Metallurgical Test Work Indicates Favourable Recoveries and Identifies Areas for Optimization at Marimaca
N e w s R e l e a s e
Metallurgical Test Work Indicates Favourable
Recoveries and Identifies Areas for Optimization at Marimaca
V a n c o u v e r , B r i t i s h C o l u m b i a , J u n e 2 4 , 2 0 2 0 – M a r i m a c a C o p p e r C orp. (“Marimaca Copper” or the
“Company”) (TSX: MARI) is pleased to provide a summary of the metallurgical test work which has been
completed for its flagship Marimaca Copper Project (“Marimaca” or “the Project”), as well as an outline of
the current detailed metallurgica l work, which is ongoing and i s expected to be completed in the current
quarter.
Highlights
The three phases of column and bottle roll test work already completed indicated fast leaching and
favourable recoveries, especially in the dominant oxide mineral zones which comprise the majority
of the deposit
o Average 84% recovery of the tota l copper was obtained in bottle roll testing completed on ore
samples taken from mineral zones comprising the expected early years of mine life
Average recoveries were 4.8% higher than average acid soluble copper across all samples
Indicates leaching recovery, in a heap leach operation, is like ly to exceed the acid soluble
copper percentage for the mineral sub‐zones of Marimaca
Phase 4 test work is underway and expected to be completed late r this month with results to be
released during Q3
o Includes material from La Atomica and Atahualpa which were outside of the original mine plan
o Tests will include acid leaching with seawater, with and without added chloride ions, conducted
in bottle rolls; 30cm mini‐columns; 1.5m columns; and in a ROM leach characterisation for low
grade material
Phase 5 test work will commence in Q3 to further refine results from first four phases and address
variability across the deposit
Michael Haworth, Executive Chairman of Marimaca Copper commented:
“Metallurgy is one of the key de‐risking milestones to address in the development of any mining project.
For Marimaca, we have already completed multiple phases of test work to assess the deposit’s metallurgical
characteristics.
“The results have been very pleasing, especially with respect to the materials which approximately comprise
the first five years of the potential mine life, which is the a ll important payback period. The results show
recoveries of over 84% of total copper, on average, in laborato ry scale testing. Perhaps most importantly,
these results exceeded the expected acid solubility ratio of the ore samples tested. This means that some of
the minor copper bearing minerals, which weren’t initially iden tified as acid soluble, are also amenable to
acid leaching and gives us great optimism for the potential for h i g h e r r e c o v e r i e s i n a n e v e n t u a l h e a p
leaching operation.
“It is also clear that, with the amount of technical work and de‐risking milestones achieved already, we are
well ahead of a typical PEA stage of development. The Phase 4 m etallurgical program, which is due to be
completed later this month and released during the third quarter, will significantly advance our knowledge
and provide additional data across many parts of the deposit. T his will provide the Company with a robust
geometallurgical model which, in turn, will allow a detailed life of mine analysis of metallurgical recoveries
for future studies. Phase 5, which is expected to commence in t he 3rd quarter of this year, will allow us to
focus on optimizing a very exciting copper project, as we move into the next phases of study.”
Marimaca Copper Project Overview
Marimaca Copper released an updated Mineral Resource Estimate (“MRE”) for Marimaca of 70 million
tonnes, with an average grade of 0.60% total copper, within the Measured & Indicated Categories
(approximately 420Kt of contained copper) and 40 million tonnes , with an average grade of 0.52% total
copper, within the Inferred Category (approximately 224kt of contained copper) (refer release on 2
December 2019). This represents an increase of almost 10 0% from t he MRE rele ased in April 2018 and
makes the Project one of the most significant copper oxide discoveries in Chile in the last decade.
The Company is currently undert aking a PEA for the Project, whi ch is anticipated to b e completed in July
2020. The Project is expected to benefit from low upfront capita l d e v e l o p m e n t c o s t s a n d , d u e t o t h e
favourable geometry of the orebody and relatively simple oxide processing through SX‐EW, management
believes the Project will have very competitive operating costs, delivering compelling economics in the PEA.
Overview of Metallurgical Test Work Programs Completed
The Company has completed three phases of metallurgical test work between April 2017 and March 2018,
with a fourth phase currently underway and expected to be compl eted and released to the market in the
coming months. A fifth phase, which extends the previous progr ams will commence in the 3 rd quarter of
2020. The results of Phases 1, 2 and 3 were included in the NI43‐101 Definitive Feasibility Study for
Marimaca 1‐23, released on the 29th of June 2018.
