Analysis of the Lead Refining Method Using Aluminum

ORIGINAL RESEARCH ARTICLE Analysis of the Lead Refining Method Using Aluminum DANIEL MALECHA , MACIEJ ZUBKO , PIOTR _ ZABIN ´SKI , and STANISŁAW MAŁECKI The purpose of this study was to investigate the processes occurring during the refining of lead with aluminum, by analyzing and studying ternary Pb-(M)-Al systems, where M is one of the following metals: Sb, As, Se, Cu or Ni, which are the main contaminants of secondary lead from recycling waste lead-acid batteries. The Pb-Sb-Ca system, crucial for removing antimony while retaining tin, was also analyzed. The research included analysis of 2and 3-component phase systems simulated, process kinetics under laboratory conditions for pure ternary systems, and chemical and phase composition analysis. Phase analysis showed the presence of permanent aluminum compounds such as AlSb, AlAs, Al 2 Se 3 ,Al 3 Ni and phases with copper in the dross. In addition to the direct association of aluminum with a given contaminant, aluminum oxides such as Al 0.5 Sb 0.5 O 2 and AlAsO 4 as well as calcium oxide with antimony Ca 4 Sb 2 O 7 were also found in the dross. On the basis of the tests carried out, 680 C was considered the optimal temperature for starting the refining process, with the amount of aluminum that was approx. The research provides new scientific data toward more efficient secondary lead refining technologies relevant to recycling waste lead-acid batteries and producing lead-tin alloys for the battery industry. DANIEL MALECHA is with the AGH University of Science and Technology, Faculty of Non-Ferrous Metals, al. Mickiewicza 30, 30059, Krakow, Poland and also with the Baterpol SA, ul. Obr. Westerplatte 108, 40-335 Katowice, Poland. Contact e-mail: [email protected] MACIEJ ZUBKO is with the Institute of Materials Engineering, Faculty of Science and Technology, University of Silesia, 75 Pułku Piechoty 1a, Chorzow 41-500, Poland and also with the Department of Physics, Faculty of Science, University of Hradec Kra ´love ´, Rokitanske ´ho 62, Hradec Kra ´love ´ 500 03, Czech Republic. PIOTR _ ZABIN ´SKI and STANISŁAW MAŁECKI are with the AGH University of Science and Technology, Faculty of Non-Ferrous Metals. Manuscript submitted January 5, 2025; accepted April 27, 2025. Article published online May 30, 2025 METALLURGICAL AND MATERIALS TRANSACTIONS A VOLUME 56A, AUGUST 2025—2957 https://doi.org/10.1007/s11661-025-07813-5 The Author(s) 2025 I. INTRODUCTION NOWADAYS,the main raw materials for lead production are not lead ores, but recycled materials, primarily waste lead-acid batteries (WLAB). Controlled recycling of WLABs in developed countries minimizes the leakage of harmful substances into the environment and the negative impact of lead on the health and safety of workers and the general public. Moreover, using urban minerals such as WLABs, the amount of solid waste generated is reduced. [1–3] The life cycle of a lead-acid battery (LAB) in developed countries where relevant legislation has been implemented is a model example of a closed-loop economy. [4–6] LABs once associated mainly with traditional internal combustion vehicles now play a key role in a wide spectrum of modern technologies. Their versatility and reliability make them applicable not only to electric and hybrid vehicles, but also to the rapidly growing segment of single-track vehicles, such as electric bicycles, scooters and motorcycles. [7–9] These batteries are the foundation of uninterruptible power supply (UPS) systems, guaranteeing uninterrupted operation for industrial plants and key infrastructure during emergencies. [10–13] LABs are also an indispensable component in power systems based on renewable energy sources, such as solar panels or wind turbines, where they act as energy storage and enable efficient use of energy, thus replacing fossil fuels, which contributes to sustainable development and environmental protection. [11,14–16] The technology used in lead-acid batteries is still being developed, innovations are mainly related to improving the performance and increasing the life of the cells. [17–20] A promising direction for the development of LABs is hybrid lead-carbon systems which are able to deliver more power and provide a longer life cycle compared to classic LABs. [14,21,22] As a result of corrosion and passivation processes, the average useful life of a LAB is only approx. 2-4 years. This relatively short lifespan results in a significant amount of waste from WLABs each year. [1,23,24] In developed countries, the dominant LAB recycling technology involves shredding the battery and precisely separating its individual components. This process yields valuable materials like lead paste, metallic fraction from plates and connectors, polypropylene from housings, and less valuable but also usable materials like separators and electrolyte. This method of recycling allows for the efficient recovery of raw materials, contributing to environmental protection and sustainable resource management. [25–30] The lead extracted from the plates, terminals and battery paste is remelted and refined, allowing it to be reused in the production of new LAB. Polypropylene, in turn, is processed into re-granulate, which is used in the production of new battery housings. [30–33] Depending on the type and purpose of the battery, its lead plates and connectors contain different alloying additives. The main ones are tin and antimony, which improve the mechanical properties and corrosion resistance of the plate. Calcium, aluminum, selenium and arsenic are also added in smaller amounts to further enhance the battery’s performance. [34–37] The average tin content of the alloys used for battery plates and connectors has been increasing over the last decade and is currently around 0.45 pct in lead after melting the metallic fraction from WLAB. [38] 2958—VOLUME 56A, AUGUST 2025 METALLURGICAL AND MATERIALS TRANSACTIONS A The metallic fraction recovered from WLAB recycling, which includes shredded lead plates and connectors, is usually processed in a rotary or melting furnace. Thanks to its minimal oxide and sulfate content, there is no need for an extensive cycle of its processing. [30,39] The raw lead obtained by this process must each time undergo a refining process to meet the stringent chemical composition requirements for lead alloys for the manufacture of battery plates and connectors. [34–36,40,41] WLAB recycling is dominated by methods based on lead pyrorefining, while hydrometallurgical and electrolytic methods are used much less frequently, mainly on small-scale installations that are pilot in nature. [30,42–47] The