Estudio comparativo de la determinación del tamaño de partícula por dos métodos : tamizado en seco y disfracción láser

Abstract

The aim of this work was to compare the analytical performance of the laser diffraction technology for the particle size determi - nation by the classical dry sieving procedure for particles bigger than 80 micrometers. Sand was used as reference sample. The sieving was done using one mechanic equipment through a battery of standard ASTM sieves numbers 20, 40, 70 and 170 with vibration time of 15 minutes. The tri-laser diffraction method consists on the incidence of three laser beams on the particles to evaluate their dimensions and produces a frequency histogram for the representation of the size ranges. After sieving, the sample was reconstituted by mixing by a rotary sample divider of high accuracy and reproducibility to get representative sub-portions. An amount was suspended in water, mechanically stirred and introduced in the equipment for measurement and graphical processing by the instrument software. Ten replicate determinations were done by each method for statistical evaluation by the method of the moments and Falk and Ward method, concluding that laser diffraction rates the sample in similar way as sieving but with differences regarding kurtosis coefficients for the population distribution of each technique.