A novel and cleaner process for lead and silver recycling from multiple lead-containing wastes, e.g., lead ash, lead sludge, lead slag, and ferric sludge, by reductive sulfur-fixing smelting was proposed. In this process, coke and iron-containing wastes were employed as reductive agent and
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A novel and cleaner process for lead and silver recycling from multiple lead-containing wastes, e.g., lead ash, lead sludge, lead slag, and ferric sludge, by reductive sulfur-fixing smelting was proposed. In this process, coke and iron-containing wastes were employed as reductive agent and sulfur-fixing agent, respectively. A Na
2CO
3-Na
2SO
4 mixture was added as flux. The feasibility of this process was detected from thermodynamic and experimental perspectives. The influence of Fe/SiO
2 and CaO/SiO
2, composition of the molten salt, coke addition, smelting temperature, and smelting time on direct Pb recovery and sulfur-fixation efficiency were investigated. The optimal process conditions were determined as follows:
WCoke = 15%
WPb wastes,
= 0.7/0.3, Fe/SiO
2 = 1.10, CaO/SiO
2 = 0.30, smelting temperature 1200 °C, and smelting time 2 h, where
W represents weight. Under these optimum conditions, 92.4% Pb and 98.8% Ag were directly recovered in crude lead bullion in one step treatment, and total 98.6% sulfur was fixed. The generation and emissions of SO
2 can be avoided. The main phases in ferrous matte obtained were FeS, NaFeS
2, Fe
2Zn
3S
5, and a little entrained Pb. The slag was a FeO-SiO
2-CaO-Na
2O quaternary melt.
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