View of the Kennecott Copper concentrator in Utah, USA. (Photo: iStock)

It’s widely understood that the global shift towards electrification will necessitate a huge increase in demand for the metal; S&P Global predicts that demand for copper will double by 2035, opening up a supply gap from 2025 that “could threaten climate goals and poses serious challenges to achieving net-zero emissions by 2050.”

“Copper scarcity may also jeopardize international security,” the team wrote in a 2022 blog post. “Projected annual shortfalls will place unprecedented strain on supply chains. The challenges this poses — reminiscent of the 20th-century scramble for oil — may be accentuated by an even higher geographic concentration for copper resources and downstream industry to refine it into products.”

S&P proposes three options to increase supply from current levels: the expansion of existing mines or the creation of new ones; higher capacity utilization or increasing output as a percentage of a mine’s total capacity; and recycling and/or urban mining to extract copper from discarded electrical goods and other waste.

These are all viable in varying degrees, though there are multiple hurdles. Identifying economic resources and extracting them are key challenges, but perhaps even more so is the subsequent processing of material to produce metal that’s ready for use or reuse.

Technical and ESG Challenges
Satish Rao, Managing Director at innovation strategy firm, Clareo, and his colleague, Grant Caffery, Director, Australia, outlined the main technical challenges: “Ore grades are declining globally, which necessitates processing larger volumes of ore to extract the same amount of copper,” Rao said. “This increases energy and water usage and generates more waste. As simpler deposits are depleted, the ores being processed are becoming increasingly complex, requiring more sophisticated and energy-intensive techniques to extract copper.”

Jaco Labuschagne, Process Engineering Manager at FLSmidth agreed: “These factors will not only impact the financial viability of copper projects, but also their ‘social license to operate’, particularly in rural and remote areas which host new deposits.”

Comminution and flotation, which are key processes in concentration, consume significant amounts of energy and water, which can exacerbate the environmental and social impact of processing operations. Coupled with this, many mines rely on older technologies that are less efficient and more costly to operate and maintain, due to capital constraints and complex process steps.

There are also societal challenges playing out to varying extents. Rao explained: “Rising resource nationalism, where countries rich in mineral resources are demanding the beneficiation of these resources occur within their borders, is increasing. This is often coupled with demands for local ownership and higher royalties,” he said. “There’s a growing need to ensure that that local communities who are impacted by mining and mineral processing see net-positive benefits from activities in their region.”

Increasing demand for copper and declining head-grades are driving mines to move and process
ever greater volumes of material. (Photo: iStock)

E&MJ also caught up with Alan Boylston, Director of Process Engineering at Metso, at the MINExpo 2024 event in Las Vegas in September. “Issues such as resource scarcity and increasing power and water consumption are front of mind for copper operators today,” he said. “But equipment and systems are only one half of the equation. The other issue, which is having a growing impact, is the scarcity of skilled talent.”

Skills shortages are having a growing impact on mine operators, OEMs and engineering firms alike. In the US and other key mining jurisdictions, there used to be multiple universities with mineral processing programs, but that capacity has shrunk in recent years and the number of metallurgists and process and chemical engineers who are graduating each year is dwindling rapidly.

“At Metso, we’re working to find solutions for this challenge, including partnering with a company called Metcelerate which helps us to take chemical engineers and train them to become metallurgists through a two-year program,” said Boylston. “We also run the Metso Training Academy in Mesa, Arizona, where we train our customers to operate and maintain their flowsheet, so that they can get the most from their investments. Unless the industry puts greater emphasis on training and retaining talent, there simply won’t be enough people to run mines and concentrators going forward.”

Concentrating on Emerging Technologies
Copper concentrators, which are typically comprised of multiple systems and processes, produce concentrates of around 20%-30% copper that can be further processed, via smelting, to produce elemental copper. Each plant’s objective is to maximize value from a given raw material by recovering the maximum amount of metal from ore.

“The ‘concentrator’ approach was developed over 100 years ago when the first flotation circuit was deployed,” said Caffery. “While there have been no fundamental changes to flowsheets as a whole, there have been incremental improvements within each of the plant systems over the years: crushing and grinding of ore, addition of water, reagents, frothers, air, and skimming and drying of the concentrate. More recent advancements include ore preconditioning, where microwave and high-voltage pulse treatments are enhancing comminution efficiency. New classification technologies such as semi-inverted cyclones, reflux classifiers, and crossflow classifiers provide enhanced separation of fine and coarse fractions which can lead to optimized throughputs and a reduction in energy consumption.”

