Improving Cu-Mo Recoveries in the Vizcachitas Project

Magín Torres, Senior Metallurgist. Cia Minera Vizcachitas Holding – Los Andes Copper

Agenda

• Vizcachitas Project Overview

• Background

• Preliminary rougher flotation assessment

• PFS test work plan

• Sample selection

• PFS test work and results

• Final Remarks

Vizcachitas Project Overview

• Chile’s next major copper mine• Cu-Mo porphyry located in the Province of San Felipe, V Region, Chile.• 100% owned by Los Andes Copper Ltd (TSX-V: LA)• Currently undertaking a PFS study (since mid-2019)• 110 ktpd concentrator

PFS Study Key Drivers Process Design Criteria

Reduce Energy Consumption

• HPGR Comminution circuit• Aim for a P80 >=240 µm

Reduce Water Consumption • Dry-stacked Filtered Tailings

depositReduce Footprint and environmental Risk Santiago

Vizcachitas

Los Bronces

El Pachón

Andina

Los Pelambres

Background

• First metallurgical test work in 1996

• Vizcachitas is a primary ore (mainly chalcopyrite)

• Main gangue minerals are hard silicates (80%) and phyllosilicates (20%)

• Low presence of clays (<1%)

• Reagent formula based on a XIPS/DTP mix + MIBC

• 2017-2018 test work showed good metallurgical recoveries at P80 coarser than 240 microns

• One of the first task of the PFS study was to study the effect of process water in the flotation stage.

PEA FormulaTap WaterpH=10.5, Cp=38%

87% Cu81% Mo

Crude SeawaterCrude SeawaterpH=7.5, Cp=38%

90% Cu85% Mo

New Formula (PFS-A)Crude SeawaterpH=7.5, Cp=30%Frother mix w/o NaHS

93% Cu87% Mo

ORP screeningCrude Seawater+NaHS 100,-100mV

91% - 90% Cu82% - 78% Mo

Crude seawater preliminary assessment (rougher)

Flotation testing was conducted on a “Upper Zone” composite from the 2018 testwork

PFS metallurgical test work

Mine Plan

SampleSelection

Ore Characterization

Definition ofthe Reagent

FormulaGrindingKinetics

Process Water Assessment

Flotation TestRougher, Cleaner,

OCT and LCT

PFS Sample Selection

Sample Represent

AND Andesite lithology of southern area

BXI Breccia lithology of southern area

DIO Diorite lithology of southern area

TON Tonalite lithology of southern area

N16Y First 6 years of northern area

N712Y Years 7-12 of northern area

0%

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25%

30%

35%

0.18-0.270.27-0.360.36-0.450.45-0.540.54-0.630.63-0.720.72-0.81 0.81-0.9 0.9-0.99 0.99-1.08

Freq

uen

cy,

%

Copper grade, %

Cu grade histogram for sample N712Y

Plan Sample

Sample selection criteria• Represent main lithologies of the first 12 years of the mine plan.• Drill core samples above the cutoff grade• Individual drill core samples matched the Cu ore grade

distribution.• Individual core samples covered the entire volume defined in the

first 12 years of the mine plan.

Mineralogical characterization (Optical + QEMSCAN)

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100%

AND BXI DIO TON N16Y N712

Ore mineralogy (sulphides)

CHALCOPYRITE CHALCOCITE COVELLITE

BORNITE MOLYBDENITE PYRITE

GALENA+SPHALERITE As+Sb SULPHIDES

Formula PEA PFS-A PFS-B PFS-CWater Tap Water Crude seawater Crude seawater Tap WaterSolids, %wt 38 30 30 30Agitation time 1 min 5 min 5 min 5 minpH 10.5 7.5 7.5 7.5Collector #1 10 g/t XIPS 20 g/t XIPS 20 g/t XIPS 20 g/t XIPSCollector #1 20 g/t ditiophosphate 20 g/t ditiophosphate 20 g/t thionocarbamate 20 g/t thionocarbamateFrother #1 15 g/t MIBC 5 g/t MIBC 5 g/t MIBC 5 g/t MIBCFrother #2 30 g/t PP-Glycol 30 g/t PP-Glycol 30 g/t PP-GlycolModifier #1 20 g/t of Diesel 20 g/t of Diesel 20 g/t of Diesel 20 g/t of DieselModifier #2 Lime to adjust pH Lime to adjust pH Lime to adjust pH Lime to adjust pH

Cell operating parameters• Denver 2-liter cell• Agitation Speed: 1400 rpm• Gas flow: 10 L/min• Froth scrap frequency: 1 in 10 s

PFS Rougher flotation assessment: Reagent Formulas

PFS Rougher flotation assessment

• Preferred formulas are • PFS-A (crude seawater)• PFS-C (tap water)

• Improvements over PEA formula• Copper (avg)

• PFS-A +3.5%• PFS-C +3.1%

• Moly (avg)• PFS-A +9.1%• PFS-C +8.6%

LessVariability

LessVariability

Regrinding evaluationLower regrinding P80’s improves Cu concentrate grade and cleaner recoveries.