These tests have been carried out b y G e o m e t S . A . , a w e l l k n o w n Chilean laboratory with considerable
experience in metallurgical programs for copper deposits in Chile. Phase 4 has been designed and executed
under the supervision of Marcelo Jo of Jo & Loyola Process Cons ultants, who has 35 years’ experience in
processing. He is supported by Randolph E. Scheffel, a Consultant Metallurgical Engineer with over 35
years’ experience in copper processing.
These tests were completed on materials obtained from Marimaca to characterise the metallurgical
response of the deposit to diffe rent operational conditions. Th e first three phases were performed on a
variety of parameters including agglomeration conditions, granu lometry, column height, irrigation rates
and acid consumption. These tests were followed up with more de tailed analysis including bottle roll Iso‐
pH tests.
The fourth phase program, which is almost complete, comprises broader, more detailed and rigorous
programs, which will provide the final technical data and information required for a Preliminary Feasibility
Study.
A fifth phase will be undertaken to refine any remaining areas of potential risk or gaps in information and
knowledge of the Project. This will likely include optimisation of both acid consumption and recoveries, as
well as addressing variability across the deposit, and providin g information for the completion of a
Definitive Feasibility Study.
Figure 1 below shows the locations of samples used in Geomet Phase 1‐2‐3‐4 testing programs.
Figure 1: Plan Showing Location of Samples from Marimaca
Geomet Test Work Programs Phases 1 to 4
METALLURGICAL TESTING PHASES 1 & 2
The first two phases of metallurgical test work, carried out in April and September 2017, were preliminary
in nature and designed to characterize the Marimaca Project’s copper oxide metallurgical response. Seven
composite samples were prepared for column leaching tests, considering the mineral zones of the deposit
which were identified at that time.
The copper oxide species present are brochantite, atacamite, ch rysocolla and copper wad. The observed
gangue minerals include scarce calcite. Most of the oxides occur as fractures impregnation and filling.
The following table shows the chemical characterization of each sample, the main copper species and
composite location.
Sample CuT % CuS % Solubility
Rate %
Average Acid
Consumption
kg/t
Mineralogical Characterization (location)
M1 0.88 0.71 80 49 Chrysocolla (Pit 2)
M2 1.47 1.17 79 32 Brochantite/A tacamite > Supergene sulfide (Pit 2)
M3 0.49 0.32 65 53 Wad dominant (Pit 2)
M4 0.81 0.71 87 39 Chrysocolla (Pit 1)
M5 1.14 0.97 85 39 Brochantite/Atacamite (Pit 1)
M6 0.62 0.47 75 30 Wad dominant > Supergene sulfide (Pit 1)
M7 0.58 0.40 69 23 Mixed Primary Sulfides‐Supergene > Oxides (High Pit)
Table 1: Summary of Sample for Met Testing Phases 1 & 2
Phase 4
Phases 1‐3
Description of the Tests
In April 2017, Geomet S.A. laboratory was commissioned to start Phase 1 of the initial metallurgical
program which included the mechanical preparation of the ore sa m p l e s , i t s c h a r a c t e r i z a t i o n , h e a d
granulometry analysis, sulphation tests, ISO‐pH tests, leaching tests at two granulometries in seven
columns of 6” diameter and 1 meter height in duplicate, tailin gs analysis was considered for each test. A
key outcome of the tests was the estimation of potential copper dissolution that may be expected in a
leaching operation, which is the ratio of acid soluble copper ( CuS %) to total copper in a sample (CuT %)
(the acid Solubility Ratio), as shown in the above table. The l aboratory procedure to determine CuS is to
contact a 1 g of pulverized ore sample with 50ml of sulfuric acid solution at 5% v/w, while agitating for one
hour and analyze the copper dissolution.
Based on the previous Phase 1 results, Geomet S.A. was commissioned in September 2017 to execute Phase
2 of the metallurgical program using the same samples, which considered more specific parameters to
further optimize the testing results, to inform future process design parameters, including:
Particle size: ‐ 90% below half inch
Irrigation Rate – reductions in irrigation rates from phase one to find an optimal rate
A c i d i n A g g l o m e r a t i o n – s u l p h a t i o n t e s t s t o i d e n t i f y a c i d d e f i cit and triangulate optimal acid
application
Column Leaching – Tests performed at different heights ranging from 1.6m to 3.0m
Leaching time, application rate and acid consumption
Conclusions
The overall metallurgical response from the first phase showed favourable results supporting good
recoveries for the different ore samples tested.