The primary impact of declining head grades over the years has been on the scale of equipment. Almost universally, equipment including primary, secondary and tertiary crushers, mills, flotation cells, and thickening and filtration units, have been ‘super-sized’ to enable higher volumes of material to be processed. However, the relatively low efficiency and recovery exhibited in some of these processes means that many are reaching the limit of their effectiveness.

Challenges surrounding water scarcity are mounting for many copper processing
operations. (Photo: iStock)

The cyclical nature of mining means that when commodities experience headwinds, operators tend to fall back on conventional circuit designs and technologies, because, as Dierx explained, the engineering blueprints can be copied to reduce upfront costs and improve the net present value (NPV) of a project. However, there’s growing recognition that this approach might be shortsighted. “It’s better to look at the actual operational performance and financials over the lifeof- mine (LOM),” he told E&MJ.

Improving Comminution Efficiency
As noted, over the past 20 years, HPGRs have become an accepted alternative to SABC circuits, especially in hard-rock sulphide applications, offering energy efficiency improvements in the 20%-30% range. Labuschagne said: “The same HPGR technology has been demonstrated to promote the micro-cracking of ore, which is also beneficial in leaching applications and flotation operations.”

Boylston agreed: “The introduction of HPGRs is one of only a handful of step changes that we’ve seen in copper concentration. This method not only reduces energy consumption in comminution, but also reduces the amount of steel media that’s consumed in milling. Particle- based and bulk ore sorting which can be applied to preconcentrate ore ahead of grinding, milling and flotation are other important developments.”

Around 4%-7% of global electricity consumption is related to comminution, and in line with its responsible ambitions, the mining industry is exploring other more sustainable and methods, such as single particle breakage coupled with air classification to enhance process efficiency. The potential application of high-voltage pulse technology, as offered by companies like Francebased startup I-ROX, are also promising in reducing energy footprints.

The enrichment and separation of minerals from waste rock is critical to value recovery. Several approaches are utilized depending on the properties of the target mineral, with flotation being the most common in copper. In recent years there’s been a shift towards using coarser grind sizes to feed recovery circuits using new separation technologies, like coarse particle flotation (CPF) — flotation at >250 microns. CPF offer benefits not only in flotation, but also in downstream grinding and dewatering circuits.

Dierx explained: “CPF enables the processing of hard, lower grade ores at coarser fractions. It also reduces energy consumption in comminution and, because the tailings are coarser, they’re easier and safer to manage.” Rao added: “Coarse particle technologies allow increased mill throughput by enabling the flotation of larger particles than previously possible. Fines flotation also supports a finer grind size and achieves better separations. These developments signify a progressive shift towards more efficient and cost-effective mineral processing, leveraging advanced technologies to overcome traditional limitations.”

As new mineral resources are found in increasingly arid locations, often in highly competent ores, miners are also exploring and opting for dry processing solutions. “We’ve seen this, for example, with multi-stage HPGRs combined with air classification,” added Dierx.

What About Leaching?
Heap leaching is widely used in North and South American copper operations for its simplicity, robustness, flexibility, and relative low-cost in treating oxide and lower- grade secondary sulphide ores. This method and its core technologies haven’t changed much over the years. However, the industry is now turning its attention to leaching primary sulphide ores, such as chalcopyrite — the most abundant and commercially significant source of copper from sulphide minerals globally.

Rao explained: “The challenge in leaching chalcopyrite is the passivation layer on the surface of the mineral which acts as a barrier between the copper ore and the lixiviant, rendering the leaching process less effective. The leaching reaction kinetics in ambient temperatures also depend upon the solution chemistry and ore composition and can lead to long cycle times, sometimes up to 500 days. Recovery from conventional heap leaching processes is also lower than that from concentrator circuits due to the larger particle sizes, as the ore being leached is not subject to grinding.”

