The paper focuses on the improved process of metal recovery from lithium-ion batteries (LIBs) lithium nickel manganese cobalt oxide (NMC) cathode waste materials by using hydrometallurgical methods. In the acid leaching step, the essential effects of acidity concentration, H₂O₂ concentration, leaching time, liquid-solid mass ratio, and reaction temperature with the leaching percentage were investigated in detail. The cathode material was leached with 2M H₂SO₄ and 10 vol. % H₂O₂ at 70 °C and 300 rpm using a liquid-solid mass ratio of 30 mL/g. In order to complete the recovery process, this paper designs the proper separation process to recover valuable metals. The leach liquor in the recovery process uses Cyanex 272 to first extract Co and Mn to the organic phase. Secondly, Co and Mn are separated by using D2EHPA, and a high purity of Co is obtained. Thirdly, Ni is selectively precipitated by using DMG, and Ni is completely formed as a solid complex. Finally, in the chemical precipitation process, the remaining Li in the leach liquor is recovered as Li₂CO₃ precipitated by saturated Na₂CO₃, and Co, Mn, and Ni are recovered as hydroxides by NaOH. This hydrometallurgical process may provide an effective separation and recovery of valuable metals from LIBs waste cathode materials.

Mineral carbonation using alkaline wastes is an attractive approach to CO₂ utilization. Owing to the difference between waste CO₂ and feedstock CO₂, developing CO₂ utilization technologies without CO₂ purification and pressurization is a promising concept. This study investigated a potential method for CO₂ utilization via direct aqueous carbonation of synthesized concrete fines under atmospheric pressure and low CO₂ concentration. The carbonation reaction with different solid–liquid ratios and different concentrations of introduced CO₂ was examined in detail. Under basic conditions, a CO₂ uptake of 0.19 g-CO₂/g-concrete fines demonstrated that direct aqueous carbonation of concrete fines under atmospheric pressure and low CO₂ concentration is effective. The CaCO₃ concentration, degree of carbonation, and reaction mechanism were clarified. Furthermore, characterization of the carbonated products was used to evaluate ways of utilizing the carbonated products.