Spent Lead Paste Research Articles

In-situ carbon encapsulated Pb/PbO nanoparticles derived from spent lead paste for lead-carbon battery

The sulfation and serious hydrogen evolution reaction render a substantial obstacle for the further development of lead-carbon batteries (LCBs). Herein, lead tartrate precursors derived from spent lead paste are pyrolyzed to in-situ synthesize a carbon encapsulated Pb/PbO nanoparticles, which are introduced as additives into the negative electrodes of LCBs. The in-situ formed carbon encapsulation Pb/PbO nanoparticles ensure the long-lasting inhibition of the hydrogen evolution reaction in the negative electrodes. The discharge capacity after the introduction of the composites is improved by 24 % compared with the control at 0.1C, and the cycle life is almost twice as long as the control. The remarkable hydrophilicity of the composites as 3D electro-osmotic pumps facilitates the absorption and transportation of electrolyte to the negative active materials. Additionally, the carbon encapsulated Pb/PbO nanoparticles could provide abundant nucleation sites for Pb/PbSO4 conversion and reinforce the reversibility of the transformation between the substances. Benefiting the cooperative interaction between the multiple mechanisms in the composites, the sulfation and serious hydrogen evolution on the negative electrode are dramatically inhibited, consequently thus contributing to the admirable promotion of the overall performances of LCBs.

A Review on Lead Extraction from Ore and Spent Lead Paste by Hydrometallurgical Processes

A Review on Lead Extraction from Ore and Spent Lead Paste by Hydrometallurgical Processes

Recovering metallic lead from spent lead paste by slurry electrolysis

Spent lead paste, the most challenging component of discarded lead-acid batteries, contains approximately 70 % Pb. Improper handling of lead-acid battery waste poses severe risks to both the environment and human health. Here, we present a novel and short process for directly recycling metallic Pb from spent lead paste by chlorine slurry electrolysis and investigate the parameters that affect Pb recovery rate and cathodic current efficiency. Our experiments showed that under optimal conditions (250 g/L NaCl, 0.8 mol/L HCl, 10 g/L Pb2+, 30 A/m2, 40 g/L pulp concentration, 65 °C, and 12 h), the Pb recovery rate and cathodic current efficiency were, respectively, 90.54 and 85.25 %. During slurry electrolysis. Cl- combined with Pb in spent lead paste in the anode chamber, converting lead oxides and insoluble PbSO4 into soluble lead chloride complexes ([PbCl3]-, [PbCl4]2-). Driven by the electric field and concentration gradient, the lead chloride complex ions then migrated to the cathode region, where they were reduced to metallic Pb with a purity higher than 99 %. The application of this cost-effective and efficient novel method can contribute to the sustainable reuse of waste lead-acid batteries and other Pb-bearing scrap.

Electron-transfer dynamics and photocatalytic H2-production activity of PbS@Cu2S nanocomposites

BackgroundLead citrate is a precursor that can be prepared by recycling the spent lead paste of lead-acid batteries. Lead citrate is used to synthesize lead oxide, which can be repeatedly utilized for the lead-acid battery application. MethodsWe report a new application of lead citrate precursor to synthesize PbS@Cu2S nanomaterials for photocatalytic H2 production. PbS@Cu2S was prepared by microwave-assisted hydrothermal and ion-exchange processes. The electron-transfer dynamics and H2-production activity of PbS@Cu2S photocatalysts were studied. Significant findingsA S-scheme heterojunction is proposed based on the results of Tauc plots, ultraviolet photoelectron spectroscopy, the electron paramagnetic resonance scavenger test, and in situ near-edge X-ray absorption fine structure (NEXAFS) analysis. Results of in situ NEXAFS reveal the transfer of photoexcited electrons from PbS to Cu2S. By loading an optimized amount of Cu2S, the carrier separation and photocatalytic activity of PbS@Cu2S photocatalysts are improved. This technology can transform the lead citrate precursor to the PbS@Cu2S photocatalyst with excellent high H2 production activity (3824 μmol g−1 h−1).

