Altus Strategies PLC - Excellent gold recoveries at Diba project in Mali
Altus Strategies Plc / Index (EPIC): AIM (ALS), TSX-V (ALTS) & OTCQX: ALTUF / Sector: Mining
Altus Strategies Plc
("Altus" or the "Company")
Excellent Gold Recoveries at Diba Project in
Altus Strategies Plc (AIM: ALS, TSX-V: ALTS, OTCQX: ALTUF) (''Altus'' or the ''Company'') announces excellent results from metallurgical testwork on oxide and sulphide samples from the Company's 100 % owned Diba gold project ("Diba" or the "Project") in western
· Excellent gold recoveries from oxide and sulphide samples from Diba gold project in
- 98.3 % recovery at moderate (75 μm) grind size on oxide sample for CIL scenario
- 86.8 % recovery at moderate (75 μm) grind size of sulphide samples for CIL scenario
- 95.8 % recovery at coarse (6.3 mm) crush size on oxide sample for heap leach scenario
· Expectation for a significant upgrade to existing Preliminary Economic Assessment ("PEA")
· Existing PEA which applied a gold price of
- Generated a robust
- Modelled 80 % gold recovery for oxide heap leaching, compared to 95.8 % reported
- Did not envisage a CIL processing route, thereby excluded all sulphide ounces
· Significant resource growth and discovery potential considered to exist at Diba:
- Current Mineral Resource Estimate ("MRE") remains open along strike and down dip
- Seven further prospects within 7 km of MRE have yet to be systematically drill tested
- A resource expansion and target definition drill programme is now being planned
"The results of the metallurgical testwork on both oxide and sulphide material from Diba are simply excellent. Heap leach amenability shows 95.8 % gold recovery at a coarse crush size. This recovery is significantly higher than the 80 % modelled in the current PEA which we reported on in July. More significantly, the testwork on fresh (sulphide) samples shows that CIL processing will likely be very effective, with 86.8 % gold recovery at attractive grind sizes.
"Diba already boasts a robust
"Aside from the existing resource area, Altus has defined seven priority prospects at Diba, none of which have ever been systematically drill tested. These prospects are all located within 7 km of the current mineral resource, which itself is only 13 km from the multi-million ounce Sadiola gold mine. Altus is currently planning a drill programme for Diba and we look forward to providing an update on this in due course."
Preliminary Economic Assessment to be updated
The Company has engaged Mining Plus UK Ltd to update the existing Diba PEA to incorporate the higher oxide recoveries reported in this release (95.8 % compared to 80 % used in the existing PEA). Importantly, the PEA will be broadened to model CIL processing to incorporate the current sulphide MRE of 33,600 ounces at 1.12 g/t Au Indicated and 153,300 ounces at 1.05 g/t Au Inferred as set out in Table 2. Incorporating the oxide and sulphide resource and using the higher processing recoveries is expected to have a materially positive impact on the current
Metallurgical Testwork Programme
Grinding Solutions Limited of
Table 1. Summary of testwork on Diba oxide and sulphide samples
Grind Size (μm)
Au Recovery (%)
NaCN Consumption (kg/t)
CaO Consumption (kg/t)
90 % < 3 hours
85 % < 24 hours
Results of bottle roll testing on oxide samples
Coarse ore bottle roll testing on the oxide sample has shown that excellent gold extractions of up to 95.8 % can be achieved at crush sizes down to 6.3 mm, high extractions were also observed for crush size up to 16 mm where gold extraction of 94.5 % was observed. Final extractions are achieved after a leach period of approximately 240 hours.
Results of fine ore leach tests on sulphide samples
Whole fine ore leach tests on the sulphide sample reached 86.77 % at a grind size of 75 μm. Cyanide consumption for the tests was low, ranging between 0.02 kg/t and 0.18 kg/t NaCN. Lime consumption ranged between 0.51 kg/t and 0.71 kg/t CaO.
