Ribbon blenders — intended service:\nRibbon blenders are designed primarily for which type of mixing duty?

Introduction / Context:
Ribbon blenders are ubiquitous in food, pharma, and chemicals for dry blending and paste mixing. Recognising their operating mode and suitable materials helps avoid misapplication where high shear, emulsification, or continuous throughput is required.

Given Data / Assumptions:

• Horizontal U-trough with inner and outer helical ribbons on a central shaft.
• Batch operation with top loading and bottom discharge.
• Materials are powders or pastes with moderate to low flowability.

Concept / Approach:
Counter-rotating ribbon flights create axial counterflow and radial mixing, ideal for homogenising powders, adding small liquids, and handling thin pastes. They do not provide the intense shear of rotor–stator mixers nor the continuous, steady-state operation of in-line static mixers. Therefore, the exclusive intended service is batch mixing of powders/pastes.

Step-by-Step Solution:

Verification / Alternative check:
OEM datasheets specify batch volumes, blend times, and suitability for powders/pastes; not for continuous liquid blending.

Why Other Options Are Wrong:

• (a), (d) refer to continuous liquid/slurry mixing; not a ribbon’s forte.
• (c) High-shear emulsification requires rotor–stator or colloid mills.
• (e) Gas–liquid dispersion uses impellers or ejectors, not ribbons.

Common Pitfalls:
Expecting ribbons to deagglomerate hard lumps; pre-milling may be required.

Final Answer:
Batch mixing of non-flowing powders and thin pastes