Lead Calcium Tin Research Articles

Study on electrochemical properties of lead calcium tin anode for hydrometallurgy

This study aims to investigate the electrochemical properties of lead calcium tin (Pb–Ca(0.14%)–Sn(1.04%)) anode employed in hydrometallurgy. Various methods were employed, including cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS), to comprehensively characterize the behavior of this alloy under diverse operating conditions. The findings of this investigation indicate that the Pb–Ca(0.14%)–Sn(1.04%) anode demonstrates remarkable corrosion resistance and a lower oxygen evolution potential in comparison to conventional lead anodes. As a result, enhanced operational efficiency can be achieved. Furthermore, the incorporation of Ca and Sn in the alloy has a substantial positive effect on its mechanical properties, thereby rendering the anode more resilient in harsh operating environments. Consequently, this contributes to reduced maintenance costs. Overall, this study underscores the promising potential of lead calcium tin anodes in promoting more sustainable and efficient hydrometallurgical processes.

Exploring As-Cast PbCaSn-Mg Anodes for Improved Performance in Copper Electrowinning

Lead calcium tin (PbCaSn) alloys are the common anodes used in copper electrowinning (Cu EW). Given a large amount of energy consumed in Cu EW process, anodes with controlled oxygen evolution reaction (OER) kinetics and a lower OER overpotential are advantageous for reducing the energy consumption. To date, magnesium (Mg) has never been studied as an alloying element for EW anodes. As-cast PbCaSn anodes with the addition of Mg were examined herein, revealing an improved performance compared to that of the industrial standard PbCaSn anode. The alloy performances in the early stages of anode life and passivation were established from electrochemical studies which were designed to simulate industrial Cu EW process. The 24-hour polarization testing revealed that the Mg alloying depolarizes the anode potential up to 80 mV; thus, resulting in a higher Cu EW efficiency. In addition, scanning electron microscopy and X-ray photoelectron spectroscopy revealed that the alteration of the alloy microstructure and the corresponding interfacial reactions contribute to the changes of the anode electrochemical performances. The present study reveals for the first time the potency of Mg alloying in reducing the overpotential of PbCaSn anode.

Precipitation in a lead calcium tin anode

Abstract Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 °C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn3 particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment.

Study of precipitation hardening in lead calcium tin anodes for copper electrowinning

A suitable yield stress for Pb anodes with 0·07%Ca and 1·3%Sn of 6 mm thickness for copper electrowinning is achieved by means of deformation and precipitation hardening processes, their useful life being dependent on this yield stress. The objective of the present work was to optimise the precipitation hardening, by finding the best cooling conditions for the anodes in the moulds and the optimum hot rolling temperature. The results show that increasing the cooling rate of ingots beyond the rate of natural cooling enhances the precipitation hardening. At least 45 days of aging are necessary to reach stable conditions for the precipitation hardening, with precipitates formation as CaSn3. The hot rolling temperature does not have a significant effect on the precipitation hardening of the anodes.

Study on the microstructure and electrochemical properties of lead–calcium–tin–aluminum alloys

A detailed investigation of the effects on the microstructure and electrochemical properties of lead–calcium–tin–aluminum alloys of adding tin and calcium was undertaken. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) were used to study the anode electrochemical behavior (such as the growth of lead dioxide, a passive film and the evolution of oxygen) of the lead grid alloy in sulfuric acid solution. The structure and corrosion morphology of the lead alloy were observed and analyzed using a polarizing microscope, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The experimental results show that the grains gradually became smaller as the content of calcium increased, and the content of tin decreased, in the alloy. The size and shape of grains were related to the ratio of tin to calcium content in the alloys. The linear sweep voltammetry and AC impedance measurements suggested that the preferred ratio of tin to calcium content, r, is between 9 and 15, and the optimum range of tin content in the alloys is 0.8–1.1%.

Contribution of the associated complex in a binary liquid to model the Ca–Pb–Sn ternary system

Thermodynamic modeling of the Ca–Pb, Ca–Sn and Ca–Pb–Sn systems was carried out with the help of the CALculation PHase Diagram (CALPHAD) method. The thermodynamic parameters related to these systems were determined from experimental phase diagram and thermodynamic information available in the literature and by our own ternary experimental investigations (X-ray diffraction, metallographic and thermal analyses). The calcium–tin and calcium–lead systems can be described with the association model for the binary liquid with ‘Ca2Sn’ and ‘Ca2Pb’ as the associated species composition. The introduction of new interaction parameters related to the binary and ternary liquids, leads to an accurate restoration of the most important experimental data. Thus, industrial process applied on the lead calcium tin alloys used as electrode materials in lead acid batteries find some justifications.

