Over the last decade, rare-earth elements (REEs) have become critical in the European Union (EU) in terms of supply risk, and they remain critical to this day. End-of-life electronic scrap (e-scrap) recycling can provide a partial solution to the supply of REEs in the EU. One such product is end-of-life neodymium (NdFeB) magnets, which can be a feasible source of Nd, Dy, and Pr. REEs are normally leached out of NdFeB magnet waste using strong mineral acids, which can have an adverse impact on the environment in case of accidental release. Organic acids can be a solution to this problem due to easier handling, degradability, and less poisonous gas evolution during leaching. However, the literature on leaching NdFeB magnets waste with organic acids is very scarce and poorly investigated. This paper investigates the recovery of Nd, Pr, and Dy from NdFeB magnets waste powder using leaching and solvent extraction. The goal was to determine potential selectivity between the recovery of REEs and other impurities in the material. Citric acid and acetic acid were used as leaching agents, while di-(2-ethylhexyl) phosphoric acid (D2EHPA) was used for preliminary solvent extraction tests. The highest leaching efficiencies were achieved with 1 mol/L citric acid (where almost 100% of the REEs were leached after 24 h) and 1 mol/L acetic acid (where >95% of the REEs were leached). Fe and Co—two major impurities—were co-leached into the solution, and no leaching selectivity was achieved between the impurities and the REEs. The solvent extraction experiments with D2EHPA in Solvent 70 on 1 mol/L leachates of both acetic acid and citric acid showed much higher affinity for Nd than Fe, with better extraction properties observed in acetic acid leachate. The results showed that acetic acid and citric acid are feasible for the recovery of REEs out of NdFeB waste under certain conditions.
Despite the significant reduction of phosphorus (P) discharge in the Baltic Sea in the last decades, obtained through the implementation of some approaches within the Helsinki Convention, eutrophication is still considered the biggest problem for the Baltic Sea environment. Consequently, the reduction of P load is an urgent need to solve, but the complexity of both the environmental and legislative context of the area makes this process difficult (more than in the past). Eutrophication is an intricate issue requiring a proper framework of governance that is not easy to determine in the Baltic Sea Region where the needs of several different countries converge. To identify the most suitable strategy to reduce the eutrophication in the Baltic Sea, the InPhos project (no. 17022, 2018–2019, funded by the European Institute of Innovation & Technology (EIT) Raw Materials) adopted a holistic approach considering technical, political, economic, environmental and social aspects of P management. With the aims to raise awareness about the P challenge, foster the dialogue among all the stakeholders, and find solutions already developed in other countries (such as Germany and Switzerland) to be transferred in the Baltic Sea Region, the InPhos project consortium applied the methodology proposed in this paper, consisting of three main phases: (i) analysis of the available technologies to remove P from waste streams that contribute to eutrophication; (ii) analysis of the main streams involving P in Baltic Sea countries to highlight the potential of more sustainable and circular P management; (iii) study of the current context (e.g., already-existing initiatives and issues). This approach allowed us to identify four categories of recommendations and practical actions proposed to improve P management in the Baltic Sea region. During the project, the consortium mainly addressed social aspects. Following steps beyond the project will be more quantitative to determine the techno-economic feasibility of circular P management in selected demo cases in the region.
This paper proposes a new method for producing nano-SrFe12O19 powder by the citrate precursor route using solid waste as a source of iron. This solid iron-containing waste, which exists in the form of an oily sludge, is produced by a cold rolling mill. This sludge was first subjected to a process, including sulfuric acid leaching, oxidation, precipitation, and nitric acid leaching, to obtain an iron nitrate (Fe(NO3)3) solution. Next, the Fe(NO3)3 solution was mixed with a strontium nitrate (Sr(NO3)2) solution obtained by subjecting strontium carbonate to nitric acid leaching. Subsequently, citric acid, as chelating agent, and ammonia water, as precipitating agent, were added to the mixed solution to form a gel. The gel was dried and spontaneously combusted, then annealed at different temperatures for 2 h in flowing air. The effects of the Fe3+/Sr2+ molar ratio and annealing temperature on the formation, morphology, and magnetic properties of SrFe12O19 were investigated. The results showed that single-phase SrFe12O19 powder was obtained by decreasing the Fe3+/Sr2+ molar ratio from the stoichiometric value of 12 to 11.6 and increasing the annealing temperature to 1000 °C for 2 h. Adjustment of the Fe/Sr molar ratio to 12 and the annealing temperature to 900 °C enabled the magnetic properties to be optimized, including saturation magnetization (Ms) 80.2 emu/g, remanence magnetization (Mr) 39.8 emu/g, and coercive force (Hc) 6318 Oe.
29 September 2017 in Acta Crystallographica Section E Crystallographic Communications
The reaction of diethyl malonate with phthaloyl chloride in acetonitrile in the presence of triethylamine and magnesium chloride results in the formation of the title compound, diethyl 2-(3-oxo-1,3-dihydro-2-benzofuran-1-ylidene)propanedioate, C15H14O6. One of the ester groups of the diethyl malonate fragment is almost coplanar with the isobenzofuran unit, while the plane of the other group is perpendicular to it [dihedral angles = 5.45 (3) and 83.30 (3)°, respectively]. The C—C and C—O distances both in the heterocyclic furan ring and the diethyl malonate fragment are indicative of the dipolar delocalization occurring within the isobenzofuran unit. This delocalization is likely to be responsible for the unusual intermolecular O...O contact [2.756 (2) Å], established between the O atom of the furan ring and the carbonyl O atom of the diethyl malonate fragment. In the crystal, weak C—H...O interactions are observed, which link the molecules into [100] chains.