By Rebecca Todesco, Assistant Editor, Mining Magazine
Global emissions targets and pledges have spurred a flurry of activity in countries around the world, with a range of locations and companies looking to embrace innovations and technology that will advance them towards net zero emissions targets. A report by the International Copper Association Australia (ICAA) has explored what this changeover will look like for copper mining and strategies the industry can utilise to propel itself towards a more sustainable future.
Net zero emissions targets have seen a strong uptick in the adoption of green technologies and renewable energy across a multitude of industries around Australia and the world. The Australian resources and mining industry is not immune to this wave of change, with increased demand for minerals that are needed for the green energy movement, like copper, and decreasing mineral ore grade placing additional pressure on mine operators and mining companies.
The ICAA’s Zero Emission Copper Mine of the Future – Material Movement report and innovation roadmap unpacks and explores the current drivers for copper demand in emissions-free energy systems, especially in relation to international emissions reduction agreements. Also discussed in the report is the adoption of renewable energy, either at the site or supplied from nearby grid-connected systems, and electrifying mining systems.
The Material Movement report is the third study in three years concentrating on the cutting edge technology that can help copper mines reach net zero emissions, with another two more reports planned. The ‘copper renaissance’, as the ICAA report calls it, is also being driven by the diversification and increasing application of electrical-based technologies, including electric vehicles (EVs), and the necessary charging network, batteries, transmission infrastructure, and renewable energy generation they require.
Although Latin American output continues to dominate the copper sector, Australia ranks as the sixth largest copper producer in the world, with refined copper use predicted to grow 3.2 per cent to 26,126kt in 2022 from 2021 levels.
The increased demand for copper coupled with declining ore grades will mean more material will be moved at copper mining sites around the world.
The Material Movement report and roadmap delves into five separate technical themes – fragmentation, convey and sort, haulage, dispose and reuse, and digital and automation – and explores technology solutions that are available for each theme, covering Horizon One (today), Horizon Two (tomorrow), and Horizon Three (future solutions), and providing a guide for copper producers to reduce or eliminate site emissions related to material movement.
However, the report is also very clear on the fact that there is no one-size-fits-all solution for emissions reduction, with the costs of technologies and their readiness levels constantly changing and evolving. The report instead offers a snapshot of the state of the industry in mid-2022 while advising that primary copper producers that make wise decisions, prepare earlier and carry out plans well will be at an advantage over the late responders.
Fine tuning fragmentation
Making up the primary stage in the extraction process to recover minerals from an orebody, fragmentation involves fracturing waste and mineralised rocks into a variety of particle sizes, enabling the efficient movement of material in a downstream process.
Every stage of the fragmentation process requires energy to reach a desired particle size and is usually achieved by one of two processes; high pressure grinding systems to achieve optimum particle sizing for maximum economical mineral recovery, or the blasting of in situ rock for bulk material movement.
Knowledge of the geological and geotechnical properties of various rock types is necessary to achieve optimum particle size with minimum energy input. A key challenge of fragmentation is drill and blast strategy that does not achieve appropriate fragmentation, which can then result in significant cost impacts related to loading, hauling, and primary crushing.
Other challenges also include difficulties involved with avoiding dilution when ore and waste are in close proximity and the risks associated with underground blasting, including contamination of underground water systems due to explosives seeping into underground aquifers.
The Material Movement report references innovation available for current use, including technology for drill alignment, blast monitoring technology, blast simulation technology, and cloud-based systems. The asset upgrades and capital replacement the report explores in regards to fragmentation include wireless initiating systems, underground drill fleet electrification, and ultra-high intensity blasting techniques.
Additionally, surgical mining, in situ recovery (ISR) mining methods, and surface drill fleet electrification were introduced as Horizon Three operations which can aid copper producers to reduce site emissions related to material movement.
Convey and sort process transformation
The convey and sort process refers to the activities of transporting and identifying mineralised ore and gangue material within the mining operation. In a copper operation, conveyor systems are utilised for material and ore transportation, ultimately delivering the mineralised ore to a plant for processing or to a primary crushing station.
Ore sorting refers to the process of separating material into various mineralised grades – high grade, low grade, or waste, to name a few – with sorting often achieved by passing the ore over a variety of sensors which evaluate the chemical or physical properties of the material and identify the rock particle to be separated by using amplified mechanical, hydraulic or pneumatic processes.
A fundamental challenge in conveying and ore sorting involves the dimensions and size of the system, as they are fixed assets and cannot be incrementally contracted or expanded. Underloading systems can lead to excessive power consumption per unit of material moved, whereas overload can result in excessive system maintenance.
Conveyor monitoring and protection, near face sorting, mechanical ejection, and regulation of belt speed are some of the current operations being utilised by copper producers for incremental improvement. The report lists regenerative belt conveyors, magnetic resonance technology, automated and integrated conveyor systems, and distributed drive technology as some of the Horizon Two processes which will help copper producers in their emissions reductions schemes.
The future operations that can help reduce emissions in conveying and sorting processes, as detailed in the report’s innovation roadmap, include underground vertical conveyor systems, real-time data analytics, integrated solutions and coarse particle flotation.
