  Mid-Infrared (IR) silicate dust bands observed in heavily obscured active
galactic nuclei (AGNs) include information on the mineralogical properties of
silicate dust. We aim to investigate the mineralogical picture of the
circumnuclear region of heavily obscured AGNs to reveal obscured AGN activities
through the picture. In our previous study Tsuchikawa et al. (2021), we
investigated the properties of silicate dust in heavily obscured AGNs focusing
on the mineralogical composition and the crystallinity with Spitzer/IRS 5.3-12
micron spectra. In this study, we model the full-range Spitzer/IRS 5-30 micron
spectra of 98 heavily obscured AGNs using a one-dimensional radiative transfer
calculation with four dust species in order to evaluate wider ranges of the
properties of silicate dust more reliably. Comparing fitting results between
four dust models with a different size and porosity, 95 out of the 98 galaxies
prefer a porous silicate dust model without micron-sized large grains. The
pyroxene mass fraction and the crystallinity are overall consistent with but
significantly different from the previous results for the individual galaxies.
The pyroxene-poor composition, small dust size and high porosity are similar to
newly formed dust around mass-loss stars as seen in our Galaxy, which
presumably originates from the recent circumnuclear starburst activity. The
high crystallinity on average suggests dust processing induced by AGN
activities.
