Energy-saving recovery of lead from waste lead paste via in-situ hydrometallurgical reduction and electrochemical mechanism

Abstract

The reasonable prudent disposal of secondary lead resources including waste lead-acid batteries has become a growing concern to prevent the adverse impacts. Herein, a facile zero-emission hydrometallurgical reduction approach is proposed for the recovery of spent lead paste (SLP) possessing energy-saving and high current efficiency merits. The effect of activated carbon (AC) additives on lead recovery efficiency, desulfurization efficiency, cathode current efficiency, and energy consumption was investigated during the hydrometallurgical reduction of SLP. The introduction of AC promotes the current efficiency and shortens the electrolysis time, which contribute to the diminution of the whole energy consumption. Especially, the specific energy consumption of hydrometallurgical reduction drops to 483.5 kWh t–1 with 2.0% AC from the initial 596.6 kWh t–1. Notably, the nucleation mechanism of lead on the SLP cathodes all follows three-dimensional instantaneous growth with the diffusion control. Moreover, the SLP plates after hydrometallurgical reduction could be directly employed as the negative electrodes of lead-carbon batteries, avoiding the formation stage. The electrochemical hydrometallurgical reduction with carbon additives presents a promising strategy for enabling zero emissions, low energy consumption operation of SLP recovery and reutilization.