Constancia Project Process Plant Design and Start-Up

Presentation Outline

• project scope, location and background

• process plant overview

• plant capacity and design basis

• general design approach

• process plant design

• plant start-up

Project Scope

The Constancia project consists of a large-scale porphyry copper deposit in southern Peru at 4,200 masl including:

• open pit mine.

• process plant for recovery of copper and molybdenum concentrates.

• tailings management facility.

• associated infrastructure including power supply, water supply, workshops and accommodation camp.

The project was built for a cost of approximately US$1.75 B.

Project Location Figura– Mapa de Ubicación del Área del Proyecto / Figure 1

Constancia

Project

630 km south-east of Lima; 110 km south of Cusco, Peru.

Project Background

• Sept 2009 – GRDMinproc (now AMEC) completes DFS.

• 2010 – Norsemont contracts Ausenco to complete a Feasibility Study Optimisation Review.

• Feb 2011 – Ausenco completes Technical Report (with input from SRK and Knight Piesold).

• 2011 – HudBay acquires Norsemont (and Constancia Project).

• 2011 – Ausenco commences engineering work for permitting and FEED phase.

• 2012 – Beneficiation concession permit received in June 2012.

Project Background

• 2012 – Hudbay’s board approves construction in August 2012.

• 2014 – copper concentrate production commences Dec 2014.

• 2015 – commercial production achieved April 2015.

Mineralogy and Major Ore Types

• majority of mineralisation associated with potassic alteration and quartz veining (occurring as chalcopyrite-bornite-pyrite mineralisation in Type A and B veinlets).

• high-grade hypogene copper mineralisation found in Type A stockwork.

• pyrite/chalcopyrite ratio is relatively low ranging from 1:1 to 2:1.

• occurrence of molybdenite generally increases with depth and is associated with Type B veinlets.

• oxide mineralisation occurs locally – shallow and volumetrically small.

• supergene enrichment occurs immediately below the oxide cap.

• transition (mixed) mineralisation present over a limited interval where supergene and hypogene mineralisation co-exist.

Mineralogy and Major Ore Types

Abundance of major ore types:

Ore Type Relative Abundance (%)

Hypogene 63

Supergene 20

Skarn 1 6

Skarn 2 / High Zn 11

Process Plant Overview

Key unit processes:

• primary crusher

• stockpile and reclaim

• grinding and pebble recycle

• copper flotation and regrind

• copper concentrate thickening

• copper concentrate filtration and load out

• tailings thickener

• molybdenum flotation

• molybdenum concentrate handling

• reagents and services

Process Flowsheet

Process Plant

Design Basis Summary – Throughput

Plant throughput:

• plant capacity 25.3 Mt/y

• plant capacity 38,000 t/d (per line)

• plant capacity 76,000 t/d (total)

Note: The Constancia plant is capable of treating up to approximately 86,000 t/d (28.8 Mt/y at 91.3% availability) subject to ore competency and SAG mill feed size with throughput expected to average 80,000 t/d.

Design Basis Summary – Operating Availability

Operating availability:

• crusher operating hours: 6,132 h/y (70%)

• grinding / flotation operating hours: 8,000 h/y (91.3%)

• concentrate filter operating hours: 7,200 h/y (82.2%)

Design Basis Summary – Nominal Grade and Recovery

Product Nominal Concentrate

Grade Nominal Recovery

Copper Concentrate 26% Cu 90%

Moly Concentrate 45% Mo 55%

Average feed grades: 0.39% Cu; 105 g/t Mo Average annual copper production: 82,000 t (contained metal in conc)

General Design Approach

• use of natural ground contours

• minimise height of structures

• minimise use of fully enclosed buildings

• use of tower crane (construction & operations)

• compact plant footprint

• location of sub-stations and MCCs

Key objective – capital efficient design (minimise capital and operating cost without compromising safety, operability and maintainability).

Primary Crusher

Primary crusher criteria:

• crushing work index CWi = 20 kWh/t (design)

• 4,125 t/h (nominal) / 6,000 t/h (design)

• dump pocket designed for 250 t haul trucks (2 points for direct tipping).

• single primary gyratory crusher (FLSmidth 1600 x 3000 TSU 1,000 kW).

• top service machine serviced by overhead crane.

• drive-in ramps for clean out of dump pocket and discharge vault.

Primary Crusher

Stockpile / Reclaim

Stockpile criteria:

• single open conical stockpile

• stockpile capacity (live) = 16 h

• stockpile capacity (total) = 200,000 t

• reclaim feeder rate (each) = 1,600 t/h

• dual reclaim lines (2 apron feeders per line)

• free draining tunnels

• common ventilation system.

Stockpile / Reclaim

Grinding

P75 values (above) for each ore type used in the absence of any other relationship linking ore properties to the block model.