Many of the technologies discussed above can play an important role in improving the efficiency and recovery of leaching operations too. For example, Boylston noted that bulk ore sorting can help miners to better identify which materials to send to the concentrator versus the leach pad — higher grade process inputs reduce the amount of time, energy and water spent in downstream processes.

“HPGR is one of the best technologies for increasing efficiency in leaching,” he added. “The micro-cracks and fissures created in rock particles by HPGRs allow the acid to seep through the material more effectively. This enables higher recovery and faster leach kinetics. Reducing the time material spends on the leach pad from, say, 300 days to 100, could have a significant impact on project economics, increasing throughput and recovery, and lowering acid consumption.”

Novel approaches, including the development and application of new lixiviants to penetrate the passivation layer exhibited by primary sulphide minerals, enhance reaction kinetics at ambient temperatures and reduce cycle times, are also being explored by different companies. “Leaching of sulphides is an oxidation process, and typically air is used as the oxidant,” Rao told E&MJ. “However, several solution providers are exploring alternative oxidants to accelerate the leaching process. These stronger oxidants increase the reaction kinetics, which increases the rate of heat release that can potentially increase heap temperature. This forms a positive feedback cycle by further increasing reaction kinetics.”

Other companies are using novel catalysts to prevent the formation of the passivation layer in chalcopyrite, and some are looking to biological approaches that involve microorganisms and bacteria, which are often naturally occurring and can aid the leaching process. Microorganisms can be utilized to trigger the ferric leach process for example. Solution providers are combining disciplines, including physical and electrokinetic with chemical approaches, examples include Ekion’s electrokinetic approach that uses an electric process to extract metals, and Anglo American’s SandLix which combines physical and chemical approaches, considering three aspects of particle size, temperature and chemistry.

Heap design and operational considerations also influence recovery and cycle time, and several solution providers provide technologies to improve heap design and operation, such as adding heat to the heap.

Super-size or Minimize?
Looking ahead there are a handful of trends and technologies that could provide the next wave of ‘step change’ improvements in copper processing. As head grades decline and equipment size increases, one opportunity to innovate is by ‘bucking the trend’ and reducing equipment size while maintaining throughput or even increasing it.

For instance, while FLSmidth continues to roll out its latest generation of conventional flotation cells — the WEMCO II — which feature an updated flotation mechanism for increased wear life and better air control, the company is also furthering the development of its novel Reflux Flotation Cell (RFC).

High-pressure grinding rolls (HPGRs) have become an accepted alternative to the industry standard
SAG-ball-pebble crusher (SABC) circuits. (Photo: Weir)

Metso’s Concorde pneumatic flotation cells also offer greater efficiency with a smaller footprint but aimed at fine and ultra-fine particle recovery. Launched in 2021, Concorde cells are suited to finely disseminated and complex orebodies and offer an economic pathway to process these ores while reducing operational costs and energy and water consumption per ton of metal produced. In November 2024, Metso announced it will expand its portfolio with modular Concorde Cell Plant Units. These consist of prefabricated and pre-installed containerized units which streamline the setup process and minimize on-site installation work.

There’s also the possibility to go bigger but with better efficiency. For example, in April 2024, Metso launched the Vertimill 7000 vertical screw type stirred mill. This model features the same high energy efficiency as the company’s previous Vertimill models, but with 50% more power. For example, one Vertimill 7000 can replace multiple smaller stirred mills to achieve the same power output. Vertimill grinding mills also offer an alternative to ball mills, providing up to 40% better energy efficiency and, through their vertical design, a 50% reduction in the plant footprint.

Leveraging Synergistic Technologies
The effective integration of state-of-theart technologies also offers huge potential. For example, through the synergistic combination of CPF, enhanced classification, high efficiency grinding, and advanced strategies for tailings dewatering and water treatment, it could be possible to unlock new efficiencies in bulk mining. Such approaches can reduce capital and operating expenses, increase recovery, and pave the way for processing lower- grade ores economically.

Caffery explained: “Linking the processes of CPF and high efficiency grinding offers system level benefits. For instance, CPF facilitates early gangue rejection, enabling the economic processing of lower head grades. This is complemented by high efficiency grinding which, when paired with preconditioning of the ore to weaken rock structure, significantly enhances grinding efficiency.”

