Ribbon Blender
Principle
- In ribbon blenders, solids are mechanically mixed and powdered, using a shuffle action.
- An agitator ribbon is embedded in a semicylindrical trough, which is centered on a central shaft. See Figure for an example of this. While mixing, two ribbons counteract each other. Solids move slowly along one ribbon, while solids move quickly along the other ribbon. It is not necessary to join the ribbons in a continuous line. The turbulence produced by the counteracting ribbons occurs in addition to the solids moving through the trough.
- If the trough does not need to operate under pressure or vacuum, it can be open or lightly covered. If the trough does need to operate under pressure or vacuum, it is heavily-walled and closed. For thin pastes and powders that don't flow well, ribbon blenders are highly effective.
Construction
There are three types of ribbon blenders: U-shaped troughs, shells, and spiral spiral agitators. Helical ribbons (also known as spirals) are welded on top of the shaft of the agitator. A ribbon stirrer is also known as a "double" helical ribbon agitator since it contains an internal and external helical ribbon. Counteracting blades are provided in order to break lumps and aggregates, but also for high shear. A motor drives the ribbon blenders, which are coupled to a gearbox and a gearbox. For 1000 kg of product mass to be blended, they are powered by motors that have 10HP to 15HP. According to the products being mixed, the specific power ranges between 3 and 12 kW/m2. To prevent material from leaving the container, a Sealing arrangement is provided where the shaft exits the container. Feed hoppers are usually used to feed the material into the mixer. Bottom discharge spouts are also provided.
Working
Ribbon blenders are used in the pharmaceutical industry to mix granules, pellets, dry powders, and other solid forms. Ribbon blenders are commonly used to mix polymer blends, composite fillers, and pharmaceutical powders for pharmaceutical manufacturing. There are many uses for ribbon blenders. Their various functions range from mixing to vacuum drying to granulating to coating solid particles with a very fine powder or minor liquid component.The clearances between the through surfaces and agitator tips in high quality ribbon blenders are tightly controlled. Blenders that are constructed and fabricated properly combine powders quickly, efficiently, and thoroughly. Ribbon blenders are said to be capable of achieving complete mixing in as little as 15 minutes for ingredients of similar particle sizes and bulk densities. Powders, liquids, powders, as well as liquids and powders can be combined in ribbon blenders. When some of the materials are present in very small quantities, the mixing process is carried out to the highest levels of accuracy. For homogeneous blends with minor components, ribbon blenders are ideal. In manufacturing facilities limited by overhead space, horizontal ribbon blenders are commonly used. Vertical ribbon blenders are easy to charge, blend gently, and discharge thoroughly.
Uses
Using a ribbon blender, you can blend large quantities of dry material, wet material, bulk drugs, chemicals, and cosmetic powders.Merits
- Both batch and continuous operations are possible with ribbon blenders.
- Headspace is less of a requirement
Demerits
Ribbon blenders are incapable of achieving 100% discharge.
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