Lithium is a metal with a highly promising outlook for future global demand. Its industrial processing relies on two primary methods: production from brines through solar evaporation ponds and production from rock sources via flotation, roasting, and subsequent leaching. Chile is currently the world’s second-largest producer of lithium, surpassed only by Australia. However, Chile’s lithium production process is significantly advantaged by the exceptionally high lithium concentration in the Salar de Atacama—the highest in the world—and the region’s high solar radiation, which enables the most cost-effective solar evaporation process globally. Despite these comparative advantages, Chile’s lithium production has stagnated in recent years. This stagnation can be attributed to the need for more flexible legislation surrounding the lithium industry or an increase in the number of CEOLs (Lithium Exploitation Contracts) to regain its position as the leading global producer of lithium. Furthermore, increased investment in national universities and research centers is essential to foster the development and implementation of new, clean technologies for future projects. By addressing these challenges, Chile has the potential to solidify its role as a key player in the global lithium market while promoting sustainable industrial practices.

The growing demand for lithium for lithium-ion batteries and energy storage systems has driven the exploitation of natural brines in the “Lithium Triangle” (Chile, Argentina, Bolivia). However, the presence of boron, which is highly soluble and exhibits amphoteric behavior, poses a critical challenge to achieving battery-grade purity standards (<5 ppm). This element interferes with the crystallization and morphology of lithium carbonate (Li₂CO₃), reduces recovery efficiency, and affects the chemical stability of lithium phases. Due to its molecular characteristics and strong affinity for water, boron is difficult to remove using conventional methods. This work presents a critical review of current technologies for its removal from lithium-rich brines, including ion exchange with functionalized resins, adsorption, liquid–liquid extraction, and electrochemical methods. Their principles, efficiencies (60%–95%), selectivity towards Li⁺ and Mg²⁺, sustainability, reusability, and industrial feasibility are analyzed. A comparison shows that ion exchange and adsorption offer high selectivity and reusability, liquid–liquid extraction stands out for its efficiency but has lower sustainability, and electrochemical methods exhibit high sustainability with variable efficiency. The choice of the most suitable technology will depend on the specific composition of the brine and the operating conditions of the plant.

Rhenium is one of the rarest and most strategically important metals, indispensable in high-temperature superalloys and platinum–rhenium catalysts used across the aerospace and petrochemical industries. Owing to its limited primary reserves, recovering rhenium from secondary sources, such as spent catalysts, superalloy residues, and metallurgical dusts, has become vital to ensuring supply security. This review examines technological developments between 1998 and 2025, focusing on how operational parameters, including temperature, leaching time, reagent concentration, and solid-to-liquid ratio, govern dissolution kinetics and overall process efficiency. Comparative evaluation of hydrometallurgical, alkaline, and hybrid processes indicates that modern systems can achieve recovery rates exceeding 98% through selective oxidation, alkaline activation, or combined pyro and hydrometallurgical mechanisms. Acid–chlorine leaching facilitates rapid, low-temperature dissolution; alkaline sintering stabilises rhenium as soluble perrhenates; and hybrid smelting routes enable the concurrent separation of rhenium and osmium. Sustainable aqueous systems employing nitric and ammonium media have also demonstrated near-complete recovery at ambient temperature under closed-loop recycling conditions. Collectively, these findings highlight a technological transition from energy-intensive, acid-based pathways towards low-impact, recyclable, and digitally optimised hydrometallurgical processes. The integration of selective oxidants, phase engineering, circular reagent management, and artificial intelligence-assisted modelling is defining the next generation of rhenium recovery, combining high extraction yields with reduced environmental impact and alignment with global sustainability goals.

Due to the scarcity of high-grade minerals on the Earth’s surface and the ever-increasing demand for critical metals required in the production of clean energy, the search for alternative sources has become essential. Ferromanganese crusts, a mineral resource located in the depths of the ocean, contain high concentrations of valuable metals, particularly cobalt (Co) and manganese (Mn). A leaching process using sulfuric acid, with the addition of steel scrap, has been proposed for processing this resource. The study investigated the extraction of manganese (Mn) and cobalt (Co) under acidic conditions at 25 °C, employing a factorial experimental analysis. Statistical models were adjusted using response surface methodology to evaluate the effects of time and the ferromanganese crust/Fe(res) (iron residue) ratio as predictive variables. The results demonstrated that the extraction of Mn and Co could be effectively modeled through multiple regression, with strong goodness-of-fit indicators. Optimal extraction was achieved at extended durations (30 min) and lower ferromanganese crust/Fe(res) ratios (1/3) for the sampled values. Gradient analysis revealed that extraction efficiency was directly proportional to time and inversely proportional to the ferromanganese crust/Fe(res) ratio, except in the case of Co extraction at higher durations and lower ratio levels. Additionally, no precipitation of Mn or Co species was observed in the analyzed residues.

Copper smelting slags represent a growing environmental and metallurgical challenge due to their large volumes and their content of unrecovered critical metals such as copper. Although conventional treatment relies mainly on acidic leaching, more sustainable hydrometallurgical routes are required to valorise these residues. In this study, an alternative copper extraction process is proposed based on alkaline glycine complexation and the use of ferromanganese crusts as an unconventional oxidising agent. Leaching tests were performed using two slags (A and B) at ambient conditions. Copper recoveries up to 59.7% (slag A) and 25.7% (slag B) were achieved at 1 M glycine without external oxidants. The addition of ferromanganese crusts (1:1 and 2:1) resulted in marginal increases (up to 61.1% and 29.1%, respectively), attributed to the limited oxidative performance of MnO₂ at near-neutral pH. The results demonstrate that glycine is a viable lixiviant for copper recovery from slags at room temperature and highlights, for the first time, the use of naturally occurring Fe–Mn crusts as oxidants in alkaline leaching systems. This work contributes to the development of more sustainable valorisation strategies for metallurgical slags and offers a basis for future optimisation of alkaline complexation routes.

The growing global demand for lithium (Li⁺), driven by its strategic role in energy storage technologies, faces a critical challenge in its recovery from brines: the selective separation of Li⁺ and magnesium (Mg²⁺) ions. Because Li⁺ (ionic radius ≈ 76 pm) and Mg²⁺ (≈ 72 pm) have almost identical ionic radii despite their different charge, their coordination and hydration behaviour are difficult to discriminate at the molecular level. The high Mg²⁺ content in natural brines, such as those from the Atacama Salar, delays the efficiency of conventional extraction processes, which also result in significant Li⁺ losses. In this context ionic liquids (ILs) are emerging as alternative solvents with tunable properties, low volatility, and high thermal stability, although their environmental performance depends strongly on their chemical structure, toxicity, aqueous solubility, and recyclability, offering advantages over traditional organic extractants. This study evaluates the use of ionic liquids in liquid–liquid extraction systems for the selective removal of Mg²⁺, analysing operational parameters such as pH, organic-to-aqueous phase ratio (O/A), and extractant concentration. This review critically compares ionic-liquid-based extraction systems by relating Mg²⁺/Li⁺ selectivity to extractant structure, coordination chemistry, and key operational variables, while also considering the main limitations associated with their application to high-salinity brines. By linking macroscopic extraction performance to the underlying coordination chemistry, hydration-shell disruption, and computational screening tools such as quantum chemical calculations and COSMO-RS, this approach supports the rational, molecular-level design of environmentally responsible extractants for brines with a high Mg/Li ratio.