Copper supply and demand factors

Copper supply and demand factors

Copper enjoys a versatile range of applications, due to its favourable properties including conductivity, malleability, and durability. Copper is a critical input for a range of modern industrial applications and is at the heart of the clean energy transition.

There is a growing recognition of the important role copper producers play in meeting climate action including the creation and sustainability of a low carbon future. Demand is increasing for socially and environmentally sustainable mining practices, while at the same time producers are facing challenging operational pressures that include declining ore grades. Copper producers need to adapt and enhance their ways of working to meet these challenges. Overall, the clean energy transition opportunity highlights the strategic imperative to extract ore in a manner that optimises available resources, while protecting the environmental, health and social benefits for all stakeholders. Leading assurance and transparency initiatives such as Copper Mark are predicted to play a key role in guiding and assuring that upstream copper supply chains meet expectations. These initiatives secure copper’s role as the conductor metal of choice in the zero emission energy transition. This transition is part of a “mega trend” affecting the copper mining industry in many ways.

As part of a global shift to a low carbon future, there has been remarkable growth in the adoption of renewable energy technologies, which, according to the International Energy Agency (IEA), accounted for approximately 30 percent of global energy generation in 2020. 1 With renewable energy generation expected to grow a further 8 percent in 2021 and continue an upward trajectory, so too will the demand for copper grow as an essential commodity required in componentry for renewable generation and low carbon technologies. Although supply chains have been disrupted due to the COVID-19 pandemic and the Russia-Ukraine war has complicated short term energy transitions, analysts forecast that the medium/long term trend towards renewables may accelerate. 2

The copper renaissance is also driven by the diverse and growing application and consumer base of electrical based technologies. These applications include electric vehicles (EVs) and the supporting charging network, transmission infrastructure, batteries, and renewable energy generation.

According to Australia’s Office of the Chief Economist, the demand for EVs, which contain up to five times more copper than conventional cars, continues to exceed expectations. 3 The use of copper in EVs, batteries and chargers could account for as much as 10 percent of world refined copper by 2030.

The rate of growth in the number of applications, alongside the intensity of copper in clean technology applications, provides the line of sight to copper producers to implement sustainable and low emission mining practice. The opportunity for copper producers is to promote and deploy technology advancement and demonstrate leadership to deliver on environmental and socially sustainable objectives.

5.1. Copper production

Refined copper production derived from a mining operation is referred to as ‘primary’ or ‘mined’ copper production, as it is produced from a primary raw material source.

In 2021, global annual mined copper production was 21,253 kt (kilo tonnes or thousands of metric tonnes), an increase of 2.4 percent on 2020 levels. Global mine production is forecast to reach 23,102 kt in 2022, a significant 8.7 percent increase to 2021 output. 4 A buoyant copper market is driving an upswing in exploration expenditure that may incentivise development projects into production.

Latin American output continues to dominate the copper sector, with Chile and Peru combined delivering 37 percent of global mined copper production. Australia ranks as the 6th largest copper producer in the world as shown in Figure 1.5

Copper use by end use segment

As the world continues to modernise and embrace the energy transition at pace, refined copper use is projected to grow 3.2 percent to 26,126 kt in 2022 from 2021 levels. Demand is estimated to rise at a compounded average growth rate (CAGR) of 2.1 percent to 28,054 kt in 2027 from 2020 levels (Figure 2).6 Use indicators predict the global demand for copper is expected to outpace production in the foreseeable future.

The adoption of electric vehicles (EVs) and battery storage technologies accelerated rapidly over the last decade, led by the dominant markets of China, Europe and the USA. The EV market outlook continues to strengthen due to a range of factors including the intersection of policy support, technology improvements, charging infrastructure and a rising commitment from vehicle manufacturers.7 According to the IEA, EV sales reached 6.6 million in 2021, representing almost 9 percent of the global car market.8

In order for EVs to continue their current growth trajectory, the reliable supply of minerals (including copper), alongside EV production capacity will need to expand at a rapid rate. While the uptake of EVs and other energy technologies is anticipated to represent an upward share growth of total refined copper use, traditional copper use such as electrical and communications still accounts for the majority of applications as shown in Figure 3. 9

Copper demand

As noted by He (2022), predicting accurate copper demand is complex and influenced by a range of interactions due to a variety of dynamics related to end use, including industry sectors, clean energy innovation and adoption, market and consumer behaviours, and policy interventions.10 He (2022) presents five scenarios to model future copper demand including models that factor in sustainable use-reuse-recycling, lowering of copper intensity through to the adoption of green technologies. All scenarios indicate an increase in total copper use over the long term.