Leach kinetics were rapid with 70% to 80% of total copper recovered within the first one third of the leach
cycle. Recoveries ranged from 77% +‐3% for the Chrysocolla to 5 8% +‐3% for the mix of primary sulphide
and supergene oxides. Average acid consumption across the samples was, on average, slightly over 40kg/t,
indicating a mid range acid consumption profile. The table below shows recoveries and acid consumptions:
Sample CuT % CuS % Recovery (%) Acid Consumption (kg/t) Mineralogical Characterization (location)
M1 0.88 0.71 77% +‐3% 42 +‐ 4 Chrysocolla (Pit 2)
M2 1.47 1.17 67% +‐ 3% 50 +‐ 4 Brochantite/Atacamite > Supergen e sulfide (Pit 2)
M3 0.49 0.32 62% +‐ 3% 52 +‐ 4 Wad dominant (Pit 2)
M4 0.81 0.71 77% +‐ 3% 42 +‐ 4 Chrysocolla (Pit 1)
M5 1.14 0.97 76% +‐ 3% 37 +‐ 3 Brochantite/Atacamite (Pit 1)
M6 0.62 0.47 70% +‐ 3% 38 +‐ 3 Wad dominant > Supergene sulfide (Pit 1)
M7 0.58 0.40 58% +‐ 3% 40 +‐ 3 Mixt Primary Sulfides‐Supergene > Oxides (High Pit)
Table 2: Phase 1 & 2 Summary of Metallurgical Results per Sample
Given the preliminary nature of t h i s t e s t i n g , i t w a s e x p e c t e d that significant further optimisation and
improvement would be achieved in following test work campaigns w i t h r e s p e c t t o r e c o v e r y a n d a c i d
consumption.
METALLURGICAL TESTING PHASE 3
Phase 3 testing, which was completed in March 2018, was primarily focused on defining the metallurgical
response on ore samples which would be expected to be representative of the first five years of extraction.
For this reason, the samples tested had a higher proportion of brochantite/atacamite and chrysocolla. 37
composites from 13 drill holes were selected, 10 reverse circulation (RC) and 3 diamond drill holes (DDH).
Test Description
This test program included the h ead chemical characterization o f all composites (CuT, CuS, FeT, Al, Mg,
CAA, CO3, AlS, FeTS and MgS) and the completion of 42 iso‐pH 1. 5 tests, 37 of them at 48hrs and 5 at 72
hrs.
Main Results
The results of the bottle tests are summarized in table 3 below.
Virtually all samples show total copper recoveries which exceed ed the acid solubility ratio for the sample.
This confirmed the work completed and results received in Phases 1 & 2.
Sample
ID
Leach
Time
CuT CuS Solub.
Ratio
Avg.
Copper
Ratio
Leach
Rec./CuS
Acid Consumption Head
(h) AQ (%) (%) Recovery
(%) (%) Gross Net CO3 CAA
(kg/t) (kg/t) (%) (kg/t)
M‐4 48 1.01 0.81 80 84.7 1.06 35.8 22.9 0.15 28.8
M‐5 48 0.74 0.48 64.73 74.8 1.16 30.4 22.1 0.15 35.5
M‐6 48 0.37 0.26 70.05 82 1.17 44.3 39.8 1.1 48.1
M‐7 48 0.87 0.55 63.35 74.9 1.18 33.3 23.3 0.05 37.8
M‐8 48 1.66 1.36 81.64 84.6 1.04 40.8 19.4 0.05 40.2
M‐9 48 1.13 0.87 77.1 84.7 1.1 40.3 26 0.45 50.3
M‐10 48 0.67 0.53 79.54 86.5 1.09 39.9 31.2 0.4 37.5
M‐10 72 0.67 0.53 79.54 87.7 1.1 42.3 34 0.4 37.5
M‐11 48 0.61 0.47 76.78 83.7 1.09 39.4 31.6 0.6 34.6
M‐12 48 1.05 0.96 90.93 93.3 1.03 42.2 27 0.1 48.2
M‐13 48 0.65 0.56 86.27 88.7 1.03 33.5 24.8 0.4 52.2
M‐13 72 0.65 0.56 86.27 89.9 1.04 40.4 32.4 0.4 52.2
M‐1 48 0.5 0.43 85.03 83.7 0.98 45.3 39.6 0.82 36.8
M‐2 48 0.46 0.37 81.08 86.9 1.07 44.7 38.8 0.86 37.5
M‐3 48 0.62 0.48 77.56 82.9 1.07 47 40.1 1.05 35.3
M‐14 48 1.77 1.63 91.9 95.8 1.04 75.9 52.7 1.9 83
M‐15 48 1.32 1.09 82.39 91.4 1.11 71.7 54.2 2.48 69.2
M‐16 48 0.83 0.63 75.55 76.7 1.02 64.7 56.4 2.62 70.7
M‐17 48 0.38 0.28 74.84 80.5 1.08 81.9 77.8 3.86 75
