A grindability test is a procedure that evaluates the resistance of a material to ball milling. This test is an effective way to calculate and compare the Bond Work Index (BW¡) of different ores. The higher the Bond Work Index, the more difficult it is to grind the material. This procedure is important to mineral processing industries as it helps to determine the proper equipment necessary for grinding by estimating the power and energy needed to achieve desired grinding results. Sepro Labs provides industries with mineral testing solutions such as the Bond Work Index test to increase on-site equipment efficiencies.

How Is This Procedure Done?

A test sample is stage-crushed to a 3.5mm maximum feed size and compacted into a 700cc tube. Once properly measured, the sample is placed in a universal F.C. Bond Ball Mill to accurately calculate the Bond Work Index of the material.

After a set number of revolutions, the sample is removed and screened over a 100 mesh sieve. The undersize is removed and weighed to calculate the rotations for the next cycle. The oversize is added back into the F.C. Bond Ball Mill along with new feed. This cycle is repeated until the milling produces stable results for three consecutive cycles. The grindability can then be calculated based on these results.

What Materials Have The Highest Grindability?

The Bond Work Index is measured in kWt/h and typical values range from 7 to 20+. Soft material has a BW¡ between 7 and 9kWt/h, and anything over 14kWt/h is considered hard. The hardest materials can reach over 20kWt/h!

Gypsum, clay, and potash all have a low BW¡s between 6-9 and can be easily ground. Emery, graphite, and flint have extremely high BW¡s of 62, 47, and 28 respectively. Tin is right in the middle of the scale with a BW¡ of 11.5.

The right mineral and metallurgical testing procedures like grindability can help determine the right equipment for large scale projects. To learn more about the metallurgical testing services we offer, and how they can make an impact on your projects, contact Sepro Labs at 1-604-888-7604.