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Pressure hydrogen reduction (Pre-H2) is an important technology in hydrometallurgy, which is widely applied in the production of metal powders, coated composite powders, and metal oxides. In the 5G era, Pre-H2 is concerned in the electronic material manufacturing because of its clean, efficient, stable, and other characteristics. In this paper, the thermodynamic and kinetic principles of Pre-H2 in a liquid-phase environment are described, and the process methods, powder conditions, process parameters, and related applications of various products are summarized. In addition, this paper investigates the effect of liquid additives on powder morphology, reaction rate, quality of the process, and provides feasibility guidance for improving the process technology.

The possibility of sorption extraction of nickel from leaching solutions of oxidized nickel ores of the Buruktal deposit is considered. Ionite Lewatit TP220 with bis-picolylamine functional groups is effective for nickel recovery against the background of high iron contents. Lewatit TP220 is mechanically strong enough for use in the resin-in-pulp process. Nickel sorption with satisfactory performance occurs both in the variant of sorption leaching and extraction from clarified solutions. At sorption from the pulp, the capacity for nickel was 5.44 mg/g, for iron, 25.17 mg/g. The use of 20% sulfuric acid provides quantitative nickel desorption. To obtain a higher quality nickel-containing product, it is recommended to additionally purify the resulting eluates from iron.

Spent catalyst used for denitration by selective catalytic reduction (spent SCR denitration catalysts) is one of the important urban mines due to the high content of TiO2 (~85 wt%) and the massive accumulation amount (over 100, 000 tons), therefore, value-added reutilization of titanium in spent SCR catalysts is considerably meaningful. In this paper, a novel method is proposed for converting the titanium oxide in spent SCR denitration catalysts to metallic titanium. Specifically, titanium dioxide (TiO2) was firstly obtained from spent SCR denitration catalysts after removing the impurities by hydrometallurgy process. Then, TiO2 is converted to Ti2CO by carbothermic reduction method, and Ti2CO was further purified by oleic acid capture. Finally, by utilizing the as-prepared Ti2CO as the consumable anode in the NaCl-KCl molten salt, high-purity metallic titanium was deposited at cathode, all confirming the feasibility for the conversion of low–grade TiO2 in the spent catalysts, from 60 wt% to high–purity metallic Ti (99.5 wt%), furthermore, the energy consumption of this process is 3950 kWh tonne−1 Ti, which is lower than that of most traditional titanium metallurgy methods. The method herein can provide new insights for the value-added recycling of titanium resources in urban mines.

The cathodes of spent ternary lithium-ion batteries (LIBs) are rich in nonferrous metals, such as lithium, nickel, cobalt and manganese, which are important strategic raw materials and also potential sources of environmental pollution. Finding ways to extract these valuable metals cleanly and efficiently from spent cathodes is of great significance for sustainable development of the LIBs industry. In the light of low energy consumption, ‘green’ processing and high recovery efficiency, this paper provides an overview of different recovery technologies to recycle valuable metals from cathode materials of spent ternary LIBs. Development trends and application prospects for different recovery strategies for cathode materials from spent ternary LIBs are also predicted. We conclude that a highly economic recovery system: alkaline solution dissolution/calcination pretreatment → H2SO4leaching → H2O2reduction → coprecipitation regeneration of nickel cobalt manganese (NCM) will become the dominant stream for recycling retired NCM batteries. Furthermore, emerging advanced technologies, such as deep eutectic solvents (DESs) extraction and one‐step direct regeneration/recovery of NCM cathode materials are preferred methods to substitute conventional regeneration systems in the future.

The authors attempted to investigate the copper recovery possibilities from low-grade mixed sulfide-oxide ore in the present paper. The randomized leaching experimental results in sulfuric acid sol...

