The leaching model and leaching kinetics of lithium slag in alkaline solution

Lithium slag is a silica-aluminum solid waste, and its leaching activity in alkali solution determines its application prospect in alkali-activated cementitious materials. In this study, based on the leaching characteristics of lithium slag in sodium hydroxide solution, combined with microscopic testing methods, investigates the leaching activity of Si, Al, and Ca in lithium slag under different alkali concentrations, leaching times, and leaching temperatures. The interrelationships between the physicochemical properties, leaching behavior, and reaction activity of lithium slag were revealed, and a leaching model for lithium slag was established to elucidate the leaching kinetics process. The results indicate that compared to leaching time, alkali concentration and leaching temperature have a more significant impact on the leaching of Si and Al in lithium slag. The leached Si and Al in lithium slag mainly participate in the formation of N-A-S-H and C-A-S-H reaction products. The optimal leaching scheme was obtained through a predictive model for Si and Al leaching from lithium slag. The leaching process of lithium slag in sodium hydroxide solution is controlled by the diffusion behavior of the product layer, with activation energies for leaching Si and Al being 23.9562 kJ/mol and 24.3278 kJ/mol, respectively.