According to the World Bank, demand fundamentals for copper remain strong, regardless of advancements, market penetration of clean energy generation, and storage technology scenarios. This is because copper is a mineral that is used across a wide variety of systems. 11 Furthermore, copper is not entirely dependent on one specific technology or sector. In addition, copper is also required for new and enabling infrastructure to support the energy transition.

Policy directives, decarbonisation and EV commitments across a range of major copper use markets including China, US and EU all indicate compelling structural demand fundamentals in the foreseeable future.

Copper supply

Primary production

In recent years copper developments have focused on advancing the lowest-risk projects. Coupled with ongoing socio-economic factors such as pandemic lockdowns, work stoppages, and delays and disruption to supply chains, copper supply growth in existing operations remained relatively flat over the past two years.

Significant new copper discoveries and developments include the underground extension of the Grasberg’s Kucing Liar in Indonesia and Kamoa-Kakula Phase 3 in the Democratic Republic of Congo (DRC). Many known resources remain undeveloped due to low grade ore characteristics or challenges related to fiscal or political uncertainty in the host country. Table 1 presents a summary of analysis of projects by major producing region that have progressed to Environmental Impact Assessment (EIA) phase. Several are experiencing delays in the permitting process that can take multiple years to gain approval.

Table 1: List of major pre-production copper projects

REGIONPROJECTOWNERSHIPPROJECT PHASE
North AmericaCopper WorldHudbay MineralsPEA Phase
MasonHudbay MineralsDeposit
Resolution CopperBHP 45% / Rio Tinto 55%Feasibility
PebbleNorthern Dynasty MineralsPEA
Twin MetalsAntofagastaPre-Feasibility
Kerr-Sulphurets-MitchellSeabridge GoldPre-Feasibility
RosemontHudbay MineralsDevelopment
El ArcoGrupo MexicoDevelopment
South AmericaMichiquillayGrupo MexicoDevelopment
Tia MariaGrupo MexicoDevelopment
Quebrada Blanca (QB) 2 & 3Teck 60% / Sumitomo 30% / ENAMI 10%Construction
La GranjaRio TintoExploration
El PachonGlencoreExploration
Los AzulesMcEwen MiningPEA
El Abra (Sulphide Zone)Freeport McMoRanFeasibility
Radomiro Tomic SulphidesCodelcoDevelopment
Agua Rica - MARAYamana GoldFeasibility
Nueva UnionTeck 50% / Newmont 50%PEA
Norte AbiertoBarrick / NewmontFeasibility
Los Bronces UndergroundAnglo AmericanEA
AfricaKamoa-Kukula Phase 3Ivanhoe MinesConstruction
Mutanda SulphidesGlencoreCommission
Tenke Fungurume SulphidesChina Molybenum Co. Ltd 80% / Gecamines 20%Expansion
Lubambe ExtensionLubambe Copper Mine LimitedPre-Feasibility
Indonesia/ PNG/ PhilippinesBeutongAsiamet Resources / PT Emas Mineral MurniPre-Development
Grasberg - Kucing Liar (UG)Freeport-McMoRan 48.76% / PT Inalum 51.2%Development
Frieda RiverGuangdong RisingFeasibility
Wafi GolpuNewcrest 50% / Harmony Gold Mining Company Ltd 50%EIS Phase
TampakanSagittarius MinesFeasibility
RussiaAk-SugskoyeGolevskaya Mining and Ore CompanyPre-Development
BaimskayaKaz MineralsBFS

Recent unrest and protests at significant copper operating regions including Peru and Chile indicate sustained supply side risks for existing and expanding projects. For example, the Las Bambas copper mine in southern Peru that contributes 2 percent of global copper supply may cease production for an indefinite period due to local protests and transportation issues.12 Political instability in neighbouring Chile further adds to supply problems.

