Method 65 Determination of fineness of grinding 150 jm100 mesh fraction

Thoroughly mix the unground approximately 100 g duplicate sample prepared in Method 6.4. Heat this portion at 100°C until dry and thoroughly mix. Weigh 20 g, to the nearest 0.01 g and transfer to the sieve with the lower receiver attached. Shake the sieve by hand for 5 min, frequently tapping the side. Disintegrate soft lumps such as can be caused to crumble by the application of the fibres of a soft brush, taking care that the hard part of the brush does not make contact with the sieve and that the brush is not used to brush particles through the sieve. Brush out the powder in the lower receiver and weigh. Replace the receiver and repeat the shaking and tapping procedure for 2 min. Add the powder in the receiver to the first portion and weigh. Repeat the process until not more than 0.04 g passes through the sieve during 2 min. Calculate the fineness by expressing the weight of the material passing through the sieve as a percentage of the weight of the portion of the dried sample taken for sieving.

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