Metals

In the ecoinvent database, the metals sector comprises economic activities including mining, the production of semi-fabricated metal products up to the metal fabrication activities in the manufacturing sector that produce finished metal goods.

Oct 7th, 2024

Metals are ubiquitous in society and are used in a wide range of applications, from those in traditional sectors, such as construction and manufacturing, to those in advanced modern telecommunications and information technology. Furthermore, global economic and technological development continues to drive up demand for an ever-broadening array of metals, many of which are geochemically scarce and occur as by-products of base metal production. This has given rise to a metals sector that is characterized by complex global trade flows and interdependent, interconnected, and international production chains.

While metal products are vital to the functioning of modern-day societies, their production can cause severe environmental damage. Mining degrades the environment, depletes natural resources, and may lead to the dispersion of toxic substances in the environment, while mineral processing and production of refined metals often require significant amounts of energy. Consequently, the use of metals throughout the supply chains of other products may contribute significantly to the environmental impacts of those products. According to the International Resource Panel, metal production is responsible for about 10% of global climate change and 12% of particulate matter-related health impacts.

Sector Overview

In the ecoinvent database, the metals sector comprises activities from the mining and beneficiation of natural resources to the production of metal and mineral commodities. The production of a specific metal (or metals) is represented as a chain of linked activities. Chains start with “mine operation” activities that cover the mining and beneficiation of ores and yield one or multiple metal/mineral concentrates. Concentrates are subsequently processed through one or multiple activities to yield refined metals. The number of datasets that make up a production chain varies between metals, with some chains comprising many intermediate steps, production routes, and final products, such as iron and steel production. In other cases, all production activities from mining through to refining are aggregated into one single activity, such as “cobalt production.”

For some metals, datasets are available for multiple production routes based on different technologies. For instance, two chains of datasets are available for primary copper production through either pyrometallurgy or hydrometallurgy, while there are also datasets for secondary copper production from recovered copper scrap. Users of the database can, therefore, choose copper produced from a specific production route, such as primary copper produced by pyrometallurgy. Alternatively, they may select a mix of copper obtained from different primary and secondary sources, by using the dataset “market for copper, cathode.” In total, there are more than 400 datasets related to metals production producing more than 200 different products.

Sector Highlights

Mining and Quarrying Operations

The database contains more than eighty datasets from more than twenty geographies that model the extraction of natural resources from the ground. While some of these datasets integrate several steps of the production chain from mining to final product, others are focused on specific mining operations. Mining and quarrying activities produce more than eighty intermediate and final mineral commodities such as metal concentrates (e.g., copper, platinum group metal or rare earth oxide concentrates), refined metals (e.g., gold, silver, or cobalt), and mineral aggregates (e.g., sand, gravel, or dolomite). These commodities include base metals, precious metals (including platinum group metals), rare earth elements, and other mineral products. While some datasets are global averages, others are regionally specific (e.g., rare earth element mining mainly happens in China) and for some (e.g., copper or gold) different datasets for different geographies are available.

Metal Production

Raw commodities, such as metal concentrates, are further refined and beneficiated to final metal products. In the database, different technologies are considered. For instance, two chains of datasets are available for primary copper production through either pyrometallurgy or hydrometallurgy. Final metal products cover base metals (copper, lead nickel, zinc), several precious metals (e.g., gold, silver, platinum group metals), and rare earth element oxides.

Metal Working

To obtain semi-fabricated and final metal products, such as sheets, coils, and bars, the refined metal needs to undergo some additional processing. The ecoinvent database contains over eighty activities that model some of these steps, mainly for aluminium, iron, and steel. These activities include drilling, milling, turning, and extrusion, as well as data for generic metal working. With these datasets, it is possible to model the different steps required to produce specific metal parts.

Recycling and Secondary Materials

Metals and metal products can be recycled and used as secondary materials. In the ecoinvent database, this is represented by so-called “treatment” activities (e.g., “treatment of copper scrap by electrolytic refining”). The outputs of these activities correspond to those of primary production (e.g., “copper, cathode”) and supply the market datasets (e.g., “market for copper, cathode”). “Treatment” activities, together with activities to treat tailings and slags produced during mining and smelting, overlay the metals and waste management sectors.

Treatment of Tailings

Mine tailings are the main waste produced during the mining and beneficiation of metal ores and are typically deposited in tailings impoundments. In the long term, these impoundments can pose a risk to the surrounding environment, particularly in the case of tailings produced from sulfide ores. The potential environmental impacts resulting from the long-term storage of sulfidic tailings depend on a variety of factors, such as the composition of the tailings, the characteristics of the impoundment, and the climatic conditions.

To capture the range of potential environmental impacts related to tailings from metal mining, the ecoinvent database contains datasets that model the impoundment of sulfidic tailings for six different host metals (such as copper or nickel), covering in total nineteen countries, which account for the main shares of the mining of these metals. Additionally, a dataset for the impoundment of sulfidic tailings that represents an average composition is available.

Use Cases

Data on metals production can be used in life cycle assessment, carbon footprint (greenhouse gas accounting), material flow analysis studies, and can support Environmental Product Declarations (EPDs) for various products and services.

Data Providers

Notable providers of LCI datasets on metals activities include, but are not limited to:

Editors

Louis Brimacombe (Main Editor), University of Sheffield, United Kingdom
Robert Istrate, Assistant Professor of Industrial Ecology, Leiden University
Dieuwertje Schrijvers, Project Manager, WeLOOP

Relevant Sources

Charikinya E., Broadhurst J., Dlamini R., Goga T., Harding K., Russo V., Viljoen D. and von Blottnitz H., (2019). Life Cycle Inventories of Primary Production of Precious and Scarce Metals – South Africa. ecoinvent Association, Zürich, Switzerland. Accessible at SRI project results (registration required).

Soni H., (2019). Life Cycle Inventories of Iron and Steel – India. ecoinvent Association, Zürich, Switzerland. Accessible at SRI project results (registration required).

Classen, M., Althaus H.-J., Blaser, S., Tuchschmid, M., Jungbluth N., Doka, G., Faist Emmenegger, M., Scharnhorst, W., (2009). Life Cycle Inventories of Metals. Final report ecoinvent data v2.1, No 10. Dübendorf: Swiss Centre for Life Cycle Inventories. Accessible in the Reports section of version 2. of the ecoinvent database.