Sorption Properties of Natural Sulfides with Respect to Technetium

Technetium sorption properties of Fe 2+ -bearing minerals and different metal sulfides were studied by batch and column experiments. Pure stibnite (SbS 3 ), pyrrhotite (FeS), pyrite (FeS 2 ), galena (PbS) and loell ingite (FeAs 2 ) fix Tc to a great extent (> 95 % of TcO 4 - starting inventory). They appear to be favourable backfill materials for redox-sensitive radionucli-des. Physico-chemical processes of fixation and possible fixation modes are discussed.