While the ramp up of major new projects may address a short-term supply balance Wood Mackenzie (2022) note that the compelling demand profile for copper and a declining current pool of advanced mining projects could result in a predicted longer term (10-year) supply gap of up to 5Mt to 2031.13

Copper recycling

Recycling and the circular economy must be examined when considering future copper supply. Copper is a circular material. Unlike many materials, it can be perpetually recycled without loss of performance or qualities. According to the Copper Alliance, more than 30 percent of annual copper use is from a recycled source, and an estimated two thirds of copper produced since 1900 is still in productive use.14

Loibl et al. (2021) note that navigating the pathways between copper scrap and recycled copper is complex. The process and material flows of collection, sorting and separation, and metallurgical metal recovery are often carried out by different sets of actors. To achieve improvements in recycling rates also involves a range of players including companies and institutions concerned with technological research, technology commercialisation, regulation, material flow analysis and optimisation and impact assessment.15

The Climate-Smart Mining Initiative was launched by the World Bank in 2017 to support sustainable production and supply of minerals required to meet the clean energy transition and that mineral-rich developing countries can also benefit. World Bank analysis (2020) demonstrates that while the copper industry’s significant recycling rate and potential for improvements are apparent, recycling alone will not be enough to ensure a stable supply of copper and meet future demand. 16

As the world pivots to a low carbon future, continued mining for new copper will be needed to satisfy demand for renewable energy hardware. All stakeholders along the minerals production, recycling and clean technology supply chains will play roles that optimise the mineral inputs required for the clean energy transition including applications related to renewable energy technologies and energy storage.

The solution to meeting the growing demand sustainably is a combination of these two processes: an efficient, sustainable upstream mining system and high recycling rates to optimise copper stocks currently available in society. See section 9 of “The Zero Emission Copper Mine of the Future – The Water Report” for further discussion on the circular economy. 17

Material movement

The world is decarbonising, and it is apparent that copper remains a crucial part of the story, presenting a significant opportunity to producers. Meeting future demand will require an increase in primary copper which will trigger a virtuous cycle of existing asset optimisation, project investment, and the potential for technology development and adoption.

Will an increase in upstream copper production also increase the volume of material to be moved, and what does this mean in the context of emissions? This section examines the symbiosis and complexity between upstream copper production, material movement and emission intensity highlighting the imperative for producers to address decarbonisation at the operating level.

How is copper mined

Copper ore is extracted via underground methods, open cut, or a combination of both depending on the nature, depth and type of ore deposit. Copper ore can be extracted from either oxide or sulphide orebodies, and extraction and processing methods vary depending on orebody type and geological composition. See the initial “Zero Emission Copper Mine of the Future” Roadmap report, section 5.3 for an overview. 18

Open cut mining refers to the development of a large excavation where material is fragmented and moved using a combination of blasting techniques and earthmoving equipment. In a typical open cut operation surface vegetation and waste rock are removed to reach the location of the metal ore body. Benches are carved into the walls of the excavation to provide geophysical stability as the excavation progressively deepens. The mining of copper ore is sequenced to maximise the recovery of metal ore in the orebody, with the excavation progressing deeper as the upper levels of the orebody become depleted. The ore is then transported elsewhere for processing and refining. The development of a large-scale open cut mine is capital intensive and typically requires a significant volume of ore and waste rock to be removed per tonne of copper produced. The extraction of a copper resource from open cut methods can result in environmental impact, and remediation processes are required to return the site back to its original state at the end of economic mine life.

Underground mining is performed when the location of the orebody cannot be accessed or is not economically extractable by open cut methods. A range of methods can extract underground copper, and the method selected depends on the size, shape and grade of the ore body (Figure 5). 19Methods include cut and fill, stope mining, block cave mining and in situ. For most methods, underground mining involves the construction of a shaft or tunnel to reach the ore deposit that is located under the surface. Passages are required to be cut from the shaft at different levels to access different parts of the ore body. Once the ore is recovered, it may undergo primary crushing, and material is hoisted or hauled to the surface for further beneficiation and processing.