Improving classification by optimizing the separation and reduction of fines further amplifies grinding efficiency and minimizes the recirculation of fines, allowing for a more energy-efficient grinding process. Air classification, in particular, presents a significant opportunity.

Dierx explained: “To maximize size reduction, HPGRs typically operate in closed circuits and utilize a wet or dry screen to classify or separate the higher proportion of fines generated by the rolls. Conventional grinding solutions, like SAG and ball mills, use water and grinding media to create size reductions and move the material through the system. In contrast, Weir’s ENDURON HPGRs with air classification use air from fans to move the ground product through the system and separate product that needs to be recycled through the HPGR for further grinding.”

To do this efficiently, the machine incorporates both static and dynamic classification systems. The static portion of the system removes coarser particles for recirculation to the HPGR before they reach the dynamic classifier and cause wear. The fans then blow the finer particles up into the dynamic classifier, where the final product cut is made, eliminating the need for ball or rod mills in some circuits. Dierx added: “There is a trend towards taking a more holistic, systems-based approach to designing and implementing transformational flowsheets. For instance, Weir recently completed a comprehensive study highlighting the opportunity to reduce energy use and emissions in comminution using a combination of three alternative technologies.”

In this study, the alternative technologies were evaluated against a conventional comminution circuit design for a typical Chilean copper mine processing 15 Mt/y of ore. Each circuit was based on a ‘rock-to-recovery’ system boundary; that is, reducing rock directly from the mine to a size that enables mineral recovery. The four configurations considered were: 1. A conventional comminution circuit based on a SAG mill and ball mill. 2. A circuit in which an ENDURON HPGR replaced the SAG mill at the initial grinding stage. 3. A circuit that included an ENDURON HPGR, plus a vertical stirred mill replacing the ball mill; and 4. The addition of an Eriez HydroFloat CPF unit to the aforementioned flowsheets.

The study demonstrated that replacing conventional technology with innovative solutions could cut energy usage by 40%, while avoiding 50% of CO2e (carbon dioxide equivalent) emissions. Weir recently expanded its range of ENDURON screens with the launch of the ENDURON ELITE at MINExpo 2024. This is a large, high-capacity banana screen, available in a range of sizes with the largest weighing in at 50 tons. Corné Kleyn, Weir, Global Product Manager, Vibrating Equipment, explained: “Weir’s transformational flowsheet solution needs screening both upstream and downstream of the HPGR, which produces high tonnage, fine material requiring small separation sizes. Notably, by screening HPGR discharge product at 1-mm, Weir’s transformational flowsheet only requires a single vertical stirred mill, delivering significant energy reductions compared to conventional grinding circuits.”

With declining ore grades and fewer large mines coming into operation, existing mines need to process higher tonnages, which, in turn, requires higher screening capacity. “This presents some design challenges,” Kleyn added. “Weir recently developed an exciter capable of driving a screen with a deck that spans 4.27-m.” Addressing tailings and water issues is also important within the current paradigm. Efficient dewatering of tailings allows for safer, more stable storage and facilitates water recycling. This is critical in minimizing environmental impact and addressing both water scarcity issues and increasing regulatory and societal pressures for sustainable mining practices.

There are also opportunities to repurpose tailings into valuable products, such as aggregates and construction materials, by taking advantage of their composition and the processes they have already undergone. Such approaches can lower the environmental burden from tailings while creating new value.

Optimizing Processes With AI
Process optimization through digitalization is another important shift. Weir unveiled its new digital offering, NEXT Intelligent Solutions, at MINExpo. Ole Knudsen, Weir, Senior Director, Digital, said: “This extends and expands our current capabilities and transforms our process optimization services into real-time digital solutions. In recent years, Weir has been focused on harnessing digital technologies to improve equipment performance, availability and product quality — overall equipment effectiveness.”

Having recently added artificial intelligence (AI) capabilities to its suite of digital solutions through the acquisition of SentianAI, Weir is now harnessing these technologies to optimize entire circuits and processes. Meanwhile, FLSmidth opened its new Global PerformanceIQ Hub, a state-ofthe- art digital technology centre at its Salt Lake City headquarters, to help mining customers maximize their plant’s potential. Labuschagne said: “As operations expand into more remote areas, there’s a need to provide world-class support to our customers remotely. The Global Performance IQ Hub allows FLS to provide a range of digital services, from basic provisions, such as monitoring asset health, through to advanced process control (APC) on a 24/7 basis.”

