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How to Avoid Sample Segregation from Rolling (2 replies)

Bob Mathias
10 months ago
Bob Mathias 10 months ago

"Equal particle sizes of a different specific gravity tend to settle in a fluid bed" Your vibration test should yield dense particles at the bottom if the particles were sized equally. Without proper sizing efficient separation cannot be achieved. My sense of it is that you may have similar results to the rolling segregation test.


John Koenig
10 months ago
John Koenig 10 months ago

While evaluating the magnetite deposits along the Pacific coasts of Guatemala and Mexico [near Tapachula] I experience a similar result using a large riffle splitter to try and make homogeneous 1 kg samples from wet 10 to 35 kg field samples. The large wet field samples were mixed with a shovel and then dried in the sun on large sheets of plywood, then stored in 5 gallon pails or in plastic commercial garbage bags inside white rice sacks. Ripple splitting was used to try and homogenize the sample and make approximately 1 kg samples for analysis and resource estimation.

However after just three riffle splits it became apparent that additional riffle splitting of the sampling just created streaks of magnetite in the split samples.
Might the motion of dried magnetite grains create a static charge and therefore an affinity for the grains to stay together?
That was my original thought. However I'm sure there are a multitude of mitigating factors involved in this process and all need to be identified and evaluated to find a solution to the problem

Maya Rothman
10 months ago
Maya Rothman 10 months ago

I think that the magnetic forces overcome any electrostatic ones. These magnetic forces are long range and act in liquid as well as dry.

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