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We present the preparation and characterization of pure lead monoxide obtained through recycling of the lead paste recovered from exhausted lead acid batteries. The recycling is based on a hydrometallurgical procedure reported in a STC Patent, that includes simple chemical operations (desulphurisation, leaching, precipitation, filtration) and a final thermal conversion. Materials obtained by treatment at 600 °C consist predominantly of β-PbO. The electrochemical behaviour of Positive Active Mass (PAM) prepared from different materials (or mixtures) is then investigated and compared. An optimized oxide material, obtained by prolonged (8 h) thermal treatment at 600 °C, consists of pure β-PbO and appears suitable for preparation of battery elements, alone or in mixture with a small fraction (10%–30%) of traditional industrial leady oxide. The resulting battery performances are similar to those obtained from pure leady oxide. In comparison with traditional recycling processes, the proposed method guarantees lower energy consumption, limited environmental impact and reduced operating risk for industry workers. [ABSTRACT FROM AUTHOR]

The main objective of this manuscript is the description of a mobile demonstration plant designed and built for the recovery of metals from waste of electrical and electronic equipment and other waste such as spent batteries and exhausted industrial catalysts. The plant was designed within the European FP7 framework HydroWEEE-demo (2012–2016) and can offer an effective proposal to addressing the problem of the electronic waste, reducing the environmental impact of their not correct disposal, recovering critical materials as rare earths and precious elements, and giving economic benefits, moreover by it, it is possible to overcome the problem of moving hazardous wastes from one country to another one. Details about the process to recover rare earths from fluorescent materials are presented. Two alternative treatments are showed with and without recirculation of the residual solutions. Economic analysis shows that with the actual product price (14 €/kg) only the process, in which solution recirculation is present, provides a return on the investment. Positive gain is possible if the plant works at its highest capacity and if the price growths up to 20 €/kg the gain increases about 20% of operating costs (process with recirculation, 2 batch/day). In the process without recirculation of the solution, to obtain the same ratio between gain and operating cost it is necessary that the price increases up to 26 €/kg. About other e-wastes, economic analysis has shown that the highest gain is provided from the PCB treatment. [ABSTRACT FROM AUTHOR]

• Efficient and economic production process can mitigate criticality of germanium. • US germanium resources remain unused due to inefficiency in production. • Production processes including leaching, precipitation, and separation are reviewed. • Separation includes precipitation, solvent-extraction, ion-exchange, and adsorption. • Ge chemistry differs from other cations as it remains as neutral species in acidic pH. Germanium (Ge) is one of the critical elements of modern technologies, with supply risk, inefficient production, and increased demand. It is used in high technology applications such as infrared systems, fiber optics, polymer catalysis, electronics, and solar cells. Its demand is expected to increase due to lack of suitable substitutes, increasing demand for solar cells and 5G networks, and the continuous increasing trend of Ge demand for the past 20 years. Globally, 130 tonnes (t) of Ge are being produced (2020) primarily in China. Germanium is recovered as a byproduct from Zn-refineries and coal fly ash. Yet very low amount (<3%) of Ge contained in Zn-ores and fly ash is recovered worldwide, which suggests that the criticality of Ge is due to lack of economical and efficient extraction and recovery process rather than lack of resources. Worldwide, it is estimated that Zn-ores contain 7–13 kt Ge, and coal and coal fly ash, 25–112 kt. The production of Ge involves leaching followed by recovery of Ge by chlorination-distillation, precipitation, solvent extraction, ion flotation, supported liquid membranes, ion exchange, or solid-phase extraction. Leaching from Zn-refinery residues is primarily done with mineral acids, whereas from coal fly ash is achieved with organic ligands. Ge is different from common metal cations, as it exists as neutral species in acidic pH (1–7). Thus, organic ligands are used to form anionic germanium-ligand complexes in solvent extraction and ion-exchange processes so that the species can be separated through anion-exchange. Alternatively, chelating solvent extractants, chelating ion-exchange resins, and ligand functionalized adsorbents in solid-phase extraction (SPE) are used to recover Ge. The primary challenges in Ge hydrometallurgical production are high energy and chemical requirements in precipitation/chlorination-distillation, high chemical consumption, impurities co-extraction, and waste stream generation in solvent extraction, and lack of selective and high-capacity adsorbents in SPE. An improved, efficient, and economical production method, utilizing unconventional resources, can reduce Ge supply risk. SPE has various advantages over other processes, which makes it an attractive option to recover Ge efficiently and economically. [ABSTRACT FROM AUTHOR]

