In the hydrometallurgical recycling process for lead–acid batteries, there are three desulphurization processes of lead pastes with oxalate, carbonate, and alkaline solutions. The desulphurized lead products (i.e., lead oxalate, lead hydroxide, and lead carbonate) are then smelted to produce lead ingots.
A novel approach to recover lead oxide from spent lead acid batteries by desulfurization and crystallization in sodium hydroxide solution after sulfation. Resour.
Conclusions The desulphurization of lead pastes is the key process in recycling of lead–acid batteries. In this study, the thermodynamic constraints for three hydrometallurgical routes of desulphurization of lead pastes are presented.
In the desulphurization processes of lead pastes, the transformation or reduction of lead dioxide (plattnerite and scrutiny) is a problem. In the current practice, reductants are needed in reduction of lead dioxide. The reductants that have been used in hydrometallurgical routes include lead sulfide [ 3] and glucose [ 35 ].
To verify that the regenerated sodium hydroxide could effectively desulfurize lead paste, we performed desulfurization reactions on three batches of waste lead paste. The experimental results are shown in Table 1. Table 1. Desulfurization of lead paste by regenerated NaOH. NO.
NaOH was used as the direct desulfurizer for lead paste, and lime was used to regenerate NaOH from the mother liquid at sufficient concentrations for desulfurization.