83.8 85.8 88.1

13.2 12.0 10.23.0 2.2 1.7

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203 45 25

P80 of rougher concentrate

Liberation of Cu primary sulfides in the Rougher concentrate

Free Middlings Locked

Rougher concentrate without regrind

Cleaner – Scavenger Flotation tests (1)

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First Cleaner Flotation Kinetics for Moly

45 micron, pH=11.5, Seawater 45 micron, pH=11.5, Tap water

37 micron, pH=11.5, Tap water 37 micron, pH=12, Tap water

25 micron, pH=11.5, Tap water 25 micron, pH=12, Tap water

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Time, min

First Cleaner Flotation Kinetics for Copper

45 micron, pH=11.5, Seawater 45 micron, pH=11.5, Tap water

37 micron, pH=11.5, Tap water 37 micron, pH=12, Tap water

25 micron, pH=11.5, Tap water 25 micron, pH=12, Tap water

Used seawater in rougher flotation and tap water in cleaner flotation

• Moly recoveries decreases with the presence of Mg+2 and Ca+2 ions at pH>9.5 (Lina Uribe PhD thesis, 2017)• Sulphates favor gangue flotation and decreases concentrate grade (Sinche-Gonzalez et al 2021 and Dzingai et al 2020)

Cleaner – Scavenger Flotation tests (2)

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First Cleaner Flotation Cu concentrate grade

45 micron, pH=11.5, Seawater

45 micron, pH=11.5, Tap water

37 micron, pH]=11.5, Tap water

37 micron. pH=12, Tap water

25 micron, pH=11.5, Tap water

25 micron, pH=12, Tap water

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First Cleaner Flotation Mo Concentrate grade

45 micron, pH=11.5, Seawater

45 micron, pH=11.5, Tap water

37 micron, pH=11.5, Tap water

37 micron, pH=12, Tap water

25 micron, pH=11.5, Tap water

25 micron, pH=12, Tap water

Locked cycle test work and final concentrate analysis

LCT Feed

Rougher

CleanerRegrinding

Scavenger

Bulk Concentrate

Combined Tails

Regrinding_Combiner

8.780 23.735

4.970 4.384

0 997.084

Rougher - Con

8.780 8.780

4.970 5.059

0 1,151.056

LCT Feed - Prod

100.000 100.000

0 0.479

0 113.832

Scavenger - Con

0 14.955

0 3.987

0 906.692

Bulk Concentrate_Combiner

1.790 1.798

24.400 24.400

5,412.3905,412.380

Combined Tails_Combiner

98.090 98.202

0.0409 0.041

16.797 16.840

Rougher - Tail

91.220 91.220

0.038 0.038

14.000 14.000

Scavenger - Tail

6.870 6.982

0.08 0.08

53.940 53.940

TPH - Solids (Exp) TPH - Solids (Bal)

Assay - Cu (Exp) Assay - Cu (Bal)

Assay - Mo (Exp) Assay - Mo (Bal) Sample Cu Mo Fe S Au Ag

Unit % % % % g/t g/t

Conc 24.4 0.54 24.9 30.3 0.4 50

Conc 22.9 0.64 26.2 30.4 0.6 65

• Concentrate grade weighed average of the first 12 Years

• As: 0.16%

• Sb: < 0.04%

• Bi: < 0.01%

• Only a single cleaner stage is required.

• Vizcachitas will produce clean concentrates.

Final Remarks

• Rougher recoveries were improved in 3% for Cu and 8% for Mo by operating at a pH 7.5 and by adding a stronger frother in the formula.

• Operating at a coarser P80 in the primary grinding stage (240 µm) requires further regrinding (25 µm) to achieve an appropriate liberation for cleaner/scavenger stages.

• The use of crude seawater deteriorates global moly recoveries and copper concentrate grades, even if tap water is used in the cleaner stages.

• Vizcachitas will produce clean concentrates. For the first 12Y overall recoveries are 91.4% Cu and 75% Mo.

END of Presentation