M‐17 72 0.38 0.28 74.84 82.9 1.11 85.3 81 3.86 75
M‐18 48 0.78 0.68 87.42 88.9 1.02 39.3 29.6 0.32 61.1
M‐19 48 0.54 0.45 82.54 81 0.98 57.7 52.2 1.65 58.1
M‐20 48 1.14 0.9 78.78 80 1.01 78.1 65.7 2.57 68.4
M‐21 48 0.82 0.72 88.46 87.5 0.99 18.5 8.8 4.34 30.5
M‐22 48 1.18 1.09 92.83 90.5 0.97 66.7 52.4 2.13 44.5
M‐23 48 1.65 1.58 95.62 93.9 0.98 97.7 76.9 3.96 86.5
M‐23 72 1.65 1.58 95.62 93.9 0.98 104.6 83.9 3.96 86.5
M‐24 48 1.62 1.41 86.82 89.8 1.03 51.9 32 0.31 37.3
M‐25 48 0.4 0.31 77.7 82.8 1.07 33 28.1 0.59 18.1
M‐26 48 1.05 0.87 82.83 82.7 1 41.8 29.1 0.36 49.4
M‐27 48 0.54 0.43 80.36 82.1 1.02 35.4 29.2 0.63 33.2
M‐28 48 0.43 0.33 78.32 79.7 1.02 43.1 38.2 1.37 38.9
M‐29 48 0.57 0.5 88.88 88.7 1 60.2 52.9 1.97 46.8
M‐30 48 0.85 0.62 73.9 84.2 1.14 48.5 39.2 0.2 38.6
M‐31 48 0.59 0.36 62.26 78.3 1.26 32.5 26.4 0.58 38.9
M‐32 48 0.72 0.52 72.55 82.8 1.14 40 31.6 0.74 27
M‐33 48 0.47 0.34 71.52 77.6 1.09 48.1 43 1.71 71
M‐34 48 0.76 0.57 74.71 80.4 1.08 51.6 42.7 1.66 41.8
M‐35 48 1.04 0.61 58.81 72.5 1.23 46.2 35.5 0.74 12.3
M‐35 72 1.04 0.61 58.81 71 1.21 52.3 42.1 0.74 12.3
M‐36 48 0.42 0.34 80.79 82.4 1.02 59.1 54.1 2.16 46.1
M‐37 48 1.84 1.56 84.63 87.2 1.03 79.8 56.8 2.39 71.2
Table 3: Iso‐pH tests, CuT recovery and acid consumption
Conclusions
For the 42 samples, average recoveries exceeded the acid solubility ratio of the samples by nearly 5%.
The average total copper extracti on was 84.15%, and the average of the acid solubility ratio was 79.4%
across the samples.
This confirmed the conclusion from previous test work, that a portion of the acid insoluble copper, in some
cases a very meaningful portion, was dissolved. This also agree s with the assessment of the likelihood of
leaching potential of the materi als tested to exceed the acid s olubility ratio. This is thought to be a result
of the increased exposure time to acid – in the case of the bot tle rolls, exposure time of 5hrs and 72hrs,
when compared to 1hr in the initial acid solubility test.
The average net acid consumption across the samples was 39.3 kg/t continuing to indicate a mid range acid
consumer. It should be noted that acid consumption may be further optimised by adjusting concentrations,
but this work will be completed in later phases of testing.
METALLURGICAL TESTING PHASE 4
The Phase 4 metallurgical test work program commenced in January 2020 and is expected to be completed
by the end of June 2020 and released during the 3 rd quarter. Following on from the results received in
Phases 1, 2 and 3, this phase was designed to be broader in its coverage of the metallurgical response of
Marimaca, providing significantly more detail with respect to c ertain mineralisation sub zones and
addressing some aspects of variability across the deposit.
Composite samples were taken considering the updated mineral subzones, which are now defined as
follows:
Bronchantite / Atacamite;
Chrysocolla;
Wad;
Mixed; and
Enriched.
Each zone has different copper mi neral species and, it was note d, in the tests conducted in the Phase 3
program, the overall leaching recovery exceeded the acid solubility ratio across the samples. Assessing the
leaching characteristics of each subzone, and their true leaching potential, will be an important step in
developing a robust geometallurgical model, which can consider variability across the deposit and provide
data to optimize future design.