Molten salt mediated low-temperature direct roasting of spent lead paste

Traditional pyrometallurgy for recovery of spent lead paste suffered from high energy consumption, massive reducing agent and toxic SOx gas emission. Here, a sustainable molten nitrate salt mediated approach was proposed to realize low-temperature (500 °C) direct roasting of waste lead paste. Efficient desulfurization could not be realized via single direct smelting of the mixture containing spent lead paste, Na2CO3 and NaNO3. The introduction of Na2CO3 desulfurizer could promote the chemical conversion with PbSO4, while the process still required relatively high temperature above 900 °C to realize relatively high desulfurization efficiency. After the introduction of NaNO3 molten salt into spent lead paste-Na2CO3 system, the original solid-solid reaction in spent lead paste-Na2CO3 system was changed to solid-liquid-solid contract, providing more reaction probability between Na2CO3 and PbSO4 phase in spent lead paste. As a result, high-purity lead oxide powders were obtained with 98.7% desulfurization and 99.2% lead recovery ratio. A profit of $378.2 per ton spent lead paste could be achieved from the economically evaluations. The proposed novel pyrometallurgy approach eliminated the emission of harmful SOx from the decomposition of PbSO4 phase and releases of lead containing wastewater, offering a robust lead oxide recovery substitute from secondary lead resources while possessing significant environmental and economic benefits.

α-PbO Recovery from Spent Lead Paste by Coalesced Reduction and Sulfur Fixation

α-PbO Recovery from Spent Lead Paste by Coalesced Reduction and Sulfur Fixation

An environment-friendly strategy for recovery of α-PbO from spent lead paste: Based on the thermochemical reduction of PbO2 with ammonium sulfate

During the process of recycling lead from waste lead-acid batteries, how to minimize the wastage of chemical reagents and prevent secondary pollution is a significant research subject. In this study, a method for preparing α-PbO based on low-temperature thermochemical reduction of PbO2 was proposed. Using (NH4)2SO4 as the roasting agent, the purity of PbSO4 in spent lead paste was improved by reducing PbO2 at low temperatures. The thermochemical mechanism revealed that the thermochemical process consists of three different stages of (NH4)2SO4 decomposition and PbO2 reduction. The purity of PbSO4 in spent lead paste could be increased to 98.43 % by controlling the thermal reaction conditions (M (SO42−: TPb) molar ratio of 1:1, roasting temperature, and time of 340 °C and 1.5 h, respectively). Then, the desulfurization of PbSO4 with (NH4)2CO3 obtained PbCO3, and α-PbO with a purity of 96.87 %-98.57 % could be obtained by pyrolysis of PbCO3. Finally, 95.63 % of NH4+, 97.34 % of SO42−, and 77.71 % of CO32− could also be recovered for the regeneration of (NH4)2SO4 and (NH4)2CO3. This study provides a feasible technology for green recycling of spent lead paste.

A clean process for liquid-phase synthesis of α-PbO based on the selective leaching of lead sulfate from spent lead paste

In the recycling process of waste lead-acid battery paste, the traditional hydrometallurgical process of recovering α-PbO as a product presents the issues of the high concentration of alkali and the waste alkaline solution cannot be recycled. This study seeks a clean process for the liquid-phase synthesis of α-PbO based on the selective leaching of lead sulfate from spent lead paste. The pre-treated spent lead paste was initially leached with a sodium acetate solution to obtain a lead acetate solution. The leaching rate of PbSO4 in the leaching process was 99.87%. Metal impurities such as Fe and Ba could be removed. Then the lead acetate solution was mixed with NaOH particles to synthesize α-PbO. The purity of α-PbO obtained could be reached above 99.99% when the molar ratio of M(nOH-/Pb2+) was 3:1, the reaction temperature was 85 ℃, and the reaction time was 40 min. Meanwhile, a reaction pathway was also proposed in which β-PbO could be converted to α-PbO rapidly at low alkali concentrations. Furthermore, the recirculation process of the waste alkaline solution did not result in the accumulation of metal impurities and did not affect the purity of the α-PbO. The non-recyclable waste alkaline solution could be used to prepare sodium acetate solutions and sodium sulfate by-products. This study provides a feasible method for green recycling of spent lead paste.

Preparation of High-Purity Lead Chloride and Lead Oxide from Spent Lead Paste by Crystallization

Preparation of High-Purity Lead Chloride and Lead Oxide from Spent Lead Paste by Crystallization

