Testwork: Crushing work index

Testwork: Bond Crushing Work Index

Test name

Bond Low-Energy Impact Crushing Work Index

Abbreviation Alternate Forms WiC CWI IWI LEIT

Typical F80 size Typical P80 size 100 mm 20 mm

Models

Bond models

The Bond low-energy impact crushing work index (more informally, the Bond crushing work index) is not as common as the Bond ball mill work index, and it is a notoriously noisy test.

The test is a 'per-specimen' test where individual specimens of prepared rock are hand-picked by the test operator and placed into the apparatus. Typically twenty specimens are chosen to represent a sample and the result reported is the average of those specimens.

There is a high-energy impact work index which is a different (and incompatible) test. The high-energy test has fallen into disuse and any recent (post year 2000) test labelled as a "crushing work index" can confidently be assumed to be the low-energy impact test.

Sample Requirements

The test requires 20 large lumps, minimum dimension 75 mm. When using drill core, use whole-diameter HQ or PQ size core.

Test Inputs

Not applicable.

Test Outputs

SAGMILLING.COM uses only metric units; if the laboratory reported work index in "short ton" units, multiply that value by 1.1023 and enter the result.

The laboratory will report the following information:

• N° specimens: The number of specimens tested (typically 20)
• min The metric work index of the sample with the lowest result
• max: The metric work index of the sample with the highest result
• stdev: The standard deviation of metric work index of all the samples
• WiC: The arithmetic average of the metric work index of all the samples
• density: The water-displacement density of the specimens prior to testing, in kg/L (also referred to as 'specific gravity')

Modelling

Crushing mill work index is used in the SAGMILLING.COM Bond/Barratt specific energy consumption model.

The work index is used to calculate the energy requirement to break rocks in the coarse size range, from >100 mm down to about 10 mm - 20 mm.