In this study, magnesia–nickel silicate ore was investigated, which contained 0.83% Ni and antigorite, chlorite, magnetite (Fe3O4), quartz, and mica as the main minerals. Chloride roasting and magnetic separation were used to treat the ore. The addition of red mud enhanced the transformation of nickel silicate to a strongly magnetic mineral mainly comprising metallic Ni and that of hematite to Fe3O4 and metallic Fe. Test results showed that a Ni concentrate with a Ni content of 11.41% and Ni recovery of 92.77% was achieved under the following optimal conditions: roasting temperature: 1373.15 K; roasting time: 120 min; CaCl2 dosage: 20%; coke dosage: 14%; red mud dosage: 30%; magnetic field intensity = 0.14 T; and grinding fineness: 90%

This paper characterized the microstructure and physical properties of the scale from a uranium mine in Xinjiang by SEM, XRD and FT-IR. Based on the orthogonal experiment design, the formula of HClO4: EDTA: (NaF + HNO3) = 4:1:5 is selected. The results show that the scale remover has the functions of dissolution, lattice damage and dispersion. The selected collaborative scale removal method can effectively remove the scale in the uranium mining process and has certain application value.

Neodymium (Nd) and dysprosium (Dy) based rare earth (RE) magnets are critical to green economy due to their vital role in permanent magnet applications such as electric motors and generators. The accumulating RE magnet waste in the form of end-of-life products (EoL), criticality of supply-demand, and the huge environmental costs associated with RE mining translated into an increased focus on RE recycling processes in the last decade. Environmentally friendly pyrometallurgical techniques were developed as an alternative to the traditional hydrometallurgical route due to the generation of large amounts of waste in hydrometallurgy. Liquid metal extraction (LME) is a promising pyrometallurgical technology as it has the ability to handle a wide variety of scrap feed materials, from swarf to ingots; to produce clean material with minimal impurities; and to allow the separation of metallic species without metallothermic reduction. So far, magnesium, silver, copper, and bismuth have been used as LME agents while exploration of other possibilities is ongoing. This article presents a systematic review of previous studies on the extraction agents in terms of the reaction mechanisms, behavior of the RE elements, extraction efficiencies, and the formation of intermetallic compounds during the process.

Lithium-ion batteries (LIBs) are employed in various electronic devices and industries. The recovery of valuable metals from spent LIBs has attracted much interest due to potential environmental is...

The growing demand for lithium-ion batteries will result in an increasing flow of spent batteries, which must be recycled to prevent environmental and health problems, while helping to mitigate the raw materials dependence and risks of shortage and promoting a circular economy. Combining pyrometallurgical and hydrometallurgical recycling approaches has been the focus of recent studies, since it can bring many advantages. In this work, the effects of incineration on the leaching efficiency of metals from EV LIBs were evaluated. The thermal process was applied as a pre-treatment for the electrode material, aiming for carbothermic reduction of the valuable metals by the graphite contained in the waste. Leaching efficiencies above 70% were obtained for Li, Mn, Ni and Co after 60 min of leaching even when using 0.5 M sulfuric acid, which can be linked to the formation of more easily leachable compounds during the incineration process. When the incineration temperature was increased (600–700 °C), the intensity of graphite signals decreased and other oxides were identified, possibly due to the increase in oxidative conditions. Higher leaching efficiencies of Mn, Ni, Co, and Li were reached at lower temperatures of incineration (400–500 °C) and at higher leaching times, which could be related to the partial carbothermic reduction of the metals.

Over the years, the generation of Waste Electric and Electronic Equipment has been significantly increased, which leads to environmental and economic concerns. Thus, it is fundamental to develop treatment methods for these residues. Printed Circuit Boards are essential components of electronic equipments. In this sense, printed circuit boards are composed of remarkable metals, in particular, copper and silver at high and low concentrations, respectively. These metals can be recovered by the hydrometallurgical process followed by a chemical purification step. Therefore, the aim of this study was to leach silver and copper from two different printed circuit boards (memory board and motherboard) from obsolete computers by hydrometallurgical route based on only one-stage leaching in oxidant media. When compared to the motherboard, a higher recovery rate of Ag was obtained from memory boards 83% and 33%, respectively. Whereas, similar recovery rates of copper were observed for memory board and motherboard, 48% and 46%, respectively.

