limestone

Complete sample amount has been given into the mortar. Because of the limited amount of sample, we cannot give a proper forecast how long 100 g of sample need to be ground to an equal fineness. At least, a batch wise grinding of sample is possible for sure (2x 50 grams).

It is also marked that original sample can contain particles up to 6 mm. In the sent sample, only particles < 2 mm have been found. Eventually the scraper has to be lifted for the first minute of grinding until all coarse particles will be comminuted to < 2 mm before the scraper will be positioned properly. This way, sample will not jam in front of the scraper.

A small portion of sample has been packed after 5 minutes of dry grinding for demonstration.

Because sample did not start sticking yet, we proceeded grinding for a total of 10 minutes. After checking the fineness of ground sample with Laser Particle Sizer ANALYSETTE 22 MicroTec plus, largest particles should be ~ 120 µm with d50 < 15,9 µm and already 94,7% < 60 µm.

The desired d90 < 63 µm has been reached already.

Sample use to stick to mortar and pestle very soft, so still longer dry grinding times are possible to achieve a better dry grinding result.