The material moved and environmental impact in underground mining is generally less when compared to open cut methods. In underground methods, some waste rock must still be brought to the surface for further separation.

Physical processes

A mining operation will seek to minimise the volume of waste moved while maximising the efficacy of material transportation. Minimising waste material is explored through a design phase that defines and optimises the parameters of the mine boundary to achieve maximum economic benefit. The material inside the boundary is excavated by open cut or underground methods. Both activities require the vertical movement of material from the point of extraction to a processing destination.

Waste material is classified as either unmineralised or mineralised when associated with an ore where the grade is deemed too low for it to be economically processed.

According to Henckens (2020) primary copper ore grades were in the range of 10 – 20 percent until late in the 19th century. During the early part of the twentieth century this decreased to 2 - 3 percent. Since the 1950’s grades have been in steady decline with some active operations as low as 0.4 percent. 20

Taking a nominal copper mine grade at 0.5 percent of an orebody means that 99.5 percent of the mineralised material is directed to a waste stream. In 2021 primary copper production was reported to be 21,253 kt. This example indicates that at a 0.5 percent grade, more than 4 billion tonnes of mineralised waste would be handled through the extractive process per annum.

Waste material when associated with economic mineralised ore is referred to as gangue and is removed during the minerals processing stage and deposited as tailings. This report primarily focuses on the movement of unmineralised and sub economic mineralised material prior to processing and less on the management of tailings post mineral processing.

Achieving a desired material size is a key factor in optimising the efficacy of material movement through the mining and beneficiation process. The operational challenge is that smaller material size preparation requires greater energy to fragment the waste and ore.

The first stage of material movement occurs in blasting operations where material is fractured to a target size so that it can be more easily excavated and transported.

Blasting also seeks to minimise further downstream crushing and grinding activities. Designated waste material is transported by a haulage vehicle and/or conveyor to waste dumps.

In an open cut operation waste dumps are located to minimise the total distance travelled by earth moving machinery and to avoid the possibility of double handling waste material at a later stage. Waste from underground operations could be temporarily stored above ground, prior to being returned underground as backfill or paste. Backfill is used to fill empty stopes or underground voids left after mining activity. Depending on the underground method, backfilling provides a necessary function to the success of the underground mine as it aids in achieving local and regional geotechnical stability and further supports the amount of mineralised ore recovered from an operation.

Material that contains mineralised copper and gangue is transported to the run-of-mine (ROM) pad where it is fed into crushers and grinders for further fragmentation and beneficiation.

Understanding cut off grade and rock to metal ratio (RMR)

Cut off Grade

A copper operation will establish a cut-off grade (COG) which is the minimum grade that a material is considered for reserve determination and economic and planning elements for mining and processing. There are several factors that determine an optimal COG including consideration of cashflow contribution and cost of production. Waste or gangue is the material that does not meet COG and therefore lacks utility and value when mined. 21

An open cut mine “strip ratio” refers to the amount of waste that must be moved to expose and extract an ore reserve that has met COG. For example, a typical large scale open pit mine could have a strip ratio of 3:1 indicating that 3 tonnes of waste must be moved to expose 1 tonne of copper ore.

Ore grade relates to the amount of copper metal contained in the copper ore. Waste generated from movement, sorting and processing of ore is referred to as “gangue”. As exhibited in (Figure 7), once ore has passed through mineral processing, waste material is generally deposited in tailings storage facilities (TSF).

Given current industry grade settings, it is clear that the amount of primary copper produced is in decline relative to volume of ore processed.

Figure 7 - A flow chart showing the relationship of cut-off grade, gangue and waste

Copper RMR

Another important metric for understanding mine wastes, environmental burdens and material impacts is the “Rock to Metal Ratio” (RMR) which is defined as the quantity of rock removed (ore and waste) to produce a refined unit of a mineral commodity. 22

An assessment of RMR can provide a further dimension when comparing material impacts in the context of material choice. Specific to copper, RMR can enhance understanding of the impact of extraction relative to surface disturbance, the generation of tailings, energy intensity and emissions.