A Novel Quantitative Analysis Method for Lead Components in Waste Lead Paste

In this study, a method for determining the lead components in waste lead paste was proposed, using simulated and spent lead paste as research objects. To compare the effectiveness of different determining methods, we selected three methods for comparison and investigated the reasons for measurement deviation. The results indicate that the measurement deviation in the current method primarily stems from the following three factors: (1) Pb is soluble in an acetic acid solution under certain conditions; (2) Pb and PbO2 undergo redox reactions; and (3) hydrogen peroxide can undergo redox reactions with Pb. It is feasible to determine the lead content using the kinetic rules of Pb and PbO2 in the acetic acid-hydrogen peroxide system. The method of determination proposed in this paper is as follows. Firstly, lead dioxide is dissolved in hydrogen peroxide under acidic conditions. Subsequently, the concentration of lead dioxide is determined, and the quantity of hydrogen peroxide consumed is recorded. Then, a new sample is taken, and the lead oxide is dissolved in an acetic acid solution. The concentration of lead oxide is determined using the EDTA·2Na titration method. The residue of lead sulfate in the filtrate is dissolved in a sodium chloride solution, and its concentration is determined using the EDTA·2Na titration method. Based on the previously recorded volume of hydrogen peroxide, the remaining lead dioxide in the residue is dissolved in a mixture of acetic acid and hydrogen peroxide. The remaining lead dioxide is then removed from the new sample employing kinetic principles. Finally, the residual metallic lead in the sample is dissolved in a nitric acid solution, and its concentration is determined using the EDTA·2Na titration method.

Eco-friendly and efficient strategy for lead recovery from spent lead paste by bagged cathode solid-phase electroreduction

Spent lead paste is a registered hazardous solid waste containing high-grade lead. Disposal of spent lead paste with high efficiency and the low energy consumption is of great importance in the view of environment and resource recycling. Herein, a novel, eco-friendly and cost-effective process for direct electroreduction of spent lead paste with bagged cathode to produce metallic lead in Na2SO4 electrolyte is proposed. Thermodynamic analysis proves that direct solid-phase electroreduction of spent lead paste in Na2SO4 electrolyte is feasible. The bagged cathode improves the lead recovery ratio and current efficiency. The mechanism of the solid-phase electroreduction is discussed, and the optimum electroreduction conditions are established, under which a cathode current efficiency of 98.5%, desulfurization rate of 99.6%, lead recovery ratio of 97.3%, and energy consumption of 587.2 kWh per ton paste are achieved. The electrolyte can be facilely regenerated and recycled by neutralization with lime. A closed-loop, economical and high-efficiency process for manufacturing metallic lead from spent lead paste has thus been proposed, which can be potentially used for practice.

Energy-saving recovery of lead from waste lead paste via in-situ hydrometallurgical reduction and electrochemical mechanism

The reasonable prudent disposal of secondary lead resources including waste lead-acid batteries has become a growing concern to prevent the adverse impacts. Herein, a facile zero-emission hydrometallurgical reduction approach is proposed for the recovery of spent lead paste (SLP) possessing energy-saving and high current efficiency merits. The effect of activated carbon (AC) additives on lead recovery efficiency, desulfurization efficiency, cathode current efficiency, and energy consumption was investigated during the hydrometallurgical reduction of SLP. The introduction of AC promotes the current efficiency and shortens the electrolysis time, which contribute to the diminution of the whole energy consumption. Especially, the specific energy consumption of hydrometallurgical reduction drops to 483.5 kWh t–1 with 2.0% AC from the initial 596.6 kWh t–1. Notably, the nucleation mechanism of lead on the SLP cathodes all follows three-dimensional instantaneous growth with the diffusion control. Moreover, the SLP plates after hydrometallurgical reduction could be directly employed as the negative electrodes of lead-carbon batteries, avoiding the formation stage. The electrochemical hydrometallurgical reduction with carbon additives presents a promising strategy for enabling zero emissions, low energy consumption operation of SLP recovery and reutilization.

Batch Production of Lead Sulfate from Spent Lead–Acid Batteries via an Oxygen-Free Roasting Route: A Negative-Carbon Strategy

Multicomponent lead compounds, including lead (Pb), lead oxide (PbO), lead dioxide (PbO2), and lead sulfate (PbSO4), in spent lead–acid batteries (LABs), if not properly disposed of and recycled, will cause serious pollution and damage to the ecological environment. Pyrometallurgical smelting performed above 1000 °C often incurs high energy consumption and lead pollution. In this study, a low-temperature (300 °C), oxygen-free roasting process was proposed. With potassium bisulfate (KHSO4) as the roasting reagent, the uniform conversion of multicomponent lead compounds from spent lead paste (SLP) to PbSO4 was successfully realized in one step. We observed that PbO2 species were relatively chemically stable, during the oxygen-free roasting. However, the decomposition of PbO2 into PbO can be achieved by heating to 300 °C, resulting in an effective conversion to PbSO4. The optimal conditions for PbSO4 production were a heating temperature of 300 °C, an SLP/KHSO4 mass ratio of 1:1, and a holding time of 10.0 min. Life cycle assessment results show that the recycling of 1.0 t spent LABs can reduce carbon emissions of 2.45 t CO2 and smog of 0.13 t. Our research provides an emission-free, low-temperature, and negative-carbon strategy for facile and cost-effective recycling of spent LABs, as an alternative to traditional pyrometallurgical smelting.

