teck – aurubis: an integrated mine to metal approach to develop high arsenic copper deposits using...
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8/9/2019 Teck – Aurubis: An integrated mine to metal approach to develop high arsenic copper deposits using the CESL process
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Introduction
Strong demand for copper from emerging economies will place increasingpressure on developing new mine capacity
Future capacity will increasingly have to be mined from non-traditionalcopper resources, specifically those with lower grades, more complexmineralogy, and increasing levels of deleterious elements
One element that has garnered considerable industry attention is arsenic,where concentrations in existing and future mines appear to be on the rise
Arsenic is among the most challenging elements for copper smelters tocontrol as it contributes to environmental concerns during metallurgicalprocessing and materials management
Photo: Antamina Operation, Peru
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The Arsenic Challenge
Lack of arsenic processing capacity from2015 onwards: 30 kt to 40 kt of arsenic
0.16%
0.22% 0.22%
Increasing arsenic levels in concentrates and increasingly restrictiveenvironmental legislation worldwide is widening the gap between capacityto handle arsenic in smelters and arsenic in concentrates
71 78 172 19481 87 142 165
2008 2010 2015 2020
X :Arsenic in concentrates [kt]
X :Arsenic smelting capacities [kt]
Assumption: Maximum global average
arsenic in concentrate blend: 0.21% As
71 78 172 194
2008 2010 2015 2020
.
X :Arsenic in concentrates [kt]
:Global average arsenicconcentration
X
Source: Internal analysis, data from Brook Hunt
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Teck – AurubisTechnical Partnership (1 of 2)
Teck and Aurubis independently identified increasing arsenic content incopper ores and copper concentrates as an emerging challenge, andpotential opportunity, for the copper industry
Teck has developed a proprietary hydrometallurgical process (CESL) to
treat copper concentrates, including those with elevated arsenic
Aurubis is the leading processor of complex custom concentrates by usingenvironmentally sound state of the art technologies
sustainable mine to metal solution to exploit future copper resources highin arsenic concentration
Photos: Copper production, Aurubis operations, Germany
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Teck – AurubisTechnical Partnership (2 of 2)
Strategic joint investment to solve technical issues related to treatingconcentrates with elevated arsenic using hydrometallurgy
Strong technical, environmental, safety, and product stewardship alignmentbetween companies
Provides an environmentally sound and cost effective on-site processingroute for high arsenic bearing copper and copper-gold ore bodies
Copper-Arsenic
Exploration
Mining
Milling
Concentrate
Smelting
Refining
Cu Products
Recycling
Mining
Milling
CESL Refinery
Cathode
Processing Route
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Teck-Aurubis’ approach to processing high arsenic bearing concentrates isfavorable as mineral extraction and arsenic fixation takes place in a singleautoclave vessel
The technology effectively treats refractory copper sulphide mineralswithout the use of exotic reagents, ultra-fine grinding, or extremetemperature and pressure
Importantly CESL technology uses existing commercial technologies suchas ressure oxidation solvent extraction and electrowinnin
CESL Copper-Arsenic Technology
It has been thoroughly developed and proven at scale achieving highmetallurgical recoveries and product quality requirements
Photos: Vale’s 10ktpa copper cathode CESL refinery, Brazil
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CESL Copper Process
Copper minerals are oxidized and leachedusing recycled raffinate
− Arsenic minerals: predominantlyenargite (Cu3AsS4) and tennantite
(Cu12As4S13)
Autoclave conditions: 150°C, 1380 kPa,60-90 minutes retention time
Copper Concentrate
Pressure oxidation
Cu leach residuewashin
on ons promo e arsen c o reac wiron and precipitate as ferric arsenate
Cu leach residue is washed and filtered
Partial neutralization of raffinate for acidbalance control
Leach liquor is processed through solventextraction
Copper is transferred to pure electrolyte
stream and cathodes plated
Solvent extraction
Electrowinning
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CESL Gold Process
Gold and silver are leached at elevatedpressure with recycled cyanide solution
Limited dissolution of sulphur because ofshort leach retention time
Gold and silver recovery using standardcarbon Adsorption-Desorption (ADR) andelectrowinning technology
Cu leach residue
Pressure cyanide
leach
Precious metalsrecovery
opper recovery rom so u on ancyanide regeneration from recycledsolution (Acidification)
Cyanide recovery from plant effluentstream (Volatilization – Reneutralization)
Cyanide destruction by conventionalmeans on minor bleed stream
Cyanide recovery
Cyanide Destruction
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Technical Program