Figure 8 - A schematic showing the relationship between material moved to produce one tonne of copper ore (Nassar et al., 2022)

Nassar et al. (2022) studied 25 commodities and nearly 2000 operations including 431 copper operations. While copper RMR is not especially significant relative to other commodities (Figure 9), it is significant (Figure 10), when combined with total volume of material moved (25 percent) from the set of 25 commodities examined.

Figure 9 - An analysis RMR by commodity type (Nassar et al., 2022)

Figure 10 - A comparison of RMR by copper operation (Nassar et al., 2022)

***Understanding the Rock to Metal Ratio enhances knowledge of the relationship between ore mined and waste rock removed during upstream mining and processing. This crucial understanding will shape the future supply of minerals and the emissions relationship to material movement. RMR understanding can guide decisions that deliver high impact.*

The selection of mining method is an important factor that determines RMRs because of the different amounts of waste material that will be removed. For example, even with the same ore grade, an underground mine with minimal waste rock removal would have a lower RMR than an open pit mine. Methods such as in situ leaching that require no material movement will have a negligible RMR when compared to conventional copper operations with similar grades.

For copper, as ore grades decline and as accessible, high-grade orebodies are excavated and processed, it is apparent the industry will face an ongoing challenge with material movement. The application of RMR in the future will reveal better understanding of the material intensity of copper production and may emerge as an important tool in supply chain analysis to inform transparency, assurance and responsible sourcing initiatives.

Copper production, emissions and energy intensity

The significance of material movement required to produce a quantity of copper ore is compounded in the context of increased copper demand. However, accurate base case information and a prediction of the impact of material movement to emissions and energy demand across the copper industry is limited. This is not surprising given the complexity of the copper cycle, the scale and variability of upstream processes at a site level. Emissions will likely vary according to a range of site factors including size of operation and extraction method, equipment selection and power source. This must be well understood to enable effective decisions related to technology adoption and mitigation strategies.

The Zero Emission Copper Mine of the Future Reports Phase 1 and Phase 2 - Water highlight some studies that explore emissions across the copper cycle. According to Azadi et al. (2020), emissions associated with primary mineral and metal production in 2018 were equivalent to approximately 10 percent of the total global energy- related greenhouse gas emissions in the same year. 23

Watari et al. (2022) present emissions across the entire copper cycle noting that the global copper cycle currently contributes an estimated 0.3 percent of global emissions. 24 The study further considers projected copper demand and use to 2050 and forecasts an increase from 0.3 percent to approximately 2.7 percent of the total emissions budget by 2050 in the absence of technology adoption and mitigation measures. The study recommends a range of actions across the cycle including upstream production involving a combination of energy efficiency improvements, electrification, and aggressive recycling.

Azadi et al. (2020) also explored emissions related to the major stages of production in the primary copper supply chain. Fuel and electricity consumption associated with open pit and underground mining processes are the major source of emissions. However, the magnitude of emissions at a whole of site level can be variable due to site specific differences associated with mining methods, equipment selection and the mineral processing activity.25

When evaluating specific measures or technologies to reduce emissions in the context of material movement, there is emerging activity across the mining sector to consider both direct (Scope 1) and indirect emissions beyond the operation boundary (Scope 2). Increasingly Scope 3 emissions are analysed. Addressing fuel use may result in the electrification of equipment, process optimisation and equipment replacement. This highlights the importance to take a whole of system approach in emission analysis. Emission consideration across the copper production cycle will drive energy demand and source, choice related to low emission products and services, and downstream use. The adoption of low emission business models requires a whole of system approach and an understanding of base case and potential (Scopes 1, 2, and 3) emission impacts.

Case Study: Scope 3 emissions

The National Greenhouse and Energy Reporting Scheme (NGER) and Greenhouse Gas (GHG) protocol define Scope 3 emissions as emissions that are generated indirectly because of activities from sources that are not owned or controlled by a reporting entity’s business. 26 Leading mining industry bodies including the International Council on Minerals and Metals (ICMM) and the Mineral Council of Australia (MCA) support this definition.

