Mako Mining Announces Favorable Metallurgical Test Results from the Historical Dumps at San Albino, with Gold Recoveries of 96.4% which Includes Gravity Recoveries of 48.1%

Mako Mining Announces Favorable Metallurgical Test Results from the Historical Dumps at San Albino, with Gold Recoveries of 96.4% which Includes Gravity Recoveries of 48.1%

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VANCOUVER, BC, Oct. 5, 2020 /CNW/ – Mako Mining Corp. (TSXV: MKO) (OTCQX: MAKOF) (“Mako” or the “Company”) is pleased to report that it has completed further metallurgical tests on its wholly-owned San Albino gold project (“San Albino”) located in Nueva Segovia, Nicaragua. The scope of the testwork was aligned with the design of the San Albino mill currently under construction, which is scheduled to be complete in January 2021. The gravity-cyanidation flowsheet design is based on extensive mineralogical and metallurgical investigations completed in the 2016-19 period to define the mill design parameters as well as preliminary testwork completed in 2016. The historical dump material available on site from previous mining activity represents the potential for more than 120,000 tonnes not previously considered in the preliminary economic assessment (“PEA”), dated April 29, 2015 and available under the Company’s profile on SEDAR at www.sedar.com. The historical dump material will be used for start-up of the mill.

Akiba Leisman, Chief Executive Officer of Mako states that “these metallurgical results provide a positive assessment of the historical mining dumps that can be processed during start-up. In addition to verifying the grade of the historical dump material, this testwork further confirms that the processing plant flowsheet being constructed should achieve high recoveries of gold and silver. Importantly, the historical dump material contains grades significantly higher than the cutoff grade being used to calculate the updated mineral resource at San Albino, which has been slightly delayed and is expected to be released later this month. The higher grades of the historical dump material should also be helpful in prepping the processing plant to handle the high-grade vein material once the commissioning is complete, which is expected to occur in early Q2.”

The sample composites used to assess the amenability to processing in the mill currently under construction of the primary historical dump material (“Cancha #1”), were obtained from two randomly selected drill holes using a quarter of the drill intercepts to provide 12 samples totaling 33.4 kg. A composite sample of the Cancha #1 material for the metallurgical work was subjected to metallic assays and triplicate fire assay, the procedure previously completed in other testwork to address the presence of free gold. A sample was prepared from previous testing of San Albino oxide mineralization for cyanidation testwork for purposes different than the Cancha #1 material although data is presented here along with the cyanidation testwork on the Cancha #1 sample. The assays for the Cancha #1 main composite sample averaged 4.73 g/t Au and 17 g/t Ag while the grade of the San Albino oxide gravity tailings sample from previous testing averaged 6.07 g/t Au and 20 g/t Ag. The head grades of the samples tested are as follows:

AnalyticalMethodCancha # 1 Composite Heads (Before Gravity Processing)
Au g/tAg g/t
Metallics3.2918
Fire Assay5.7216
Fire Assay5.0819
Fire Assay4.8116
Averages4.7317
 
 Cancha #1 CIL Test Heads*San Albino Oxide CIL Test Heads*
1st CIL Test2.22156.0720
2nd CIL Test2.10136.0720
Averages2.16146.0720
*The Cancha #1 material and San Albino Oxide CIL Test Heads were part of separate metallurgical programs and not tested for direct comparison. They are only shown together in this summary table for informational purposes.

The gravity separation on the Cancha #1 material, from bench scale testing averaged recoveries of 48.1% Au and 18.2% Ag. The gravity tails from the Cancha #1 sample tests were subjected to cyanide leach tests for 48 hours which extracted a further 47.8% Au and 70% Ag raising the combined recovery on the Cancha #1 material to 96.4% Au and 88.3% Ag. The gravity tails of the San Albino oxide sample was leached in cyanide under the same conditions as the Cancha #1 sample with the cyanide level maintained at 2.0 g/l and the pH at 10.5 to 11. The testing indicated that the processing of the Cancha #1 material would require higher cyanide consumption and longer leach times than other mineralized types previously tested. The testing showed that the leach kinetics of the San Albino oxide gravity tails were more rapid and require leach times within design parameters. The Au and Ag extractions from CIL on the San Albino oxide gravity tails sample were 94.8% Au and 62.2% Ag. Despite the slower kinetics and higher reagent consumptions shown for the Cancha #1 sample, the San Albino mill now under construction will provide the processing conditions necessary to achieve high recoveries on this style of mineralization. A summary of two tests on each material, of the main parameters of the cyanidation testwork on the two samples is as follows:

SampleP-80
Grind
Size
Leach
Time
Composite
Heads
Gravity
Recovery
CIL Test
Heads
CIL
Extraction
Overall
Recovery
Reagents
MicronsHoursAu g/tAg g/tAu %Ag %Au g/tAgg/tAu %Ag %Au %Ag %Cyanide kg/tLime kg/t
Cancha #1101-102484.731748.118.22.161447.870.096.488.35.442.22

The amount of organic carbon in the Cancha #1 sample was measured with carbon showing 0.18%, which is similar to the San Albino oxide gravity tails. This is the first testing of historical dump material and the particle size distribution shown in the Bureau Veritas report indicates that the Cancha #1 material is similar to the previously tested materials in terms of clay content.

Sampling, Assaying, QA/QC and Data Verification

All sample preparation, compositing, and test work was performed or overseen by independent lab, Bureau Veritas Laboratories in Vancouver, Canada. Their processes and assaying results met the requirements of the Company and its employees, including Senior Metallurgical Engineer Craig L. McKenzie, and are traceable and well documented.

Qualified Person

Ross MacFarlane P. Eng. of Watts, Griffis and McOuat Limited (“WGM”), Associate Metallurgist and Joe Hinzer, P.Geo., the President and Director of WGM, both independent of Mako and “qualified persons” under NI 43-101 have reviewed and approved the written scientific and technical disclosure contained in this press release.

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