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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