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, H 2 O 2 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 H 2 SO 4 and 10 vol. % H 2 O 2 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 Li 2 CO 3 precipitated by saturated Na 2 CO 3 , 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.
Carbon capture and utilization (CCU) has attracted increased attention as a means to mitigate and adapt to climate change. CCU technology regards CO 2 as a raw material and reduces CO 2 emissions. However, purity and pressurization requirements in most CCU technologies are high. Flue gas that is emitted from industries and transportation requires advanced purification and pressurization, which limits the development and decreases the feasibility of CCU application. Hence, a new approach to CCU technology without CO 2 purification and pressurization is desirable. This study reviews differences between the CO 2 purity and pressure of waste CO 2 and feedstock CO 2 , reviews difficulties of CO 2 purification and pressurization in recent developments of CCU, and provides several promising examples of CCU technologies without CO 2 pressurization and/or purification. Various promising CCU technologies and their future research prospects are discussed. Mineral carbonation and biological conversion appear to be possible solutions as CCU technologies without CO 2 purification and pressurization. For all other CCU approaches, research trials to decrease the required CO 2 purity and pressure of the feedstock CO 2 will be required.
Mineral carbonation using alkaline wastes is an attractive approach to CO 2 utilization. Owing to the difference between waste CO 2 and feedstock CO 2 , developing CO 2 utilization technologies without CO 2 purification and pressurization is a promising concept. This study investigated a potential method for CO 2 utilization via direct aqueous carbonation of synthesized concrete fines under atmospheric pressure and low CO 2 concentration. The carbonation reaction with different solid−liquid ratios and different concentrations of introduced CO 2 was examined in detail. Under basic conditions, a CO 2 uptake of 0.19 g-CO 2 /g-concrete fines demonstrated that direct aqueous carbonation of concrete fines under atmospheric pressure and low CO 2 concentration is effective. The CaCO 3 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.
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