main impurities found in WLAB recycled lead are antimony and tin, and to a lesser extent arsenic, copper, selenium, nickel, tellurium, zinc, thallium and sulfur. Refining takes place by oxidizing unwanted elements with injected oxygen/air or oxidizing agents such as sodium nitrate and caustic soda (a process based on the so-called Harris method). [28,41,48–50] Regardless of the type of oxidative refining used, tin is one of the first elements to be removed from lead and goes into dross and dust, from where its recovery becomes difficult. [32,51] This process requires the implementation of expensive hydrometallurgical technologies to recover this valuable metal as much as possible. [52–54] Tin is widely used in industry, increasing demand for it and leading to the development of more efficient methods of recovery from recycled materials. [55–58] This metal increases strength, reduces corrosion and improves the castability of lead, which is why it is a very commonly used additive in currently used lead-calcium alloys for the production of battery plates where its value can reach 1.7 pct, while in alloys for the production of connectors its value can be approx. 3 pct. [34,36] The use of metallic aluminum for the removal of copper, nickel, antimony, arsenic, selenium and tellurium is well-known in the fire refining method for lead. [28,31,41,59] It has also been shown on laboratory and industrial scales that these impurities are removed while virtually all the tin is retained in the lead. [38,60] The purpose of this study is to investigate and verify the processes involved in refining lead with aluminum by analyzing Pb-(M)-Al ternary systems where M is one of the following elements: Sb, As, Se, Cu or Ni, which are the main undesirable impurities in WLAB recycled secondary lead. In addition, the Pb-Sb-Ca ternary system which is also key in the context of refining lead from antimony while retaining tin has also been studied. [60] First, the analysis of binary and ternary phase systems simulated through Thermo-Calc 2024a software was carried out. Using the CALPHAD method, theoretical compositional relationships and the potential formation of beneficial intermetallic phases during lead refining using aluminum or calcium were analyzed. [61] Theoretical analyses performed using Thermo-Calc 2024a software were additionally supported by data from The Open Quantum Materials Database (OQMD). [62,63] Pure ternary systems were then formed under laboratory conditions and changes in elemental concentrations were observed. Through XRD analysis of the resulting dross, the type of compounds formed was determined. This type of analysis of ternary systems and the resulting metal-combining compounds has provided new scientific data on the kinetics of the refining process. In addition, an attempt was made to determine the optimum starting temperature of the lead refining process using aluminum and the optimum amount of aluminum added at the beginning of the process, which is also a novelty in the literature data and replenishes the knowledge gap regarding liquid mobility in Pb-based liquid phase. It should be noted that the research conducted on a laboratory scale focused on selecting the optimal parameters for the very beginning of the lead refining process using aluminum and calcium. Therefore, the degree of lead refining that was achieved in the research determines only the first phase of this process, in order to achieve the full degree of refining on an industrial scale, this process should be continued longer or repeated by adding Al / Ca again. The research conducted will contribute to the development of more efficient and cost-effective technologies for refining secondary lead with aluminum, enabling more effective removal of impurities while preserving tin. This has important implications for WLAB recycling and lead-tin alloy production. II. MATERIALS AND METHODS A. Materials The base material for the first stage of the study was WLAB recycled refined lead with a purity above 99.97 pct (pure lead). Its chemical composition is shown in row 1 of Table I, the full chemical composition including measurement uncertainty is shown in supplementary Table S-I (refer to online supplementary material). Depending on the sample, one of the following elements was added to this lead: Sb, As, Cu, Ni, Se or Te. The purity of each of these metals was claimed by their manufacturer to be above 99 pct, which was also verified by ICP-OES chemical analysis (the results of the analyses are presented in supplementary Tables S-III to S-VII). The final ingredient was metallic aluminum Table I. Chemical Composition of Lead Used in Research (Wt Pct) Pb Sn Sb As Se Cu Ni Pure Lead 99.98 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 Secondary Lead 96.73 1.52 1.66 0.05 0.01 0.002 0.0002 METALLURGICAL AND MATERIALS TRANSACTIONS A VOLUME 56A, AUGUST 2025—2959 with a purity of over 98 pct (supplementary Table S-VIII). As mentioned in the introduction, in addition, tests were carried out using pure calcium and antimony on the Pb-Sb-Ca ternary system, where Ca purity was also above 98 pct (supplementary Table S-IX). WLAB recycled lead not fully refined was used in the second stage of the study (secondary lead). The only refining operations that were carried out were the process of drossing, copper removal and sulfur removal. [38,48,50] The chemical composition of lead is shown in row 2 of Table I(the full chemical composition along with the measurement uncertainty is shown in supplementary Table S-II of the supplement). The second part of the study used the same aluminum as the first part. B. Methods For laboratory-scale testing, 13.6 kg of lead with the chemical composition listed in Table Iwas used each time. The first step was to melt and heat pure lead to a temperature of approx. 700 C in a laboratory resistance furnace with Kanthal wire heating element model PT 12/7O-ST (Czylok sp. z o.o, Poland) with an automatic temperature maintenance system MRT-5 V (Igloo sp. z o.o., Poland) and temperature setting accuracy, in 1 C increments. The furnace had a heating chamber measuring /200 9250 mm, which housed a steel crucible measuring /135 x 185 mm, a sheet thickness of 4 mm and a working volume of approx. 