Leaching properties of Mn-slag from the pyrometallurgical recycling of alkaline batteries: standardized leaching tests and influence of operational parameters.

In the present study, different complementary leaching tests were applied to a Mn-rich slag sample that was not thoroughly studied until now, in order to understand the potential mobility of the elements (Mn, Si, Fe, Ca, K, Mg, Al) within it. Several standard leaching tests (EN 12457-1 and -2, and TCLP) were carried out in order to compare results to regulatory values: the Mn-rich slag studied could be considered as 'inert' waste with respect to the release of the main trace metallic elements (Cu, Ni and Zn). In order to have a better understanding of the environmental behaviour of the Mn-rich slag constituents, other tests were performed. These experiments revealed that the dissolution of the Mn-rich slag was favoured for pH < or = 6. The mobility of the major elements was governed by the solubility of the primary solid phases and the precipitation of secondary minerals. The Visual MINTEQ modelling allowed the leaching results to be completed. From an environmental point of view, the reuse of this slag in acidic conditions has to be rejected due to the dissolution of the main solid phase.