Technical Information
Key Topics:


Sample Preparation (from dill core sections)

Breakage test using the Geopyörä device

Product size analysis

Density measurements (for DWI estimations)

Test Concept
Geopyörä test provides specific parameters for mining and mineral processing. These parameters, along with equipment details and operating conditions, can analyze and predict comminution performance. Geopyörä measures major comminution parameters like Axb, DWI, SPI, and BWI.
The Geopyörä breakage test uses counterrotating wheels to crush rocks with controlled reduction ratios. It allows automated feeding of rocks without stopping or resetting between breaks. The test measures applied force and energy consumption for each breakage event. The force applied depends on rock compressive strength. Varying the degree of reduction allows mapping the rock's response to force and energy. Precise measurement of absorbed energy is necessary while ensuring secure grip and compression of rocks until fracture.
Test Procedure
Sample Preparation

Break drill core with hammer and chisel (not needed for bulk ore samples)

Crush the sample using a jaw crusher with CSS at 20 mm

Sieve the sample using the following (six) screen apertures:

> 31.5 mm

> 26.5 mm,

> 22.4 mm,

> 19 mm,

> 16 mm,

> 13.2 mm


Choose the largest size fraction with more than 30 particles for testing

Discard flaky particles

Divide the particles into 2 batches (for high and low energy tests) if you're doing a Full test

There's no need to used two batches for the Light test (single energy)

Breakage test using the Geopyörä device

Run the calibration procedure

Set the gap and speed for high and low or single energy tests

Weigh and feed one particle at a time

In Geopyörä V1 an external scale be connected to the computer

In Geopyörä V2 the feeder and scale are already integrated to the device


Record weights and test measurements into template spreadsheet.

Collect the product for particle size analysis
Product size analysis

Prepare a deck with the following (six) sieves:

1 Pan

1 Bond sieve

2 sieves above t10 size

2 sieves below t10 size


Sieve for 5 minutes using a RoTap

Record the following in template spreadsheet:

Total mass

Mass above t10 sieve

Mass below Bond sieve


Upload template spreadsheet into Geodata for analysis

View preliminary results immediately and download final report after 7 days.
Density measurements (for DWI estimations)

Select all particles above 16 mm that have not been tested

Weight particles, suspended in air and then in water (Archimedes method)
Geopyörä test validation
The following section provides data comparing the accuracy of the Geopyora tests with the primary tests in the communication market. All the data presented has been collected from various papers and publications.
Geopyörä Axb comparison
Geopyörä utilizes breakage data to calculate the Specific Comminution Energy (Ecs). The resulting breakage product is then sieved, allowing for the calculation of the percentage passing onetenth of the initial mean particle size (t10). By establishing the mathematical relationship between the breakage index (t10) and the comminution specific energy (Ecs), it becomes possible to fit a data set to obtain values for the parameters A and b.
The provided image illustrates a parity plot, which compares the estimated Axb values obtained by Geopyörä with the reference values from the SMC Test® Axb.
A comparison was made between the t10 curves generated by JKDWT and Geopyörä®, considering the first three energies for each of the five different size intervals. It is important to note that while the SMC Test® used five energies, Geopyörä® only utilized three energies within each size interval. The provided image depicts the plot of the curves from each test, including the measured points, for all three tests conducted.
Geopyörä DWI comparison
The Drop Weight Index (DWi) is an important measure of rock strength, derived from the SMC Test®. It is widely utilized in the industry and has a substantial database comprising over 35,000 samples from more than 1,300 ore bodies. To determine the DWi using Geopyörä results and facilitate a comparison with the reference result obtained from the SMC Test®, the following equation was employed.
The image is the Drop Weight Index parity plot, and the table presents a statistical comparison and shows robust correlation between the Geopyörä results and the SMC Test® reference results, indicated by a high parity RSquared value of 0.98.
Geopyörä BBMWI comparison
Geopyörä utilizes a correlation model to calculate the BBMWi (Bond Ball Mill Work Index). The model incorporates the sizespecific energy (SSE) and was initially designed to estimate BBMWi using the available reference data
Where P150 is the percentage of the breakage product passing in 150 microns.
A majority of the samples used for this validation were tested in the Standard Bond Ball Mill using a closing sieve size of 150 microns. However, some samples used different closing sieve sizes. Despite the variation in the Bond Ball Mill Work Index (BBMWI) data due to this discrepancy, but t he database was so robust that the developed model was capable of accurately describing the entire database without the need to split in different models for each CSS.
A power fuction was developed where c and d are fitted constants and proved to be the optimal model to correlate SSE and BBMWI with a fit Rsquared of 0.70
The corresponding graph shows a parity plot, where 87% of the samples fall within the ±15% dispersion range, represented by the blue data points. In addition, the table provides a summary of the comparison statistics, indicating an exceptionally robust correlation, with a high parity RSquared value of 0.99.
Single energy vs Two energies
Geopyora provides two versions of its test: the single energy and the two energies model, both including SG measurement. The two energies model is the standard procedure for Geopyora's test, while the single energy model is a new offering that is currently undergoing validation. However, initial results have been promising, and Geopyora has started providing this option to its clients.
Dr. Marcos Bueno conducted simulations using the single energy version, which resulted in excellent yields. The simulations achieved an R² value of 0.93, matching the results obtained from simulations using the two energies variation.