The solubility ratio for copper oxides such as atacamite, brochantite and chrysocolla, which dissolve quickly
when exposed to acid, is a good predictor of leachability. Howe ver, where the minerlization has several
c o p p e r b e a r i n g m i n e r a l s w i t h d i f f e r e n t d i s s o l u t i o n c h a r a c t e r i s tics under these leaching conditions, the
c o p p e r a c i d s o l u b i l i t y r a t i o m a y u n d e r e s t i m a t e t h e a c i d l e a c h i ng potential for heap leach operations,
especially where some copper sulphides such as chalcocite, covellite and bornite are present, as these
sulphides could be partially dissolved under oxidation conditions.
For this reason, it is also common to assay for cyanide soluble copper when assaying copper oxide samples.
T h i s g i v e s a n i n d i c a t i o n o f t h e total leaching potential because cyanide dissolves some of the copper
sulphides that may be present in the sample and assumes that, during the leaching operation, some
oxidation reactions, such as, fe rric leaching and/or cupric chl oride leaching occur. Due to these reactions
during sulphide leaching it can be inferred that copper dissolu tion in a leaching operation may materially
exceed the copper acid solubility ratio identified. Phase 4 metallurgical testing is addressing this point
through both mini column and 1.5 m column testing under different leaching conditions.
Tests being undertaken in Phase 4 include:
Head Chemical Characterization with sequential copper analysis
Particle size characterization
1.5 iso‐pH test with and without seawater
Acid and chloride leaching tests in 30 cm mini‐columns
1.5 m columns tests; and
ROM leaching in 1m3 iso containers of a low grade wad sample with minor presence of
chrysocolla, atacamite and secondary sulphides.
METALLURGICAL TESTING PHASE 5
Phase 5 metallurgical testing will be informed by the results a nd synthesis of information obtained in all
the previous metallurgical testing programs. Scoping is currently underway for this work and the Company
expects that this will provide s ufficient information required for a bankable feasibility study and to move
into detailed design and engineering.
The test work program will consid er parameters including, but n ot limited to, agglomeration conditions,
column height, granulometry, irrigation rate, acid concentration and leaching cycle time.
A core objective of the Phase 5 test plan is to complete the full evaluation of metallurgical variability of the
resource, extending on the variability work which is being comp eted as part of the Phase 4 program. The
sample base used in this program will be much larger and will p rovide data on multiple permutations of
mineral sub‐zone which may be expected during operations.
Qualified Person
The technical information in thi s news release, including the i nformation that relates to geology, drilling
and mineralization was prepared under the supervision of, or h as been reviewed by Sergio Rivera, Vice
President of Exploration, Marimaca Copper Corp, a geologist with more than 36 years of experience and a
member of the Colegio de Geólogos de Chile and of the Institute of Mining Engineers of Chile, and who is
the Qualified Person for the purposes of NI 43‐101 responsible for the design and execution of the drilling
program.
The Qualified Person for other content than geological information of this news release is Luis Tondo, Chief
Executive Officer and Director of Marimaca Copper, a mining eng i n e e r w i t h m o r e t h a n 3 0 y e a r s o f
experience and a Fellow of The Australasian Institute of Mining and Metallurgy, who is the Qualified Person
for the purposes of NI 43‐101.
All QPs confirm they have visited the project area, reviewed relevant project information, allowing the
correct technical judgement in their respective areas of expertise, in turn used in the writing and reviewing
the contents of this news release.
Marimaca Copper and the Marimaca Project
Marimaca is fast becoming recogn ised as one of the most signifi cant copper discoveries in Chile in recent
years as it represents a new typ e of deposit which challenges a ccepted exploration wisdom and promises
to open up new frontiers for discoveries elsewhere in the count ry. Marimaca is hosted by intrusive rocks
while the numerous manto deposits in the same region are hosted by volcanics. With a lack of new copper
exploration discoveries in Chile, the growing Marimaca resource is a high‐profile development project as it
is situated in the coastal belt at low elevation close to Antofagasta and Mejillones. This prime location could
enable its future development at a reduce capital cost relative to many other copper developments.
Marimaca will benefit from nearby existing infrastructure inclu ding roads, powerlines, ports, a sulphuric
acid plant, a skilled workforce and seawater and a relatively low environmental impact.
Contact Information
For further information please visit www.marimaca.com or contact:
Tavistock
+44 (0) 207 920 3150
Jos Simson/Emily Moss