A comprehensive 24-month technical work program started in Q3 2009 toassess the application of CESL technology to high arsenic bearing copperand copper-gold concentrates
The program included a series of bench, continuous pilot, and
demonstration scale testing to achieve the following main objectives:
− Determine level of occupational exposure to arsenic during pilotoperations
−
− Assess arsenic deportment in the copper and gold processes andgenerate representative final residue samples for stability analysis
− Develop protocol and complete residue stability program with Dr.George Demopoulos (Professor, McGill University, Montreal, Canada)
− Confirm engineering design criteria, materials of construction and de-risk the scale-up of the gold process by operating a demonstration plant
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Technical ResultsSummary (1 of 3)
Copper and Gold Plant Leaching Results
High copper extractions (~97% - 98%) were achieved at bench and pilotfrom a wide range of arsenic bearing concentrates (~1.4% - 4.6% arsenic)
Near quantitative deportment of arsenic to Cu leach residue (>99%);minor levels of arsenic leached into circulating process solution (
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Technical ResultsSummary (2 of 3)
Health and Safety
Sample data confirmed air quality (
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Technical ResultsSummary (3 of 3)
Gold Demonstration Operations
Project exceeded ramp up targets to design rates in first few months
To date has achieved exceptional metallurgical performance:
− 90% - 95% gold extraction and 85% silver extraction from gold plant
− >98% gold recovery and >95% silver recovery from leach liquor
− 93% c anide recover from AVR lant
−
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Case Study (1 of 3)
Collectively Teck and Aurubis have completed multiple preliminary financialevaluations to assess the commercial viability of a mine to metal operationfor high arsenic resources using CESL technology
The economic assessment presented in this paper incorporates
metallurgical results from a series of high arsenic bearing copperconcentrate samples, two from Northern Peru projects
Mine-mill1, and refinery2 cost estimates were gathered from externalconsultin and service rou s and ast CESL feasibilit studies
Project Assumptions - Mine, Mill, CESL Refinery
~200k t/a copper cathode
~65k oz/a gold~1.3M oz/a silver
~3,500 US$M ~1.10 US$/lb Cu
Equivalent3
1 - Brook Hunt Copper Mine Cost Service (March 2011): Greenfield Projects Capital Intensity2 - Internal estimate: Factored from third party engineering cost estimates for CESL Cu-Au refinery3 - Brook Hunt metal prices (March 2011): 2.50 US$/lb Cu, 900 US$/oz Au, 15 US$/oz Ag
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Case Study (2 of 3)
The positive results of the case study show that developing an integratedmine to metal project on an arsenic containing copper-gold deposit can beeconomically feasible with today’s long-term metal price assumptions
With a break-even copper price of ~2.00 US$/lb, the economics of a
project of this scale are robust enough to show a noteworthy positivereturn given the current market forecasts
NPV Sensitivities
Cu Price CAPEX OPEXconom c a ua on – re ax
Financial Metric Project
NPV4 ~1,700 US$M
IRR ~14%
Break-Even Price ~2.00 US$/lb
4 - 8% Discount Rate-$1,000
-$500
$0$500
$1,000
$1,500
$2,000
$2,500
$3,000
$3,500$4,000
-30% 0% +30%
N P V
( $ M i l l i o n s )
Change in Cost and Price
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Case Study (3 of 3)
As industry best practices were assumed for the mine-mill component ofthe case study, the following aspects related to the hydrometallurgicalrefinery are discussed:
− Residue Management: safe storage of stable form of ferric arsenate
bearing residue in a lined pond with long term monitoring is possible
− Air Quality: lower direct impact on air quality from hydrometallurgicalrefinery; impact from indirect emissions comparable to industry standards
− a er se m ss ons: ne wa er eman or process compares we o
traditional copper market standards; use of seawater is possible
− Health & Safety: occupational exposure to arsenic is expected to be lowand manageable based on recent pilot trials of high arsenic bearingconcentrates
− Community Social Responsibilities and Potentials: positive proactiveengagement is critical; in country value added production of coppercathode has the potential to yield significant additional benefits to thecommunity
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Conclusions
The implementation of CESL technology through an integrated mine-to-metal approach is a sustainable option for the processing of ore fromarsenic challenged copper resources
The technical program undertaken by the Teck-Aurubis partnership has
confirmed: metallurgical performance objectives, sound environmental,health and safety performance standards, and commercial assumptionsand project economics
This success is allowing Teck and Aurubis to pursue copper resources not
previously considered for development using an economically competitiveand environmentally superior process
Photos: Teck South American operations
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