Corresponding to the technological developments, production and consumption of nickel have increased greatly over time due to its unique mechanical and chemical properties. Therefore, the production of nickel will always keep its importance. The availability of laterite ores, which are oxide type ores, is 86% of the nickel reserves on the Earth, and the processes used in the production of nickel from sulfide type ores have negative environmental effects. Therefore, recovery of nickel from lateritic ores has become increasingly important in recent years. In this study, the aim was to determine the optimum parameters of nickel and cobalt production from limonite type lateritic nickel ores, which were taken from Manisa Caldag region of Turkey, using atmospheric pressure sulfuric acid leaching and pug-roast-leach process. When the results obtained in these processes were compared, it was found that the Ni leaching efficiency is nearly 8% higher and iron leaching efficiency (contamination) is nearly 4% lower in the pug-roast-leach process. Furthermore, the pug-roast-leach process was completed in 33% lower time compared to the atmospheric pressure sulfuric acid leaching process.

This study presents an up-to-date review on the methods and technologies applied for the recovery of Co from end-of-life Li-ion batteries. Considering the upcoming world demand for electric vehicle...

Abstract The state of the art for the recovery of metals from steel industry by-products using hydrometallurgical processes is reviewed. The steel by-products are different slags, dusts, and sludges from a blast furnace (BF), basic oxygen furnace (BOF), electric arc furnace (EAF), and sinter plant, as well as oily mill scale and pickling sludge. The review highlights that dusts and sludges are harder to valorize than slags, while the internal recycling of dusts and sludges in steelmaking is inhibited by their high zinc content. Although the objectives of treating BF sludges, BOF sludges, and EAF dust are similar, i.e., the removal of zinc and the generation of an Fe-rich residue to be returned to the steel plant, these three classes of by-products have specific mineralogical compositions and zinc contents. Because wide variations in the mineralogical composition and zinc content occur, it is impossible to develop a one-size-fits-all flow sheet with a fixed set of process conditions. The reason for the interest in EAF dust is its high zinc content, by far the highest of all steel by-products. However, EAF dust is usually studied from the perspective of the zinc industry. There are not only different concentrations of zinc, but also variations in the all-important ZnO/ZnFe2O4 (zincite-to-franklinite) ratio. In many chemical processes, only the ZnO dissolves, while the ZnFe2O4 is too refractory and reports to the residue. It only dissolves in concentrated acids, or if the dust is pre-treated, e.g., with a reductive roasting step. The dissolution of ZnFe2O4 in acidic solutions also brings significant amounts of iron in solution. Finally, due to its high potassium chloride content, sinter-plant dust could be a source of potassium for the fertilizer industry. Graphical Abstract

In this study, the mechanism of enhancing Fe removal from metallurgical grade silicon (MG–Si) by the novel metal-assisted chemical leaching (MACL) purification methods have been investigated. The typical impurity phase Si2Fe was selected to study interface reactions between the impurity phase and lixiviant. Based on density functional theory (DFT), the interactions of HF leaching, CuACL and AgACL on Si2Fe were revealed through studying the evolution behaviors of atom geometric structure, density of states and bond population, which showed that the stability of Si2Fe structure weakened with the orders of AgACL > CuACL > HF leaching. It was found that the lengths of Si–Fe bonds and metallicity of Si2Fe were successively increased when Si2Fe interacted with HF leaching, CuACL and AgACL, respectively. Compared with HF leaching, MACL weakened Si–Fe bond populations and increased H Fe bond populations, further destroyed the stability of Si2Fe structure. The experimental results showed that the impurity Fe removal rates were 94.30% for HF leaching, 95.75% for CuACL, and 97.27% for AgACL, respectively, which was highly consistent with the theoretical simulation results. The study provides a theoretical basis for enhancing Fe removal from silicon through MACL produces, indicating that MACL methods have a potential application in deep removal of impurity Fe from silicon in the future.

