Maintaining saturated conditions in two cemented paste backfill (CPB)-mixtures (1-3 wt.% of binders) based on cyanidation tailings was vital for reducing the pyrrhotite oxidation rate and the release of Cu, Ni and Zn. The opposite was true for As, that desorbed from Fe-precipitates and formed soluble Ca-arsenates. Flooding of CPB-fillings could be a long-term process, where unsaturated zones can form within CPB-masses. At this stage, leachates from CPBs (1 wt. %), became acidic, causing As-release to decrease but the opposite for Cu. In CPBs (3wt. %), As-release was unaltered but the Zn-release increased as binder-related Zn-phases dissolved in alkaline conditions.