A techno-environmental study and analyses of the processing options to produce nickel and cobalt from primary and non-primary sources available in Australia for use in battery manufacture

Zac J Hearne

doi:10.60867/00000094

Environmental regulatory reform and shifting stakeholder expectations is creating an imperative for transparent and scrutable environmental impact data for the precursors used in clean energy technologies such as nickel and cobalt. The production of these metals and their compounds is associated with significant challenges of environmental performance and transparency, with the latter often in conflict with concerns of confidentiality. Assessing potential environmental impacts through the standardised methodology of Life Cycle Assessment (LCA) relies on the availability of valid, accurate, reliable and granular Life Cycle Inventory (LCI) data. In such cases where inventory data from primary and secondary sources is incomplete, simulation-based environmental impact data derived from steady-state mass and energy balance process models can be used as an innovative means to address LCI data gaps. This study uses a simplified gate-to-gate LCA approach to assess key inputs and outputs in the domestic production of nickel and cobalt materials used for the battery supply chain, identifying the stages of production with the greatest potential environmental impact. The study utilises balanced mass and energy data generated by process-based model development and simulation of four production pathways using commercial METSIM® software. These include the production of nickel sulfide concentrate from sulfide ore via conventional froth flotation, the production of battery-grade nickel sulphate hexahydrate (NiSO4.6H2O) from high-grade sulfide concentrate via a novel low-temperature oxidative leaching process, nickel hydroxide intermediate production from limonitic laterite ore via conventional high-pressure acid leaching and nickel cathode production from end-of-life lithium ion batteries via a novel leaching and purification process. Several environmental impacts are analysed based on a simplified LCA approach, with key elements of LCA applied including boundaries and allocations. The study assumes materials production, including all material and energy inputs, are supplied and located in Australia. Where applicable, the location has been specified as the Kwinana Industrial Area of Western Australia. The analysis for the modelled battery supply chain materials production pathways indicated that the largest drivers of potential environmental impact, and in particular combined global warming potential (GWP), were the stages of feed preparation, leaching, and product recovery. The simulated production of mixed hydroxide precipitate (MHP) from limonitic laterite ore had a combined GWP impact of 12.9t CO2-eq per tonne of contained nickel. Similarly, the simulated l combined GWP impact of nickel sulfide concentrate from sulfide ore was 3.00t CO2-e per tonne of contained nickel, 6.12 t CO2-e per tonne of contained nickel for the production of nickel sulfate hexahydrate from sulfide concentrate, and 8.48 t CO2-e per tonne of contained nickel for the production of nickel cathode from end-of-life lithium ion batteries. In most cases, allocation of the combined GWP impact by mass resulted in higher impacts due to the higher amounts of nickel produced relative to other co-products, where conversely economic allocation results in lower environmental impacts due to the lower value of nickel on a total revenue basis when considering the value of all saleable products. The study highlights the potential for improving the environmental performance of nickel and cobalt battery materials production, principally through renewable power integration, upstream and downstream processing unit operation integration, and novel processing route development. The findings for the study are relevant for the domestic nickel and cobalt battery materials sector and highlight the use and potential of process simulation for enhancing the accuracy and usability of LCI . While some of the production pathways may not fully represent dominant industry practice, they represent pathways in which the industry is currently progressing based on changes in feedstock and alternative, cleaner technologies. The main purpose of the study was achieved in developing detailed process flow diagrams, design criteria, and environmental impact data based on key elements of LCA to ground the study in its intended purpose in demonstrating the significant potential to enhance the accuracy and usability of LCA by embedding the use of simulation-based mass and energy balance. There are several limitations of this work, including the conversion of environmental impact data to LCI data, requiring the development and application of characterisation factors specific to the local context to enable accurate LCI. Future work is recommended in expanding the analysis of environmental impact to additional production pathways and in utilising the work to conduct full LCA in compliance with the relevant ISO standards.

A techno-environmental study and analyses of the processing options to produce nickel and cobalt from primary and non-primary sources available in Australia for use in battery manufacture

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