Life cycle assessments for green mining

A team of researchers at the University of Exeter, Minviro, the British Geological Survey, and the Circular Economy Solutions Unit has recently determined the benefits of utilizing a life cycle assessment (LCA) or "cradle to grave" evaluation in the ongoing endeavor to facilitate and improve green mining techniques.

Generally used to assess the environmental impacts associated with the life cycle of commercial products, from extraction to the use and disposal of said products, in a new scientific review published in "Nature Review Earth & Environment," the team has outlined how an LCA that integrates considerations around the geology, mineralogy, and geometallurgy, can help identify potential hotspots before new extraction operations begin.

This new approach could allow geologists to help select potential exploration targets that naturally lend themselves to lower environmental impacts – resulting in finding the best metal deposits with the lowest potential in natural disturbance.

"Understanding the environmental impacts of emerging technologies over their entire life cycle, particularly the raw materials supply stage in the case of clean energy technologies, is key to ensure that they are truly sustainable," said Xiaoyu Yan, Environment and Sustainability Institute at the University of Exeter.

The scientific review, "Towards sustainable extraction of technology materials through integrated approaches," explores the requirements and challenges of a low-carbon future, primarily the materials necessary to facilitate that future.

The first line of the abstract truly hits the nail on the head, "The transition to a low-carbon economy will be material-intensive."

Albeit simple, the fact of the matter is, mining will be imperative.

The key points expressed in the paper are as follows:

• The 2020s will see substantial demand for growth for lithium, cobalt, nickel, graphite, rare-earth elements, manganese, vanadium, and other materials, due to the transition to renewable energy.

• Production of battery-grade or equivalent purity technology metals can have an extensive range of climate change and environmental impacts.

• The impacts of technology material production are rooted in geology. Consideration of geology and mineralogy allows a better understanding of the main drivers for technical recovery (both gangue and ore), which influences the process routes needed to manufacture technology materials.

• Different process routes have different environmental impacts, which can be quantified and compared using life cycle environmental impact methodologies.

• Life cycle assessment can be used to uncover hotspots in the development phase for mitigation before new operations are built.

As becoming more prevalent in the news regarding the global low-carbon transition, the ongoing and incoming electrification of transportation system require a notable quantity of technology metals and materials. Shifting from internal combustion engines to electric vehicles and the deployment of solar photovoltaic and wind power are considered the three major technologies for decarbonization.

Access to raw materials that enable these technologies, generally termed "technology materials," is critical to the energy transition. However, the systems that deliver these engineered materials come with local and global pressures on the environment.

These impacts have thus been determined to necessitate quantifiable and, wherever possible, mitigatable actions to circumvent contrary outcomes toward decarbonization. Essentially, the environmental impact of extracting, processing, refining, and embedding these raw materials in a low-carbon economy does not limit the impact reduction of the technology itself.

"In this review, we give an overview of the methods that can quantify the environmental impacts of technology materials production. We discuss the key features and qualitative environmental credentials of REE (rare earth elements), Li (lithium), Co (cobalt), Ni (nickel), Mn (manganese), V (vanadium) and graphite deposits, before showing how quantitative geometallurgy-LCAs can be conducted from exploration to mining, processing, refining and manufacturing, so that the environmental impact can be assessed," the authors penned in the report. "While only a selection of technology materials (REEs, Li, Co, Ni, Mn, graphite, V) are included in this review, it should be noted that the rapid evolution of technology and material substitution means that many more materials will fit the criteria of technology materials in the future. A discussion of the social and governance issues related to the production of technology materials is beyond the scope of this review, but is an essential subject for continued research."

Low-carbon materials need low-carbon tech too

Often forgotten when it comes to manufacturing, extraction to production has many steps in between, necessary to a final product.

Moving elements from ore in the ground to the EV manufacturing industry, for example, requires several distinct steps for each material in question.

From extracting and processing the raw material to manufacturing chemicals that match the specification required for applications in battery manufacturing or neodymium-iron-boron magnet formation, the various stages can occur in different parts of the world and have different impacts.

