Compared with conventional pyrometallurgical recycling, hydrometallurgical recycling offers distinct advantages by mitigating emissions of waste gas and lead-containing dust; however, it also encounters challenges in effectively eliminating metal impurities from spent lead paste. This study presents a novel hydrometallurgical process for the recovery of spent lead paste, which entails the production of high-purity lead chloride through crystallization, coupled with the recovery of lead oxide via dechlorination, thereby realizing the preparation of high-purity recovered products. First, sulfated lead paste was leached using a sodium chloride solution. Lead could be completely leached when the solid–liquid ratio was 40 g·L⁻¹, the concentration of sodium chloride solution was 250 g·L⁻¹, the reaction temperature was 80 °C, and the leaching time was 20 min. Subsequently, the leachate was filtered and further treated through dilution with distilled water (at 1.6 times) at 0 °C, thereby yielding high-purity lead chloride through the crystallization process, wherein metal impurities were effectively prevented from precipitating out. Finally, the lead chloride product was dechlorinated using sodium hydroxide solution. The dechlorination conditions were as follows: the solid–liquid ratio was 136.09 g·L⁻¹, the crystallization temperature was 0 °C, and the concentration of sodium hydroxide solution was 11.51 mol·L⁻¹. α-PbO was obtained under these conditions. In this study, spent lead paste was recycled with the advantages of low energy consumption and no harmful gas emissions, thereby providing a new idea for recycling lead-containing waste.

Graphical Abstract

中文翻译：

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废铅膏结晶法制备高纯氯化铅和氧化铅

与传统的火法冶金回收相比，湿法冶金回收具有明显的优势，可以减少废气和含铅粉尘的排放；然而，如何有效去除废铅膏中的金属杂质也面临着挑战。本研究提出了一种回收废铅膏的湿法冶金新工艺，通过结晶生产高纯氯化铅，并通过脱氯回收氧化铅，从而实现高纯回收产品的制备。首先，使用氯化钠溶液浸出硫酸化铅膏。当料液比为40 g·L ^-1、氯化钠溶液浓度为250 g·L ^-1、反应温度80 ℃、浸出时间20 min时，铅可以完全浸出。随后，将渗滤液过滤，并在0℃下用蒸馏水（1.6倍）稀释进一步处理，通过结晶过程得到高纯度的氯化铅，有效防止了金属杂质的沉淀析出。最后，使用氢氧化钠溶液对氯化铅产物进行脱氯。脱氯条件为：固液比136.09 g·L ^-1，结晶温度0℃，氢氧化钠溶液浓度11.51 mol·L ^-1。在此条件下得到α-PbO。本研究对废铅膏进行回收利用，具有能耗低、无有害气体排放等优点，为含铅废弃物的回收利用提供了新思路。

图形概要