2 dm 3 . Lead temperature was additionally monitored via an external temperature meter EMT-111 (Czaki Thermo-Product sp. z o. o., Poland). An alloying additive in the form of one of the pure metals was then added in a closed steel cage in the shape of a cylinder with a diameter of 60 mm and a height of 90 mm: Sb, As, Se, Cu or Ni. The set temperature was 700 C, which in most cases, allowed the additives to dissolve quickly in the lead. The assumed concentrations of alloying elements were 5.5 pct for Sb and As, 1 pct for Ni and 0.5 pct for Se and Cu. A steel cage was then pulled out and an additive in the form of pure aluminum was inserted. The steel cage was completely immersed in lead each time to avoid oxidation of the metals added to the lead, and stirred at a constant speed of 120 rpm using a laboratory stirrer JJ-1 (Vevor, China). Steel cage with aluminum inside was immersed in lead for a period of 60 minutes. The addition of aluminum had the character of a refiner whose task was to remove previously added elements. A metal sample was taken every 10 minutes to determine the chemical composition of the resulting lead alloy. The final element of the first part of the study was to collect the dross that formed on the surface of the lead alloy bath using a steel ladle. The total length of the ladle was 30 cm, and its bowl was circular in shape with a diameter of 55 mm and a depth of 9 mm with twenty drilled holes with a diameter of 5 mm. This design of the ladle allowed the liquid metal to separate, with the result that just the dross remained on the bowl of the ladle. The dross was weighed on a scale model B15 (Axis sp. z o.o., Poland), with a reading accuracy of 5 g. An illustrative schematic of the test stand, along with a simplified diagram of the procedure of the tests carried out, is shown in Figure 1. Fig. 1—The research platform consisted of the following elements: (1) a resistance furnace model PT 12/7O-ST Czylok, (2) an electric stirrer with adjustable rotational speed JJ-1 Vevor, (3) an external temperature sensor EMT-111 Czaki; (4) a steel cylindrical basket into which the alloy additives were placed; (5) a steel spoon with drilled holes for removing dross. 2960—VOLUME 56A, AUGUST 2025 METALLURGICAL AND MATERIALS TRANSACTIONS A In order to compare the removal rates of Sb, As, Se, Cu and Ni by Al at the same initial concentration, the previous experiment was repeated for antimony, arsenic and nickel. In each of the three cases, a lead alloy containing about 0.4 pct of the given additive was obtained. Then, as before, the same amount of aluminum (120 g) was placed in a steel cage and stirred for 60 minutes, taking a sample of the lead alloy every 10 minutes. The second separate piece of research was an attempt to determine the optimal parameters for the first phase of the lead refining process using aluminum. The research was conducted on the same test stand as in the first part of the study. In this case, the first step was to melt lead from recycled lead-acid batteries (Table I row 2—secondary lead) and then add pure aluminum to the steel cage. This process was repeated for the same lead at different temperature variations and the amount of aluminum added. For safety reasons, during experiments and preparation of samples for analysis, adequate ventilation was ensured, and masks were worn to protect against toxic gases that could be generated during these processes (e.g., lead fumes, arsenic hydrogen, etc.). C. Analysis of Chemical and Phase Composition The analysis of the chemical composition of lead and lead alloys obtained during the study was carried out using Spark Optical Emission Spectrometry (S-OES) ARL iSpark 8860 Fire Assay Analyzer (Thermo Fisher Scientific Inc., Switzerland). This spectrometer is dedicated to lead analysis, which allowed for very high precision of measurements. For additional verification, the results were also analyzed on an older model of the S-OES ARL 4460 Metals Analyzer (Thermo Fisher Scientific Inc., Switzerland). Samples were taken in accordance with the guidelines of the EN 12402:1999 standard, [64] while analyses on the spectrometer were performed in accordance with the guidelines of the ENV 12908:1997 standard. [65] The uncertainty of the measurements, with a 95 pct confidence interval, was calculated using OXSASsoftware version 2.6. It takes into account both the standard deviations between individual partial measurements and the uncertainty ranges of the certified reference materials. Before analysis, each metal sample of both lead and aluminum was milled on a semi-automatic milling machine HAF2 (Herzog Maschinenfabrik GmbH & Co. KG, Germany). Analyses of the composition of alloying elements in the form of pure metals (Al, Sb, As, Se, Cu, Ni, Ca) and the dross generated in the process were carried out using an inductively coupled plasma optical emission spectroscopy (ICP-OES) Ultima Expert (Horiba Ltd, Japan). The dross samples were ground using a mortar mill Pulverisette 2 (Fritsch GmbH, Germany) until the grain size was below 0.1 mm. The metal samples were crushed manually using cutting tongs. From the Fig. 2—Al-Sb phase diagram. Fig. 3—Al-As phase diagram. Fig. 4—Al-Cu phase diagram. METALLURGICAL AND MATERIALS TRANSACTIONS A VOLUME 56A, AUGUST 2025—2961 prepared material, 0.500 g ±0.001 g of an averaged sample was taken and weighed on an electronic balance WAS 220X (Radwag, Poland). Before the ICP-OES analysis, all materials were dissolved in aqua regia (HNO 3 + 3 HCl) using a microwave mineralizer Ethos EASY SK 15 (Milestone Srl, Italy). Inthefirstpartofthestudy,significantconcentrations of elements such as arsenic, nickel and selenium were found in lead, their concentrations exceeded the calibration curve on the spark spectrometer. For that reason an additional verification measurement was performed on an inductively coupled plasma optical emission spectroscopy, in accordance with the procedure described above. X-ray diffraction measurements were performed to study the phase composition of the resulting material. Measurements were done using a Malvern Panalytical (Malvern Instruments, UK) Empyrean diffractometer using a nickel-filtered Cu Ka1,2 radiation (k=1.5406A ˚) and equipped with a PIXcell3D ultra-fast solid-state hybrid detector. The measurements were performed in a reflection mode, in the Bragg–Brentano geometry (h–hscan technique), within the 2hrange of 10–100.Thedivergentslitoftheincidentbeamwas1/2 wide, and additionally, Soller slits of 0.04 rad were used. The ICDD Card PDF5 database was used to analyze the obtained diffractograms. III. RESULTS AND DISCUSSION A. Theoretical Analysis of Phase Systems: Al-(M), Sb-Ca, Pb-(M)-Al and Pb-Sb-Ca With Thermo-Calc 2024a software and using the TCBIN database: TC Binary Solutions v1.1 thermodynamic calculations were performed regarding the phase Fig. 8—Pb-As-Al phase system at 700 C. Fig. 5—Al-Ni phase diagram. Fig. 7—Al-Sn phase diagram. Fig. 6—Al-Pb phase diagram. 