An alternative process using barium compounds recycling for producing battery grade lithium hydroxide from a crude Li2SO4 solution

• An alternative process using barium compounds for producing battery-grade lithium hydroxide from a crude Li 2 SO 4 solution was proposed. • BaSO 4 precipitated from the lithium conversion process was roasted at 1200°C for 3h with carbon power to produce BaS. • BaS produced is reacted with CO 2 purging to produce BaCO 3 and then roasted at 1200°C for 3h with carbon power to produce BaO. • Recycled BaO is used to produce battery-grade lithium hydroxide and the yield for lithium and barium were over 90% and 98%, respectively. • The proposed process is novel as no waste material generated while producing battery-grade lithium hydroxide and can be reduced operating costs by recycling the agent. This study presents an alternative method for producing battery-grade LiOH⋅H 2 O from a crude Li 2 SO 4 solution, emphasising the recycling of barium compounds through a series of sequential steps, including two-step roasting, leaching, and precipitation. Initially, a reaction between Ba(OH) 2 ⋅8H 2 O and a crude Li 2 SO 4 solution yielded battery-grade LiOH⋅H 2 O, while precipitating BaSO 4 . The BaSO 4 was then roasted at 1200°C for 3 hours in the presence of carbon powder as a reducing agent, producing BaS. The BaS was then leached in water with CO 2 purging, resulting in BaCO 3 , which was subsequently oxidised at 1200°C for 3 hours to produce BaO. This BaO was recycled into the primary process for producing battery-grade LiOH⋅H 2 O. Barium recovery was over 98% at each step for both the original reaction and reproduced BaO from the recycling process except during BaCO 3 precipitation (>93%), where the inefficiency of the lab-scale CO 2 purging apparatus. However, residual barium in the solution was recycled back into the process. The battery-grade LiOH⋅H 2 O precipitation recovery was over 90% for both the original and recycled process, with the remaining lithium in the solution also being recycled throughout the process. Further details are discussed in the following sections. The proposed process offers simplicity in scalability for bulk production and holds the potential to contribute to the battery recycling industry. A techno-economic analysis was conducted and discussed to evaluate the feasibility of the proposed approach.