The research presents an effective approach to achieve the selective separation of rare earth elements (REEs) from waste Nd-Fe-B magnets. Investigations show that the use of a two-stage roasting process can significantly reduce the amount of ammonium sulfate required and improve the separation efficiencies of REEs. During the first low-temperature roasting stage, almost 80% of REEs can be transformed

A shearing-enhanced goethite process for iron removal is proposed to overcome the difficulties in process reaction control and non-uniform mass transfer. The reaction kinetics of the oxidation of Fe2+ to α-FeOOH and crystal growth of α-FeOOH were studied in a ZnSO4-FeSO4 system. Oxidation and crystal growth experiments were performed under the following conditions: shearing speed = 1000–4000 rpm, flow

In this paper, the effect of Mn2+ (≤160 mg/L) on the anodic film properties and corrosion behavior of Pb-0.07%Ca-1.25%Sn anodes in acidic CuSO4 electrolyte is clarified. The anode was polarized in an electrolyte containing different concentrations of Mn2+ ions for 48 h to obtain a stable oxide film on the surface. The phase composition and morphology of the oxide layer formed on the Pb-0.07%Ca-1.25%Sn

A brass ash sample was characterized, presenting a high content of Zn (50.1%) and Cu (18.9%), with zincite, tenorite, quartz, willemite, and metallic Zn and Cu as major phases. It is a heterogeneous material composed of agglomerated particles of different shapes and sizes. Aiming at reaching the requirements for the subsequent Zn electrolysis step in a hydrometallurgical route to recover Zn and Cu

This work aimed to obtain the kinetic parameters of the hydrothermal dissolution of a Brazilian glauconitic siltstone (known as Verdete) with calcium hydroxide. Heat treatments were carried out in stainless steel autoclaves internally coated with Teflon in conventional and rotary (84 rpm) furnaces. The aqueous fraction of hydrothermal products was analyzed by flame photometry and pH-metry. The product

Enargite is a representative arsenic-bearing copper resource, and pyrite is often found co-existed with it. Understanding the effect of pyrite on enargite (bio)leaching is of vital importance for the recovery of copper from enargite. The galvanic interaction between enargite and pyrite in bioleaching and electrochemical systems was investigated. Bioleaching experiment showed that the addition of pyrite

At present, low-grade nickel sulfide ore with high-alkaline gangue has replaced high-grade nickel sulfide ore as the main raw material for the extraction of nickel. Traditional pyrometallurgical smelting processes have problems such as high energy consumption, large loss of valuable metals, and low comprehensive resource utilization. In this paper, an improved process that uses chlorination roasting

Production of ferronickel from limonitic laterite ore using hydrogen reduction and cementation was studied by relying on a novel hydrometallurgical process consisting of the key steps: calcination, reductive roasting with hydrogen gas, 2-stage atmospheric hydrochloric acid leaching, and cementation with Fe. The introduction of the reusability of H2-reduced limonitic laterite as a cementation agent

With the development of society, solid waste, such as coal fly ash has caused serious environmental problems. Extraction of high value metals from coal fly ash is vital for sustainable development and maintenance of social economy. This work aimed to present a nonhazardous and efficient electrolysis method to extract selective iron products from coal fly ash leachate. Compared with current precipitation

Production of gold from copper-rich gold ores has received particular attention due to some technical and economic challenges associated with the ready dissolution of most copper minerals during cyanide leaching. This leads to excessive consumption of cyanide by forming copper cyanide complexes, which adversely affect downstream recovery and cyanide detoxification processes. In this study, a novel

The industrial validated technology used in gold mining that deals with copper‑gold ores is the SART process, which allows a viable treatment for these complex minerals. The clarification or thickening stage in this processing, in which copper precipitates are separated, has several challenges such as copper losses (as solids in the overflow or by re-dissolution due to the high residence time) and

The gold-bearing dust generated during the roasting process of refractory gold concentrates is valuable as a secondary gold resource. In this study, the effects of different pre-treatment methods on the removal of harmful elements and gold extraction from gold-bearing dust by cyanidation after pre-treatment were studied based on mineralogical analysis. The results showed that the dust belonged to refractory

