Particle Size Analysis on rod-mill "mis-grind" of 10mm granite chippings

With this stack of sieves

I did a sieve analysis as the Particle Size Analysis on an early test grind done in my rod-mill [video on my YouTube channel].

The ground / comminuted material

The rod-mill batch charge of 10mm granite chippings are what would be used to surface a pathway. This serves as a useful "test" and "reference" feed to investigate the mill performance.

The reason for wanting to get a Particle Size Analysis on this grind is that it was so wrong.
Seeking to suppress dust-formation (that was achieved!), I fed the granite chippings to the mill wet, giving a damp ground product.
The comminute, damp, "caked" around the periphery of the rod-mill shell, giving a "nonsense" inhomogenous grind.

Hence - interesting case to do a particle size analysis on.
Likely to throw challenges broadening the learning of sieve analysis.

The comminute sieved

I wet-sieved to eliminate dust-formation.
The separation into sieve sizes is seen here:

The sub-sieve very-fines (lower right-hand-side) have cemented together as a clay would in drying.

The sieve-sizes used were, in microns (micro-metres):

The masses on each sieve were:

Aperture mass(gr)
6350	21
4760	42
3180	116
2400	141
1200	932
600	774
300	787
150	346
75	111
-75	615

By arithmetic (addition) - the sum total of these masses is 3885 g (3.885 kg)

Graphed...

Amount on each sieve - and finally the "sub-sieve" beneath the smallest aperture sieve - expressed as a percentage of the total mass...

A data "nonsense" I rectified in the presentation : the sieve series is predominantly a geometric progression of halving size.
However, 6350microns and 3180microns are misfits in that series.
This

crowded those parts of the "sieve aperture size" axis
gave a non-comparable amount of mass on the "misfit" and next size below sieves - hence 4 points affected

This was rectified by adding the "6350microns" mass to the 4760microns mass, and likewise the "3180microns" mass to the 2400microns mass - and not plotting the 6350micron and 3180micron points.

Hence the data plotted - aperture-size (microns) and mass (kg) - was

These sum to the same 3.885 kg, obviously.
The synthesised "37.5" point puts that sub-sieve result at the regular interval on the logarithmic scale - while being reported as "sub".

Observations / comments

Quantitative classification as presented in the graph of the sieve analysis supports the immediate impression that particle sizes "are all over the place".

Pleasing result in many ways for a first effort at sieve analysis.

(R. Smith, 09Jul2025, 10Jul2025 (cake; obsns))