Charcoal Powder

*1: We have chosen to use the complete sample (20g) for this trial because a desired amount of 10-50g has been given.

*2: The fineness does only change slowly. Therefore, we took out one sample (2,5g) to show a proper grinding result after 20 minutes of dry grinding and proceed grinding in suspension (see trial 1b).

*3: See particle size distribution after 20min of grinding with our Laser Particle Sizer ANALYSETTE 22 NanoTec, Meas.No. 433 on separate page (d10: <1,4µm; d50: <4,9µm; d90: <11,9µm).

*1: After 2,5g of sample 1a have been separated, we ground the remaining sample (d50 < 5µm / 100% <25µm) in suspension.

*2: For achieving an optimum grinding viscosity, we had to add ~ 100ml of IPA (isopropyl alcohol).

*3: To avoid overpressure, we grinded in steps of 5 minutes grinding time and 10 minutes of pausing time. After several cycles, the outside temperature should be checked (<70°C) and grinding times / pausing times should be readjusted.

*4: See particle size distribution after 60min of grinding with our Laser Particle Sizer ANALYSETTE 22 NanoTec, Meas.No. 453 on separate page (d10:<0,8µm; d50:<2,7µm; d90:<6,1µm)

Summary: We do expect, that a grinding of 50g will require a 500ml grinding bowl. Also two times grinding of 25g with a 250ml bowl should be possible. The 20mm balls have advantages in cleaning and separation of sample, a faster grinding result is expected by using 5mm balls (1200x) instead of 20mm balls (15x).

By using solvents with higher boiling points (benzine of ~ 140°C), a longer grinding time could be set.