2962—VOLUME 56A, AUGUST 2025 METALLURGICAL AND MATERIALS TRANSACTIONS A stability of binary systems for alloys: Sb-Al, As-Al, Cu-Al, Ni-Al, Pb-Al and Sn-Al (Figures 2,3,4,5,6,and 7). As can be observed in Figure 2aluminum with antimony forms the intermetallic compound AlSb with a melting point of 1058 ±10 C. [66] Similarly behaves arsenic which forms with aluminum the intermetallic compound AlAs with a melting point of 1740 ±20 C (Figure 3). [67] The aluminum-selenium binary was not present in the available databases of the Thermo-Calc software. On the other hand, available literature data indicate that the system forms the intermetallic compound Al 2 Se 3 with a melting point of 939.9 ±0.2 C. [68] Aluminum with copper forms many different phases (h, g,g¢,V,V¢,e,e¢,d,c,b,b¢, and a) depending on the temperature and concentration of the components, as can be seen from the phase equilibrium system (Figure 4), several of these phases are stable at a fixed experimental temperature of 700 C. [69,70] In the aluminum-nickel system (Figure 5), a similar situation occurs as in the case of copper depending on the temperature and concentration of the components different intermetallic compounds can be formed. [71] The calcium-antimony phase equilibrium system (not available in the Thermo-Calc software databases) shows the possibility of clique intermetallic compounds such as Ca 2 Sb, Ca 5 Sb 3 ,Ca 11 Sb 10 and CaSb 2 . Most of them are stable at temperatures even above 800 C. [72] Fig. 10—Pb-Se-Al phase system at 700 C. Fig. 12—Pb-Sb-Ca phase system at 700 C. Fig. 9—Pb-Cu-Al phase system at 700 C. Fig. 11—Pb-Ni-Al phase system at 700 C. METALLURGICAL AND MATERIALS TRANSACTIONS A VOLUME 56A, AUGUST 2025—2963 From the point of view of the refining process, a very important aspect is the behavior of aluminum in liquid lead. For this purpose, the Al-Pb phase system was analyzed (Figure 6). The Pb-Al system is characterized by the limited solubility of aluminum in liquid lead and the area of immiscibility of the two liquids. At 700 C, as reported in the literature, the solubility of Al in liquid Pb is approx. 0.2 wt pct, due to the pronounced liquid separation in this system. Phase diagrams indicate the presence of liquid phases (LIQUID, LIQUID#2) and a solid phase with an ordered FCC structure in Al-rich areas. The Pb-Al system is a typical example of liquid separation in non-ferrous alloys and, most importantly, shows no possibility of intermetallic compound formation. For the study to determine the optimal parameters for starting the lead refining process using aluminum, the Al-Sn phase system was also analyzed (Figure 7). Based on it, it can be concluded that intermetallic compounds are not formed in this system either. Phase areas include liquid and solid phases, such as FCC_A1 (typical Al structure) and BCT_A5 (Sn structure). This system is characterized by the coexistence of different phases depending on the temperature and proportion of the components, and tin and aluminum occur mainly in the form of alloys, without the formation of new chemical compounds. As in the earlier case, also using Thermo-Calc 2024a software but this time using the TCCU5 database: Cu-Alloys v5.1 phase equilibrium systems were created for the five ternary systems available in the database: Pb-As-Al, Pb-Cu-Al, Pb-Ni-Al, Pb-Se-Al, and Pb-Sb-Ca for temperature 700 C (Figures 8,9,10,11, 12,and13). The temperature of 700 C was chosen because it is practically the highest temperature reached during industrial scale processes. Therefore, it was wanted to make a theoretical and practical analysis whether at this temperature there is a chance of creating stable intermetallic compounds, thanks to which the effect of refining will be achieved. Moreover, in laboratory conditions, at temperatures below 660 C, there is practically no dissolution of Al in Pb. In the Pb-As-Al system (Figure 8), the main feature is the dominance of the liquid phase (LIQUID) in most of the plot area. However, in the range of low Pb concentrations and with increasing shares of As and Al, it is possible to stabilize the RHOMBO_A7 solid phase, which corresponds to the crystalline aragonite structure typical of arsenic. In the lower range of the Al axis with Pb participation, there may be areas of coexistence between the liquid and solid phases. The solid phase is limited by relatively narrow ranges of component concentrations. The Pb-Cu-Al system (Figure 9), is characterized by a more complex phase equilibrium, where numerous solid phases can be stabilized in addition to the liquid phase. In particular, ordered phases and solid solutions are present. FCC_L12 and BCC_B2 are ordered metallic phases that occur in Cuand Al-rich areas. The ALCU_EPS phase (e-structure—Figure 4) appears as a result of the interaction between Al and Cu, forming a complex network of solid phases. For areas closer to the Cu-Al axis, coexistence of solid solutions with the liquid phase is possible. The Pb-Se-Al system (Figure 10)is relatively simple, and the main feature is the liquid phase separation. The diagram does not show the presence of solid phases over a wide range of concentrations, indicating the dominance of liquid phases. However, in the area highlighted in white, the Thermo-Calc 2024a software reports ‘‘insufficient information,’’ so the absence of solid phases cannot be stated clearly. In the Quantum Materials Database (OQMD), it was found that in this system, in addition to the solid binary compounds such as AlSe, Al 2 Se 3 and PbSe, there may also be a ternary compound Al 2 PbSe 4 . [73] The Pb-Ni-Al system (Figure 11) is characterized by a complex network of phase equilibria in which a large number of solid phases exist in addition to the liquid phase. The BCC_B2 phase (an ordered network with a regular structure) is found in Niand Pb-rich systems, indicating that solid solutions can be formed. In Al-rich areas, AL3NI_D011 and AL3NI2 intermetallic phases are Fig. 13—Pb-Sn-Al phase system at 700 C. Fig. 14—Ternary phase diagrams Pb-Sb-Al created by the DFT OQMD database. The diagram is illustrative and does not present specific temperature parameters—it is a phase stability map. [77] . 