My Hopper Design Cliff Notes provide a nice summary of flow property test methods and bin design.
Caking and its Prevention is the non-copyright version of an article that I wrote for Chemical Engineering magazine.
Optimization of Pharmaceutical Formulations for Flow shows how Jenike's flowability coefficient FFC can be misinterpreted. It's better to measure the flow properties of a powder over a range of consolidation pressures so that critical hopper outlet dimensions and hopper angles can be calculated.
URI Notes is essentially a Word version of my book Hopper Design Principles for Chemical Engineers. I use in the powder handling course that I give at the University of Rhode Island. It requires a password to open, because I offer the text book on my home page. Send an email to greg@mehos, and perhaps I'll share it with you if you promise to keep the manuscript to yourself. I provide it to my workshop attendees.
I periodically add other documents on powder handling and processing. Be sure to visit and check for updates.