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

Abstract

Abstract 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 Na2MoO4 consumption‐regeneration‐reuse. Experimental and DFT calculations verify that MoO42− competes Pb/Ca ions and weakens the metal‐oxygen bond of PbSO4/CaSO4.2H2O in SLBP, facilitating PbMoO4/CaMoO4 formation and 99.13 wt% of SO42− elimination. Pb of 99.97 wt% is obtained as zero‐carbon precursors (PbO2 and PbMoO4) by green leaching coupled with re‐crystallization. The regeneration of Na2MoO4 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 Na2MoO4 require only water, and satisfactory re‐used desulfurization efficiency (98.67 wt%) is achieved. For the residual Na2MoO4 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 Na2MoO4 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.

Keywords

• desulfurizer recycling
• hypothermic smelting
• sodium molybdate
• spent lead–acid batteries
• zero‐carbon precursor