Results of fine ore leach tests on oxide samples
Whole fine ore leach tests on the oxide sample reached 98.3 % at a grind size of 75 μm. Cyanide consumption for the tests was low, ranging between 0.03 kg/t and 0.18 kg/t NaCN. Lime consumption ranged between 0.98 kg/t and 1.27 kg/t CaO. Leach curves were marginally downward trending towards the end of the test. Leaching was largely complete after 6 hours with the feed grade and tails grade recovery results matching well with the solution-based calculations ranging from 96.66 % to 98.36 %.
Results of flotation tests
Flotation testing was used to investigate the production of a low mass pull pre-concentrate to minimise eventual plant operating costs and capital costs. The testwork generated a flotation concentrate between 62.8 % and 67.3 % to mass pulls of between 3.9 % and 5.9 %. The results indicated that further gold recovery could be achieved by extending the flotation time and optimising reagent conditions.
Results of gravity tests
Gravity testing on oxide and sulphide samples was completed using a Falcon L40 concentrator operating at 200 G. Mass pulls to the concentrate were high at 11.6 % for the sulphide sample and 8.0 % for the oxide sample. However, gold recoveries to these concentrates were relatively low at 34.8 % and 30.7 % for the sulphide and oxide samples respectively.
The following figures have been prepared and relate to the disclosures in this announcement and are visible in the version of this announcement on the Company's website (www.altus-strategies.com) or in PDF format by following this link: https://altus-strategies.com/site/assets/files/4929/altus_nr_-_diba_met_28_oct_2020.pdf
· Location of the Diba project in western
· Location of Diba MRE area and additional targets is shown in Figure 2.
Notes on Testwork Procedures
Cyanidation Testing (Oxide Coarse Ore Bottle Roll Tests)
· Coarse ore bottle roll tests were completed on an oxide composite.
· Crush sizes of 20 mm, 16 mm, 12.5 mm, 6.3 mm utilising a 28 day maximum leach period and a 1 min/hour rolling period.
Cyanidation Testing (Sulphide and Oxide Fine Ore Bottle Roll Tests)
· Fine ore cyanide leach tests were completed on sulphide and oxide composites.
· Tests were completed using 40 % solids with grind sizes of 250 μm, 180 μm, 125 μm, 75 μm, 45 μm over two day leach period with continuous bottle rolling.
· A series of flotation tests were completed on samples of the sulphide composite to investigate the recovery of gold to a bulk sulphide concentrate. Grind sizes of 250 μm, 180 μm, 125 μm, 90 μm, 75 μm were adopted with concentrates extracted after 1, 3, 6, 10, and 15 minutes.
Gravity test work
· A 1 kg sample of each of the sulphide and oxide samples were submitted to a 1 kg single pass test using Falcon L40 multi gravity concentrate. A grind size P80 75 μm was used with Falcon concentrates cleaned with a Mozley table.
Diba Project: Location
The 81 km2 Diba (Korali Sud licence) project is located in the Kayes region of western
Diba Project: Geology and Mineralisation
Mineralisation at the Diba project is sediment-hosted within a series of stacked lenses, typically between 20m and 40m thick. The lenses are shallow-dipping at approximately 30 degrees angled to the east/east-southeast. The deposit is considered to be controlled by a number of northwest and northeast orientated structures, with gold occurring as fine-grained disseminations in localised high-grade calcite-quartz veinlets. Alteration at Diba is typically albite-hematite+/-pyrite, although pyrite content is generally very low (<1 %). The weathering profile at the property is estimated to be up to 70m vertical depth, resulting in extensive oxidation from surface. The oxide gold mineralisation at Diba is predominantly found in saprolite within 50m of surface and across a compact 700m x 700m area.
Diba Mineral Resource Estimate
The Diba project hosts an MRE of 217,000 ounces at 1.39 g/t Au (Indicated) and 187,000 ounces at 1.06 g/t Au (inferred) in both oxide and fresh domains as set out in Table 2. The MRE was previously reported by the Company on
Table 2: Diba Mineral Resource Estimate
Contained gold (oz)
(1) The MRE has an effective date of
(2) The Mineral Resources in the MRE are classified according to the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) "Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines" dated
(3) Mineral Resources are reported within a pit shell and are reported to a base-case cut-off grade of 0.5 g/t Au.