The Pb–Ca–Sn system: Experimental investigations for x(Ca) ≤ 0.25 composition and thermodynamic modelling

Lead–calcium–tin alloys are extensively used as electrodes in acid batteries. They are synthesised by casting/hardening and subject to microstructural evolution during use. The change from an “aged” metallurgic structure to an “over-aged” structure is associated, in particular, with a deterioration of mechanical properties. The determination of the Pb–Ca–Sn ternary phase diagram, and in particular the evolution of the limits of solubility of calcium and tin in a lead matrix as a function of the temperature, is essential to appreciate the oversaturation degree after hardening and to optimise the necessary thermal treatment to obtain the stabilisation of the aged state. Some experimental measurements were carried out (radiocrystallography, differential thermal analyses, microprobe, …) for the x(Ca) ≤ 0.25 composition domain. They have allowed putting in light the inconsistencies between experimental data provided by the literature. Phase boundaries information was used to model the Pb–Ca–Sn system with a CALPHAD approach. Related thermodynamic databank is presented in this paper.

Properties and application of lead–calcium–tin–aluminium–bismuth alloys for positive grids

The effects of bismuth addition less than 0.05 wt% on the electrochemical properties of lead–calcium–tin–aluminum alloys were investigated in detail. Passivation and corrosion phenomena were investigated by cyclic voltammetry, electrochemical impedance spectra, linear sweep voltammetry. The effect of bismuth on oxygen evolution and hydrogen evolution were also discussed. The experimental results show that the addition of bismuth leads to the decreases of the hydrogen overpotential and increase of the hydrogen evolution rate. Oxygen evolution rate increases with the increase of content of bismuth. The measurements of cyclic voltammetry suggested that bismuth may promote the formation of lead dioxide. A key result was that the presence of bismuth might have beneficial effect on the formation of Pb(II).

New low-antimony alloy for straps and cycling service in lead–acid batteries

Lead–antimony alloys used for the positive grids in lead–acid batteries for cycling service have generally used antimony contents of 4.5 wt.% and above. Tubular batteries for cycling service that impart high compression of the active material to the grid surface via gauntlet use alloys with antimony contents as low as 1.5 wt.%. These batteries are generally employed in less-severe cycling service. Value-regulated lead–acid (VRLA) batteries can give good cycling service without lead–antimony in the positive grid, but require a high tin content and high compression. The change in automotive battery positive grid alloys to lead–calcium–tin and the tin contents of VRLA positive grids and straps have dramatically increased the tin content of the recycled grid and strap lead in the USA, Europe, and Australia. The higher tin contents can contaminate the lead used for lead–antimony battery grids and generally must be removed to low levels to meet the specifications. This study describes a low-antimony alloy that contains a substantial amount of tin. The high tin content reduces the rate of corrosion of low-antimony positive grid alloys, improves conductivity, increases the bond between the grid and the active material, and cycles as well as the traditional 5–6 wt.% antimony alloys employed in conventional flat-plate batteries. The alloy is also used as a corrosion-resistant cast-on strap alloy for automotive batteries for high temperature service, as well as for posts, bushings, and connectors for all wet batteries.

Electrochemical behavior of lead alloys in sulfuric and phosphoric acid electrolyte

The electrochemical behavior of lead, lead–calcium–tin–aluminum and lead–calcium–tin–aluminium–bismuth alloy electrode has been studied in the electrolyte of sulfuric, phosphoric and mixed acid electrolyte. The electrochemical measurements were performed using a cyclic voltammetry technique (CV) with three-electrode system. The results demonstrated that bismuth(III) doped in the lead electrode can increase electrical capacity. The oxidation peak potential of lead alloy electrode in phosphoric acid shifted to the positive compared to that in sulfuric acid. The formation of PbHPO 4 in phosphoric acid and its passivation are responsible for the positive shift of the oxidation.

Positive grid corrosion elongation analysis using CAE with corrosion deformation transformed into thermal phenomenon

