The shortage of metallic resources is reinforcing efforts to also process mixtures which have a complex consistence. The problems of processing are versatile and require an extension of the definition of recycling in analogy to the processing of primary raw materials. Based on a general classification of the composites, the problems of collection and characterization, different recycling scenarios as well as results of own investigations were discussed using lithium batteries as example. On the basis of the intrinsic value of the several composites, the limits of efficient processing are shown.