(4) The quantity and grade of reported Inferred Resources in this estimation are uncertain in nature and there has been insufficient exploration to define these Inferred Resources as an Indicated or Measured Mineral Resource and it is uncertain if further exploration will result in upgrading them to an Indicated or Measured Mineral Resource category.
(5) Mineral Resources which are not Mineral Reserves do not have demonstrated economic viability. The estimate of Mineral Resources may be materially affected by environmental, permitting, legal, marketing, or other relevant issues.
(6) All tonnages reported are dry metric tonnes. Minor discrepancies may occur due to rounding to appropriate significant figures.
(7) Tonnages are rounded to 1,000t and gold to 1,000oz as this is an estimate.
The technical disclosure in this regulatory announcement has been approved by
For further information you are invited to visit the Company's website www.altus-strategies.com or contact:
Altus Strategies Plc
Tel:+44 (0) 1235 511 767
SP Angel (Nominated Adviser)
Tel: +44 (0) 20 3470 0470
Tel: +44 (0) 20 3470 0471
Yellow Jersey PR (Financial PR & IR)
Tel: +44 (0) 20 3004 9512
About Altus Strategies Plc
Altus Strategies (AIM: ALS, TSX-V: ALTS & OTCQX: ALTUF) is a mining royalty company generating a diversified and precious metal focused portfolio of assets. The Company's focus on
Cautionary Note Regarding Forward-Looking Statements
Certain information included in this announcement, including information relating to future financial or operating performance and other statements that express the expectations of the Directors or estimates of future performance constitute "forward-looking statements". These statements address future events and conditions and, as such, involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the statements. Such factors include without limitation the completion of planned expenditures, the ability to complete exploration programmes on schedule and the success of exploration programmes. Readers are cautioned not to place undue reliance on the forward-looking information, which speak only as of the date of this announcement and the forward-looking statements contained in this announcement are expressly qualified in their entirety by this cautionary statement.
Where the Company expresses or implies an expectation or belief as to future events or results, such expectation or belief is based on assumptions made in good faith and believed to have a reasonable basis. The forward-looking statements contained in this announcement are made as at the date hereof and the Company assumes no obligation to publicly update or revise any forward-looking information or any forward-looking statements contained in any other announcements whether as a result of new information, future events or otherwise, except as required under applicable law and regulations.
TSX Venture Exchange Disclaimer
Neither the TSX Venture Exchange nor the Investment Industry Regulatory Organization of Canada accepts responsibility for the adequacy or accuracy of this release.
Market Abuse Regulation Disclosure
Certain information contained in this announcement would have been deemed inside information for the purposes of Article 7 of Regulation (EU) No 596/2014 ("MAR") until the release of this announcement.
Glossary of Terms
The following is a glossary of technical terms:
"Au" means gold
"CIL" means carbon-in-leach
"CIM" means the Canadian Institute of Mining, Metallurgy and Petroleum
"CaO" means calcium oxide
"G" means the universal gravitational constant
"g" means grams
"g/t" means grams per tonne
"grade(s)" means the quantity of ore or metal in a specified quantity of rock
"kg" means kilogram
"km" means kilometres
"m" means metres
"mm" means millimetres
"MRE" means Mineral Resource Estimate
"NI 43-101" means National Instrument 43-101 "Standards of Disclosure for Mineral Projects" of the Canadian Securities Administrators
"NaCN" means sodium cyanide
"NPV" means Net Present Value
"oz" means troy ounce
"PEA" means Preliminary Economic Assessment, as a study that includes a preliminary economic analysis of the potential viability of a project's mineral resources
"Qualified Person" means a person that has the education, skills and professional credentials to act as a qualified person under NI 43-101
"t" means tonne (metric ton)
"μm" means micrometre
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