Rambam writes in Seder HaTefillah:
קדיש דרבנן כל עשרה מישראל או יתר שעוסקין בתלמוד תורה שעל פה ואפילו במדרשות או בהגדות כשהן מסיימין אומר אחד מהן קדיש
Kaddish DeRabbanan: Anytime ten or more Jews study torah shebe'al peh, even midrashim or aggadah, when they finish, one of them says kaddish.
This is indeed customarily performed whenever we study torah shebe'al peh during prayer, for example after korbanot before shacharit, pitum haketoret after shacharit on (weekdays and) shabbat, and bameh madlikin on Friday night.
However, I have never seen this done at minchah in any shul I've been to that recites korbanot before ashrei (some nusach sefard and many nusach edot hamizrach). It also does not appear in any siddur I've ever seen. (See e.g. here and here.)
Why does there not appear to be a custom to recite kaddish derabbanan after pitum haketoret for those who communally recite it as part of korbanot before minchah?
(I'm aware that there are those who advocate only saying kaddish derabbanan after learning aggadah specifically. If that's the case, they could easily add a suitable passage (e.g. 'yehi ratzon ... sheyibaneh beit hamikdash...') as we do after other passages of torah shebe'al peh, in order to recite the kaddish.)