Mixing: Ribbon Blender.

 

Principle:

• It's an “Agitator  Mixer”.

• It works on the mechanism of Shear and Convective Mixing.

• This type of mixers employs a stationary container to hold the material and brings about mixing by means of moving  screws, paddles or blades.

Construction:

•  Consists of a U shaped horizontal shell with an opening lid.

• Shell contains a double helical ribbon agitator that rotates inside the shell.

• The agitator shaft is fixed on the inside wall of the shell.

• The shaft can have an attachment of spray.

• Depending on the application the gap between the agitator and the wall is maintained from 3-6 mm.

• Feed material can be charged through the lid.

• The shell may have an external jacket for warming or cooling.

Working:

• The materials to be mixed are introduced to the mixer through the lid.

• The mixer is loaded approximately 40-70% of the volume to allow tumbling of the powders.

• When the mixer is started, the one set of agitator blades moves powder in one direction while the other set moves powder in the opposite direction.

• The powders are lifted and are allowed to cascade at the bottom of the container.

• After mixing the material is removed by opening the lid.

• Material with similar size and density mixes faster than the materials with density difference and particle size change.

Uses:

1. For mixing large volumes of dry solids.

2. Solid liquid mixing.

3. Lubrication of dry granules.

4. Coating of powders with a small amount of liquids.

Advantages:

1. Batch and continuous operation.

2. Ability to cool or heat the materials.

3. Place required is comparatively less.

Disadvantages:

1. Damage to fragile substances.

2. Less application of shear.

Commonly Asked Questions:

1. Define Mixing. With help of a diagram describe the principle, construction and working of the Ribbon Blender.

2. Write a short note on Ribbon Blender.