Ore Type Axb Value BMWi

(kWh/t) SG

DWi (kWh/t)

Percentile P75 P50 P75 P75 P75

Hypogene 38 42.5 15.9 2.54 7.3

Supergene 77 90 12.8 2.47 3.7

Skarn 76 120 11.5 3.73 3.8

Ore competency and hardness criteria:

Grinding

Parallel grinding circuits using dual geared drive systems selected due to:

• higher installed SAG mill power (available with geared mills) achieved required maximum throughput.

• maintenance issues associated with GMD mills in the 5 years prior to 2011.

• de-risking plant start up with parallel grinding lines.

• less complex systems for maintenance.

• lower or equivalent capital cost.

Grinding

Comparison of single GMD and dual geared SAG mill system costs:

Item GMD System Geared System

Mill and motor cost (US$M) 39 32

Installed cost (US$M) 61 50

Reclaim and SAG feed system (US$M) 15 20

Approximate total cost (US$M) 76 70

Grinding

• two parallel SAG / ball mill grinding lines with pebble recycle circuits (SAB):

o SAG mills: 10.97 Ø x 7.3 m EGL, 16 MW (dual pinion)

o ball mills: 7.92 Ø x 12.36 m EGL, 16 MW (dual pinion)

o Warman 650 cyclone feed pump (2 MW)

o Krebs gMax26 hydrocyclones

• nominal feed rate(per line) = 1,584 t/h

• product size P80 = 106 micron

• pebble crushers required in Year 6 (harder ore)

Grinding Services

• overhead crane (service cyclones and add ball mill balls).

• drive-on ramp to grinding mill floor.

• drive-in sumps for clean up.

• mill feed chute transporter (RME).

• separate SAG mill and ball mill liner handlers (RME).

• dedicated reline hoists and bolt hammers for SAG and ball mills.

Grinding

Copper Flotation

Copper flotation circuit consists of:

• two parallel lines of mechanical rougher flotation.

• rougher concentrate regrind.

• three stage cleaner circuit comprising:

o mechanical first cleaner flotation.

o mechanical cleaner scavenger flotation (in open circuit).

o mechanical second cleaner flotation.

o column second cleaner (two in parallel).

Copper Flotation Overview

Parameter Units Value

Rougher mass recovery % 9

Rougher stage recovery % Cu 94

Cleaner 1 stage recovery % Cu 85

Cleaner-scavenger stage recovery % Cu 92



Cleaner 3 concentrate grade % Cu 26

Copper Rougher Flotation

Rougher flotation criteria:

• design residence time = 25 min.

• design pulp density = 36% solids.

• mass recovery = 9% (average grade).

• two parallel lines of 7 x Outotec e300 cells.

• forced air tank cells, dual level control dart valves per cell.

• 250 kW direct drive via Moventas gearbox.

Copper Flotation

Copper Rougher Regrind

Rougher regrind criteria:

• product size P80 = 25 micron

• agitated surge tank capacity = 20 min

• specific energy = 8 kWh/t

• Krebs gMax15 hydrocyclones

• single M10,000 Isamill (3 MW) in open circuit

• layout allows for second regrind mill (future) if required

Copper Regrind

Copper Cleaner Flotation

First cleaner flotation criteria:

• cleaner residence time = 12.5 min.

• cleaner scavenger residence time = 15 min.

• 4 x Outotec e130 cleaners.

• 5 x Outotec e130 cleaner scavengers.




Second cleaner flotation criteria:

• Second cleaner residence time = 8 min.

• 3 x Outotec e130 cleaners.




Third cleaner criteria:

• superficial gas velocity 1.5 cm/sec

• carrying capacity = 2 t/m2/h.

• wash water bias ratio = 0.2

• two CPT columns 4.87 m Ø x 12 m high.

• cavitation air sparge system.

Copper Flotation Services

Copper flotation services:

• Outotec Courier OSA system (9 streams).

• LP air blowers to tank cells.

• dedicated compressors to column cells.

• flotation plant serviced by tower crane.

• maintenance stands for servicing cell mechanisms.

Bulk Concentrate Thickening

Bulk Cu-Mo concentrate thickened (to remove residual reagents ahead of moly flotation).

• unit settling area rate = 0.2 t/m2/h.

• underflow pulp density = 60% solids.

• 24 m Ø HRT concentrate thickener (hydraulic drive).

• froth skimmer fitted to recover fine concentrate.

• thickener overflow treated in Jameson flotation cell to minimise loss of Mo fines.

Copper Concentrate Thickening

Final copper concentrate (moly tail) thickened and filtered.


• underflow pulp density = 60% solids.

• 24 m Ø HRT concentrate thickener (hydraulic drive).

• froth skimmer fitted to recover fine concentrate

• separate flocculant preparation facility for concentrate thickeners

Copper Concentrate Handling

Copper Concentrate Filter

Key criteria:

• filter feed tank capacity = 24 hours.

• filter feed capacity = 97 t/h.

• two Larox PF 108/144 M60 160 filters.

• dedicated compressors/receivers for filter pressing and drying air.

Copper Concentrate Loadout

Key criteria:

• 7 days covered storage capacity.

• direct discharge to bunkers.

• truck wheel wash.

• weighbridge.

