Cleaner Extraction of Lead from Complex Lead-Containing Wastes by Reductive Sulfur-Fixing Smelting with Low SO2 Emission

Abstract

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 Na2CO3-Na2SO4 mixture was added as flux. The feasibility of this process was detected from thermodynamic and experimental perspectives. The influence of Fe/SiO2 and CaO/SiO2, 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, W Na 2 CO 3 / W Na 2 SO 4 = 0.7/0.3, Fe/SiO2 = 1.10, CaO/SiO2 = 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 SO2 can be avoided. The main phases in ferrous matte obtained were FeS, NaFeS2, Fe2Zn3S5, and a little entrained Pb. The slag was a FeO-SiO2-CaO-Na2O quaternary melt.

Efficient and low-energy mechanochemical extraction of lead from dumped crystal glass waste

“…The only documented method of Pb recovery from crystal glass waste is pyrometallurgy through reduction-melting (Jani and Hogland, 2017), an energy-intensive (1100 °C) process that also emits Pb-containing particulates (Li et al 2019). Thus, an alternative process is needed to lower the energy footprint and eliminate such emissions.…”

Spent Lead-Acid Battery Recycling via Reductive Sulfur-Fixing Smelting and Its Reaction Mechanism in the PbSO4-Fe3O4-Na2CO3-C System

“…5 Pyrometallurgy is presently the predominant route worldwide for recycling LAB, 10 in which high-temperature treatment of spent LABs in a blast, electric, reverberatory, or rotary furnace without pre-desulfurization is employed. 11,12 In the hydrometallurgical process, 13,14 a pre-desulfurization step 15 is necessary. Na 2 CO 3 , NaOH, and K 2 CO 3 solutions or citric acid and citrate salts are usually adopted as desulfurization reagents.…”

“…The novelty of this process is the treatment of various iron/lead-bearing wastes, SO 2free sulfur fixation, a much shorter flowsheet, absence of harmful byproducts, and wide adaptability for different secondary materials. 12 This work investigated the detailed lead extraction and sulfurfixing mechanisms in the PbSO 4 -Fe 3 O 4 -Na 2 CO 3 -C system, thermodynamically and experimentally. The phase transformations and microstructural evolution processes were characterized, and the lead extraction and sulfur-fixing reaction mechanisms proposed.…”

Recovery of Lead and Zinc from Zinc Plant Leach Residues by Concurrent Dissolution-Cementation Using Zero-Valent Aluminum in Chloride Medium

“…Pb, for example, is extremely toxic to babies and children and is known to cause various disorders of the reproductive organs, central nervous system, and kidneys [14][15][16]. Therefore, the reprocessing of ZPLRs for metal removal/recovery could address both environmental and resource concerns associated with these waste materials.Pyrometallurgical [17,18] and hydrometallurgical [19,20] techniques can be employed to recover valuable metals from ZPLRs. When appropriate, the latter approach is preferred because it is less energy-intensive and generates wastes (e.g., solid residues) that may cause less or no secondary environmental pollution.…”

“…Pyrometallurgical [17,18] and hydrometallurgical [19,20] techniques can be employed to recover valuable metals from ZPLRs. When appropriate, the latter approach is preferred because it is less energy-intensive and generates wastes (e.g., solid residues) that may cause less or no secondary environmental pollution.…”