2964—VOLUME 56A, AUGUST 2025 METALLURGICAL AND MATERIALS TRANSACTIONS A present. FCC_L12 and the coexistence of this phase with the liquid phase or other phases indicates a highly complex equilibrium, especially in the region of medium concentrations of components. However, there may be an inconsistency in the legend description generated by the Thermo-Calc 2024a software, because FCC_L12 is part of order-disorder model used to describe both disordered FCC_A1 and FCC_L12. According to the isothermal section plotted, FCC_L12 probably should be the FCC_A1, and FCC_L12#2 probably should be the Ni 3 Al-based ordered L12. The Pb-Sb-Ca system (Figure 12) is relatively simple compared to the previous ones. In this case, the predominant equilibrium is between a liquid phase and a single solid phase. The BCC_A2 phase (simple regular network) is stable in Sband Pb-rich regions. Areas with a dominance of solid solutions combined with liquid phase are significant in the range of average Ca concentrations. According to the DFT OQMD database, in this ternary system there are a few theoretical compounds that can be stable, such as: Ca 2 Sb, Ca 5 Sb 3 ,Ca 11 Sb 10 , CaSb 2 Pb 2 . [74] However, at 700 C the CaSb 2 phase is no longer stable, so the refining effect may be smaller than at lower temperatures. [72] As in the binary systems, also to analyze the optimal parameters of the refining process, the Pb-Sn-Al ternary system was analyzed for a temperature of 700 C (Figure 13). This diagram shows the dominance of liquid phases, including a single liquid phase (LIQUID) and liquid mixtures of different compositions (LIQUID#2, LIQUID#3). The only solid phase at this temperature detected by the Thermo-Calc 2024a software is HCP_A3, however, the available data do not indicate the possibility of a solid phase forming in this system at 700 C. [75,76] All of the systems analyzed exhibit varying degrees of phase complexity, with significant opportunities for solid phases in certain concentration ranges. The greatest potential for the formation of ordered intermetallic structures and solid solutions is shown by the binary systems Ni-Al (Figure 5) and Cu-Al (Figure 4), which is also visible in their ternary systems with Pb (Figures 9 and 11). In the databases available by the authors for Thermo-Calc 2024a software there was no Pb-Sb-Al phase system, therefore its graph from the DFT OQMD database is presented in Figure 14. [77] The diagram (Figure 14) shows that in this ternary system there are no additional solid phases compared to the binary Al-Sb system, where a stable AlSb phase is formed with a melting point of 1058 ±10 C (Figure 2). B. Lead Refining in Pure Ternary Systems The laboratory experiment consisted of six identical cycles. First, lead was heated to 700 C, then an additive was added in the form of one of the pure metals (Sb, As, Se, Cu or Ni), and aluminum. In order to be able to observe the change in concentration of the introduced first alloying element (Sb, As, Se, Cu or Ni), which is a deliberately added impurity, an effort was made to introduce as much of it as possible into the lead. In the case of antimony and arsenic, it was possible to obtain an alloy of several percent, since the solubility of these metals in lead at 700 C is high. [78,79] In contrast, for copper, selenium, and nickel this solubility is much lower. [80–82] At higher concentrations of these metals, solidification of the lead alloy occurred at the temperature at which the experiment was conducted. Therefore, for these elements, the content in lead ranged from 0.4 to 0.8 percent. The exact amount introduced into the 13.6 kg of lead of each metal and their resulting concentrations are shown in Table II. Through the physical limitations of the capacity of the steel cylindrical cage, and the high solubility of antimony and arsenic Table II. The Amount of Alloying Additives Introduced into Lead and Their Pct By Weight at the Beginning and at the End of the Experiment Alloy Additive Added Quantity (g) Expected Conc. (Wt Pct) Obtained Conc. (Wt Pct) Added Amount of Al* (g) Obtained Al* Conc. After 20 min. (Wt Pct) Conc. After 60 min. (Wt Pct) Sb 792 5.5 5.47 120 0.19 5.22 As 792 5.5 5.44 120 0.10 3.39 Se 68 0.5 0.36 120 0.13 0.16 Cu 68 0.5 0.39 120 0.17 0.24 Ni 137 1.0 0.81 120 0.15 0.31 Sb (Ca) 792 5.5 5.41 120 0.52 4.54 *Ca in the last case. Fig. 15—Percentage of element removal by aluminum or calcium. METALLURGICAL AND MATERIALS TRANSACTIONS A VOLUME 56A, AUGUST 2025—2965 the temperature of 650 C proposed in the industrial scale tests was too low, which was also confirmed by later tests on an industrial scale (after the publication of the studies), where the problem occurred several times that at this specific temperature of aluminum application the refining process did not occur and, similarly to laboratory conditions, aluminum did not dissolve in lead. During the second and third runs (at 660 Cand 670 C), the refining process occurred, but more slowly and to a lesser extent than at the higher temperatures. This effect, presumably, was due to the longer time it took for the aluminum to dissolve while immersed in the steel cage in the lead alloy. The longer melting time of aluminum was associated with a shorter time for the total dissolved aluminum to react with the impurities, which translated into the degree of their removal from the lead. The series conducted at temperatures from 680 Cto 700 C followed a very similar pattern. The differences between them were within the calculated measurement uncertainty. The magnitude of the measurement uncertainty shown in the graph is due to running each sample twice—the measurement uncertainty is the result of the difference between the averaged values of these samples and the standard deviation of the analysis performed by the OXSASspectrometer software. The value of the standard deviation was also related to the relationship observed in individual sample analyses and consisted of the occurrence of higher concentrations of antimony, arsenic and selenium in cases of simultaneously elevated aluminum content. This was due to the difficulty of separating the dross floating on the surface of the metal from the collected alloy for analysis. It was also observed that the tin content, which occurred at 1.52 ±0.05 pct in the base material, remained at the same level during the 120 minutes of the experiment. The exception was the trial at 700 C, during which, at the end of the process, its level dropped slightly, to a value of 1.32 ±0.09 pct. The constant level of tin contained in lead confirms that both the Sn-Al binary system (Figure 7) and the Pb-Sn-Al ternary system (Figure 13) do not form solid intermetallic compounds. As mentioned earlier, Figure 21(a) shows the sum value of the percentage removal of impurities, however, it is worth mentioning that for samples at temperatures from 680 C to 700 C, after 40 minutes of refining, the arsenic and selenium content dropped to less than 5 ppm. The antimony content in all batches decreased slightly, as, for example, for 680 C, the initial antimony level was 1.66 ±0.04 pct, and after 120 minutes of refining it was 1.32 ±0.05 pct. After the first stage of testing, 680 C was considered the optimal