Tailings Thickening

Key criteria:


• 75 m Ø HRT thickener (hydraulic drive).

• final tailings thickened (50-55% solids) and pumped to TSF.

• dedicated flocculant preparation facility.

• single duty set (5 x Weir Warman 20/18) tailings pumps.

• layout allows for future standby pump set.

• single tailings 750 mm diameter pipeline (HDPE-lined steel).

Tailings Thickening

Molybdenum Plant

Key criteria:

• rougher feed density 30% solids.

• cleaner feed density 15% solids.

• flotation capacity to accommodate high recirculating loads.

• Mo concentrate grade 45% Mo.

• Mo circuit recovery 85.7% (overall recovery = 60%).

Molybdenum Flotation

• two stage rougher conditioning (dilution, pH and Eh control)

• mechanical rougher flotation (FLSmidth inert gas cells).

• five stage cleaner circuit comprising:

o first cleaner conditioning (pH and Eh control)

o mechanical first cleaner flotation.

o mechanical cleaner scavenger flotation (open circuit).

o second cleaner conditioning (pH and Eh control)

o mechanical second cleaner flotation.

o mechanical third cleaner flotation.

o mechanical fourth cleaner flotation.

o Jameson cell fifth cleaner flotation.


Parameter Units Value

Rougher mass recovery % 10

Rougher stage recovery % Mo 95

Cleaner 1 stage recovery % Mo 90

Cleaner-scavenger stage recovery % Mo 85





Cleaner 5 concentrate grade % Mo 45


• mechanical roughers 6 x Wemco No 164 (28 m3) inert gas cells.

• mechanical first cleaner 5 x Wemco No 144 (14 m3) inert gas cells.

• mechanical cleaner scavenger 4 x Wemco No 144 (14 m3) inert gas cells.

• mechanical second cleaner 4 x Wemco No 144 (14 m3) inert gas cells.

• mechanical third cleaner 5 x Wemco No 120 (9 m3) inert gas cells.

• mechanical fourth cleaner 4 x Wemco No 84 (4 m3) inert gas cells

• Jameson cell fifth cleaner Z1200/1.


• enclosed conditioning tanks, hoppers and flotation cells vented to a caustic gas scrubber (H2S)

• Outotec Courier OSA system (5 stream)

• liquid carbon dioxide and evaporator (pH adjustment)

• supplementary inert gas (nitrogen) used to deplete O2

• moly flotation plant serviced by mobile crane

Molybdenum Concentrate Dewatering

Final Mo concentrate thickened, filtered, dried and bagged.

• filter feed tank 24 h capacity.

• concentrate thickener (HRT) 4 m diameter.

• Larox PF 4.7/6.3 filter press with dedicated compressor.

• filter moisture < 15%.

Molybdenum Concentrate Dewatering

• Metso D1216-5 Holoflite dryer (1 t/h).

• product moisture 5%

• wet gas scrubber with SO2 gas sensor.

• product storage bin capacity 24 h.

• bag loader capacity 4 st/h.

Molybdenum Services

• NaHS scrubber for flotation circuit and NaHS storage tanks.

• Nitrogen purge to inert gas flotation cells.

• H2S sensor on exhaust stack.

• H2S and O2 sensors located at NaHS addition points and various locations around the plant.

Reagents and Consumables

Copper Plant:

• lime slurry (quicklime slaker)

• primary collector (Cytec A-3302)

• frother (Cytec AF-65)

• flocculant (tailings)

• flocculant (concentrate)

• grinding media (SAG, ball, regrind mills and lime slaker)

Reagents and Consumables

Molybdenum Plant:

• NaHS depressant

• promoter (diesel + emulsifying agent)

• carbon dioxide (liquid storage and evaporator) pH modifier

• nitrogen gas (PSA unit)

• flocculant (concentrate)

Plant Water Services

• process water

• raw water / fire water

• potable water

• gland seal water

• cooling water

• molybdenum process water

Air Services

• dedicated HP air compressors for : o primary crusher o column cells (one per column) o concentrate filters (drying and

pressing) o molybdenum filter o tailings filters (7 duty / 1 standby) o quicklime unloading.

• all other HP air supplied from plant air system (two duty / one standby).

• LP blowers for copper flotation air (two duty / one standby).

Project Start Up

Key milestone dates:

• 24 Oct 2014 – First ore crushed.

• 16 Dec 2014 – First ore milled through Line 2 (L2).

• 27 Dec 2014 – First copper concentrate produced.

• 24 Jan 2015 – L2 grinding off-line due to bearing damage.

• 1 Feb 2015 – start-up of L1 grinding circuit.

• 16 Mar 2015 – L2 grinding resumed operation.

• 29 Mar 2015 – 3 consecutive days at design throughput.

Plant Start-Up Performance

“Since the end of the second quarter, daily throughput has averaged approximately 80,000 tonnes and copper recoveries

have averaged approximately 75%”, Q2 Management Discussion and Analysis (29 July 2015).

GRACIAS.

Hudbay’s permission to present this information is gratefully acknowledged.

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