Shipping emissions form a significant part of the commodity supply chain’s carbon footprint, particularly for those commodities reliant on the mass transport of low-grade ores and concentrates. Roskill has analyzed the trend in carbon intensity of shipping using spodumene concentrate as an example. Spodumene concentrates currently represent more than 50% of refined lithium supply worldwide (on a lithium carbonate equivalent basis), with Western Australia accounting for a significant portion of that.

Roskill estimated the variation in carbon intensity over time of shipping a 15,000t parcel of spodumene concentrate a distance of 7,000 km from Port Hedland, Australia to the port of Zhenjiang near Shanghai, China.

Roskill’s analysis shows that the carbon intensity will decrease over time, as the effect of increasing efficiency hurdles under the EEDI are incorporated and older, less efficient ships fall out of service. However, the estimated reduction in carbon intensity from 2008 levels by 2030 is 3.2%—at least an order of magnitude below the IMO’s ambition.

The relatively small parcel size of spodumene shipments results in a higher carbon intensity per tonne of material shipped, Roskill noted. Transporting larger cargo tonnages on larger vessels benefits from an increased economy of scale and would result in proportionally lower CO₂ emissions. For example, data in the table below show how a ten-fold increase in the cargo tonnage results in a three-fold reduction in carbon dioxide intensity.

This highlights the benefits increased economies of scale would have on this part of the spodumene supply chain, Roskill said. Companies shipping mineral cargoes may wish to consider increasing the size of delivered parcels where possible, utilizing a single vessel for multiple/mixed parcels, and insisting upon freighters using newer and more efficient ships, as possibilities to reduce their carbon footprint, Roskill suggested.

Regulatory background. Under its pollution prevention treaty (MARPOL), the International Maritime Organization (IMO) adopted mandatory measures to reduce greenhouse gas emissions from international shipping: the Energy Efficiency Design Index (EEDI) and the Ship Energy Efficiency Management Plan (SEEMP).

Coming into effect in three 5-yearly phases from 2015, the EEDI specifies increasing hurdle levels for the reduction in CO₂ emissions of new ships relative to a reference line based on average ship efficiency between 2000-10.

In 2018, the IMO set out a vision to reduce the carbon intensity of international shipping by 40% by 2030, relative to 2008 levels.

Background Data. Statistics obtained by Roskill show that:

• Spodumene concentrate shipping parcel averaged approximately 15,000t in 2020;

• Vessels transporting this type of cargo tend to be ‘handysize’ bulk carriers with an average age of 9 years. Handysize refers to a dry bulk carrier with a capacity between 10,000 and 34,999 DWT; and

• The dominant destination for exports of spodumene in 2020 was China.

Lithium is extracted from lithium minerals found in spodumene (a pyroxene mineral consisting of lithium aluminum inosilicate, LiAl(SiO₃)₂) or in water with a high concentration of lithium carbonate (brine). Although originally global lithium supply was dominated by hard-rock mineral sources, in the early 1980s, large-scale lithium brine operations commenced in South America. Today, the world’s lithium production is split evenly between hard rock and brine, according to the Australian Trade and Investment Commission (Austrade), which is seeking to secure an expanded place for Australia in the lithium-ion battery value chain.

Processing spodumene deposits follows conventional hard-rock mining and processing practices. Ore is mined via drill and blast methods, then excavated and trucked to a central processing facility. The ore then undergoes multiple stages of crushing to reduce the particle size to below 6 mm. Following flotation and magnetic separation, the wet concentrate is filtered and prepared for transportation as a 6% lithium oxide (LiO₂) concentrate.

Resources

• Javier Rioyo , Sergio Tuset & Ramón Grau (2020) “Lithium Extraction from Spodumene by the Traditional Sulfuric Acid Process: A Review,” Mineral Processing and Extractive Metallurgy Review doi: 10.1080/08827508.2020.1798234