Powder blends are rarely as stable as they seem. A perfect mix can fall apart during transfer. Segregation occurs when different particles separate based on their properties. This leads to inconsistent product quality.

Segregation causes serious risk in many industries. Food products may lose flavor or texture. Pharmaceutical dosages become inconsistent. Chemical batches often fail due to poor distribution.

Most segregation happens after mixing. It occurs silently during flow, filling, or storage. That’s why prevention starts with understanding the root causes.

Segregation isn’t random. It results from predictable mechanical forces. A comprehensive review of heap flow segregation describes how particle motion and flow behavior lead to distinct mechanisms. Each type has a different origin and demands its specific solution.

Let’s explore the five key mechanisms.

Smaller particles fall through gaps between larger ones. This happens during movement or vibration.

When it occurs:

• While powders fall from height

• During transport on vibrating surfaces

• In blends with broad particle size ranges

How to prevent it:

• Reduce drop height during filling

• Add fines similar in size to coarse particles

• Install flow-slowing inserts or baffles

• Use mass flow hoppers instead of funnel flow

Air entering the powder lifts lighter particles upward. These settle later or not at all.

When it occurs:

• During rapid discharge from bins or silos

• When air gets trapped beneath powders

• With low-density or hollow particles

How to prevent it:

• Vent silos properly

• Reduce discharge speed

• Use deaeration pads or porous inserts

• Apply light compaction post-mixing

Heavier particles travel further during filling. Lighter particles stay closer to the source.

When it occurs:

• At conveyor endpoints

• During free-fall into containers

• When using rotary valves or feeders

How to prevent it:

• Use deflection chutes to guide material

• Shorten drop distances

• Fill from below or with central tubes

• Install flow diverters to control particle paths

Fine particles rise with air movement. They often drift away from the bulk.

When it occurs:

• In pneumatic conveying systems

• During open-air transfer or venting

• With blends containing very fine powders

How to prevent it:

• Use enclosed transfer lines

• Switch to vacuum-based conveying

• Install settling zones before product exits

• Add dust-control agents if compatible

When filling containers, material forms a heap. Fines roll off the slope. Coarse particles remain in the center.

When it occurs:

• While filling big bags or hoppers

• When powder is poured into heaps

How to prevent it:

• Fill containers using a rotating nozzle

• Add mechanical leveling systems

• Use multiple feed points

• Gently vibrate during filling to settle fines

Segregation rarely looks obvious. But testing can reveal it early. A 2024 review of quantitative measurement methods outlines techniques for detecting size-based separation at scale.

Sample at multiple depths
Compare top, middle, and bottom portions
Use inline sensors for real-time feedback

Even well-mixed powders can segregate again. Your equipment design plays a key role.

Human error often undoes process improvements. Teams need clear, simple rules:

• Don’t overfill containers

• Always use standard fill rates

• Avoid unnecessary powder movement

• Secure lids and vents during transfer

Reinforce best practices through repeatable procedures.

PDF includes:

• Overview of all five mechanisms

• At-a-glance checklist with symptoms and fixes

• Flowchart: Diagnose and act on segregation events

Click here to download the toolkit