Electrolytic production of metallic neodymium is carried out in fused neodymium fluoride salts containing neodymium oxide. Two major challenges pertaining to neodymium production in fluoride salts are a) low solubility of neodymium oxide in fluoride melt, b) possibility of anodic gas evolution (CO, CO ₂ , CF ₄ , C ₂ F ₆ ). In this study, iron is used as a reactive anode in the electrolysis process, promoting electrochemical dissolution of iron into the melt, preventing PFC (perfluorocarbon) gas evolution at the anode. Further, the rare earth oxide is converted to rare earth fluoride by the use of iron fluoride formed as the result of iron dissolution. Thus, the fluoridizing agent is constantly regenerated in-situ which enables the continuous conversion of neodymium oxide feed. The cathodic product is Nd–Fe alloy which can be used as a master alloy for the production of NdFeB magnets.

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Rare earth elements (REEs), along with other metals, will play a pivotal role in the transition towards a low-carbon economy. Primary mining of REEs consists of multiple steps, is energy intensive and has an adverse environmental impact. Thus, the current scenario of “use and throw” of REEs after a single use in a product is untenable. Furthermore, the REEs are classified as critical metals by the US and EU due to the monopoly of China over REE production. Thus, recycling REEs from secondary resources and end-of-life (EOL) waste products can help effectuate a circular economy by a) reducing the environmental impact of primary mining, b) reducing the dependency on imports and formulating a secure supply chain, c) avoiding landfilling and incineration...@en

In this manuscript, we demonstrate a room temperature electrochemical process for efficiently recycling NdFeB magnet waste. First, the magnet waste was completely leached with HCl and then, in-situ electrochemical oxidation was performed to selectively oxidize Fe(II) in the leachate to Fe(III). Finally, oxalic acid was added directly to the electro-oxidized leachate which selectively precipitated more than 98% of rare earth elements as rare-earth oxalates. The calcination of rare-earth oxalates produced mixed rare-earth oxides of 99.2% purity and a marketable Fe(III) solution as by-product. The electro-oxidized leachate was also subjected to an alternative neutralization route in which ammonium hydroxide was added to remove iron as ferric hydroxide. The iron free leachate with rare earth elements and cobalt was then subjected to oxalic acid precipitation treatment, which finally produced rare-earth oxides of 99.7% purity. Furthermore, a cobalt-rich solution was obtained in the end and electrowinning studies performed on the solution showed the feasibility of recovering pure metallic cobalt.

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NdFeB magnet waste is one of the important secondary resources from which rare-earth elements (REEs) can be recovered. Herein we present an electrochemical route to selectively extract REEs from the magnet waste at room temperature. First, the magnet waste was partially leached with HCl. The partial leachate along with undissolved magnet waste was taken in the anolyte side of a two compartment reactor separated by an anion exchange membrane whereas the catholyte consisted of sodium chloride solution. The Fe(ii) present in the leachate was oxidized and precipitated as Fe(OH)₃ while more than 95% of REEs were extracted into the solution. Subsequently, oxalic acid was used to selectively precipitate REEs as rare-earth oxalates. Hydrochloric acid liberated during the oxalic acid precipitation process could be directly reused in the partial leaching step. Sodium chloride was the only chemical consumed during the electrolysis. The effect of the NaCl concentration in the anolyte and catholyte on the extraction of metals was investigated. From magnet waste to rare-earth oxides, the developed recycling process is environmentally friendly and consumes only electricity, NaCl and oxalic acid.