The possibilities of extracting valuable components and producing selective good-quality concentrates from hard-to-beneficiate crude ores are considered for the disseminated copper–nickel ores from the Norilsk district. The stated aim is achieved by a combined technology including beneficiation and hydrometallurgical processes. Beneficiation is aimed at producing a rich copper concentrate and a nickel–pyrrhotite product. The aim of the hydrometallurgical process is the leaching of a nickel–pyrrhotite product followed by the flotation production of a nickel concentrate. The flotation hydrometallurgical processing of a nickel–pyrrhotite product makes it possible to produce nickel concentrates of a higher quality than those synthesized using a traditional technology.

The increase in nickel and cobalt consumption encourages the exploration of different resources. Limonite ore exploration is carried out through the hydrometallurgical route. After nickel and cobal...

Metallurgical & materials engineering 26(2), 199-208 (2020). doi:10.30544/513 special issue: "Hydrometallurgical operations and processes", Published by [Verlag nicht ermittelbar], Belgrade

Mixed hydroxide precipitate (MHP) is a nickel intermediate product that has economical benefits to downstream leaching of lateritic marginal ores. Usually, this product is subsequently processed and refined to produce nickel by hydrometallurgy, but an alternative route can be made integrating hydrometallurgy and pyrometallurgy. Assessing the overall consumption of ferroalloys to obtain stainless steel, as an increasing practice performed in China, the synergy of nickel extraction from laterites by leaching and precipitation as MHP with the production of MHP agglomerates applied as raw material to furnaces of ferronickel production is a very attractive practice. This work aims to further the technological development of an agglomerated product feasible to hydro-pyro integration. The agglomeration experiments were performed by traditional pelletizing (firing the pellets) and cold bonded pelletizing (aging the pellets by appropriate stocking). Appropriate compositions were prepared with MHP, additives and binders for each of these routes. A specific study of binder composition was made to find an adequate melting point. The produced pellets were tested to prove their properties by crushing strength tests. The standardization applied to iron ore was followed. The best result of crushing strength was 98.52 daN/pellet. The agglomerates with approved crushing strength for use in electric furnaces were smelted to produce alloys containing nickel; the agglomerates were characterized by scanning electron microscopy. The alloy obtained was metallic ferronickel with sulphide precipitates. Therefore, MHP pellets can be precursors of nickel alloys, which have to be refined to obtain the desirable composition.

Many recycling processes have been developed for spent Li-ion batteries (LIBs), such as pyrometallurgy, hydrometallurgy, and direct recycling. For all the recycling methods, however, impurities are...

In 2003, Railsback proposed the Earth Scientist’s Periodic Table, which displays a great deal of elemental geology information in accordance with the natural environment of the earth. As an applied science, metallurgy is based on mineral composition and element behavior, that is similar to geochemistry. In this paper, connections and similarities between geology and metallurgy are identified, based on geochemical laws and numerous metallurgical cases. An obvious connection is that simple cations with high and low ionic potential are commonly extracted by hydrometallurgy, while those with intermediate ionic potential are extracted by pyrometallurgy. In addition, element affinity in geology is associated with element migration in metallurgic phases. To be specific, in pyrometallurgy, lithophile elements tend to gather in slags, chalcophile elements prefer the matte phase, siderophile elements are easily absorbed into metal melt, and atmophile elements readily enter the gas phase. Furthermore, in hydrometallurgy, the principles of hard/soft acids and bases (HSABs) offer an explanation of how precipitation and dissolution occur in different solutions, especially for fluoride and chloride. This article provides many metallurgical examples based on the principles of geochemistry to verify these similarities and connections.

Because of the high cost of energy, hydrometallurgy is frequently preferred to smelting to extract metals from ores. Many of these processes involve leaching of the metal with an acid, often sulfuric acid. However, there are some processes that use alkaline leachates, such as sodium hydroxide. Hot alkaline solutions present somewhat different corrosion problems to acidic ones and this paper presents data on the corrosion performance of metals and polymers in hot alkaline solutions. Some case histories from the mineral processing industry are used to demonstrate the importance of correct material selection in these corrosive solutions.

