Purification of Dunino halloysite by H2SO4 leaching and magnetic separation

The article presents results of purification and comminution of raw halloysite from the Dunino deposit. The aim of the study was to clean halloysite from Dunino deposit with acid (H 2 SO 4 ) leaching and to remove iron impurities in order to obtain fine grained fractions smaller than 20 μm, which can be used in future for manufacturing polymer-aluminosilicate composites. The proposed method, where nanotubes (HNT) and nanoplates (HNP) were separated, consisted of several simple stages including crushing, milling magnetic separation and sedimentation. A multi-stage process resulted in three products: heavy iron oxide fraction, HNP and HNT mixture ( 20μm).