This study investigates the most suitable conditions for the combined separation of nickel and zinc ions from aqueous solution using triethylenetetramine (Trien) as a neutral organic chelating ligand and sodium dodecyl sulfate (SDS) as an anionic collector for ion flotation. The interaction of nickel ions with Trien at various pHs and Trien concentrations, and that of nickel ions with SDS, are studied

The shift to electric mobility necessitates recycling the metals from lithium ion battery waste. Ion exchange was studied for use in the removal of impurities from synthetic lithium ion battery waste leachate in laboratory-scale batch and column experiments. Aminomethylphosphonic acid functional chelating resin (Lewatit TP260) was capable of removing Fe, Al, Mn, and Cu from the leachate, while leaving

The behaviour of nickel (Ni), cobalt (Co) and major impurities such as aluminium (Al), trivalent chromium [Cr(III)] and ferric iron [Fe(III)] during the partial neutralisation of synthetic pressure acid leach (PAL) liquors and pulps was investigated. Ferric iron precipitation took place between pH85°C 2 to 3, and up to 54% of Cr(III) and 42% of Al were co-precipitated with Fe(III). Haematite appeared

Extraction and separation of hafnium (Hf) from zirconium (Zr) in HNO3 solution were carried out with Cyanex572 as extractant. Hf could be selectively extracted with an optimized extraction rate of 76.8%, and the separation factor between Hf and Zr could reach up to 15.7 when the concentration of Zr(IV), Hf(IV), H+, NO3− and (NH4)2SO4 in aqueous phase were fixed at 110 g/L, 3.0 g/L, 2.6 M, 1.8 M and

Alkali extraction is the main process for extracting tungsten from wolframite. But it produces hazardous waste residues which are difficult to dispose of. Acid decomposition and hydrogen peroxide dissolving tungstic acid from decomposition residue is a new route for extracting tungsten from wolframite. The new method can resolve problems caused by alkali route. The dissolution behavior of tungstic

High-pyrrhotite tailings are highly reactive and can easily oxidize and produce acidity and/or metal-laden drainage under some disposal conditions, while at the same time this material may contain significant metal values. CanmetMINING is currently developing a stirred-tank bioleaching process to recover nickel and cobalt (both critical for electric vehicle batteries) from pyrrhotite-rich tailings

Iron removal in the nickel industry is achieved by precipitation and filtration, and for enhanced process efficiency, the filtration step must be improved. A mixed-suspension-mixed-product-removal (MSMPR) reactor set-up operating at steady-state was established, simulating industrial conditions, and the effect of temperature and residence time on filtration performance of the precipitated akaganéite

The primary pathways by which nickel (Ni) and cobalt (Co) loss could occur from acidic sulfate solution during partial neutralisation of synthetic nickel laterite pressure acid leach solutions (to pH 4 at 85 °C) was investigated. Knowledge of the avenues by which Ni and Co loss occurs will enable minimisation of valuable metal losses through optimisation of the partial neutralisation process. Precipitation

Although societal interest in lithium has grown due to its increased demand for manufacturing of lithium ion batteries (LIBs), recent research studies about LIB recycling with solvent extraction did not focus on Li recovery and Li remained in the raffinate contaminated with impurities. In this research presented direct Li recovery from LIB waste leachate prior to Ni and Co is a novel and promising

Laboratory scale batch EC experiments were performed on real metallurgical industry wastewater (MIWW). The most suitable process conditions were found to be: Al anode, a current of 1.05 A (150 A/m2) and a treatment time of 5 min (175 C/L). Operating costs and electrical energy consumption values were very low, 0.065 €/m3 and 0.44 kWh/m3, respectively. In the most suitable process conditions, 96% of

Arsenic-alkali residue (AAR) is one of the major hazardous solid wastes produced by the antimony (Sb) smelter industry and may pose a serious threat to the local environment and public health. However, effective method for the treatment of AAR is still lacking. In this study, a new method for the effective treatment of AAR is proposed for the use of AAR from a Sb refinery. This treatment of AAR includes