Valve-regulated lead-acid (VRLA) batteries have been commercially available for more than 20 years and have been enthusiastically embraced by users of uninterruptible power supplies (UPS) because of the anticipated reduction in installation and operating costs, smaller footprint and fewer environmental concerns. In Japan, communication networks are demanding reduced costs and longer life from their batteries. Among the factors limiting the life of VRLA batteries, the corrosion of positive grid material has been proven to cause elongation of the plates, loss of electrical contact and shorter lifetime. The content of Sn is also a key factor and addition of Sn in the grid alloy results in better performance in creep resistance, tensile strength and corrosion resistance [R. David Prenagaman, The Battery Man, vol. 39, September 1997, p. 16. I. Mukaitani, T. Sakamoto, T. Kikuoka, Y. Yamaguchi, H. Tsubakino, Proceedings of the 40th Battery Symposium in Japan, 1999, p. 99]. A key point is what the ratio of Sn to Ca should be, since too much Sn may lead to even worse elongation of the plates [I. Mukaitani, T. Sakamoto, T. Kikuoka, Y. Yamaguchi, H. Tsubakino, Proceedings of the 40th Battery Symposium in Japan, 1999, p. 99]. We have determined that microstructure control with a composition of lead–calcium–tin (Pb–Ca–Sn) alloy is optimal for better performance of the plates [I. Mukaitani, T. Sakamoto, T. Kikuoka, Y. Yamaguchi, H. Tsubakino, Proceedings of the 40th Battery Symposium in Japan, 1999, p. 99]. We developed a “simulation of current collector corrosion elongation“ which is a technique of estimating corrosion elongation from the current collector design [I. Mukaitani, K. Hayashi, I. Shimoura, H. Takabayashi, M. Terada, A. Takemasa, I. Takahashi, K. Okamoto, Proceedings of the 44th Battery Symposium in Japan, 2003, p. 652]. Corrosion elongation occurs as the corrosion material layer grows out of the current collector metal. We resolved this problem using generally CAD software “ Solid Works” and computer aided engineering (CAE) software “ ANSYS” with corrosion elongation transformed into thermal elongation. We established a current collector corrosion elongation forecast and found that the microstructure controlled the Pb–Ca–Sn alloy; thus newly designed VRLA batteries (MU-series [A. Takemasa, I. Mukaitani, Y. Yoshiyama, K. Fukui, T. Sakamoto, T. Kuwano, M. Fukuda, H. Misaki, K. Uwatari, Shin-Kobe Technical Report 9 (1999) 11] for telecommunication and LL-series [H. Takabayashi, T. Shibahara, Y. Mastuda, K. Fukui, S. Hazui, Y. Matsumura, S. Kondo, Shin-Kobe Tech. Rep. 11 (2001) 35] for electric energy storage) which are lightweight and have long life are introduced here.

Development of new positive-grid alloy and its application to long-life batteries for automotive industry

Abstract Positive-grid corrosion and its resulting creep or growth is one of the major causes of the failure of automotive lead–acid batteries. The importance of grid corrosion and growth is increasing given the tendency for rising temperatures in the engine compartments of modern vehicles. In order to cope with this situation, a new lead alloy has been developed for positive-grids by utilizing an optimized combination of lead–calcium–tin and barium. In addition to enhanced mechanical strength at high temperature, the corrosion-resistance of the grid is improved by as much as two-fold so that the high temperature durability of batteries using such grids has been demonstrated in both hot SAE J240 tests and in field trials in Japan and Thailand. A further advantage of the alloy is its recycleability compared with alloys containing silver. The new alloy gives superior performance in both 12-V flooded and 36-V valve-regulated lead–acid (VRLA) batteries.

New lead alloys for high-performance lead–acid batteries

Consumers require lead–acid batteries with a high level of reliability, low cost and improved life, and/or with less weight and good tolerance to high-temperature operation. To reduce the thickness (weight) of the grids, the alloy materials must exhibit higher mechanical properties and improved corrosion resistance. In this study, the performance of negative and positive grids is evaluated in battery tests. The results demonstrate that continuously cast and expanded grids made from barium-doped lead–calcium–tin alloys meet performance requirements. For negative grids, improvement in the mechanical properties can lead to reliable thinner grids. For positive grids, the alloys exhibit improved mechanical properties and greater corrosion resistance. These features provide extremely good creep behaviour during battery operation such that performance under the hot SAE J240 test is superior to that achieved previously with expanded grids.

Thermodynamic assessment on the Pb–Ca–Sn ternary system

Thermodynamic modelling of the Pb–Ca–Sn ternary system was carried out with the help of the CALculation of PHase Diagrams (CALPHAD) method.The binary borders related to the ternary system were investigated. The lead–tin system is already calculated, the calcium–tin and calcium–lead systems can be described with the association model in binary liquid. The establishment of the modelling of the Pb–Ca–Sn phase diagram was done after collecting own experimental information. The introduction of new interaction parameters related to the ternary liquid, leads to an accurate restoration of the experimental data.Calculated isothermal, isoplethal sections and liquidus surfaces are presented. They confirm that the calcium solubility in lead matrix drastically decreases with the introduction of tin as well as with the decreasing of temperature. The industrial process applied to the lead–calcium–tin alloys finds some justifications in the calculated phase diagram.

