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SGS's comminution experts use the JK Drop-Weight Test to characterize ore samples, an important first step to understanding ore variability before designing or optimizing grinding circuits or production forecasting.


The JKTech Drop-Weight Test was developed at the Julius Kruttschnitt Mineral Research Centre. The test measures the appearance function of the ore for five size fractions in the range of 13 to 63 mm, at various energy inputs (0.1 to 2.5 kWh/t). The results are subsequently reduced to two parameters:  A and b.

The Drop Weight apparatus consists of a system for dropping a variable weight onto different size rock specimens from various heights. As part of the procedure the abrasion characteristic of the sample (ta) is also determined using a tumbling test.

These ore specific parameters can be used in grinding circuit modeling and simulation using the JKSimMet software package. Combinations of crushing, autogenous grinding (AG) or semi-autogenous grinding (SAG), classification, and secondary grinding can be modeled and simulated.  Crushing energy requirements can be estimated from the drop-weight test, and AG/SAG energy requirements can be estimated from the simulation.

Results can be used to simulate operating plants to assess changes in ore types, classification sizes, ore feed size distribution, ball load, grate apertures, use of pebble crushers, etc. Simulation can also be used when designing new circuits to examine various configurations and refine equipment selection and performance.

Feed Sample Requirements:

65 kg of minus 4” ore is prepared by the testing facility to minus 2 1⁄2”.

SGS's team of experienced engineers will conduct the JK Drop-Weight Test in combination with other bench-scale tests and circuit simulation. The use of many methodologies provides you with a bankable solution that is unmatched in its rigor. Contact us to optimize the comminution design for your orebody.

* Mineral Comminution Circuits – Their Operation and Optimisation, Napier-Munn T. J., Morrell S, Morrison R. D., Kojovic T, Chapter 4, JKMRC Monograph Series in Mining and Mineral Processing 2.