Innovations in haulage
Material haulage is an integral activity across the mining value chain and covers every aspect of ore and waste movement, commencing from the time of fragmentation to arrival at a destination, such as the direct deposit to waste or storage zones or beneficiation and mineral processing stream.
The demand for material haulage is surging across the copper mining industry as a result of a number of factors, like increased volume related to market demand, declining ore grades, and hauling distance and depth. Most equipment used in mining operations, including haulage equipment, is powered by internal combustion engines (ICEs), using diesel fuel. The transition to alternate hauling technologies, which mitigate or entirely eliminate diesel use, is a crucial step towards the zero emission copper mines of the future.
Stringent industry standards have been introduced in an attempt to address and regulate diesel efficiency and use. One of the most immediate issues related to diesel use in mine vehicles is the release of harmful particulate matter into the air.
Additionally, fuel supply chain and price risks are also becoming more apparent across all industries with global fuel prices facing increased upward pressure. This has prompted moves to convert to electric-powered equipment, which boasts advantages over diesel-powered equipment including higher service life, lower maintenance requirements, higher energy efficiency and reduced generation of pollutants, heat and noise.
Some of the biggest challenges or barriers in converting haul trucks in mines to all-electric and/or carbon-neutral infrastructure include up-front capital expenditure (CAPEX), refuelling and charging infrastructure, technology maturity and availability, supply chain availability, creation of policies and regulatory settings, and skills development.
Remote operation of haulage trucks, shovels or supporting processes, as well as ICE monitoring and control systems, and ICE energy recovery systems and technologies are some of the practices in use today to mitigate diesel consumption. The ICAA roadmap offers ICE emissions controls, renewable diesel/biofuels, autonomous haulage, and fast charging systems as some of the ‘tomorrow’ technologies which can propel copper mines to a greener future.
The ICAA report predicts that these kinds of strategies will eventually lead to future operations like embedded pure battery-electric and hybrid, inductive/wireless charging, hydrogen fuel and renewable P2X products, and hydrogen- electric hybrid BEVs.
Making a circular economy through dispose and reuse
The dispose and reuse theme entails the material movement specifically linked to the generation and storage of waste rock and tailings from the primary production of copper, with the ‘reuse’ element encouraging a shift to a more circular economy model rather than the traditional ‘take-make-use-dispose’ model.
As such, a roadmap that features the dispose and reuse theme introduces options to reconstruct waste material movement which can reduce overall emissions and drive efficiency efforts across a site when compared to existing practices. Current operations to do so involve the sensing, monitoring and surveillance, backfill technologies, accelerated mechanical consolidation (AMC), and waste material planning, design, scenario modelling and optimisation.
The ICAA report offers options for asset upgrades and capital replacement like dry stacking, shared knowledge platforms, novel dewatering-press filtration, and advanced crusting agents and dust control. Such processes could eventually lead to Horizon Three technologies like novel dewatering, trace mineral recovery – sulphide leaching and bio mining – and trace and low grade mineral recovery – electrokinetic in situ leaching (EK-ISL).
Digital and Automation transformation
Current practice has mines relying heavily on individuals to record and report information for downstream collation and interpretation, so the main purpose of digital and automation technologies is to unlock greater efficiency and enhance interoperability.
The ever changing nature of operations may give rise to circumstances where data may not be gathered to time, cost or effort, which can then cause performance inefficiencies due to information and data from one business unit not readily transmitted to other parts of the business where direct benefits could be realised.
The copper industry is constantly required to improve efficiency and productivity which often calls for a comprehensive approach encompassing all aspects of the mining operation, from exploration and development through to production and post-mining activities.
Information technology can play a crucial role in this process, but automation implementation also faces operational challenges, including harshness of the mine environment which can be damaging to sensors, actuators, and other equipment. Technology and procedures in practice today involve utilisation of Industrial Internet of Things (IIoT), autonomous UGV/UAV for inspection applications, and pervasive geospatial information systems.
These kinds of practices can help to pave the way for Horizon Two technology like machine learning-based orebody modelling, autonomous vehicle technology and adoption, and anomaly prediction and preventative maintenance, eventually leading to Horizon Three innovations like robotic precision drilling and advanced communication technologies.
Mine operating systems are already under pressure, and with declining ore grades and copper demand predicted to grow by 21 per cent each year until 2027, it is more critical than ever to boost the sustainability of material movement at copper mines and ultimately cut emissions entirely.
The processes of fragmentation, conveying and sorting, haulage, disposing and reusing, and digitalisation and automation are open to technological advances – available today (Horizon One), in the near future (Horizon Two) or long term (Horizon Three) – which are essential to cutting emissions.
Although there is no one-size-fits-all-solution due to the differences between open cut, underground and hybrid operations, adopting innovations and new technologies has the ability to transform copper mines and propel copper producers towards net zero operations futures.
The full Zero Emission Copper Mine of the Future – Material Movement report can be accessed at https://copper.com.au/about/projects/roadmap-to-zero/zero-emission-copper-mine-of-the-future-material-movement-report/.
