Lead paste was firstly desulfurized with sodium carbonate, in the meanwhile lead sulfate was converted into lead carbonate and the form of lead metal and lead oxides remained unchanged, and then the desulfurized lead paste was reduced by charcoal under vacuum.
There are four main components in spent lead acid battery: polymeric containers, lead alloy grids, waste acids and pastes. Among them, the pastes mainly comprise lead oxide (∼9%), lead dioxide (∼28%), lead sulfate (∼60%) and a small amount of lead (∼3%) (Zhu et al., 2012a).
Conclusions A research investigation for recycling lead from lead paste in the spent lead acid battery under vacuum has been developed in this work.
Hence, based on the minimum specific gravity of industrial lead paste slurry, the concentration of desulfurizer required for sodium-calcium double alkali lead paste desulfurization was estimated to be at least 2.32 mol/L. 3.2. Mechanism of a novel process of lead paste pre-desulfurization
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.
The new sodium-calcium double-alkali lead paste pre-desulfurization process proposed in this paper involved the direct reaction of lead paste with NaOH solution. Relatively cheap lime was reacted with the mother liquor, the sodium sulfate produced by desulfurization, to regenerate NaOH.