Making fines from soft, non-abrasive materials:\nWhich mechanism is best suited to produce fines from soft, non-abrasive solids?

Introduction / Context:
Choosing the dominant size-reduction mechanism based on material characteristics improves efficiency and product quality. Soft, non-abrasive materials do not require heavy compression or high-impact devices; instead, rubbing/abrasive contact (attrition) more gently produces fines with controlled top size.

Given Data / Assumptions:

• Material is soft and not highly abrasive (low wear risk).
• Goal is fine powder rather than coarse fracture.

Concept / Approach:
Attrition mills (e.g., pin, disc, or colloid mills) subject particles to sliding/rubbing between surfaces, leading to progressive surface removal and fine production. Compression devices (rolls, jaws) create larger, blocky fragments; cutting devices are for fibrous or sheet-like materials, not fine powders. Pure impact can overproduce ultra-fines with poor control and may heat-sensitive materials adversely.

Step-by-Step Solution:

Verification / Alternative check:
Applications like milling soft organics or pigments use attrition or pin mills to achieve fine, narrow distributions.

Why Other Options Are Wrong:

• Compression: coarse crushing rather than fine powdering.
• Cutting: suited to fibrous materials and particle length control.
• Impact-only: may lead to wide distributions and heat issues.

Common Pitfalls:
Overmilling soft materials with impact mills causing melt/smear; attrition offers better thermal control.

Final Answer:
Attrition