Demand for minerals for the green transition is predicted to grow significantly in the run up to 2050. However, most economically attractive mineral deposits, in terms of resource volume, grade and location, are already being mined.
Deposits that remain undeveloped, including for key minerals such as copper, tend to be lower grade and may require new technologies and extraction approaches to facilitate timely development.
As such, it’s likely that the future of mining will require a wide mix of solutions bespoke to orebodies, local communities and owner priorities, and modular mining and mineral processing plants could play an important role in unlocking new supply.
What is modular processing and is it new?
Modular mineral processing plants use equipment that’s designed to be delivered to site and set up with minimal construction and are also suitable for relocation. Think of equipment that can fit onto a truck, or shipping-container sized processing modules that are designed to fit together like toy bricks.
Modules are fabricated and pre-assembled prior to dis-assembly, packing and shipping. As multiple modules can be fit together, plant throughputs can range from 50-500+ tonnes per hour (t/h).
Global engineering firm, Sedgman, has a long history of delivering both small and larger scale mineral processing facilities.
The company’s first modular processing plants were developed in the 1990s in Indonesia and Australia and were designed to treat 200-300t/h of ore. In the late 2010s, 550t/h plants were delivered and, more recently, Sedgman’s modular plant designs have been focused on copper and other base metal ores.
Modular processing is well suited for small-scale ‘surgical’ mining techniques seeking to treat smaller quantities of higher-grade ore.
What’s driving different mining approaches?
The average timeframe from ore discovery to first production for new mining projects is typically around 15 years. This is driving miners to focus on the expansion of current mineral resources, though the extraction of lower grade ores or satellite orebodies.
Small, modular preconcentration technologies can support economic extraction by reducing costs for the transport of waste to an existing or centralised processing facility.
Considering the drive to net zero, another paradigm that’s being challenged at this moment is the model of operating mines 24/7 based on reliable baseload power. This is particularly the case for remote sites, those without access to decarbonised grids, or mines that can justify a high capital investment in wind, solar and energy storage assets.
As the industry increasingly recognises the untapped value in reprocessing tailings from historic or current operations, small-scale, modular plants can also be deployed to reprocess these materials, generating additional revenue.
In some cases, this can provide the opportunity to dewater and store tailings more safely and thereby reduce an operation’s environmental impact.
Considering the long permitting timeframes for new mines, extracting critical minerals from currently permitted sites can shorten project timelines and improve sustainability.
Another consideration is that many promising orebodies are not being developed due to lack of social acceptance. In fact, research by the Sustainable Minerals Institute in Queensland has shown that 54% of critical minerals pipeline projects are located on or near Indigenous lands.
For many projects, innovative mine designs based on geometallurgical knowledge as well as place-based environmental and community co-design will be needed to gain community acceptance to unlock undeveloped resources.
There are a number of promising case studies of community ownership of renewable energy projects that can be used as models.
When does modular win over more traditional approaches?
The following are some key characteristics that may mean a project is suitable to use a modular processing approach:
- Smaller, higher-grade deposits: Higher-grade, smaller deposits can support the use of relocatable modular processing and may be suitable for emerging selective mining approaches. One example is Novamera’s suite of surgical mining technologies, which The Intelligent Miner ran an article about recently. The Novamera team was also involved in the TAD Scalable & Adaptable Mining initiative which described how surgical mining can reduce waste brought to surface for smaller narrow-vein deposits.
- Scattered multiple orebodies: Preconcentration of ores at a satellite operation prior to transportation to a centralised processing facility can make otherwise uneconomic deposits attractive. Preconcentration facilities can be remote from services, so are particularly suitable for flexible design options that can adapt to variable power availability from renewables. In addition, modular piloting facilities could be used by several different mine owners in a region to support acceleration of critical minerals development. There are examples of fixed ‘common user’ facilities being developed, such as the Queensland Resources Common User Facility (QRCUF) in Queensland, Australia.
- Speed to production: Starting small to limit barriers to approvals, as well as fast construction times can support forward cashflow and help companies to capitalise upon rising commodity prices. Small start-up projects with scalability through additional modules can be attractive where additional time is required to define the resource more fully.
- Remote location: Prefabricated modules can support faster construction times in remote locations where experienced construction labour is scarce. Modular construction also has the benefit of improved safety through reducing on-site work hours. This can be considered in the broader context of a remote mine with a small orebody where relocatable mining equipment and energy sources are applied. This approach could include using a smaller electric fleet, and mechanical cutting mining systems as well as relocatable solar and batteries.
- Secondary processing of wastes: Secondary mineral recovery remains a largely underexplored area. Future studies should include the feasibility of progressive recovery of secondary minerals, not just at the end of a mine’s primary mineral life. Since energy and water have already been consumed in the mining and processing stages, recovering additional minerals could significantly increase the efficiency and sustainability of mining operations.
- Anticipated changes to orebody over life of mine: Where changes to the orebody are anticipated over time (such as moving from open pit to underground operations, or transitioning between oxide and sulphide ores), relocatable facilities or facilities designed to adjust the flowsheet with additional modules, can support adaptability.
What technical challenges are involved?
The throughput of modular mining systems is generally limited by the footprint of comminution equipment able to be transported without disassembly.
Emerging comminution technologies have great potential for improving modular processing designs, with some providing higher throughputs with lower footprint and energy requirements.
While it would be ideal to have standard designs for modular plants, the unique challenges each mine site presents, including variations in mineral composition and geological conditions, often necessitate customisation of modular systems and typically provides a better value proposition.
Remote locations can also be challenging in terms of power supply. For miners seeking alternatives to diesel, the consideration of using firmed solar power (solar energy that has been stored or supplemented with another energy source to meet electricity demand) requires more flexibility on the use side to adapt to periods of limited power.
With standard comminution approaches, this is not achievable. However, emerging technologies and designs are being developed that can support throughput ramp up and down based on power cost or availability, and so can support increased renewable penetration.
Environmental, social and governance considerations
While a modular approach to mining is not inherently more sustainable than large-scale mining, there are a few differences that can support lower impacts. These include lower concrete volumes in construction, and a relocatable plant can mean quicker timeframes for rehabilitation.
However, a bigger impact can be achieved where modular preconcentration facilities are used to reduce waste being transported, and through targeting higher-grade satellite orebodies with relocatable facilities and precision mining.
The suitability for extracting critical minerals from historic tailings can also be considered an environmental advantage, particularly where this involves the relocation of tailings to more safely manage mine waste.
Finding the greatest value
In the near term, modular mining and mineral processing approaches could provide a practical, cost-effective solution for mine owners that are looking to develop multiple, high-grade, small-scale satellite orebodies within a region, and are able to leverage a relocatable processing facility and mining equipment across multiple projects.
As the energy transition accelerates, demand for critical metals like copper and lithium is predicted to outstrip supply. Higher commodity prices may also drive the application of modular processing technologies to historic mine wastes to improve environmental outcomes alongside the recovery of critical minerals.
It’s clear that, in the correct context, small-scale, modular mining and mineral processing approaches can provide a valuable and viable tool for sustainable metals production, allowing operators and communities to work together to bring previously overlooked resources online.
Jenny Agnew is Business Sustainability Manager, and Lyndon Ryan is Manager, Business and Project Development, at Sedgman. To continue the conversation, connect with Jenny and Lyndon on Linkedin.