Novel PbO@C composite material directly derived from spent lead-acid batteries by one-step spray pyrolysis process

A one-step spray pyrolysis process is investigated for the first time in the field of spent lead-acid batteries (LABs) recycling. The spent lead paste that derived from spent LAB is desulfurized and then leached to generate the lead acetate (Pb(Ac)2) solution, which is then sprayed directly into a tube furnace to prepare the lead oxide (PbO) product by pyrolysis. The low-impurity lead oxide product (9 mg/kg Fe and 1 mg/kg Ba) is obtained under the optimized conditions (the temperature of 700 °C, the pumping rate of 50 L/h, and the spray rate of 0.5 mL/min). The major crystalline phases of the synthesized products are identified to be α-PbO and β-PbO. In the spray pyrolysis process, Pb(Ac)2 droplets are sequentially transformed into various intermediate products: H2O(g)@Pb(Ac)2 solution, Pb(Ac)2 crystals@PbO, and the final PbO@C product. Owning its carbon skeleton structure, the recovered PbO@C product (carbon content of 0.14%) shows better performance than the commercial ball-milled lead oxide powder in battery tests, with higher initial capacity and better cycling stability. This study could provide a strategy for the short-route recovery of spent LABs.

Research on process modeling and simulation of spent lead paste desulfurization enhanced reactor

In the reaction process of carbonate desulfurization lead paste, the produced PbCO3 is easily wrapped in the outer periphery of PbSO4 to form a product layer, hindering the mass transfer process. Therefore, it is necessary to break the PbCO3 product layer. In this work, the rotor stator-reinforced reactor was selected as the enhanced desulfurization reactor for the purpose of breaking the PbCO3 product layer and promoting mass transfer. The breakage process of the PbCO3 product layer generated during the PbSO4 desulfurization was modeled. Computational fluid dynamics simulation to the rotation conditions was carried out to theoretically analyze the fluid flow characteristics of PbSO4 slurry and the wall shear stress affecting the breakage of PbCO3 product layer. By optimizing the rotation conditions, the distribution ratio of effective rotor wall shear stress range achieved 96.1%, and the stator wall shear stress range reached 99.15% under a rotation of 2000 r·min−1. The research work provides a reference for analysis of the mechanism of product layer breakage in the PbSO4 desulfurization process, and gives a clear and intuitive systematic study on the fluid flow characteristics and wall shear stress of the desulfurization reactor.

Green hydrometallurgical extraction of metallic lead from spent lead paste in the methanesulfonic acid system

As the mainstream process for recycling waste lead-acid battery paste to produce metallic lead ingots, pyrometallurgical smelting generally suffers from disadvantages such as high energy consumption, lead vapor and sulfur dioxide emissions. Hydrometallurgical extraction has received widespread attention because of its energy-saving and environmentally-friendly features. An innovative and efficient process for the hydrometallurgical recovery of lead paste was presented in this paper. In order to significantly improve the leaching efficiency of lead, PbSO4 in the lead paste was firstly converted into acid-soluble Pb3(CO3)2(OH)2 or NaPb2(CO3)2OH in Na2CO3 solution. At the same time, the insoluble PbO2 was reduced to PbO by the addition of Na2SO3. The pretreated product was then leached in MSA solution to obtain the lead-containing leachate, which was finally electrodeposited to produce lead deposits and to regenerate MSA. Under the optimized conditions, a dense and flat lead plate (purity greater than 99.99 %) could be obtained and the total lead recovery ratio in the whole process can reach 95.28 %. The cathode current efficiency and specific energy consumption in the lead electrodeposition procedure were 99.31 % and 598.91 kWh/t Pb, respectively. The electrolyte waste could be returned to the leaching process as the leaching agent. In contrast to the traditional fluorosilicate/fluoroborate and chloride systems, the environmentally-friendly MSA system with high lead solubility and low volatility, has promising applications in the field of lead hydrometallurgy.

