Energy–fineness relationship: As the target product becomes finer in grinding, how does the specific energy requirement generally change?

Introduction / Context:Grinding energy is a dominant operating cost in mineral processing and cement. All classical comminution laws predict higher energy demand as product size decreases, with the severity depending on the theory and the fineness regime. Recognising the monotonic increase is crucial for realistic feasibility studies and energy budgeting.

Given Data / Assumptions:

• Normal brittle materials; dry or wet grinding.
• Comparable feed size; only product fineness changes.

Concept / Approach:Rittinger’s law (E ∝ new surface) dominates at fine sizes and grows rapidly as size decreases. Bond’s law (E ∝ 1/√P − 1/√F) applies widely to ball milling and also increases as P gets smaller. Even Kick’s law (log ratio) rises with greater overall reduction. Hence, finer targets require more energy per ton than coarser ones, often nonlinearly so.

Step-by-Step Solution:

Verification / Alternative check:Plant data show specific energy climbing steeply as Blaine fineness (cement) or P80 (minerals) is pushed lower.

Why Other Options Are Wrong:

• Decrease/same/negligible: contradict empirical laws and experience.
• Fixed multiplier (1.5×): energy rise depends on the actual fineness, not a constant factor.

Common Pitfalls:Underestimating the energy penalty when tightening product specs; consider circuit upgrades (HPGR, classification) to manage energy.

Final Answer:Increases