Ribbon Blender Working Principle | Ribbon Blender Machine
• Ribbon blenders mix solids by mechanical shuffling and are used to handle dry powders.
• A ribbon blender consists of a horizontal semicylindrical trough incorporating a central shaft and a helical ribbon agitator. A typical ribbon blender is shown in Fig. In this mixer, two counteracting ribbons are mounted on the same shaft. One of the ribbons moves the solids slowly in one direction, while the other one moves the solids quickly in the other direction. The ribbons may be continuous or discontinuous. Mixing takes place due to the turbulence generated by counteracting ribbons and not only by motion of the solids through the trough.
• Ribbon blenders are used for batch or continuous mixing. In batch operated ribbon blenders, the solids are charged and mix until satisfactory and discharged from the bottom. In continuously operated units, the solids are fed from one end of the trough and discharged from the other end. In the path from the feed to discharge end, solids are mixed.
• For light duty, the trough may be open or lightly covered, while for operation under pressure or vacuum, the trough is closed and heavy-walled. Ribbon blenders are very effective for handling thin pastes and dry powders that do not flow easily.
Advantages of Ribbon Blender
- Ribbon blenders can be used in both batch and continuous mode.
- High shear caused by baffles causes aggregate breakdown.
Disadvantages of Ribbon Blender
- It is quite impossible to get 100 percent discharge in the ribbon blender.
- Higher clearance between the outer ribbon's exterior periphery and the container may result in unmixed or dead areas.
- Ribbon movement near vessel walls caused by severe shear and compression can damage fragile materials and induce attrition.