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NdFeB magnets are used in wind turbines and hybrid electric vehicles and are instrumental in progression toward a low-carbon economy. Recycling rare-earth elements (REEs) from NdFeB magnet waste is an important step toward building a sustainable REE supply chain. In this study, we describe an electrochemical process to selectively extract REEs from NdFeB magnet waste at room temperature. First, an electrolysis pretreatment step was performed to convert the elements present in the magnet waste into the respective hydroxides. A dual anode system was used where NdFeB magnet waste was taken as an anode along with an inert anode in an electrochemical reactor. The inert anode was used to ensure that iron in the magnet waste was converted into the Fe(III) form in the mixed hydroxides precipitate. Subsequently, the mixed hydroxides were leached with HCl. More than 97% of REEs and cobalt leached into the solution leaving iron in the residue. REEs were then selectively precipitated as rare-earth oxalates using oxalic acid, which in turn regenerated HCl, resulting in a closed-loop process. Calcination of the rare-earth oxalates yielded rare-earth oxides of high purity (99.2%), which can be used directly for producing rare-earth metals.

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Nd-Fe-B permanent magnets are a strategic material for a number of emerging technologies. They are a key component in the most energy efficient electric motors and generators, thus, they are vital for energy technologies, industrial applications and automation, and future forms of mobility. Rare earth elements (REEs) such as neodymium, dysprosium and praseodymium are also found in waste electrical and electronic equipment (WEEE) in volumes that grow with the technological evolution, and are marked as critical elements by the European Commission due to their high economic importance combined with significant supply risks. Recycling could be a good approach to compensate for the lack of rare earths (REs) on the market. However, less than 1% of REs are currently being recycled, mainly because of non-existing collection logistics, lack of information about the quantity of RE materials available for recycling and recycling-unfriendly product designs. To improve these lack of information, different waste streams of electrical and electronic equipment from an industrial recycling plant were analyzed in order to localize, identify and collect RE permanent magnets of the Nd-Fe-B type. This particular type of magnets were mainly found in hard disk drives (HDDs) from laptops and desktop computers, as well as in loudspeakers from compact products such as flat screen TVs, PC screens, and laptops. Since HDDs have been investigated thoroughly by many authors, this study focusses on other potential Nd-Fe-B resources in electronic waste. The study includes a systematic survey of the chemical composition of the Nd-Fe-B magnets found in the selected waste streams, which illustrates the evolution of the Nd-Fe-B alloys over the years. The study also provides an overview over the types of magnets integrated in different waste electric and electronic equipment.

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The difficulties for selective metal recovery from electronic waste are induced by the high complexity of such waste stream and complicated purification procedures. In this research, an electrochemical stimulated method is demonstrated to selective recover copper from an industrially provided electronic waste. More specific, one-step selective copper recovery was achieved by combining electrochemical dissolution and deposition in ammonia-based electrolyte. In the process, copper instead of other impure metals from the electronic waste is selectively dissolved and electrochemically enhanced at the anode. On the other side of the cell, pure copper was electrodeposited at the cathode. The current efficiency was found to be significantly influenced by the applied current density if galvanostatic process was facilitated. Both temperature and copper concentration in the electrolyte were found to have positive effects on the current efficiency. In a well-controlled process, copper of 99.56 wt% purity can be obtained which can be further improved by preventing potential oxidation on the electrodeposited layer. This research provide a possibility for selective copper recovery in one-step by substantially decreasing the purification cost and simplifying copper recovery procedures from electronic waste.

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Electrolytic production of metallic neodymium is carried out in fused fluoride salts containing neodymium oxide. Two major challenges pertaining to neodymium production are (a) low oxide solubility, (b) possibility of anodic fluorine gas evolution if the electrolysis rate exceeds feeding rate of neodymium oxide. In this study, a novel method is proposed in which iron fluoride (FeF3) is used as a fluorinating agent to convert neodymium oxide into neodymium fluoride. Electron Probe Micro Analysis (EPMA) results of as-converted salt show a complete conversion of neodymium oxide into neodymium fluoride. In the electrolysis process, iron is used as a reactive anode with electrochemical dissolution of iron into the melt, thus preventing fluorine gas evolution at the anode. Therefore, the fluorinating agent is constantly regenerated in situ which enables the continuous conversion of neodymium oxide feed. The cathodic product is a Nd–Fe alloy which can be directly used as a master alloy for the production of NdFeB permanent magnets.@en