Analysis of a more sustainable method for recycling waste lead batteries: Surface renewal promotes desulfurization agent regeneration

Rapid recovery of high pure PbO from spent lead acid battery without desulfation and chemicals consumption method

The direct recovery of high-purity PbO from spent lead paste without a pre-desulfation process has significant industrial promise. Herein, we propose a recyclable, ultra-fast, and high value-added closed-loop of high-purity PbO recovery process by intensive multidentate coordination of histidine with crude 2PbO·PbSO4 by a rotating liquid-film (RLF) reactor and CO2 carbonation-dissociation. Parameter optimizations and kinetic calculations show the leaching time is shortened from 40 min to 60 s with 99.14 % leaching rate and 99.99 % PbO purity by internal diffusion control, where the RLF reactor promotes mass transfer and reaction rates by instantly renewing the surface of crude 2PbO·PbSO4. Furthermore, all 5 batches reveal that the separation of SO42- ions from the regenerated mother liquid with Ba(OH)2 significantly improves the recycling rate of the mother liquid and high-purity PbO product. This new strategy reveals a bright prospect of a highly efficient, high value-added, and environmentally friendly recycling route for solid waste resources.

Design and simulation of a cross-regional collaborative recycling system for secondary resources: A case of lead-acid batteries

In emerging economies, a significant amount of secondary resources are recycled by the informal sector, which can seriously harm the environment. However, some previous studies of industry management policy design ignored geographical factors. This paper introduces Geographic Information Systems into an agent-based cross-regional recycling model, and employs lead-acid batteries as an example. The model quantitatively displays the evolution of recycling markets in 31 provinces in Mainland China. Results show that: (1) High subsidies can significantly increase the number of formal enterprises in the short term, but their effectiveness decreases when the proportion of government funds in subsidies is above 80% in the long run; (2) The number of illegal recycling enterprises increases by 294% in eight inland provinces (e.g., Ningxia, Xinjiang) when all funds are invested in supervision, but this number is quite small in subsidy policy scenarios; (3) In four eastern regions, including Beijing and Tianjin, the number of illegal recycling enterprises decreases by 84% if supervision is more favored than subsidy; (4) In the optimal case where spatiotemporal factors are considered in all 31 regions, illegal recycling enterprises and waste lead emissions can be reduced by 95.59% and 45.85% nationwide. Our proposed recycling model offers a detailed simulation of multiple regions and diverse stakeholders, and serves as a useful reference for targeted recovery policies. Governments in inland regions like Ningxia and Xinjiang should implement subsidy policies, while supervision policies should be implemented in developed regions like Beijing and Tianjin.

Ultra-Fast Recyclable and Value-Added Desulfation Method for Spent Lead Paste via Dual Intensification Processes

The new low-cost clean pre-desulfation technology is very important in pyrometallurgy and hydrometallurgy. However, traditional reactors have low space-time yield and desulfation rate, resulting in high energy consumption and SO2 emissions in the industrial desulfation processes. Herein, dual rotating liquid film reactors (RLFRs) and lime are proposed to construct a recyclable, ultra-fast, and value-added desulfation method. Parameter optimization and kinetic calculations prove that the above reactions are controlled by internal diffusion, revealing that RLFR promotes the mass transfer and reaction rate. The new process greatly shortens the desulfation time of lead paste from 40 min to 10 s with a high desulfation rate of 99.7%, and the sulfation time of lime from 30 min to 30 s with a sulfation rate of 98.6% with a net profit of 55.99 ¥/ton by cost accounting. Moreover, ten batches of continuous scale-up experiments demonstrate the stability of processes, the desulfation and sulfation rates are kept at 99.7% and 98.2%, which greatly reduces the emissions of waste desulfate liquor. This work provides a new universal strategy for a sustainable, low-cost, and clean desulfation method of waste resources to achieve technical and economic feasibility.

