pit
material are generally much higher, at an average of 1.7 g/t, than
the head grades previously reported from the assaying of the fines
material during the Phase 1 and 2 bulk sampling exercises (see RNS
dated 21 March 2022). For example, the final gold concentrate of
483 g/t from Pit 4 material was from an actual head grade of 1.13
g/t, more than four times higher than the head grade of 0.26 g/t
which was previously based on Phase 2 sampling.
The conclusion can be drawn from this material increase in
overall head grade is that the whole-sample assay grades from the
bulk samples under-represented the amount of gold present in the
pits. This is likely due to the highly nuggety nature of the gold
giving rise to large variations in assay grades.
With more gold now recovered than had been anticipated, and head
grades from all pits from which the assay data is available now
being above 1 g/t (in the range of 1.13 g/t to 2.56 g/t), the
Company anticipates being able to process the Waste Tip material at
lower cut-off grades than initially anticipated.
Table 3 : Comparison of Mill Head Grades from Phases 1 and 2
with the actual Mill Head Grades processed (Blank cell corresponds
with missing Pit 5 data due to compromised sample). All samples are
-20mm size fraction. Actual Mill Head values are for Pits 1-4
only
Pit ID Mill Head Grades Mill Head Grades Actual Mill Head
Phase 1 (June 2021) Phase 2 (21/03/2022) Grades Processed
(g/t) (g/t)
1 2.68 2.30 1.90
--------------------- ---------------------- ------------------
2 0.26 0.28 1.22
--------------------- ---------------------- ------------------
3 0.88 0.83 2.56
--------------------- ---------------------- ------------------
4 0.49 0.26 1.13
--------------------- ---------------------- ------------------
5 0.79 0.72
--------------------- ---------------------- ------------------
Waste Tip Average 1.02 0.88 1.70
--------------------- ---------------------- ------------------
Next Steps
The data generated from this successful Phase 2 programme, which
has revealed significantly higher overall head grades than were
apparent from the previous sampling programme, will enable the
Company to now proceed to assess the economic potential of
processing all or part the Waste Tip.
A positive outcome from that assessment will lead to the
development of a Mining Plan, which will feed into a formal
planning application to commercially produce gold from the Waste
Tip.
Updates on other Clogau Work Streams
As stated in the RNS dated 21 March 2022, the Company submitted
additional data and analysis to the competent regulator, Natural
Resources Wales ("NRW"), in respect of its proposal to dewater the
Llechfraith Shaft at Clogau, which dewatering requires certain
permits to be obtained in respect of the discharge of mine water,
post-treatment, to the River Cwm-Llechen. The Company has now
received feedback from NRW in respect of those revised submissions.
This feedback is being considered currently and may require further
data generation by the Company. The Company and its technical
advisers remain confident that the Company will be successful in
its bid to dewater the shaft. Further details will be advised once
the Company has a better idea of the likely timeline to a formal
determination.
Further to our RNS dated 11 October 2021, our aeromagnetic UAV
(unmanned aerial vehicle) survey contractors, UAVE Limited, have
been engaged in the process for obtaining permission to fly and
have been liaising in that regard with the UK Civil Aviation
Authority to establish schedules and stake holders. The process is
anticipated to take 18 weeks in total, and the Company will provide
a further update in due course.
This announcement contains inside information for the purposes
of the UK Market Abuse Regulation and the Directors of the Company
are responsible for the release of this announcement.
Glossary
<20mm Material less than 20mm in size.
Aeromagnetic Survey A geophysical survey carried out using a
magnetometer aboard a drone. The resulting
magnetic map allows a visualization of the
geological structure of the bedrock.
Assay A process used to determine proportions
of metals and minerals in ores.
Concentrate The product from the processing of a target
mineral after waste rock and impurities
have been removed.
Feed or Feedstock Raw ore material used to supply a processing
plant.
Pitting Digging of shallow pits, usually employed
to test shallow, extensive, flat-lying bodies
of mineralization.
Sampling Taking small pieces of rock at intervals
along exposed mineralisation for assay (to
determine the mineral content).
Tailings Uneconomical waste material residue left
after the processing of ore rock.
Tonne One tonne is equal to 1 000 kilograms (also
known as a metric ton).
Waste Ore rock mined with an insufficient gold
content to justify processing
Forward Looking Statements
This announcement contains forward-looking statements relating
to expected or anticipated future events and anticipated results
that are forward-looking in nature and, as a result, are subject to
certain risks and uncertainties, such as general economic, market
and business conditions, competition for qualified staff, the
regulatory process and actions, technical issues, new legislation,
uncertainties resulting from potential delays or changes in plans,
uncertainties resulting from working in a new political
jurisdiction, uncertainties regarding the results of exploration,
uncertainties regarding the timing and granting of prospecting
rights, uncertainties regarding the timing and granting of
regulatory and other third party consents and approvals,
uncertainties regarding the Company's or any third party's ability
to execute and implement future plans, and the occurrence of
unexpected events.
Actual results achieved may vary from the information provided
herein as a result of numerous known and unknown risks and
uncertainties and other factors.
Competent Person Declaration
The information in this release that relates to Exploration
Results has been reviewed by Mr Mark Austin. Mr Austin is a member
of SACNASP (Reg. No. 400235/06), Fellow of The Geological Society
and Fellow of the Geological Society of South Africa. He has a
B.Sc. Honours in Geology with 38 years' experience.
Mark Austin has sufficient experience that is relevant to the
style of mineralisation and type of deposit under consideration and
to the activity being undertaken to qualify as a Competent Person
as defined in the 2012 Edition of the 'Australasian Code for
Reporting of Exploration targets, Exploration Results, Mineral
Resources and Ore Reserves', also known as the JORC Code. The JORC
code is a national reporting organisation that is aligned with
CRIRSCO. Mr Austin consents to the inclusion in the announcement of
the matters based on his information in the form and context in
which they appear.
For further information, please visit
www.albamineralresources.com or contact:
A lba Mineral Resources plc
George Frangeskides, Executive Chairman +44 20 3950 0725
SPARK Advisory Partners Limited
(Nomad)
Andrew Emmott +44 20 3368 3555
ETX Capital (Broker)
Thomas Smith +44 20 7392 1494
St Brides Partners (Financial PR) alba@stbridespartners.co.uk
Isabel de Salis / Catherine Leftley
Alba's Project and Investment Portfolio
Mining Projects Operated Location Ownership
by Alba
Clogau (gold) Wales 90%
----------- ----------
Dolgellau Gold Exploration
(gold) Wales 90-100%
----------- ----------
Gwynfynydd (gold) Wales 100%
----------- ----------
Limerick (zinc-lead) Ireland 100%
----------- ----------
Investments Held by Alba
Greenroc Mining Plc (mining) Greenland 54 %
----------- ----------
Horse Hill (oil) England 11.765%
----------- ----------
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