# ISO 728:2021 pdf download – Coke — Size analysis by sieving

02-17-2022 comment

7.2 Division of coke minus 22,4 mm Divide the sample (minus 22,4 mm fraction from 7.1 e) to the required minimum mass in Table 1 by means of a suitable mechanical sample divider or riffle avoiding size degradation and loss of dust. Alternatively, for division, use either the flattened heap method or the strip mixing method described in ISO 13909-6 and ISO 18283. Determine the mass of all the coke not included as part of the test sample and retain it until all analyses and calculations are complete. 7.3 Sizing sample of maximum particle size between 22,4 and 4 mm — Manual method a) Determine the mass (of the divided minus 22,4 mm fraction from 7.2) of the sample to the nearest 0,1 %. b) Position the largest aperture size sieve in the set over an empty receiver or bin. Move the sieve horizontally to and fro, with the displacement not exceeding 100 mm in either direction, to cause the pieces of coke to tumble or roll on the sieve. c) Continue the sieving motion until eight movements in each direction (a total of 16 movements) have taken place after the last undersize piece passes through the sieve. Avoid any impact when stopping the motion. d) Place the coke remaining on the sieve in a tared receiver and determine the mass of the size fraction. e) Sieve the undersize again by repeating the above process for each sieve down to and including the 4,0 mm aperture size sieve and redetermine the mass of each size fraction including the minus 4,0 mm fraction. The mass of the minus 4,0 mm fraction from 7.3 e) may also be reduced in a similar fashion to 7.2 before proceeding to 7.4.
7.4 Sizing sample of particle size less than 4,0 mm — Manual method a) Determine the mass [of the divided minus 4,0 mm fraction from 7.3 e)] to the nearest 0,1 %. b) Place the smallest aperture size sieve in the set on a receiver or bin. Brush the sample onto the sieve, fit the lid and sieve continuously for a 5 min (minute) period, as described in item c), to remove the undersize. If the sample is large, sieve it as separate portions so that not more than 75 % of the area of the sieve is covered at the end of each sieving operation. c) Hold the receiver, fitted with the sieve and its lid in the left hand so that the surface of the sieve is inclined downwards towards the left at an angle of about 30° to the horizontal. Tap the higher side of the sieve frame six to eight times with the hardwood block. While maintaining the inclination of the sieve, shake the assembly to and fro several times, also rotating it in the plane of the sieving surface through an angle of approximately 60°. d) Continue the operations of tapping and shaking alternately for a further 5 min period. e) At the end of the further 5 min sieving period, allow the suspended fines to settle for 2 min, carefully remove the lid and lift the sieve from the receiver or bin. Invert the sieve over a tray, tap the higher side of the sieve frame with the hardwood block, and then carefully brush the uppermost surface of the inverted sieve with the flat brush. Turn the sieve the right way up and add any loose particles dislodged during brushing to the oversize on the tray. f) Invert the receiver over a second tray, tap the receiver with the hardwood block and brush out any adherent fines.