<p>Lithium recovery from lithium slag via a roasting-ultrasonic-enhanced leaching process was investigated. The effects of roasting and leaching conditions on lithium recovery were investigated, and the leaching kinetics were studied using a shrinking core model. The results showed that under optimal conditions—a mass ratio of combined additives to lithium slag of 1:1, roasting temperature of 900&#xa0;°C, roasting time of 90 min, leaching temperature of 50&#xa0;°C, leaching time of 60 min, liquid–solid ratio of 12.5:1, and ultrasonic power of 220 W—a lithium leaching efficiency of 82.47% was achieved. The contents of Li, K, Na, and S in the leach residue were 0.06, 0.76, 2.15, and 1.13%, respectively. Leaching kinetics analysis indicated that the conventional leaching process was controlled by a diffusion mechanism, while the ultrasonic-assisted leaching process conformed to an interfacial reaction-controlled model. Ultrasonic treatment reduced the apparent activation energy of the leaching reaction from 20.17 to 16.27 kJ/mol. XRD analysis shows that the residues from conventional and ultrasonically enhanced leaching are mainly composed of lithium-free anorthite (CaAl₂Si₂O₈) and quartz (SiO₂), demonstrating that the combination of the roasting-leaching process and ultrasonically enhanced leaching can effectively extract lithium from the slag. SEM analysis revealed that the lithium slag particles were fragmented into smaller particles by ultrasonic vibration, and this mechanical effect facilitated the leaching reaction.</p> Graphical Abstract <p></p>