Advanced conversion of sulphate salts in circular hydrometallurgy

The EU aims to achieve climate neutrality with net-zero greenhouse gas emissions by 2050, necessitating the electrification of key sectors like mobility and energy. Lithium-ion batteries (LIBs) are crucial for this transition. To enhance strategic autonomy amid global competition and an increasingly hostile geopolitical context, the EU targets more strategic autonomy along the entire mine-to battery supply chain. This implies minimum targets for domestic extraction (10%), processing (40%) and recycling (25%) of battery raw materials. Given the strict environmental limits EU companies need to respect, a significant challenge in this mine-to-battery(-recycling) supply chain is the generation of large sulphate waste streams. Sodium sulphate is produced during lithium extraction from spodumene ores, cobalt and nickel sulphate refining, precursor cathode active material (pCAM) production for nickel-manganese-cobalt (NMC) batteries, and LIB recycling. Similarly, lithium-iron-phosphate (LFP) battery production generates ammonium sulphate waste. Addressing these waste streams economically is a major challenge for EU metallurgical and battery (recycling) companies. Prof. Koen Binnemans (KU Leuven, Belgium) proposed a solution, filing a European priority patent on July 18, 2024. The patent describes a “salt splitting process” that converts sodium sulphate into sodium hydroxide and sulphuric acid, and ammonium sulphate into ammonia and sulphuric acid, using simple inorganic reactions at moderate temperatures. The invention is a prime example of a “circular hydrometallurgical process”. The ADONIS project aims to provide the proof-of-concept for this process, while demonstrating its environmental and techno-economic superiority. If successful, ADONIS could solve the sodium and ammonium sulphate waste problem for many EU companies, enhancing their ESG credentials and easing permit acquisition. Commercialising this technology would boost the EU’s envisaged strategic autonomy.