John.k, for what it's worth, I have heard about one type of sugar-based blackpowder substitute which was actually available commercially (a few years ago in South Africa) - called Sannadex.
http://www.whitesmoke.co.za/powwow/v...0a4ba2a0e335f4
Reported to be 63% KNO3, 35% Sugar (sucrose or dextrose), and 2% Iron Oxide.
The factory milled the dry ingredients to 150-250 microns in size, then incorporated them by heating to 130-150 degrees Celcius for some unspecified period of time.
You might want to research Sannadex - it sounds like it was sold in granulated form, not tablets/pellets.