Integrated Approaches for Manganese Recovery from Silico-Manganese Sludge

This paper analyses the possibilities for the valorisation of silico-manganese sludge generated during ferroalloy production, with the aim of recovering manganese and reducing environmental impact. The study focuses on the comparative evaluation of physical and hydrometallurgical methods and the identification of an integrated process scheme.

The investigated material was characterised by physicochemical and mineralogical analyses (XRF, XRD, SEM), revealing a heterogeneous system with a variable manganese content (3.6-20.5%) and a predominantly siliceous matrix. Physical separation methods (size classification, density separation, and magnetic separation) were investigated, together with hydrometallurgical processes based on acid leaching and selective precipitation. The results show that physical methods lead to limited manganese enrichment, with low recovery rates (20-25%), due to its distribution throughout the material and its association with difficult-to-separate phases. In contrast, hydrometallurgical processes enable efficient manganese recovery, achieving yields of up to 95-96% and high-purity products (approximately 99% MnO equivalent).

The results demonstrate that integrated treatment schemes combining physical pretreatment and hydrometallurgical recovery provide the most effective route for manganese recovery from silico-manganese sludge. This approach supports the valorisation of industrial waste as a secondary resource within circular economy and sustainable resource-use strategies.