PGM LIFE CYCLE ASSESSMENT
The International Platinum Group Metals Association (IPA) has conducted a life cycle assessment (LCA) to assess the environmental impacts of the primary and secondary production of platinum group metals (PGMs). The study also evaluated the benefits of using PGMs in automobile catalytic converters (autocatalysts) to control vehicle exhaust pollution. Implats was one of 11 IPA members that contributed to the study, representing the primary producers of PGMs (from mining to production), the secondary producers of PGMs (recycling and production), as well as the fabricators of autocatalysts.
This study is the first industry-wide assessment of the life cycle of primary and secondary PGM production, and is highly representative of the industry, covering 64% of the global PGM supply. The results represent the global average primary and secondary production of PGMs by the participating members.
The six PGMs (platinum, palladium, rhodium, ruthenium, iridium and osmium) occur together in nature alongside nickel and copper. Due to their economic value and higher quantities, platinum and palladium are the most important metals in the PGM mix and also the main products. The PGMs are highly resistant to wear, tarnish, chemical attack and high temperature, and have outstanding catalytic and electrical properties. All these unique characteristics have made them indispensable in many industrial applications.
The PGM industry carried out this LCA study in order to generate a reliable, up-to-date and independent dataset of the environmental footprint of PGMs and PGM-containing products, and identify possible areas in the PGM life cycle for improving environmental performance. The LCA followed the “cradle-to-gate” approach, and included all aspects of ore extraction, the production of other raw materials, energy supply and the production of the PGMs themselves.
- The extraction and refining of PGMs is a capital, energy and labour-intensive process. PGMs are produced in low volumes and are used in very tiny quantities. The high and repeatable recyclability of PGMs means that the environmental burden of PGM production decreases with each recycling round.
- Power consumption during mining and ore beneficiation has been identified as the major impact (72%) of the production of PGMs on the environment; a further 27% of the impact comes from smelting and refining. Only 1% of impacts are attributed to recycling; the low footprint of recycling compensates for the higher footprint of primary production.
- By far the largest single use of PGMs today is for autocatalysts, a pollution control device fitted to cars, trucks, motorcycles, and non-road engines. In this application, PGMs are coated onto a substrate housed in the exhaust system where they act as catalysts to reduce levels of harmful emissions to legislated levels. PGMs enable car manufacturers to comply with emissions standards and help regulators to implement tightening emissions regulations.
The LCA illustrates that even though the impacts of PGM production appear to be high, from a life cycle perspective, these impacts are significantly mitigated by the in-use benefits, as indicated by the following findings:
- Over 1.3 tonnes of toxic and harmful polluting gases (including carbon monoxide, nitrous oxides, unburned hydrocarbons and particulate matter), are reduced by the catalytic converter systems in one EURO 5 gasoline and one EURO 5 diesel vehicle in use over 160 000km; these emissions are reduced by up to 97%.
- Emissions of carbon dioxide (CO2) are increased by between 2% and 6% through the use of autocatalysts; this is due to the conversion of carbon moNOxide and hydrocarbons into CO2 during vehicle use; however, this increase is small when compared to CO2 emissions from the combustion of the fuel used to drive the vehicle.
- The emissions reductions as a result of the use of an autocatalytic converter outweigh the emissions generated during the production of the catalyst including PGMs and other related materials used to support the functionality of the catalyst.