temperature for the start of the refining process, and a second experiment was conducted at this temperature, during which the temperature was kept constant while the amount of aluminum added was changed. Manipulating the amount of aluminum added allowed us to analyze what dose of aluminum is most effective in removing contaminants, without excessive use of this raw material. The amount of aluminum varied from 100 to 220 pct of the theoretical stoichiometric requirement for binding Sb, As and Se. The results of the experiment are shown in Figure 21(b). It shows that the amount of aluminum in the initial refining period did not have a significant impact. The exception was a trial using 100 pct stoichiometric aluminum demand, in which the removal of impurities compared to other trials was noticeably lower. In the trial using the highest amount of added aluminum, the highest rate of lead refining was initially observed; however, the final removal rate of ‘‘Sb + As + Se’’ in batches using 120 to 220 pct of the stoichiometric aluminum requirement was very similar. During this stage of testing, as before, the tin content of the lead remained constant between 1.46 and 1.57 pct. In laboratory tests conducted at 680 C for 120 minutes and various contents of added aluminum, it was possible to reduce the level of arsenic and selenium contamination to less than 1 ppm. At the same time, antimony levels have decreased from 1.66 pct to horizontally between 1.42 and 1.31 pct, depending on the sample. The average value of the antimony removal rate was 0.16 pct /h, which fits almost perfectly into the created graph of industrial-scale antimony removal rates (where for a value of 1.6 pct Sb it is approx. 0.17 pct /h). [38] According to what industrial trials have shown, the next refining step, in order to further reduce the value of antimony, should be to add aluminum back to the lead alloy, and then lower the bath temperature and remove the resulting dross. [38] In the previous study (Figure 15) Sb and As show much lower removal rates compared to Se, Cu and Ni, however, the amount of Sb and As contained in Pb is much higher than Se, Cu and Ni therefore this effect may be caused not only by the higher Gibbs free energy (Figure 18) but also by the lower ratio of aluminum to these two contaminants. This conclusion is drawn from the analysis of the graph in Figure 21(b) where a relationship was observed that increasing the amount of added aluminum increases the speed of contaminant removal especially in the first hour of the process which was the most representative in the study. This thesis is also confirmed by the study where all additions were at the level of 0.4 wt pct (Figure 20(a)) in this case antimony and arsenic were removed faster from lead than copper and selenium. Therefore, it can be stated that the ratio of aluminum to the removed element has an effect on the speed of its removal. IV. CONCLUSIONS The study provided new data on the use of aluminum and calcium in lead refining, especially in the context of removing undesirable elements while retaining tin. Analysis of the ternary systems Pb-(M)-Al and Pb-Sb-Ca allowed us to determine what compounds are formed when lead is refined with aluminum or calcium. Another goal of the study was to try to determine the optimal parameters for starting the lead refining process using aluminum. The main conclusions can be summarized as follows: 2972—VOLUME 56A, AUGUST 2025 METALLURGICAL AND MATERIALS TRANSACTIONS A 1. The use of aluminum as a refiner in ternary systems, removed nickel and selenium from lead to the greatest extent (over 50 pct). The rate of Sb removal was 0.24 pct /h, while the use of calcium as a refiner increased the rate of antimony removal to 0.87 pct / h. 2. On the surface of metallic baths after the addition of aluminum or calcium, the formation of dross was observed, varying in appearance and quantity, depending on the type of ternary system. The highest amount of dross was formed in the Pb-Sb-Ca system, while the Pb-Al-Cu system showed the worst ratio of dross to mass of element removed. 3. Analysis of the Pb-Sb-Ca ternary system showed that at temperatures below 636 C the process of refining lead from antimony with calcium would be more effective because an additional solid phase, CaSb 2 , would be formed. 4. Phase analysis of the resulting dross showed the formation of stable aluminum compounds with lead impurities such as: AlSb, AlAs, Al 2 Se 3 , CuAl 2 , Cu 6 Al 5 , NiAl 3 . In each of the samples of the phase-analyzed dross, complex oxides were found, containing elements from the given ternary system, which may have been formed both during the tests performed and also during the preparation of the dross for analysis. The same intermetallic phases will also form in process on an industrial scale. Since these phases remain stable at the temperature of 700 C, which is achieved in the process under industrial conditions, this means that also in industrial practice these impurities will be permanently bound to the aluminum, preventing their return to lead alloy. 5. At comparable impurity contents, the highest elimination rate was obtained for nickel, followed successively by arsenic, antimony, selenium and copper, with copper and selenium removal rates several times lower than nickel. 6. A temperature of 680 C was found to be the most optimal temperature to start the process of refining lead with aluminum. At lower temperatures (650 C 670 C), the process proved to be slower and less efficient, while higher temperatures (690 C 700 C) yielded no significant differences in removal rates compared to 680 C. 7. It was determined that the optimal amount of aluminum introduced as a refiner is approx. 120 pct of the theoretical stoichiometric requirement for the binding of antimony, arsenic and selenium. The smaller amount proved to be insufficient, while increasing the amount of Al to 220 pct of the theoretical stoichiometric requirement, initially accelerated the refining process, but ultimately did not significantly increase the removal rate during the first 120 minutes of the process. 8. At temperatures of 680 C700 C, the content of arsenic and selenium fell below 5 ppm after 40 minutes of refining, while the removal of antimony, whose concentration was higher, would require a longer process and lowering the temperature of the lead alloy. 