Efficient Desulfurizer Recycling during Spent Lead-Acid Batteries Paste Disposal by Zero-Carbon Precursor Hypothermic Smelting.

Recycling of spent lead-acid batteries (LABs) is extremely urgent in view of environmental protection and resources reuse. The current challenge is to reduce high consumption of chemical reagents. Herein, a closed-loop spent LABs paste (SLBP) recovery strategy is demonstrated through NaMoO consumption-regeneration-reuse. Experimental and DFT calculations verify that MoO competes Pb/Ca ions and weakens the metal-oxygen bond of PbSO/CaSO.2HO in SLBP, facilitating PbMoO/CaMoO formation and 99.13 wt% of SO elimination. Pb of 99.97 wt% is obtained as zero-carbon precursors (PbO and PbMoO) by green leaching coupled with re-crystallization. The regeneration of NaMoO is realized at 600 ℃ using LABs polypropylene shells and NaOH as reagents. Compared with the traditional smelting technologies, the temperature is reduced from ＞1000 to 600 °C. The extraction of NaMoO require only water, and satisfactory re-used desulfurization efficiency (98.67 wt%) is achieved. For the residual NaMoO after first SLBP desulfurization, the desulfurization efficiency remains above 97.36 wt% after adding fresh reagents for two running cycles. The new principle enables the reuse of 99.83 wt% of NaMoO and the recycling of 95.27 wt% of Pb without generating wastewater and slags. The techno-economic analysis indicates this strategy is efficient, economical, and environmentally-friendly.