The technologies used in a low-carbon economy demand high-purity materials with specific chemistries. However, producing these high-purity materials requires additional energy inputs and deposit characteristics that also influence the environmental impacts of production.

The lithium-ion battery of an EV contains various components, including a cathode, an anode, separators, electrolytes, current collectors, casing, and much more. The lithium, nickel, cobalt, and other materials used in these batteries require specific physical and chemical properties to ensure high energy and power density. Most importantly, battery manufacturers frequently require higher purity chemicals for their products than are historically required for other industries.

So, it cannot be overlooked when considering the logistics needed for decarbonization and the transition to low-carbon technologies. In addition, the production of the materials needs its own set of technologies to mitigate carbon output and environmental impact that would otherwise void the goal of the material in the first place.

Purpose of the LCA

As presented by the study, a life cycle assessment is equally applicable to mining and refining technology materials as it is to the rest of the supply chain.

LCAs can be used to quantify the environmental impact of services or products, as well as being widely used for commercial, consumer, and industrial products, including raw material and technology metals.

The quantification of a product's life cycle greenhouse gas emissions, often referred to as carbon footprint, represents one impact category rather than the full suite of impact categories found in life cycle impact assessment categories.

Carbon footprint has been popularized and gained traction in the last 10 years with the proliferation of corporate, project, and product accounting and reporting methodologies, yet it has been argued that this focus on a single impact category moves away from a fundamental motivation of a LCA, which is to view a range of impacts in a holistic way to avoid problem-shifting by solving one environmental problem but creating a new one in the process.

In the context of technology materials, LCAs can be used in a variety of ways. It is possible to evaluate the total environmental burdens and benefits of producing technology materials over the entire life cycle from cradle to grave. LCAs also include production of raw materials and upstream impacts from consumables such as reagents or energy, transportation, reuse, recycling, and end-of-life fate.

The LCA approach to technology material production is particularly important because of the substantial amounts of energy and material inputs required to mine, process, and refine to the required chemistry standard and purity, in addition to the associated emissions and waste outputs.

All of this would be considered under a complete life cycle assessment.

Summary and future perspectives

Mineral demand for use in EVs and battery will grow at a rapid pace until 2040. Lithium should see demand growth by over 40 times, while graphite, cobalt, and nickel by 20-25 times and REEs demand to triple by the end of the decade in a sustainable development scenario modeled by the International Energy Agency.

To meet the demand for technology materials, several new mines, mineral processing plants, and refineries will need to be developed.

With the growing recognition of ESG (environmental, social, and governance) standards, it is evidenced by the study that it will not be enough to mitigate the resource demand for the resources themselves.

Understanding environmental performance well in advance can help developers, investors, regulators, technology material buyers, and other off-takers make decisions early on, before impacts are incurred, as, after should focus on supporting early environmental impact assessments by linking geologists and LCA practitioners with mining and mineral processing engineers to develop integrated frameworks for sustainable resource development.

The electric revolution and decarbonization agenda will see a global societal shift from a fossil-fuel-based economy to a mineral-based one. The negative social and environmental impacts of mining these materials have drawn attention as production ramps up to meet the increased demand. Therefore, a focus on end-to-end raw material traceability and linking LCA performance data, along with good quality social and governance data within the supply chains, is an important step to ensure that raw materials feeding the transition have minimal impact.

As much of the infrastructure necessary to develop the chain of production needed for the transition, as well as the raw materials from the mines themselves are outsourced outside of the United States, as far as the U.S. is concerned, this paper is a succinct primer of consideration for actions to better prepare for the vacuum of demand.

More information regarding the current status of North American resource development can be read in the Critical Minerals Alliances magazine presented by Data Mine North, parent to Metal Tech News.

The full paper "Towards sustainable extraction of technology materials through integrated approaches" can be read here: https://www.nature.com/articles/s43017-021-00211-6#ref-CR26.