  The high-Tc alkali doped iron selenide superconductors KxFe{2-y}Se2 have been
recently shown to be intrinsically phase separated into Fe vacancy ordered
block antiferromagnetic regions and superconducting regions at low
temperatures. In this work, we use a microscopic five orbital Hubbard model to
obtain the electronic low-energy states near the interfaces between block
antiferromagnets and superconductors. It is found that abundant low-energy
in-gap bound states exist near such interfaces irrespective of whether the
superconductor has d- or s-wave pairing symmetry. By contrast, it is shown how
nonmagnetic scattering planes can provide a natural means to distinguish
between these two leading pairing instabilities of the KxFe{2-y}Se2 materials.
