Silica

In our first trial, we wanted to testify grinding results of higher amounts with our classic line mills.

60g of sample have been ground in a 250ml bowl. It is necessary adding ~ 45ml of water to maintain motor oil like viscosity for optimum grinding result. It might be possible grinding up to 80-100g per bowl as well.

To avoid overpressure, we ground the sample in steps of 5 minutes, followed by a programmed pausing time of 10 minutes. After several cycles, the outside temperature of the bowl should be checked (remain below 80°C); grinding time or programmed pausing time might be readjusted afterwards.

After 15 minutes of grinding in suspension, fineness has been checked with our Laser Particle Sizer ANALYSETTE 22 NanoTec plus (see meas. no. 62042 on separate page); d50 < 819nm has been achieved.

After 30 minutes of grinding, a d50 < 452nm has been found (see meas. no. 62053). After a total grinding time of 60 minutes, d50 of < 360nm has been reached. By longer grinding time, d50 value will become lowered only minimal. For this, we recommend interrupting the grinding process after maximum 60 minutes.

Probably a better grinding success will be achieved when solvents will be used with less surface tension. Also change in pH-value or a adding of grinding agents (salts or tensides might influence the result).

For 100g of sample, a 500ml bowl with 800g of grinding balls will achieve a faster grinding result. Also by using the Planetary Mono Mill PULVERISETTE 6 classic line instead of a Planetary Mill PULVERISETTE 5 classic line, speed of grinding might be improved lightly. A change of ball diameter (smaller balls) usually will not show an improvement with classic line ball mills.

Because many different samples will be ground in our application laboratory (metals, dies, and different minerals and chemicals), we like to advice checking the elemental analysis (available by the dealer or on our homepage) of grinding materials to see, what kind of traces should be found later on.

If fineness will be checked at your side too, we like to mention that fine ground particles tend to attach to each other again. We recommend using a strong Ultrasonic Cleaner to disperse the sample for several minutes again (dispersing agents like e.g. sodium di-phosphate should be used too).