9. The level of tin in the lead alloy remained stable throughout the refining process, which is a welcome result since tin is a valuable alloying additive for the production of the most popular lead alloys for gratings and connectors in LAB. [34,36] This is due to the omission of the oxidative refining process and probably to the protective layer that the aluminum created on the surface of the metal bath, preventing the oxidation of the tin. ACKNOWLEDGMENTS This work was supported by the Polish Ministry of Education and Science (Applied Doctorate Program, No. DWD/5/0149/2021). CONFLICT OF INTERESTS On behalf of all authors, the corresponding author states that there is no conflict of interest. OPEN ACCESS This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creat ivecommons.org/licenses/by/4.0/. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at https://doi.org/10.1007/s11661-025-07813-5. REFERENCES 1. H. Hou, B. Du, D. Guo, H. Xu, and Y. Fan: Environ. Impact Assess. Rev., 2024, vol. 105, p. 107389. https://doi.org/10.1016/j.e iar.2023.107389. METALLURGICAL AND MATERIALS TRANSACTIONS A VOLUME 56A, AUGUST 2025—2973 2. J. Hong, Z. Yu, W. Shi, J. Hong, C. Qi, and L. Ye: Int. J. Life Cycle Assess., 2017, vol. 22, pp. 909–18. https://doi.org/10.1007/ s11367-016-1209-3. 3. M.W. Stevenson: in Encyclopedia of electrochemical power sources, 2nd ed., G. Ju ¨rgen, ed., Elsevier, 2025, pp. 563–84. https://doi.org/ 10.1016/B978-0-323-96022-9.00295-4. 4. H. Pan, Y. Geng, H. Dong, M. Ali, and S. Xiao: Resour. Conserv. Recycl., 2019, vol. 140, pp. 13–22. https://doi.org/10.1016/j.resc onrec.2018.09.012. 5. Z. Kang, Z. Huang, Q. Peng, Z. Shi, H. Xiao, R. Yin, G. Fu, and J. Zhao: iScience, 2023, vol. 26, p. 108072. https://doi.org/10.1016/ j.isci.2023.108072. 6. J. Bu ¨ngeler and B. Riegel: in Emerging Battery Technologies to Boost the Clean Energy Transition: The Materials Research Society Series. Springer, Cham, 2024, pp. 121–41. https://doi.org/10.1007/ 978-3-031-48359-2_8. 7. J. Garche and P.T. Moseley: in Lead-Acid Batteries for Future Automobiles. Elsevier, 2017, pp. 527–47. https://doi.org/10.1016/ B978-0-444-63700-0.00018-0. 8. J. Jayaprabakar, J.A. Kumar, J. Parthipan, A. Karthikeyan, M. Anish, and N. Joy: J Energy Storage, 2023, vol. 72, p. 108689. h ttps://doi.org/10.1016/j.est.2023.108689. 9. M.L. Mamede Bezerra, M. Mendonc¸ a Silva, and S. Machado Santos: Environ. Sci. Pollut. Res., 2023, vol. 30, pp. 106260–75. h ttps://doi.org/10.1007/s11356-023-29789-8. 10. N. Bashir, H.S. Sardar, M. Nasir, N.U. Hassan, and H.A. Khan: in 2017 IEEE Manchester PowerTech. IEEE, 2017, pp. 1–6. http s://doi.org/10.1109/PTC.2017.7980993. 11. G.J. May, A. Davidson, and B. Monahov: J Energy Storage, 2018, vol. 15, pp. 145–57. https://doi.org/10.1016/j.est.2017.11.008. 12. D. Choudhary, K.S. Sangwan, and A. Singh: Sci. Rep., 2024, h ttps://doi.org/10.1038/s41598-024-67404-z. 13. P. Wang and C. Zhu: IOP Conf. Ser. Earth Environ. Sci., 2020, vol. 440, p. 022014. https://doi.org/10.1088/1755-1315/440/2/ 022014. 14. N. Vangapally, T.R. Penki, Y. Elias, S. Muduli, S. Maddukuri, S. Luski, D. Aurbach, and S.K. Martha: J. Power. Sources, 2023. h ttps://doi.org/10.1016/j.jpowsour.2023.233312. 15. R. Kandeeban, K. Saminathan, K. Manojkumar, C.G. Dilsha, and S. Krishnaraj: Mater Today Proc, 2022, vol. 48, pp. 143–47. h ttps://doi.org/10.1016/j.matpr.2020.04.238. 16. R. Perriment, V. Kumtepeli, M.D. McCulloch, and D.A. Howey: in 2023 IEEE PES/IAS PowerAfrica. IEEE, 2023, pp. 1–5. http s://doi.org/10.1109/PowerAfrica57932.2023.10363281. 17. Y. Zhang, C. Zhou, J. Yang, S. Xue, H. Gao, X. Yan, Q. Huo, S. Wang, Y. Cao, J. Yan, K. Gao, and L. Wang: J. Power. Sources, 2022, vol. 520, p. 230800. https://doi.org/10.1016/j.jpowsour.2021. 230800. 18. P.P. Lopes and V.R. Stamenkovic: Science, 1979, vol. 369(2020), pp. 923–24. https://doi.org/10.1126/science.abd3352. 19. K. Kopczynski, A. Gabryelczyk, M. Baraniak, B. Legosz, J. Pernak, P. Kedzior, and G. Lota: Int. J. Electrochem. Sci., 2018, vol. 13, pp. 11058–73. https://doi.org/10.20964/2018.11.85. 20. A.G. dos Santos, M.R.S. Vieira, F.J. da Silva, and N. Bouchonneau: Heliyon, 2024. https://doi.org/10.1016/j.heliyon.2024.e38536. 21. J. Yin, H. Lin, J. Shi, Z. Lin, J. Bao, Y. Wang, X. Lin, Y. Qin, X. Qiu, and W. Zhang: Electrochem Energy Rev, 2022. https://doi. org/10.1007/s41918-022-00134-w. 22. K. Yanamandra, D. Pinisetty, and N. Gupta: Renew. Sustain. Energy Rev., 2023., https://doi.org/10.1016/j.rser.2022.113078. 23. K. Liu, M. Wang, J. Yu, and Q. Tan: ACS Sustain Chem Eng, 2023, vol. 11, pp. 7244–52. https://doi.org/10.1021/acssuschemeng. 3c01347. 24. F. Pang, Y. Wu, X. Liu, X. Chen, L. Guo, S. Gao, K. Du, D. Wang, and H. Yin: J Energy Storage, 2024. https://doi.org/10. 1016/j.est.2024.110909. 25. B. Du, H. Hou, H. Xu, and M. Zhang: J. Clean. Prod., 2023, vol. 421, p. 138514. https://doi.org/10.1016/j.jclepro.2023.138514. 26. B. Chen, J. Cao, F. Ge, J. Zhang, and Y. Huang: J. Environ. Chem. Eng., 2022, vol. 10, p. 108454. https://doi.org/10.1016/j.jece. 2022.108454. 27. M. Li, J. Liu, and W. Han: Waste Manage Res: J. Sustain. Circ. Econ., 2016, vol. 34, pp. 298–306. https://doi.org/10.1177/ 0734242X16633773. 28. R.D. Prengaman and A.H. Mirza: in Lead-Acid Batteries for Future Automobiles. Elsevier Inc, 2017, pp. 575–98. https://doi.org/ 10.1016/B978-0-444-63700-0.00020-9. 29. W. Zhang, J. Yang, X. Wu, Y. Hu, W. Yu, J. Wang, J. Dong, M. Li, S. Liang, J. Hu, and R.V. Kumar: Renew. Sustain. Energy Rev., 2016, vol. 61, pp. 108–22. https://doi.org/10.1016/j.rser.2016.03. 046. 30. S. Arnout, B. Blanpain, D.R. Swinbourne, M. Chintinne, and M. Stevenson: in Handbook of Recycling, 2nd ed. Elsevier, Amsterdam, 2024, pp. 355–70. https://doi.org/10.1016/B978-0-323-855143.00035-X. 31. A.G. Morachevskii: Russ. J. Appl. Chem., 2014, vol. 87, pp. 241–57. https://doi.org/10.1134/S107042721403001X. 32. M. Altiner, S. Top, and S. Kursunoglu: in Recycling Technologies for Secondary Zn-Pb Resources: The Minerals, Metals & Materials Series. Springer, Cham, 2023, pp. 235–89. https://doi.org/10.1007/ 978-3-031-14685-5_7. 33. Y.-M. Li, Y. Wang, M.-J. Chen, T.-Y. Huang, F.-H. Yang, and Z.-J. Wang: Int. J. Environ. Sci. Technol., 2023, vol. 20, pp. 1037–52. https://doi.org/10.1007/s13762-022-04009-x. 34. R.D. Prengaman: in Lead-acid batteries for future automobiles. Elsevier Inc., 2017, pp. 269–99. https://doi.org/10.1016/B978-0-44 4-63700-0.00009-X. 35. R.D. Prengaman: in Encyclopedia of Electrochemical Power Sources. J. Garche, ed., Elsevier, 2009, pp. 648–54. https://doi.org/ 10.1016/B978-044452745-5.00127-1. 36. D. Pavlov: in Lead-Acid Batteries: Science and Technology, 2nd ed. Elsevier, 2017, pp. 169–243. https://doi.org/10.1016/B978-0-44459552-2.00004-3. 37. M.B. Queiroz, R.C.O. Duarte, J.F. Lima, and E.O. Vilar: J. Power. Sources, 2024, vol. 596, p. 234113. https://doi.org/10.1016/ j.jpowsour.2024.234113. 