A novel approach to recycling of copper and aluminum fragments in the crushed products of spent lithium iron phosphate batteries was proposed to achieve their eco-friendly processing. The model of pneumatic separation that determines the optimal airflow velocity was established using aerodynamics. The influence of the airflow velocity, and the density and thickness, and their ratios, of the aluminum and copper fragments on pneumatic separation were evaluated. The results show that the optimal airflow velocities of copper and aluminum fragments with and without the electrode materials are 3.27m/s and 1.67m/s, respectively. The accuracy and reliability of the present model was verified using a pneumatic separation experiment. It is concluded that graded pneumatic separation is unnecessary for the crushed particle size more than 9 mm. The experimentally determined optimal airflow velocity of the copper and aluminum fragments with and without the electrode materials is 3.3m/s and 1.7m/s, respectively. The mass fractions of the copper and aluminum fragments upon removal of the electrode materials after pneumatic separation are 97% and 96%, respectively, and both with the electrode material achieve 97.0%. The theoretically obtained optimal airflow velocities have good agreements with the experimentally obtained ones.
Keywords: Spent lithium iron phosphate battery; airflow velocity; aluminum; copper; crushing; pneumatic separation; recycling.