How often did you remove the spam and approve post?
It's hard to say without knowing more about it, since reddit is incredible strict with the mod que.
Did you regularly every day go into https://reddit.com/r/mod/about/unmoderated
and check the mod queue, check the reported queue, check the removed post queue, check the edited post queue, check the unmoderated queue?
Did you go to https://reddit.com/r/mod/about/spam and confirm some of the spam removals?
If I were to guess, it was probably the edit queu that managed to get you banned, post a normal post on your subreddit then edit later with affiliate links in a month or so.