A mechanochemical leaching process by mechanical ball milling in the aqueous solution containing Pb chloride or Pb nitrate was proposed for the separation of smithsonite and cerussite. XRD analyses revealed the formation of Pb2(CO3)Cl2 and PbCO3, respectively, in the residues by the mechanochemical reaction of smithsonite with the Pb chloride and Pb nitrate solution. These results show that smithsonite

An alkali leaching-acid leaching method was proposed to extract vanadium and enrich titanium from modified Ti-bearing blast furnace slag (MTBBFS). The optimal alkali leaching conditions were NaOH concentration 2.0 mol/L, leaching temperature 95 °C, and leaching time 90 min. The leaching ratio of V was 91.30%. After 4 times cyclic alkaline leaching, the vanadium concentration of leaching solution increased

The equilibria associated with the solvent extraction of trivalent rare earth elements (REEs) with 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHEHPA) have been previously studied by many researchers because of the industrial importance of REEs. However, quantitative analysis has been limited to relatively low concentrations of EHEHPA because of the nonideal characteristics of the organic

The effect of mechanical activation on extraction of vanadium from chromium-containing vanadate solution by precipitation with calcium salt and leaching with sodium carbonate salt was investigated. The whole process including selective precipitation of vanadium, alkali leaching of vanadium and cyclic utilization of calcium. Compared with stirring, ball milling is more effective for vanadium precipitation

Agglomeration provides substantial advantages on heap leaching, such as creating a porous heap to improve low-permeability ore leaching efficiency, as well as building an environmentally friendly heap by reducing metal releases from waste rock and tailings. In this study, we employed synchrotron X-ray computed tomography (X-ray CT) combined with a data-constrained modelling (DCM) approach to investigate

The potential sweep method, adsorption kinetics and isotherm studies, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) after adsorption tests of copper(I) and gold(I) ions using magnetite were performed to investigate the mechanism of selective copper(I) adsorption over gold(I) ion from chloride solution with small amount of cyanide. The electrochemical analysis reveals

Pressure oxidation (POX) is an effective method for base metal extraction and a pretreatment of refractory gold ores. A residue from pressure leaching of chalcopyrite concentrate was collected and investigated for gold recovery and deportment of metals. A comprehensive mineralogical analysis and gold deportment study were conducted using techniques including X-ray diffraction (XRD), optical microscope

The nonferrous metal electrowinning process is energy intensive due to the sluggish dynamics of the oxygen evolution reaction (OER) on the anode. Developing novel anode materials with high OER activity and stability is imperative. Herein, we propose a novel Pb-ceramic composite anode by introducing ZnFe2O4. In this work, Pb-ZnFe2O4 and PS-Pb anodes were prepared through powder pressing and sintering

This study explores the influences of external iron ions on the dissolution behavior of covellite minerals at different temperatures. External iron ions can significantly accelerate covellite dissolution. The copper extraction of acid covellite leaching was less than 5%, while the addition of external iron ions (ferric or ferrous ions, Fe3+/Fe2+) effectively enhanced covellite dissolution. Covellite

In this study, focused radio wave (RW) assisted leaching was investigated for the first time to considerably enhance the efficiency of copper leaching from its low-grade ores. For this purpose, the effect of exposure to radio wave electromagnetic irradiation was experimentally investigated. Two series of leaching tests were conducted, in the form of agitated slurry and fixed-bed column modes. The experimental

Cadmium (Cd), cobalt (Co), nickel (Ni), and zinc (Zn) are important components of batteries and renewable energy technologies but their recovery from pregnant leach solutions or removal from polluted soil systems and water bodies remain challenging. In this study, we report the removal/recovery of heavy metal ions (Cd2+, Co2+ and Ni2+, and Zn2+) from sulfate solutions by a novel cementation technique

Iron-containing oxides are the main minerals associated with roasted gold concentrates. The influence of different iron-containing oxides on the gold thiosulfate leaching process is very complex. In this study, we found the use of dry grinding methods can considerably eliminate the adverse effects on gold thiosulfate leaching under wet grinding conditions for a roasted gold concentrate containing hematite