Evaluation of Lead Anode Reactions in Acid Sulfate Electrolytes : II. Manganese Reactions

Lead alloys containing calcium-tin, silver, or similar combinations are the primary insoluble anodes used for copper and zinc electrowinning. One potential concern with these anodes is the detrimental effect on cathode purity from incorporation of lead corrosion products. Other factors which are important to process economics are the reaction potential and overpotential required for oxygen evolution. In addition to the inherent overpotential, impurities in the electrolyte can have a significant polarization impact, such as the films that may form when manganese is present. In order to gain a better understanding of the fundamental behavior of various concentrations of manganese ions at lead anodes, the polarization behavior of lead calcium-tin and lead-silver alloys in sulfuric acid was evaluated. A common depolarizing agent, Co(II), was also used in some cases to determine possible interactions with manganese. The data show that manganese ions are active on the lead anodes and may precipitate manganese oxide in addition to electrochemical deposition. One possible precipitation mechanism seems to occur by the disproportionation of Mn(III). Co(II) lowers the electrode potential at given current densities which decreases Pb corrosion but favors formation. © 2002 The Electrochemical Society. All rights reserved.

Manufacturing and operational issues with lead-acid batteries

An expert panel replies to questions on lead-acid technology and performance asked by delegates to the Ninth Asian Battery Conference. The subjects are as follows. Grid alloys: effects of calcium and tin levels on microstructure, corrosion, mechanical and electrochemical properties; effect of alloy-fabrication process on mechanical strength and corrosion resistance; low dross-make during casting of lead–calcium–tin alloys; future of book-mould casting; effect of increasing levels of silver; stability of continuously processed grids at high temperature. Negative-plate expanders: function of lignosulfonates and barium sulfate; benefits of pre-blended expanders; optimum expander formulations. Valve-regulated batteries: effect of oxygen cycle; optimum methods for float charging; charging and deep-cycle lifetimes; reliability testing.

Deformations in lead–calcium–tin anodes for copper electrowinning

The objective of this work is the study of mechanical and metallurgical characteristics of various lead–calcium–tin anodes for copper electrowinning, to determine a relationship between properties and distortions during their operation in the cell in order to set quality standards for new anodes that guarantee absence of distortions. The mechanical tests consist of measurement of hardness, σ o yield strength between room temperature and 80 °C by means of compression tests, and tensile strength through tensile tests. The metallurgical characterization is aimed at determining the size and shape of the grains. It is observed that the anodes that do not undergo deformation in the cell show throughout the temperature range and during equivalent time of use an average yield stress higher than that of those anodes that undergo deformation. This can be explained by the fact that, in the case of the first anodes, the final temperature of rolling corresponds to cold rolling and, consequently, deformation hardening occurs during their fabrication. The deformed anodes, however, were hot rolled.

Extending the life of maintenance-free lead/acid batteries by etching of grids in sodium hydroxide

The surfaces of lead–calcium–tin grids etched in NaOH have been characterized by using X-ray photoelectron spectroscopy (XPS) and environmental scanning electron microscopy (ESEM). It is shown that the basic lead carbonate phase, hydrocerussite, present on the surfaces of lead–calcium–tin grids is removed via etching in NaOH, due presumably to the dissolution of lead(II) salts as water soluble lead(II) complexes. Charge/discharge cycling data for non-antimonial batteries fabricated by using untreated and grid etched 2 V cells have demonstrated that the removal of grid surface hydrocerussite diminishes the rate of premature capacity loss displayed by non-antimonial batteries in the early stages of cycling. Furthermore, scanning electron microscopy (SEM) of the corrosion layers of positive plates for untreated and grid etched cells, in the initial stages of cycling, demonstrated that the removal of grid surface hydrocerussite ameliorates the problem caused by passivation of the grid corrosion layer through the formation of an uninterrupted underlayer of PbO.

A new lead alloy for automotive batteries operating under high-temperature conditions

The operating conditions of automotive and some industrial batteries are involving increasingly higher temperatures and heavier duty cycles. These place stress on the positive-grid materials which are presently not sufficiently resistant to corrosion and to creep. Conventional lead–calcium–tin–aluminium alloys can usually be optimized by a proper choice of calcium and tin contents for each specific manufacturing technology. With the new requirements of customers and the typical behaviour of these conventional alloys, however, there is no more room for improvement without searching for additional alloying elements. The work reported here shows how the doping of conventional lead–calcium–tin–aluminium alloys with barium improves mechanical properties (tensile strength and creep resistance) and increases corrosion resistance at temperatures between 50 and 75°C. Grid materials prepared by two manufacturing technologies (gravity cast; continuous cast followed by expansion) are investigated. Both the mechanical properties and the corrosion behaviour of the resulting grids are evaluated.

Structure and properties of lead–calcium–tin alloys for battery grids

Abstract The selection of an appropriate alloy composition for battery grids is essential for the performance and long life of lead/acid batteries. This investigation examines the effects of the variation of calcium (0.03 to 0.13 wt.%) and tin (0.3 to 1.5 wt.%) content on the microstructure, mechanical properties and the corrosion resistance of cast Pb–Ca–Sn battery grids. Both corrosion resistance and the mechanical properties are found to increase with increasing tin and decreasing calcium levels. The relationship between the alloy composition and the resulting properties of the grids is discussed.