By 'cleaning' the sample several times and pouring it on the sieve everything less than 32 µ will disappear.
Use a laboratory coat. Turn on the air extractor. Check if the sieve (32 m) and appliance are clean.
- 32 m sieve
- 2 stainless steel bowls
- Collecting container with outlet
By sifting the sample through a vibrating sieve with a 32 µ outlet all particles smaller than 32 m will be washed out.
The sieve with collecting container are placed on the vibrating appliance so that the outlet is inside the sink. The switch is on the front of the unit (adjustable).
The sample is rinsed again in the stainless steel bowl and stirred thoroughly. After some seconds (to let the coarse grains sink first) the upper liquid is strained on the sieve. The vibration-intensity is set in such a way that the fine material will flow away easily.
The sample is again rinsed in another stainless steel bowl, stirred and strained. This procedure will be repeated until no more fine material flows away. Then the material left in the sieve is transferred back to the coarse fraction. Some time later this, too, can be strained and the sample is placed into an oven (50º C).
All equipment used has to be cleaned thoroughly. The sieves have to be vibrated in an ultrasonic cleaning unit during 1 hour and subsequently rinsed and dried at 110º C.