Recovery of Pure Lead-Tin Alloy from Recycling Spent Lead-Acid Batteries

Spent lead-acid batteries have become the primary raw material for global lead production. In the current lead refining process, the tin oxidizes to slag, making its recovery problematic and expensive. This paper aims to present an innovative method for the fire refining of lead, which enables the retention of tin contained in lead from recycled lead-acid batteries. The proposed method uses aluminium scrap to remove impurities from the lead, virtually leaving all of the tin in it. The results of the conducted experiments indicate the high efficiency of the proposed method, which obtained a pure Pb-Sn alloy. This alloy is an ideal base material for the production of battery grids. This research was carried out on an industrial scale, which confirms the possibility of facile implementation of the method in almost every lead-acid battery recycling plant in the world.

Lead Oxide Production in Barton Reactor-Effect of Increased Air Humidity on Lead Oxide Production Parameters

The paper presents tests of lead oxidation in a Barton reactor with a capacity of 1200 kg PbO/h, divided into two series. The first series was carried out in conditions of high humidity of the air supplied to the reactor (59-61%), and the second series in conditions of low humidity (19-21%). The study used lead of various purity levels, the main impurities of which were bismuth and silver. The obtained results show that the use of air with a humidity of about 60% in the process allows us to obtain high-quality PbO and has a positive effect on processing parameters such as the amount of lead processed and the efficiency of the process. The mentioned processing parameters significantly influence the production cost of lead oxide. The effect of lead impurities on the process of lead oxidation and the quality of the obtained product was noticed. This dependence is especially visible in the case of the process efficiency, the amount of lead processed per time unit and the amount of formed scrap. The increase in the content of impurities adversely affects each of the parameters mentioned. Optimal parameters of lead oxide regarding the expected acid absorption at the level above 16 g H₂SO₄/100 g PbO and the degree of oxidation at the level of 75% were obtained for the air humidity of about 60% with the content of pollutants below 100 ppm. The paper presents data on the process parameters and the relationships between them, unpublished in the literature.

Recycling of Lead Pastes from Spent Lead–Acid Batteries: Thermodynamic Constraints for Desulphurization

Lead–acid batteries are important to modern society because of their wide usage and low cost. The primary source for production of new lead–acid batteries is from recycling spent lead–acid batteries. In spent lead–acid batteries, lead is primarily present as lead pastes. In lead pastes, the dominant component is lead sulfate (PbSO4, mineral name anglesite) and lead oxide sulfate (PbO•PbSO4, mineral name lanarkite), which accounts for more than 60% of lead pastes. In the recycling process for lead–acid batteries, the desulphurization of lead sulfate is the key part to the overall process. In this work, the thermodynamic constraints for desulphurization via the hydrometallurgical route for recycling lead pastes are presented. The thermodynamic constraints are established according to the thermodynamic model that is applicable and important to recycling of lead pastes via hydrometallurgical routes in high ionic strength solutions that are expected to be in industrial processes. The thermodynamic database is based on the Pitzer equations for calculations of activity coefficients of aqueous species. The desulphurization of lead sulfates represented by PbSO4 can be achieved through the following routes. (1) conversion to lead oxalate in oxalate-bearing solutions; (2) conversion to lead monoxide in alkaline solutions; and (3) conversion to lead carbonate in carbonate solutions. Among the above three routes, the conversion to lead oxalate is environmentally friendly and has a strong thermodynamic driving force. Oxalate-bearing solutions such as oxalic acid and potassium oxalate solutions will provide high activities of oxalate that are many orders of magnitude higher than those required for conversion of anglesite or lanarkite to lead oxalate, in accordance with the thermodynamic model established for the oxalate system. An additional advantage of the oxalate conversion route is that no additional reductant is needed to reduce lead dioxide to lead oxide or lead sulfate, as there is a strong thermodynamic force to convert lead dioxide directly to lead oxalate. As lanarkite is an important sulfate-bearing phase in lead pastes, this study evaluates the solubility constant for lanarkite regarding the following reaction, based on the solubility data, PbO•PbSO4 + 2H+ ⇌ 2Pb2+ + SO42− + H2O(l).