Insights into the dissolution kinetics of copper–nickel tailings for CO2 mineral sequestration

• Optimal leaching conditions for magnesium from copper–nickel tailings are 2 M HCl, 50 g/L solid-to-liquid ratio, and 90°C, achieving a maximum leaching rate of 83.88%. • A modified shrinking core model accurately describes the leaching kinetics, indicating a mixed control by chemical reaction and product layer diffusion. • The apparent activation energy for magnesium dissolution is 77.51 kJ·mol−1, providing insight into the rate-limiting steps. • The study demonstrates the feasibility of using copper–nickel tailings as a medium for CO2 mineral sequestration, offering a dual benefit of waste management and carbon capture.