Powdered antibiotics are conveyed without dust

When US company Macleod Pharmaceuticals, of Fort Collins, Colorado, decided to produce a new range of antibiotics, it needed to fit a bulk solids mixer, conveyor and filling machine into a confined area and reserve enough space for boxing, taping and labelling operations. After consultation with bulk solids handling specialist Flexicon, a flexible screw conveyor system was set up within Flexicon's own test laboratory facility, to simulate the application and prove the system's viability.

The antibiotics typically consist of seven or eight powdered ingredients, manually dumped from fibre drums into a 710 litre capacity ribbon blender mounted on load cells. Weight gain information on a display enables operators to dump the required amount of each material. After a mixing cycle, the powder is gravity discharged into the U-shaped charging adapter of an 80mm diameter flexible screw conveyor.

The flexible steel screw conveyor propels material through the tube and then transfers the powder through 45° across a distance of about 3.5m to feed a surge hopper above the filling machine that dispenses drugs into a variety of containers. 

The screw is the only moving part in contact with the material and can be removed rapidly between product changeovers for sanitising of the screw and the tube's crevice-free interior.

Flexicon engineers also solved design problems specific to this application by orienting the charging adapter horizontally instead of at an angle and fabricating a flange that attached tightly to the blender's valve to discharge powder directly into the charging adapter with no exposure to the atmosphere.

Due to a ceiling height restriction, the conveyor's discharge adapter also needed to be oriented as close to horizontal as the curvature of the conveyor tube would allow.