While APC isn’t a new technology, it’s one that’s not yet being used to its full potential in mineral processing. Marc Poualion, Industry Solution Director, AspenTech, spoke to this: “Some mining operations are lucky enough to have significant runway to be able to deal with challenges due to a combination of low production costs and strong commodity prices,” he said. “But circumstances can and will change. It’s therefore essential to optimize any competitive advantages in the market to more confidently ensure the longevity of the operation.”

Leading mining companies are prioritizing investments in advanced technologies for process optimization to remain ahead of the competition. The aim is to maximize the amount of metal that can be recovered from an orebody and ensure its extraction in the most efficient way possible to minimize energy, water, chemical usage and more. (Reprocessing tailings at a later date can be extremely costly should their grades eventually become economic.)

“It’s only a matter of time before advanced technologies become commonplace and part of the industry landscape in the same way that 3D computer based geological modelling and mine planning overtook manual paper and pencil drafting during the 80s and 90s,” Poualion added. “A move from manual operation of mineral processes to automated approaches is inherently more stable and reliable. It produces better metal recoveries at a lower energy cost and with the optimal amount of reagents, all of which lead to a more sustainable and profitable processing operation.”

For example, mining companies that implement AspenTech’s APC technology, Aspen DMC3, typically see reduced emissions, water consumption, waste generation or loss of economic material to tailings. This is a result of the continuous optimization and adaptation that AspenTech’s process control solutions deliver in many different types of metal recovery processes.

Similarly, mineral processing operations usually observe increased energy efficiency in the form of adapted and optimized agitation, air or liquid flow and increased metal recovery by more appropriate application and consumption of reagents. Engineers also see less of a need for continual manual adjustment of processes and equipment. Implementing a system that can adjust variables automatically in response to real-time changes also frees up precious talent to perform higher level, supervisory and problem-solving type tasks, helping to address skills shortages in certain markets.

Predicting and Preventing Maintenance Issues
Implementing prescriptive and predictive maintenance strategies is another emerging trend. “Copper recovery is an inherently complex, multi-stage process that involves several different pyroand hydrometallurgical subprocesses,” Poualion said. “For each of these, there’s one or more pieces of heavy equipment or machinery involved which can present risks to the overall metal recovery process if an unplanned outage occurs in any one of them.

“For instance, if a single stage in a crushing and screening circuit goes offline it can create starvation circumstances in the processing plant. This means that the first stage of recovery processes aren’t being utilized to full capacity, which in turn reduces the overall productivity and metal recovered for the quarter, thereby impacting revenues.”

Prescriptive maintenance and reliability solutions can prevent this type of situation from occurring and allow maintenance, processing and operations staff to minimize or eliminate the impact of such events. While there are deeply experienced maintenance engineers who can put their hand on a machine and quickly diagnose a potential problem, it takes an extensive career in maintenance to build this knowledge base. Relying only on people isn’t a scalable approach to predictive maintenance, as one person can only be in one place at a time. Humans also make mistakes when they’re tired or stressed and, despite extensive experience, problems can still fall through the cracks.

Poualion explained: “The workforce is aging, meaning that experts who are custodians of this knowledge, will eventually retire. There simply aren’t enough people entering the mining workforce to fill the knowledge gap left by retiring experts. With prescriptive maintenance solutions, machines can help fill that gap with scalability and accuracy.”

For example, Aspen Mtell uses historical data to gauge which changes need to be made and when and can also be trained by maintenance teams to recognize different types of failure events. Using AI and machine learning (ML) capabilities, the software can help recognize impending equipment failures with earlier detection across mining operations. Do you think it will be possible — practically and financially — in the future to operate concentrators without IoT-enabled digital solutions? E&MJ asked Poualion.

“There are concentrators in the field today that operate with minimal, if any, IoT devices,” he replied. “But they’re not typically among the most productive, effective or reliable. Automation, reliability and monitoring systems are becoming increasingly essential in keeping mines consistently productive and profitable. Forward-thinking mining companies understand the power of these technologies, and continue to prioritize them, even during times of downturns and cost cutting.”

