Particle Segregation Solution | Particle Blending Solution

Overview

What Are Segregation &  Blending?

Segregation results when particles separate due to differences in their size, shape, or density. It commonly happens when handling a powder blend or material with varied particle size. Common segregation mechanisms include sifting, fluidization, and dusting.

Blending (or mixing) is the opposite behavior of segregation. The process of blending occurs when a collection of particles is homogenized or multiple ingredients are mixed to obtain a uniform product. Some materials require gentle tumble blending in a controlled batch mode while others require high shear to continuously blend highly cohesive and tough-to-mix ingredients. A well-blended material does not guarantee production of a quality product due to segregation effects that may result during powder flow.

Dusting and segregation during the filling of a bin.

Blending and mixing screw.

Funnel flow is a flow pattern in which solid flows in a channel formed within stagnant material.

Mass flow is a flow pattern in which all solid in a bin is in motion whenever any of it is withdrawn.

Mass flow bins.

Mass flow binsert portable container.

Pellet segregation in V-blender.

Challenge

Why is Segregation a Problem?

Rejected product
Variable color, look, or taste
Excessive blend times
Customer complaints
Erratic dosage weight, mass
Product or process delays
Inconsistent particle size
Poor quality control

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Segregation of chocolate chips and sugar

Factors

When & Where Can Segregation Occur

Segregation often results during filling of a container, silo, or hopper. It can also be caused by vibration, agitation, or other unique forces acting on particles.

With sifting segregation, the fine particles concentrate under the point of pile impact, while the coarse particles roll off to the pile periphery. Click here for a video demonstration of sifting.

With fluidization segregation, the fine particles in an aerated powder locate towards the top of a container, while the coarse particles deaerate quickly and settle to the bottom.
With dusting segregation, the ultra-fine powder component settles at the silo or hopper walls.

The effects of segregation are strongly influenced by the type of discharge pattern occurring in a silo, bin, or hopper.

Segregation during sifting.

Segregation during fluidization.

Segregation during dusting.

Solution

How to Solve Segregation

The key to solving or preventing segregation is to evaluate the segregation tendencies of the material and understand how the bulk material will transfer through your process in bins,hoppers, chutes, or conveying systems. Mass flow discharge will reduce or eliminate the effects of sifting and dusting segregation, while funnel flow will often worsen the effects.

Jenike & Johanson engineers have the technical capabilities to diagnose the intricate differences between a blending, sampling, and segregation problem. We have the capability in our laboratories to perform physical modeling with batch and continuous blenders.