Preparation of high-purity lead carbonate and lead oxide from spent lead paste

Compared with pyrometallurgical recycling, hydrometallurgical recycling of spent lead paste has obvious advantages such as energy saving and emission reduction, however, hydrometallurgical recycling of spent lead paste is also characterized by high levels of impurities (e.g.,Fe, Ba and Cu) in the recovered products. In this study, a green process for the conversion of spent lead paste into high-purity lead carbonate is presented. The process consists of four steps: sulfation, desulfurization leaching, distillation and carbonization to obtain high-purity lead carbonate. The details are as follows: (1) Spent lead paste (mainly composed of lead sulfate, lead dioxide, lead oxide and lead monomers) was converted into sulfated lead paste using sulfuric acid, hydrogen peroxide and sodium chloride. (2) The sulfated lead paste was reacted with ammonium acetate to leach the lead while desulfurizing; the leaching rate was reached 99.94% under the conditions of 30 wt% ammonium acetate concentration, 40 °C reaction temperature and 7.5 min reaction time. (3) Glycerol was added to the mother liquor and distilled to obtain a glycerol solution containing lead acetate. (4) Using ammonium carbonate (aq) as a carbonizing agent, reacting for 20 min under the condition that the molar ratio of CO32−/Pb is 1.10 can make more than 99.9% of lead precipitate to obtain high-purity lead carbonate products. (5) The lead carbonate product decomposed into orthorhombic α-PbO at 350 °C. (6) Recovered lead oxide product has better electrochemical performance than commercial lead oxide. This process prepares high-purity lead carbonate and lead oxide products with reduced energy consumption and recycles the spent lead paste. This study provides a feasible technology for green recycling of spent lead paste.

An innovative synergistic recycling route of spent lead paste and lead grid based on sodium nitrate reuse

Hydrometallurgical route has been widely studied for its clean and controllability in recovering waste lead-acid battery. However, the current challenges are to reduce chemicals consumption and enhance the economic benefit. Therefore, we presented a sustainable approach for preparing lead oxide from the spent lead grid and lead paste based on sodium nitrate reusing. Results showed that the process indirectly and mildly completed the atomic economic reaction between lead and lead dioxide by sodium nitrate, dramatically reducing the reagents consumption. The reaction rate of the process was depended on the interfacial chemical reaction between lead grid and sodium nitrate. Through controlling the thermodynamic conditions, 99.53% of zero-valent lead (lead grid) was transformed into the layered orthogonal β-lead oxide with merely 0.0494% impurities, and 99.79% of tetravalent lead (lead dioxide in the lead paste) was converted into divalent lead (lead sulfate) in sulfuric acid solution. Afterwards, the lead sulfate was desulfurated followed by thermal decomposition, generating the rod-shaped tetragonal α-lead oxide with only 0.0233% impurities. Moreover, the products β-lead oxide and α-lead oxide used in batteries as anode materials showed excellent electrochemical performance with 482 and 518 charge/discharge cycles, respectively. Additionally, the pilot experiments proved the technological and economic feasibility of the process with a profit of $667.81/ton lead oxide. These results provide an economical and eco-friendly method for synergistically recycling waste lead grid and lead paste.

A closed-loop acetic acid system for recovery of PbO@C composite derived from spent lead-acid battery

The current hydrometallurgical recovery routes of spent lead paste generate a large amount of acid/alkali residual filtrate, bringing significant technical and environmental challenge. In this study, the low-impurity lead acetate solution was prepared by reacting desulfurized paste with acetic acid (HAc), which then reacted with citric acid to synthesize high-quality lead citrate. Further crystallizing lead citrate into larger size enhanced the filtration and separation performance. The filtrate containing 95% dose of HAc could be recirculated for leaching the next batch of desulfurized paste, so a closed-loop process of leaching reagent was realized. The leady oxide comprising carbon (PbO@C) composite was synthesized via calcination of lead citrate. Compared with the traditional lead-acid battery, the novel lead-carbon battery made of PbO@C composite showed better electrochemical performance. The green recovery process of spent lead paste proposed in this research provided a sustainable strategy to recover secondary lead via a closed-loop route.

A new desulfation process of spent lead paste via cyclic utilization of CO2–NH3·H2O

The costly desulfation processes have severely restricted the development and industrial application of hydrometallurgy lead recovery process. In this work, new high efficiency and value-added desulfation method of the spent lead paste is proposed. The new route consists of three sections as follows: (1) Desulfation of spent lead paste by ammonium carbonate; (2) Regeneration of ammonium carbonate through calcium hydroxide sulfuration and ammonia carbonation; (3) Lead carbonate decomposition to obtain the product lead oxide and CO2 to construct a high efficiency and value-added desulfation method of the spent lead paste. The regenerated ammonium carbonate filtrate is re-used in the next batch desulfation process in order to realize a green and sustainable process. For the tests of 5 cycles, the optimal average conversion rate of calcium hydroxide sulfation is up to 88.2% and the desulfation rate of lead paste is above 98.7% as well ammonium ions concentration maintains stable all the way. This work put forwards calcium hydroxide as an inexpensive desulfurizer via “ex-situ nucleation process (ESNP)” and “CO2–NH3·H2O” strategy, providing a cleaner and more economical routes to recover PbO from lead-acid batteries. The cost calculation and technical analysis indicate this new strategy is economical, efficient, and high value-added.