The objective of this study is to describe primary lithium production and to summarize the methods for combined mechanical and hydrometallurgical recycling of lithium-ion batteries (LIBs). This study also aims to draw attention to the problem of lithium losses, which occur in individual recycling steps. The first step of hydrometallurgical treatment is leaching, which is an effective method capable of transferring over 99% of the present metals to the leach solutions. Extraction of metals after leaching can be conducted using various methods, with precipitation being the most commonly used. The precipitation of other metals can result in the co-precipitation of lithium, causing total lithium losses up to 30%. To prevent such losses, solvent extraction methods are used to selectively remove elements, such as Co, Ni, Al, and Mn. Solvent extraction (SX) is highly effective, reducing the losses to 3% per extraction stage and reducing overall lithium losses to 15%. After the refining, lithium is precipitated as lithium carbonate. High lithium carbonate solubility (1.5 g/L) and high liquid to solid leaching ratios require costly and avoidable operations to be implemented in order to enhance lithium concentration. Therefore, it is suggested that more studies should focus on multistage leaching with lower L/S ratios.

During hot-dip galvanization, wastes such as bottom dross, zinc ash, spent pre-treatment solutions, and galvanizing flue dust (GFD) are generated. In scientific publications, research devoted to GFD waste recycling is absent, and companies generating this waste require a solution to this complex problem. GFD is often landfilled in hazardous waste landfills. However, it is possible to process this waste hydrometallurgically, where GFD is first leached, the solution is refined, and finally, zinc metal is obtained by electrowinning. During specific environmentally friendly leaching, not all solid GFD is dissolved, and the aim of this study is to process the remaining solid GFD residue. The analysis shows that the GFD residue material mainly contains zinc (42.46%) in the form of oxides, but there is also a small amount of polluting elements such as Al, Fe, and Pb. This study examines the leaching of the samples in HCl and H₂SO₄ under different conditions with the aim of obtaining a solution with a high concentration and high leaching efficiency of zinc. The L/S ratio of 3, 4 M H₂SO_4, and ambient temperature proved to be optimal for the leaching of the GFD residue, where 96.24% of zinc was leached out, which represents a zinc concentration of 136.532 g/L.

Lithium-ion batteries contain many of critically important metals and their effective recycling is key to the EU?s sustainable development. In the past, only metals such as Co, Ni, and Cu were recycled by pyrometallurgy, while Li and Al were concentrated in the slags and not further processed. The novel approach of pyrometallurgical treatment of the black mass offers the possibility of further hydrometallurgical utilization of the slags. This paper examines the refining of the solution obtained by leaching the slag in sulfuric acid. The most valuable element in the leach solution is Li, but it also contains Al, Si, Co, Mn, Ni and Cu, which must be removed before high-purity Li recovery is possible. Purification is achieved by adjusting the pH by adding NaOH. The results confirm that Al and Mn can be removed by 100%, Si by 93.56%, Cu by 86.36% and Cu by 61.75%. The results also confirmed that solution refining by the adding NaOH causes lithium losses ranging from 10% at pH 7 to 28% at pH 12. Therefore, it is suggested that further solution refining methods should be combined before precipitating pure Li2CO3 with minimal losses.

Currently, recycling of spent lithium-ion batteries is carried out using mechanical, pyrometallurgical and hydrometallurgical methods and their combination. The aim of this article is to study a part of the pyro-hydrometallurgical processing of spent lithium-ion batteries which includes lithium slag hydrometallurgical treatment and refining of the obtained leachate. Leaching was realized via dry digestion, which is an effective method capable of transferring over 99% of the present metals, such as Li, Al, Co, Cu, and others, to the leachate. In this work, the influence of three types of precipitation agents (NaOH, NH₄OH, Na₃PO₄) on the precipitation efficiency of Al and Li losses was investigated. It was found that the precipitation of aluminum with NaOH can result in the co-precipitation of lithium, causing total lithium losses up to 40%. As a suitable precipitating agent for complete Al removal from Li leachate with a minimal loss of lithium (less than 2%), crystalline Na₃PO₄ was determined under the following conditions: pH = 3, 400 rpm, 10 min, room temperature. Analysis confirmed that, in addition to aluminum, the precipitate also contains the REEs La (3.4%), Ce (2.5%), Y (1.3%), Nd (1%), and Pr (0.3%). The selective recovery of these elements will be the subject of further study.

The increasing demand for sustainable materials in electrical engineering has encouraged the substitution of conventional fillers in epoxy insulation with recycled industrial by-products. This study investigates the potential use of waste tire rubber particles and zinc oxide recovered from electric arc furnace dust as eco-friendly fillers for epoxy resins in high-voltage insulation applications. Four material variants were fabricated: pure epoxy, epoxy with 10 wt% ZnO, epoxy with 10 wt% tire rubber, and epoxy with 20 wt% tire rubber. The breakdown voltage of each composite was measured under AC voltage. Results indicate that the incorporation of recycled fillers influences the breakdown voltage depending on both the type and concentration of filler. The 10 wt% ZnO-filled epoxy exhibited a moderate enhancement in breakdown voltage compared to pure epoxy, attributable to interfacial polarization and charge trapping at the epoxy-ZnO interface. Conversely, tire rubber fillers introduced localized field distortion and interfacial voids, resulting in a gradual reduction of breakdown voltage with increasing filler content. The results show that ZnO from metallurgical waste can function as an effective additive to improve dielectric performance. This approach supports circular-economy principles and offers a sustainable option for future high-voltage insulation materials.

The increasing demand for sustainable materials in electrical engineering has encouraged the substitution of conventional fillers in epoxy insulation with recycled industrial by-products. This study investigates the potential use of waste tire rubber particles and zinc oxide recovered from electric arc furnace dust as eco-friendly fillers for epoxy resins in high-voltage insulation applications. Four material variants were fabricated: pure epoxy, epoxy with 10 wt% ZnO (0.7 mm thickness), epoxy with 10 wt% tire rubber (0.9 mm thickness), and epoxy with 20 wt% tire rubber (0.9 mm thickness). The breakdown voltage of each composite was measured under AC voltage. Results indicate that filler type and concentration influence breakdown behavior within each thickness group. The 10 wt% ZnO-filled epoxy exhibited a moderate enhancement in breakdown voltage compared with pure epoxy of the same thickness, consistent with interfacial modifications commonly observed in oxide-filled epoxy systems. Conversely, tire rubber fillers led to reduced breakdown performance, likely due to increased dielectric heterogeneity introduced by the elastomeric phase. No direct comparison between ZnO- and rubber-filled systems was performed due to differences in manufacturable sample thickness. The findings contribute to the evaluation of recycled fillers in dielectric composite systems within a circular-economy framework.