Earth Grounding

My past experience with feeding powders produced large amounts of static electricity at potentially very high voltages.

The current is very low however and the simplest and most effective way is to make use of the electrical service ground (as from a grounded outlet), or in some cases the steel building frame.

The real problem is how to remove the static buildup from a plastic container and/or the material itself. This you will have to experiment with. Remember, static charge builds up on non conductive materials so that presents a problem when trying to remove it: fastening a ground connection only removes the charge from the area immediately adjacent to the fastening point.

Try using multiple wires, conductive screening, conductive plastic sheets etc. and try to use a conductive material for transporting the "blends". ( A grounded wire running inside a tube or hose which itself may be non conducting will remove some charge.) If the static buildup is not too large, devices that ionize the air locally will dissipate it wherever the ions come in contact - these devices are commercially available. Raising the humidity can also help if practical.

Again experimentation is in order. Anything that will serve to bleed off static charge will help. Grounding the minute current collected is the easy part.

I hope I understood your question. Good Luck!