Neodymium-iron-boron (NdFeB) grinding slurries are the residual output of grinding as shaping process step in the production process of sintered NdFeB magnets. The treatment of the grinding slurries with the aim of recovering rare earth elements may lead to a reduced demand in primary raw materials like the rare earth elements neodymium, praseodymium and dysprosium. In this study, the possibility of recycling the contained rare earth elements, which account for up to 30 wt % in the alloy, through a pyrometallurgical process was investigated. The necessity of a thermal conditioning prior to the pyrometallurgical process is described.

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This paper focuses on the recycling of silver from spent oxygen-depolarized cathodes through an innovative combination of pre-treatment methods and leaching. A silver- and polytetrafluorethylene (PTFE)-rich fraction was produced by cryogenic milling, screening, and magnetic separation. In order to understand the kinetic leaching mechanism, the silver-rich fraction was leached by different concentrations of nitric acid and hydrogen peroxide. Results showed that nickel influences the silver leaching. This leads to complex reaction systems, which cannot be described by the Arrhenius law.