38. D. Malecha, S. Małecki, P. Jarosz, R. Kowalik, and P. _ Zabin ´ski: Materials, 2023, vol. 16, p. 5882. https://doi.org/10.3390/ma 16175882. 39. G. Hu, P. Zhang, J. Yang, Z. Li, S. Liang, W. Yu, M. Li, Y. Tong, J. Hu, H. Hou, S. Yuan, and R.V. Kumar: Resour. Conserv. Recycl., 2022. https://doi.org/10.1016/j.resconrec.2022.106391. 40. A. Felder and R.D. Prengaman: JOM, 2006, vol. 58, pp. 28–31. h ttps://doi.org/10.1007/s11837-006-0197-3. 41. T.W. Ellis and A.H. Mirza: J. Power. Sources, 2010, vol. 195, pp. 4525–29. https://doi.org/10.1016/j.jpowsour.2009.12.118. 42. M. Li, J. Yang, S. Liang, H. Hou, J. Hu, B. Liu, and R.V. Kumar: J. Power. Sources, 2019. https://doi.org/10.1016/j.jpowsour.2019. 226853. 43. T. Liu and K. Qiu: J. Hazard. Mater., 2018, vol. 347, pp. 334–40. h ttps://doi.org/10.1016/j.jhazmat.2018.01.017. 44. E. Ciro, C. Lupi, A. Mondal, and D. Pilone: J. Sustain. Metall., 2021, vol. 7, pp. 1727–35. https://doi.org/10.1007/s40831-021-004 47-y. 45. A. Mondal, E. Ciro, C. Lupi, and D. Pilone: J. Sustain. Metall., 2022, vol. 8, pp. 1744–55. https://doi.org/10.1007/s40831-022-005 98-6. 46. W. Li, W. Zhang, L. Luo, and X. Xie: Sep. Purif. Technol., 2023, vol. 310, p. 123156. https://doi.org/10.1016/j.seppur.2023.123156. 47. A.D. Ballantyne, J.P. Hallett, D.J. Riley, N. Shah, and D.J. Payne: R Soc Open Sci, 2018. https://doi.org/10.1098/rsos.171368. 48. F. Habashi: Lead, in Handbook of extractive metallurgy. Wiley-VCH, Heidelberg, 1997, pp. 581–714. 49. B. Yang, G. Zha, W. Hartley, X. Kong, D. Liu, B. Xu, W. Jiang, and X. Guo: J. Clean. Prod., 2019, vol. 219, pp. 110–16. https://d oi.org/10.1016/j.jclepro.2019.02.011. 50. C. Fleuriault: in 9th International Symposium on High-Temperature Metallurgical Processing, TMS 2018: The Minerals, Metals & Materials Series. Springer, Cham, 2018, pp. 187–97. https://doi. org/10.1007/978-3-319-72138-5_19. 51. R.D. Prengaman: J. Power. Sources, 2006, vol. 158, pp. 1110–16. h ttps://doi.org/10.1016/j.jpowsour.2006.02.079. 52. M. Li, J. Yang, S. Liang, H. Hou, J. Wang, G. Hu, Z. Li, J. Hu, K. Xiao, and B. Liu: Resour. Conserv. Recycl., 2021. https://doi.org/ 10.1016/j.resconrec.2021.105611. 53. L. Ye, S. Song, S. Yang, Y. Chen, and S. Liu: Hydrometallurgy, 2023. https://doi.org/10.1016/j.hydromet.2023.106186. 54. R. Sato, K. Hirata, and F. Tanaka: in PbZn 2020 9th International Symposium on Lead and Zinc Processing: The Minerals, Metals & 2974—VOLUME 56A, AUGUST 2025 METALLURGICAL AND MATERIALS TRANSACTIONS A Materials Series. Springer, Cham, 2020, pp. 519–29. https://doi. org/10.1007/978-3-030-37070-1_44. 55. H. Zhang, W. Chen, Q. Liu, Y. Zhang, Y. Li, X. Chen, B. Yang, and B. Xu: Vacuum, 2023, vol. 212, p. 111986. https://doi.org/10. 1016/J.VACUUM.2023.111986. 56. H. Li, W. Qin, J. Li, Z. Tian, F. Jiao, and C. Yang: Resour. Conserv. Recycl., 2021. https://doi.org/10.1016/j.resconrec.2021. 105495. 57. Y. Yu, F. Zhang, H. Wang, and J. Hu: J. Market. Res., 2022, vol. 21, pp. 2815–26. https://doi.org/10.1016/j.jmrt.2022.10.025. 58. W.J. Kim, S. Seo, S.I. Lee, D.W. Kim, and M.J. Kim: J. Hazard. Mater., 2021. https://doi.org/10.1016/j.jhazmat.2021.126071. 59. A.G. Morachevskii and T.V. Butukhanova: Russ. J. Appl. Chem., 2009, vol. 82, pp. 1317–20. https://doi.org/10.1134/ S1070427209070301. 60. D. Malecha, P. S ´wiec, R. Albrecht, P. Jarosz, and S. Małecki: JOM, 2024. https://doi.org/10.1007/s11837-024-06892-w. 61. H. Ohtani: The CALPHAD Method, in Springer Handbook of Metrology and Testing. Springer, Berlin, Heidelberg, 2011, pp. 1061–90. https://doi.org/10.1007/978-3-642-16641-9_20. 62. S. Kirklin, J.E. Saal, B. Meredig, A. Thompson, J.W. Doak, M. Aykol, S. Ru ¨hl, and C. Wolverton: npj Comput. Mater., 2015, vol. 1, p. 15010. https://doi.org/10.1038/npjcompumats.2015.10. 63. J.E. Saal, S. Kirklin, M. Aykol, B. Meredig, and C. Wolverton: JOM, 2013, vol. 65, pp. 1501–09. https://doi.org/10.1007/s11837013-0755-4. 64. EN 12402:1999 Lead and lead alloys—methods of sampling for analysis. European Committee for Standardization (CEN), Brussels, 1999. 65. ENV 12908:1997 Lead and lead alloys—analysis by Optical Emission Spectrometry (OES) with spark excitation. European Committee for Standardization (CEN), Brussels, 1997. 66. X. Su, Y. Xia, Y. Liu, C. Wu, H. Peng, H. Tu, and J. Wang: J Phase Equilibria Diffus, 2019, vol. 40, pp. 638–52. https://doi.org/ 10.1007/s11669-019-00750-y. 67. A.J. McAllster: Bull Alloy Phase Diagrams, 1984, vol. 5, pp. 577–79. https://doi.org/10.1007/BF02868319. 68. C. Shi, B. Yang, B. Hu, Y. Du, and S. Yao: J Phase Equilibria Diffus, 2019, vol. 40, pp. 392–402. https://doi.org/10.1007/s11669019-00733-z. 69. O. Zobac, A. Kroupa, A. Zemanova, and K.W. Richter: Metall. Mater. Trans. A, 2019, vol. 50, pp. 3805–15. https://doi.org/10. 1007/s11661-019-05286-x. 70. N. Ponweiser, C.L. Lengauer, and K.W. Richter: Intermetallics (Barking), 2011, vol. 19, pp. 1737–46. https://doi.org/10.1016/j. intermet.2011.07.007. 71. H. Okamoto: J Phase Equilibria Diffus, 2019, vol. 40, pp. 830–41. h ttps://doi.org/10.1007/s11669-019-00765-5. 72. H. Okamoto: J Phase Equilibria Diffus, 2016, vol. 37, pp. 350–62. h ttps://doi.org/10.1007/s11669-016-0452-4. 73. OQMD: The Open Quantum Materials Database—Region: Pb-Se-Al, (n.d.). https://oqmd.org/materials/composition/Pb-SeAl (accessed February 28, 2025). 74. OQMD: The open quantum materials database—region: Ca-Pb-Sb, (n.d.). https://oqmd.org/materials/composition/Ca-PbSb (accessed Feb 28, 2025). 75. OQMD: The open quantum materials database—region: Pb-Sn-Al, (n.d.). https://oqmd.org/materials/composition/Pb-SnAl (accessed Feb 28, 2025). 76. J.-H. Shim, H.-N. Lee, H.P. Ha, Y.W. Cho, and E.-P. Yoon: J. Alloys Compd., 2001, vol. 327, pp. 270–74. https://doi.org/10.1016/ S0925-8388(01)01426-8. 77. OQMD: The open quantum materials database—region: Pb-Sb-Al (n.d.). https://oqmd.org/materials/composition/Pb-Sb-Al (accessed March 3, 2025). 78. H. Okamoto: J Phase Equilibria Diffus, 2011, vol. 32, pp. 567–67. h ttps://doi.org/10.1007/s11669-011-9952-4. 79. N.A. Gokcen: Bull. Alloy Phase Diagrams, 1990, vol. 11, pp. 120–24. https://doi.org/10.1007/BF02841694. 80. D.J. Chakrabarti and D.E. Laughlin: Bull. Alloy Phase Diagrams, 1984, vol. 5, pp. 503–10. https://doi.org/10.1007/BF02872905. 81. J.C. Lin, R.C. Sharma, and Y.A. Chang: J. Phase Equilibria, 1996, vol. 17, pp. 253–60. https://doi.org/10.1007/BF02648495. 82. H. Okamoto: J Phase Equilibria Diffus, 2015, vol. 36, pp. 518–30. h ttps://doi.org/10.1007/s11669-015-0395-1. 83. A.J. McAlister: Bull. Alloy Phase Diagrams, 1984, vol. 5, pp. 69–73. https://doi.org/10.1007/BF02868728. Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. METALLURGICAL AND MATERIALS TRANSACTIONS A VOLUME 56A, AUGUST 2025—2975