Bioleaching is regarded as an essential technology to treat low grade minerals, with the distinctive superiorities of lower-cost and environment-friendly compared with traditional pyrometallurgy method. However, the bioleaching efficiency is unsatisfactory owing to the passivation film formed on the minerals surface. It is of particular interest to know the dissolution and passivation mechanism of sulfide minerals in the presence of microorganism. Although bioleaching can be useful in extracting metals, it is a double-edged sword. Metallurgical activities have caused serious environmental problems such as acid mine drainage (AMD). The understanding of some common sulfide minerals bioleaching processes and protection of Amd environment is reviewed in this article.

The processing of manganese nodules for the production of raw materials has been a subject of research for many decades. The nodules contain many valuable metals like copper, cobalt and nickel. In recent years, the German Federal Institute for Geoscience and Natural Resources developed a process for the processing of manganese nodules based on a combined pyro‐ and a hydrometallurgical route. Clausthal University of Technology was assigned to develop the hydrometallurgical process for the treatment of a FeNiCuCo alloy. The developed process consists of pressurized sulfuric acid leaching with the suppression of hydrogen gas formation, precipitation and solvent extraction.

In order to recover pure alumina and synthesize magnesium spinel from black dross, a hydrometallurgical process was developed. This process consisted of 1) NaOH leaching of the mechanically activated black dross, 2) removal of silicate(IV) from the leaching solution by adsorption followed by coagulation, 3) precipitation of aluminum hydroxide from the purified leaching solution, 4) synthesis of magnesium spinel. Continuous experiments on the above-mentioned steps at optimum conditions were performed. Magnesium spinel was synthesized at 1000 °C for 5 hs by the co-precipitation method. The purity of spinel was 99.99 % and its characteristics were analyzed by XRD and SEM. Mass balance of the whole process indicated that the recovery percentage of alumina from the black dross was only 34 % owing to low leaching percentage. Further work on the pretreatments of black dross to improve its dissolution behavior is needed. Keywords: Aluminum hydroxide, Black dross, Spinel, Silicate, Hydrometallurgy

Modern methods of recycling spent automotive catalysts and their main disadvantages in industrial practice are considered. The electrochlorination method is proposed as the basis of the platinum-group metals extraction technology after electric arc melting of ceramic catalysts carrier material. The results of the experimental work on the extraction of platinum, palladium, rhodium are analyzed.

Manufacturing of nickel by hydrometallurgical technology at Harjavalta plant (Finland) had been caring out since 1960 by Outokumpu. Later on, the technology was modernized and currently Harjavalta plant belongs to PJSC “MMC Nornickel”. The plant is specializing on processing of copper-nickel mattes, converter mattes and by-products, originated from “Kola MMC” and third-party enterprises. Currently, the technology for the materials processing includes oxidative autoclave leaching (POX), solvent extraction, nickel electrowinning as well as solutions purification and metal salts obtaining stages. Selective POX produces nickel solution and copper cake (Cu-cake), which is a valuable by-product of the plant. The article presents the results on investigating the possibility of Cu-cake processing using POX in sulfate media at different temperature regimes. Low-temperature POX (105 oC) allowed to extract more than 95% Cu into solution within 30-60 min, while the dominating compound of solid residue was elemental sulfur; mass output of the solid residue was 20-25%. High-temperature POX (190 oC) allowed to extract more than 98% Cu in 60-80 min; mass output of the solid residue was 2.5-5%, which significantly increased a concentration of precious metals. Mid-temperature POX (150 oC) is characterized by increased duration. Copper extraction level of 95-98% is achieved at least after 120-180 minutes of leaching. Mass output of the solid residue was 6-10%. A detailed analysis of Cu-cake and the resulting products is provided. The behavior of precious metals was considered.