The present review covers achievements in the development and application of phosphorous-containing extractants for varios metals. The extractants based on industrial organophosphorus compounds, chelating compounds, ionic liquids, as well as polymers and copolymers bearing phosphorus-containing groups capable of complexing metals have been considered. Especial attention was paid to the efficiency and

Ultraviolet-A (UVA) radiation is one of the most stressful oxidative agents that bacteria have to face in natural environments. The effect of this radiation on growth, survival, biofilm formation, and bioleaching activity of two Leptospirillum ferrooxidans strains was studied, comparing the collection strain DSM2705 with FAM-RA2, a strain recently isolated from Famatina (La Rioja, Argentina), at 3869 m

Hydrometallurgy is considered a promising method to produce solar-grade silicon (SOG-Si) from metallurgical-grade silicon (MG-Si) due to its advantages of low cost, simple operation, and easy control. Researchers have investigated different hydrometallurgy techniques for impurity removal from MG-Si. This study systematically reviews hydrometallurgy techniques for the removal of impurities from MG-Si

Recently, there has been a steady increase in demand for lithium (Li) and its compounds, accounting for 10% over the past decade. The level of production and industrial use of lithium currently serves as a development indicator of advanced countries' innovative potential. Although there are large-scale and high-quality lithium deposits in Russia (Kola and Irkutsk regions), Li production is manufacturing

To explore the evolution of characteristics of pore structure of a weathered crust elution-deposited rare earth orebody during the leaching process with different valence cations, leaching solutions with NH4+, Mg2+, Al3+ as cations were prepared to carry out simulated column leaching experiments. Nuclear magnetic resonance (NMR), scanning electron microscope (SEM) and energy dispersive spectrometry

Assisted reagents are commonly introduced into acid leaching systems to improve metal recovery. In this work, fluorite was employed to accelerate magnesium (Mg) dissolution from serpentine tailings, and the dissolution mechanism was investigated by leaching experiments, kinetics equations and reaction analyses. The effects of fluorite powder dosage, particle size, reaction temperature, sulfuric acid

The ever increasing applications of rare earth elements and their limited primary resources has compelled researchers worldwide to find alternate methods of efficient leaching from various secondary resources, in particular from end of life products. The present research work describes such a process to extract rare earth elements from coal ash using low molecular weight carboxylic acids. Different

Magnesium and magnesium-derived alloys are critical to a diverse set of industries, due to their particular physicochemical properties, including biocompatibility, low density, mechanical dampening, and hydrogen-storage capacity. Moreover, the magnesium compounds are themselves vital in agricultural, pharmaceutical, construction and broad industrial applications. Leaching is a critical step in the

This study investigated the pressure leaching of lithium and other valuable metals from lepidolite using NaOH and Ca(OH)2. The findings showed that NaOH concentration, temperature, and stirring rate are the most significant process parameters. The addition of Ca(OH)2 facilitates the leaching of lithium and minimizes the concentration of silicate and fluoride in the leach liquor by forming solid phases

Phosphogypsum waste is a potential, secondary rare earth element (REE) source that is available in very large volumes. Extraction and purification of REE from this complex waste was studied using resin-in-leach (RIL) followed by batch elution. Multiple consecutive RIL cycles with Purolite S940 resin in dilute H2SO4 solution were performed for an industrial phosphogypsum waste. REE loading (max. 0.92

Zinc-electrowinning in Zn(II)-NH4Cl-H2O systems has many advantages, such as a high current efficiency and insensitivity to F−, Cl− and metallic impurities. Additives in electrowinning are important because they influence the growth and structure of the resulting deposits and current efficiency. The effect of gelatin and polyoxyethylene ether (PEO) on the nucleation, growth mechanism, and morphology

The agglomerate microstructure determines the performance of the agglomerates in heap leaching. However, a detailed analysis of the agglomerate microstructure is still highly desirable. The purpose of this paper is to conduct a comprehensive analysis of the agglomerate microstructure to guide the agglomeration process. In this work, the microstructure of agglomerates prepared by geopolymerization was