Currently, with the rapid growth of the population, the demand for metals has increased, especially for the manufacture of electronic devices such as cell phones, computer equipment, among others. Once these devices stop working, most are sent to landfills, which represents a danger since these wastes contain metals and other materials that must be properly managed to prevent them from having a negative effect on the environment and the human being. On the other hand, e-waste contains valuable metals such as copper, gold, and silver, the concentration of which in these materials makes it cost-effective to recover. This paper presents a review of the extraction and recovery of valuable metals from electronic waste by hydrometallurgical methods, as well as patents and industrial processes related to the management and treatment of this waste.

The depletion of the ore reserves in the world necessitates the search for secondary sources such as waste products (tailings and slag). A smelter in Namibia has historic slag which accumulated over decades of its operating life. Analytical and mineralogical characterization of the slag was performed using the X-ray fluorescence (XRF) analysis, Atomic Absorption Spectrometer (AAS), ICP-OES, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) analysis, and optical microscopy analysis. The chemical analyses showed that the metal values contained in the slag were mainly copper, lead, and zinc whose average contents were approximately 0.3%Cu, 2.4%Pb and 3.2%Zn. About 10.5%Fe was also contained in the slag. Germanium was detected by scanning electron microscopy, but was however below detection limits of the chemical analysis equipment used. Based on the results, approximate conditions under which the different slag phases were formed were estimated and the recovery routes for the various metals were proposed. Analysis by both optical and scanning electron microscopy revealed that Zn and Fe occurred mainly in association with O as oxides, while Cu and Pb were mainly associated with S as sulphides. The slag consisted of three different phases; namely the silicate phase (slag), metallic phase and the sulphide phases. The slag phases were mainly glass, silicate phases and metallic and sulphide phases. It was observed that the metallic and sulphide phases were dominant in the finer size fractions (-75 µm) whereas the sulphide phase was also present in the coarser size fractions (+300 µm). An important finding from the microscopy examination was that the sulphide phases were interstitial and could be liberated from the slag. This finding meant that liberation and subsequent concentration of the sulphide phases was feasible using conventional processing techniques.

India has pledged ambitious initiatives to mitigate its growing economies’ impact on the climate, including a goal of net zero emissions by 2070. The transportation sector is one of the key sources of emissions. Therefore, fostering e-mobility within this sector is a key priority for the Indian government. The lifecycle of LiBs raises numerous concerns regarding its sustainability in production, use of rare materials, and most importantly waste management. Furthermore, this paper will highlight the case for EV battery recycling as a growing sector that also has the potential to foster circularity in the EV sector. Through the introductory section, this paper lays out rationale for battery recycling in a circular EV economy. The subsequent sections discuss the current and emerging battery technologies and their link to recycling methods whilst overviewing domestic and foreign battery recycling companies. Finally, the paper concludes with a gap assessment of the battery recycling ecosystem in India and makes recommendations to further integrate this industry into the EV supply chain. As India steers towards a sustainable future, it is imperative that the country integrates battery recycling to enhance circularity in the EV ecosystem, closing the gap between a growing number of EVs and waste management.

The orbital elactronic structure of Rare Earth Elements (REEs) contains many unpaired electrons which render them capable of storing large amount of magnetic energy in addition to being critical for hitech applications. Geological deposits are their conventional sources, and the current supply chain relies on production from these deposits. However, given their critical roles in the anticipated global energy transition, there is the need to explore other viable sources to supplement current and future supplies chains. REEs occur in coal as accessory minerals and their concentration in coal ash to levels that rival those of geological deposits has been estab;ished by sophisticated analytical chemical methods. Conmventional hydrometallurgical processes rely on acid leaching, using tioxic mineral acids. Meanwhile, organosulfonic acids have pKa values that rival those of conventional minerals acid and can, therefore, be used in hydrometallurgy but their uses in this regard are not well documented in the literature. In this extensive review, we have covered geological sources of REEs exaustively in addition to showing the potential of organosulfonic acids as environmentally benign lixiviants for REEs extraction from coal ash. We have also shown how process optimization can be achieved using advance technologies while using organisulfonic acids. Moreover, we have shown current and future global market trends regarding the production of select organosulfonic acids, and the anticipated global increase in their production motivates the use of organosulfonic acids as viable lixiviants for REEs extraction from caol ash deposits.

In pursuit of carbon neutrality, the demand for metals that are necessary for the development of clean energy technologies is rapidly increasing. Metallurgical waste, such as slag, presents a promising secondary source of these key metals. This research aims to develop an eco-friendly hydrometallurgical process to recover Cu, Ni, and Co from discarded copper/nickel slag. The high-pressure acid leaching (HPAL) was used to selectively leach Ni, Cu, and Co from the fayalite slag, yielding high leaching efficiencies of 99.9%, 89.4%, and 99.9%, respectively, with low Fe and Si tenors to the pregnant leach solution (PLS). The solvent extraction (SX) technique utilizing LIX 984N was used to selectively extract and enrich copper from the dilute PLS to about 23 g/L Cu with a very low Fe concentration of 0.05 g/L. Potassium amyl xanthate (PAX) solution was used to form Ni and Co xanthate complexes from the raffinate solution. Nickel was selectively recovered using ammonia solution, while cobalt xanthate complex was thermally decomposed and recovered as cobalt oxide solids of about 25 wt.% Co. A comprehensive process flowsheet is presented, furthermore, to realize the real application of the developed slag cleaning process, a preliminary economic evaluation was performed.