The background of this master thesis includes the economic dependence of Europe from China on rare earth elements (REE) and other critical metals. Starting with the general properties and historic developments of REE, the importance of permanent magnets is illustrated. Furthermore, the most common recycling methods of these materials are described. The focus of this thesis includes the evaluation of a hydrometallurgical recycling process which comprises an iron-cobalt-nickel and a REE recovery from permanent magnets. The conduction of three process circles provides information about the chemical behaviour of the elements during leaching, precipitation and evaporation steps. For a complete dissolving of the input material 32 % hydrochloric acid in a liquid/solid ratio of five to one is required. The use of oxalic acid achieves a yield of 98 % however the complete removal of iron cannot be achieved. For the reduction of the critical element boron in the bypass, a rise of the pH-value is needed by adding sodium resp. calcium hydroxide or zinc oxide. Major advantages of this recycling process include the separation of REE and heavy metals, the reduction of waste products and acid consumption as well as the possibility of a closed-loop process.