The Next Step Change…
Over the next decade, greater application of technologies like ML to processing plant design, engineering and recovery will allow engineers to better understand which equipment and processes are required to optimize resource extraction, as well as which asset management solutions are needed to deliver on reliability, predictability, productivity and profitability projections.

Poualion added: “AI will continue to be game changing for mining as the industry makes progress toward more autonomous operations in support of safer, more reliable and more efficient mines.” Boylston agreed: “It’s very hard to find high-grade, undiscovered copper deposits today, so it’s going to be much more capital efficient for miners to focus on getting every last bit of value out of the assets that they already have. Leveraging APC and digitalization to make incremental improvements to plant efficiency will be key to that, but so too will the reprocessing of copper waste and tailings. Again, this isn’t new, but the industry isn’t currently using the technologies and processes that are available to their fullest extent. There’s a lot of value being left on the table.”

He added that there are adjacent technologies — for example, in renewable energy — that could be leveraged to alleviate some of the challenges that copper operations are facing. In theory, if a company opted, through a power purchase agreement (PPA), to run its operations on 100% renewable energy, then the CO2 footprint of the plant would be minimal. And, if the price of renewable power continues to fall (in some geographies, mines are securing PPAs for as little as two cents per kilowatt hour) then that could have a huge impact on the economic recovery grade of copper.

“The shift to low-cost, low carbon electricity could enable mines to treat lower value run-of-mine material rather than sending it to waste dumps,” Boylston added. “That’s going to drive efficiencies and enable more value to be extracted from both current and future resources.”

In addition to dry processing, Dierx believes there will be an increased focus on improving the understanding of ore feeds through mineral characterization. “This will allow operators to reject non-valuable product before it’s processed,” he told E&MJ. “This improves process efficiency and reduces energy consumption. I think there will also be opportunities — depending upon the composition of the orebody — to create multiple streams of feed via ore sorting which can then be processed by specific plants based on the combination of equipment and processes that are best suited to each ore stream. That could potentially evolve into multiple smaller parallel circuits that are tailored for each ore stream, rather than feeding all of the material into a single, large concentrator.”

Future copper flowsheets could also incorporate novel coarse flotation technologies to reduce energy consumption. Labuschagne said: “FLSmidth’s coarseAIR flotation cell could form the backbone of future copper flowsheets. Furthermore, a holistic approach could be taken to incorporate several proven flowsheet concepts into a single concentrator complex. Ideas such as diverting low-grade feed to a leach plant and only treating higher-grade ore in a flotation plant will receive much more attention. This approach could be driven by incorporating data from mining operations into large data models, allowing for vertically integrated mine-totails operations.”

According to Rao, there are also alternative flowsheets that could address the technical and ESG challenges outlined, as well as the increasing depth of orebodies. “A transformational technology for the future is in-situ recovery (ISR),” he said. “This method extracts valuable minerals directly from ore deposits without traditional mining.”

The process begins with the drilling of wells into the orebody. These serve as pathways for a leaching solution which is injected into the mineral deposit and permeates through the rock dissolving the target minerals. The solution is then pumped back to the surface and processed to separate and recover the valuable minerals. For copper, this typically involves solvent extraction and electrowinning (SX/EW).

Rao explained that various technical challenges would need to be addressed for ISR to be widely applied, including improving orebody characterization, developing permeability enhancement techniques, designing effective lixiviants, ensuring solution flow, and having effective monitoring and control systems in place. The current regulatory landscape does not provide specific guidelines for ISR in many jurisdictions which can complicate obtaining operational permits. However, if these could be overcome, this method could, in time, prove game changing in copper.

Changes Today for a Better Tomorrow
While systems-level challenges in copper supply are mounting, and nowhere more so than in mineral and metal processing, there are technologies and processes, both emerging and established, that can be harnessed today to address them in varying degrees. Whether applied singularly, in tandem with synergistic solutions or more broadly as part of a sustainability agenda, there are options that will allow every operator, at every stage of the asset lifecycle to run their plants more efficiently and effectively.

However, to do so successfully will also require leaders who can think outside of the box, garner shareholder support for innovation, and encourage their teams to experiment with and adopt new technologies and processes.