It is estimated that 95 percent of total mining related emissions could fall into Scope 3, representing 20 percent of global emissions.27 These emissions typically fall out of a company’s direct control, (for example, metallurgical coal inputs into a steel mill). In Australia Scope 3 emissions are currently not included in the NGER scheme. Therefore at present a consistent methodology to report Scope 3 emissions in the mining industry does not yet exist.

In an attempt to provide greater transparency and reduce emissions, some mining companies, including BHP, Glencore, Vale, Rio Tinto, and Anglo American are taking a proactive approach to report and address Scope 3 emissions.

Vale has announced pathways to achieve a 25 percent reduction in scope emissions and has committed to reviewing its emission targets every 5 years. 28 Three key strategies are enabling this change.

  • Shipping: Vale has committed to the International Maritime Organization’s emission targets which include a goal of reduction by 40 percent by 2030 and absolute emissions reduction of 50 percent by 2050

  • Steel blasting: Vale is moving towards a supply of mixed high-quality products to reduce energy demand in the steel blasting processes

  • Nature: Forestry protection covering over 1 million hectares and plans of additional 500,000 hectares by 2030

Glencore is also progressing Scope 3 emission reduction and targets a reduction of 30 percent by 2035. 29 Glencore’s approach includes reshaping its portfolio to favour clean metals. This is demonstrated through their efforts to minimise coal production and expand commodities such as copper, cobalt, nickel and zinc, all of which aid in the utilisation of low emission technology such as renewable power.

Anglo American is currently targeting a reduction of Scope 3 emissions by 50 percent by 2040. 30 The reduction of emissions will be supported in two key efforts:

  • Efficiency and control: across the entire supply chain, freight, and logistics, with a particular focus on shipping

  • Product and technology: changes to product portfolio and collaboration with global customers and technologies partners in an attempt to decarbonise the steel industry.

BHP focused efforts to address shipping and transport. By 2030, BHP target a reduction of chartered shipping emissions by 40 percent. 31 The multinational is one of the founding members of the global Centre for Maritime Decarbonisation and in 2021 embarked on the first marine biofuel trial involving ocean vessel bunkering. (See section 7.1 of this report for further information.) Additionally, BHP is monitoring the energy efficiency and emissions related to charter vessels through a sustainability analytics platform which provides detailed emission insights and will be used as a tool to inform reduction measures.

Northey et al. (2013) developed and explored a dataset of global copper operations to assess the greenhouse gas emissions and energy intensity for upstream copper production including mining and processing for underground, open cut, and combined mines. The research also notes that the emissions associated with individual operations can be highly variable due to site-specific differences including the orebody composition, grade, fuel and power source, and to a lesser extent the reporting methods and procedures used by the companies.

According to CommDev, an initiative of the World Bank International Finance Corporation (IFC) copper emissions intensity is about 4.5 kg of CO2 for every kg of copper produced.32 When explored more closely to the upstream process and as shown in Table 2 (Northey et al., 2013) the energy and emissions intensity related to activities in an underground mine are lower when compared to open cut mines.33 The increased energy requirement of a combined mine is likely due to a range of factors associated with integrating the operating parameters of both operational methods. A key contributor to the increased energy intensity relates to the total vertical lift the ore is required to travel from the underground operations to the surface of the mine site. In addition to the vertical lift, there are the other operational parameters required by underground mining, including ventilation, lighting, water pumping, increased transfer points for materials handling and other necessary activities.

