  Galaxies continuously reprocess their interstellar material. One can
therefore expect changing dust grain properties in galaxies which have followed
different evolutionary pathways. Determining the intrinsic dust grain mix of a
galaxy helps in reconstructing its evolutionary history. Early-type galaxies
occasionally display regular dust lanes in their central regions. Due to the
relatively simple geometry and composition of their stellar bodies, these
galaxies are ideal to disentangle dust mix variations from geometric effects.
We therefore model the various components of such a galaxy (FCC 167). We
reconstruct its recent history, and investigate the possible fate of the dust
lane. MUSE and ALMA observations reveal a nested ISM structure. An ionised-gas
disk pervades the central regions of FCC 167, including those occupied by the
main dust lane. Inward of the dust lane, we also find a disk/ring of cold
molecular gas where stars are forming and HII regions contribute to the
ionised-gas emission. Further in, the gas ionisation points towards an active
galactic nucleus and the fuelling of a central supermassive black hole from its
surrounding ionised and molecular reservoir. Observational constraints and
radiative transfer models suggest the dust and gas are distributed in a
ring-like geometry and the dust mix lacks small grains. The derived dust
destruction timescales from sputtering in hot gas are short and we conclude
that the dust must be strongly self-shielding and clumpy, or will quickly be
eroded and disappear. Our findings show how detailed analysis of individual
systems can complement statistical studies of dust-lane ETGs.
