Why does my powder behave like a liquid? Does your process need bailing out?
This liquid like behavior can be observed in processes across a variety of industries, including:
- loading finished cement onto a barge;
- metering specialty chemicals and consumer products into bags and super sacks;
- packaging a powder beverage drink mix into a “to go” pouch;
- press feed systems producing products ranging from pool tablets to powdered metal parts used in the auto and defense industries.
At Jenike & Johanson, we refer to this liquid like behavior as “two-phase” flow, with the two-phases equating to the (1) powder and (2) interstitial air. Two-phase flow of powders can be very problematic and result in product loss, quality control problems, process non-uniformity and segregation, decreased production rates and significant maintenance concerns.
As a fist step in addressing these two-phase flow problems, we measure the underlying powder properties that affect two-phase flow behavior, including the powder’s particle size distribution, bulk density, particle density, compressibility and permeability.
The video below shows a sample of fine, low-density glass microspheres that could be prone to two-phase flow behavior.
If the powder you handle behaves in a similar way, two-phase flow effects that can negatively impact your process can occur and need to be accounted for.
We can assist you in addressing two-phase flow issues in an existing process or designing new process to prevent them by measuring the key powder properties and modeling this behavior using our software. As an example, we have used this modeling capability to redesign feed systems to tablet presses to prevent two-phase flow behavior from resulting in poor tablet properties and unacceptable variation of weight, hardness and dissolution.