Table 2: Summary of greenhouse gas emissions and energy intensity of underground, open cut and combined mines, obtained by an assessment of sustainability reports of several copper producing mines across the globe34

Mining and Processing OperationsUndergroundOpen CutCombined
Number of Mines (% of global operations)29%52%19%
Tonnes of annual copper production (%)19%73%9%
Energy Intensity (GJ / t Cu produced)Total21.926.828.3
Direct9.316.112.8
Indirect12.69.117.5
Greenhouse Gas Emissions (t CO2-eq / t Cu Produced)2.472.523.42

It is not surprising that, in the context of declining ore grades, emission intensities are further compounded. In a study by Azadi et al. (2020) declining copper ore grade resulted in a 130 percent increase in fuel consumption and a 32 percent increase in energy consumption for copper mining in Chile between the years 2001 to 2017.35 Northey et al. (2013) studied a range of copper operations to demonstrate that there is a point of inflection, where below an ore grade of around 0.5 percent Cu emission intensity also rises sharply.36

To address supply challenges and related impact to material movement factors going forward, the industry will need to consider the cost/benefit ratio of new production and corresponding emission considerations when deciding to either go deeper, deploy open cut methods of operation, or extend a project underground resulting in a combined operation.

Understanding the balance between project economics, material movement and the emission footprint when exploiting lower grade and deeper deposits will be critical in meeting the long-term demand for additional copper supply and to support appropriate decarbonisation pathways and action.

Figure 11 - Emission intensity as a function of ore grade for 28 copper operations represented by annual production (Northey et al., 2013)

Underground copper mines have become less common over the course of the 20th century and are under represented in the large projects that dominate global output.

While underground mines show promise for reduced material movement and low emissions approaches, a resurgence of underground mines would be counter to current trends. An analysis was undertaken to better understand future indicators for open cut versus underground mining with a dataset sourced and adapted from the International Copper Study Group (ICSG) 2022 Directory of Copper Mines and Plants.37

Analysis of the dataset identified 846 projects, including 523 operating mines. The operating mine dataset comprised 203 open cut operations, 192 underground mines, 56 combined operations, with the remaining 72 being uncategorised. Using scheduled start and closure data, an estimate could be determined of the number of operating copper mines over time for the 20th century, assuming that mines without a closure date are still operational.

As indicated in Figure 12 underground mining was the dominant type through much of the 20th century. The share of open pit mines began to climb dramatically in the 1990s and led by 2013. Beyond 2013 the number of new projects, of both types, slowed significantly, but open pit mining remained in a slight lead. Simply extending these trends, it could be expected that the share of open pit mines may exceed underground projects in the foreseeable future.

Figure 12 - Known open pit and underground mines through the 20th century (excluding exploration projects)

Due to the considerable variation in mine size and output, looking at mine numbers alone can be misleading. The research set out to understand the relative impacts of open pit versus underground mines relative to global output between years 2020-2026.

Restricting the dataset again, current operational mines were analysed (as opposed to mines in the planning stage) to take an average output over the reported time interval. Separating this by mine type and plotting a histogram on a log scale (Figure 13), there is a distinct difference between the distributions for underground and open-pit mines. This makes intuitive sense, since global output is dominated by a smaller number of large mines, and those mines are predominantly open cut. Of the 15 largest mining operations in the ICSG dataset, only two are underground, and a further two are reported as hybrid.

Figure 13 - A log-scale histogram of average projected mine output for 2020-2026, split by operation type

An era of declining ore grades

A study by Mudd and Jowitt (2018)38 assessed 2,301 copper deposits globally collating resources and reserves (as stated in 2015). The findings indicate likely global copper resources and supply are contained and align relative to existing copper producing regions and that the average ore grade in copper production has been declining over time (Figure 14).

There are numerous complexities that relate to the modelling of future ore grades and the conversion of resources to reserves. Defining a geological setting requires considerable effort and investment to locate an orebody and to demonstrate its economic viability.

It is common practice in the mining industry to spread exploration effort over a period of time. Often an orebody is not fully defined from the outset but aims to reach a stage of ore classification using a range of technologies and a minimal amount of drilling. The conversion of classification from resources to mineable reserves can occur at various stages during the lifespan of a mine.

Figure 14 - The decline in copper ore grade over time (Mudd and Jowitt, 2018)

Ongoing greenfield and brownfield exploration aims to expand discovery and knowledge related to a particular resource and convert it to reserves. A range of factors including market conditions and extraction methods will determine whether a project is economically viable. Noting these factors and in the absence of new high-grade discoveries, it is likely the industry will continue to recognise an era of ore grade decline.