Reusing　seed　crystal　is　beneficial　for　reducing　the　production　costs　for　cast　quasi　single　crystalline　(QSC)　silicon　ingots.　We　numerically　investigate　the　reusability　of　seed　crystal　in　the　casting　processes　with　quartz　crucible　and　silicon　feedstock　of　different　purities.　The　reused　seed　crystal　is　recycled　from　the　standard　QSC　ingot　and　has　been　highly　contaminated　by　iron　impurity.　Transient　simulations　of　iron　transport　are　carried　out　and　special　attention　is　paid　to　the　diffusion　and　distribution　characteristics　of　iron　impurity　at　the　ingot　bottom.　The　heights　of　the　bottom　iron　contaminated　region　are　compared　for　silicon　ingots　grown　from　normal　and　recycled　seed　crystals.　The　results　show　that　the　purity　of　quartz　crucible　can　influence　the　reusability　of　seed　crystal　more　significantly　than　that　of　the　feedstock.　The　recycled　seed　crystal　with　high　iron　concentration　can　be　reused　for　casting　processes　with　standard　crucible,　whereas　it　is　not　recommended　for　reusing　for　processes　with　pure　crucible.　(C)　2015　Elsevier　B.V.　All　rights　reserved.