Bond work index correlation: the work index measured in wet grinding is often adjusted to estimate dry-grinding energy. What factor is used to convert wet-grinding work index to an equivalent dry-grinding value?

Difficulty: Easy

Correct Answer: 1.34

Explanation:


Introduction / Context:
Bond’s work index (Wi) is widely used to estimate energy requirements. Because transport and cushioning differ in wet vs dry circuits, empirical adjustments are made to compare conditions.


Given Data / Assumptions:

  • Wi was measured under wet conditions.
  • We need an equivalent dry-grinding Wi.


Concept / Approach:
Industry practice applies a multiplicative factor to the wet Wi to estimate dry circuit energy, commonly about 1.34, reflecting additional energy to overcome increased coating, dispersion issues, and classification inefficiencies in dry grinding.


Step-by-Step Solution:
Start with wet Wi.Multiply by 1.34 to obtain dry Wi.Use the adjusted value for dry energy sizing.


Verification / Alternative check:
Cement and mineral processing design texts cite the 1.34 factor as a rule-of-thumb adjustment.


Why Other Options Are Wrong:
1.0: ignores known differences.0.5/0.75: opposite trend.4.34: unrealistically high.


Common Pitfalls:
Treating Wi as universal without noting test conditions (wet/dry, closing screen).


Final Answer:
1.34

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