The growing demand for electric vehicles and energy storage systems has led to a rise in battery production, resulting in a growing volume of spent batteries. To address the environmental and economic challenges associated with battery waste, efficient and sustainable recycling processes are crucial. In this context, crystallization offers a promising approach for recovering valuable metals. This study presents a population balance model (PBM) coupled with computational fluid dynamics (CFD) to simulate recovery of nickel sulphate hexahydrate (NiSO 4·6H 2O) crystals through the antisolvent crystallization technique. Growth and particle size distribution (PSD) of crystals are analyzed within a continuous 3D T-mixer system under laminar flow conditions for a single case of Re = 150. The impact of impinging flow on mixing, which affects local supersaturation and PSD, is clearly visible. Additionally, the crystal size at the distribution maximum correlates directly with supersaturation consumption. This approach provides a comprehensive framework for understanding and predicting the PSD in the crystallization process, helping to understand mixing, flow dynamics and supersaturation profiles. This study also evaluates the T-mixer's ability in promoting uniform crystal growth, targeting a narrow PSD. These findings contribute to the development of sustainable crystallization systems, supporting efficient metal recovery in battery recycling applications.