[Display omitted] • Valuable metals Mn, Ni, Co, and Li recovered from leaching solution of spent LIBs. • About 96.5% of Mn ions were separated under conditions MRMK: 2 and pH: 2. • pH, DMG, and MRND were identified as effective parameters in Ni ions extraction. • D2EHPA, TBP, pH and O/A ratio were investigated for cobalt SX operation. • Taguchi L 9 orthogonal array method was designed for the cobalt SX operation. • lithium separation reached 98.84% in specifically designed conditions. The process of recovering metals from spent lithium-ion batteries is difficult due to the complexity of the metal components. Therefore, the separation and extraction of metal ions from the leaching solution of spent lithium-ion batteries requires a set of hydrometallurgical processes. In this research, precipitation and solvent extraction processes have been used to the final recovery of metals. Initially, by applying potassium permanganate with molar ratio of manganese ions to potassium permanganate: 2 and pH: 2, 96.5% of manganese ions were precipitated and separated from the leaching solution. Then, via dimethylglyoxime in molar ratio of nickel ions to dimethylglyoxime: 0.5, and pH: 5, 96% nickel recovered, approximately. Subsequently, using 30 v/v% D2EHPA and 5 v/v% TBP respectively as an extractant and a modifier of the organic phase, and under optimal conditions of Vo/Va: 1, pH: 5, temperature 25 °C, time 20 min and mixing speed 400 rpm, it is possible to achieve 93.38% cobalt extraction efficiency and also control the loss of lithium at 16.74%. Finally, in the molar ratio of lithium ions to sodium carbonate: 0.7, temperature 100 °C, time 40 min, mixing speed 400 rpm and the pH: 12, the lithium precipitation efficiency reached to 98.84%. [ABSTRACT FROM AUTHOR]

SEM and TEM images of microparticles of arabic gum encapsulating Acidithiobacillus thiooxidans obtained by Spray Drying. The viability of the bacterium is reported with a high survival rate after the spray drying process, aimed to be applied for the removal of Ag impurities in a bioleaching process. [Display omitted] • Acidithiobacillus thiooxidans encapsulation was achieved by the spray drying method. • The best wall material for encapsulation was Arabic gum. • Spherical microcapsules with modal particle size distribution were obtained. • Rehydrated powders showed flow stability and shear thinning behavior. • Obtained microcapsules could be effectively applied in bioleaching processes. Acidithiobacillus thiooxidans is a microorganism of great interest in bio-hydrometallurgical processes, as it is potentially capable of treating complex, low-grade (purity) sulfur minerals. However, there are concerns in the metallurgical industry regarding the microbial manipulation due to problems arising related to cellular integrity, metabolic activities, genetic stability and maintainability of a continuous generation of microbial cultures. In this work, a spray drying (SD) process (inlet temperature: 150 °C, feed flow: 1.2 L/h, and atomization rate: 27,500 rpm) was adopted to encapsulate Acidithiobacillus thiooxidans using different biopolymers as wall materials. The physicochemical properties of the powders obtained by SD reveal water activity (a w) below 0.55 with less than 10% moisture, which ensures better stability of the powders during storage with a trapping efficiency above 80%. Morphology studies by scanning electron microscopy (SEM) of the microparticles showed defined surfaces with no collapsing structures, quasi-modal size particles, low viscosity of the reconstituted powders and fast release profiles. Calorimetric analysis confirmed the viability of A. thiooxidans to withstand the SD process. By infrared analysis, the same peaks of the functional groups corresponding to the biopolymers after spray drying were observed, which evidences the microorganism encapsulation (whose signal disappeared after SD). The presence of A. thiooxidans in the microcapsules was confirmed by Transmission Electron Microscopy (TEM). Finally, viability was verified by respiratory assessment of the bacterium rendering high survival rate (1.4 × 109 Cells/mL) after the spray drying process. [ABSTRACT FROM AUTHOR]