The use of organic solvents in an electrolytic system for neodymium electrorecovery by electrolysis at low temperatures is studied in the current work. More specifically, an alternative route, that of the system of DMSO (Dimethyl sulfoxide) with dissolved NdCl₃ has been researched and has given promising results. The study of this electrolytic system has been divided into two stages. Firstly, the characteristics of the electrolyte, the dissolution of NdCl₃ in DMSO, the conductivity and the viscosity of NdCl₃ solutions in DMSO at various temperatures, and the Nd complexation in the solution were studied and secondly, the electrolysis parameters and their impact on the Nd electrodeposition process were evaluated. Finally, the deposits were submitted to SEM-EDS (Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy) analysis and metallic Nd was confirmed to be electrodeposited by X-ray Photoelectron Spectroscopy (XPS) spectroscopy.

The conventional lithium extraction method involves the calcination of a-spodumene at 1050 °C so that it can be converted to the more-reactive b-spodumene and then a sulfuric acid roasting step at 250 °C. Lithium is finally extracted via leaching with water. This method is energy-intensive, leading to high capital and operational costs. In this study, the direct calcination of a-spodumene with the use of sodium carbonate and calcium oxide was examined, aiming to significantly reduce the calcination temperature and completely omit the sulfuric acid roasting step, thereby radically redesigning the lithium extraction process. The calcination product was then leached with different leaching agents, such as water and sulfuric acid, and at different temperatures. The efficiency of the additives was evaluated through the results of lithium extraction achieved during the leaching step. Different leaching agents and temperatures were investigated. The maximum lithium extraction achieved was 96%, obtained after calcination using a sodium carbonate/spodumene mixture and leaching with sulfuric acid at 90 °C. High lithium extractions, up to 83%, can also be achieved under the same calcination conditions and after leaching with sulfuric acid at lower temperatures, such as 40 °C, and for shorter leaching times.

This paper investigated the potential of thiosulfate as an alternative to cyanide for gold recovery from pressure oxidation residues. Thiosulfate leaching experiments were conducted under controlled conditions, varying parameters such as initial thiosulfate concentration, initial pH, temperature and solid–liquid mixing ratio (S/L). The results indicate that thiosulfate demonstrates promising gold recovery rates, with optimization potential through parameter adjustments. This study aimed to provide valuable insights into the feasibility of adopting thiosulfate as a gold recovery agent, promoting environmentally responsible practices in the metallurgical industry while addressing the challenges associated with pressure oxidation residues.