As an admin command, type in Cheat SaveWorld. This forces the server to save. Otherwise, in the server settings there is an interval setting, usually of 15-20 minutes. Any faster than that could cause some serious lag.
Is there a setting in the harvestable items drop rate that changes the drop rate of element dust specifically, and not just element? I don't see it listed but there are a few oddly named options to change. I have a Valguero server and would love to increase the drop rate of dust from Tek creatures. 14 dust seems a bit low.