TABLE OF CONTENTS Ross W.Smith, Ph.D.
Department of Chemical and Metallurgical Engineering
University of Nevada at Reno
Reno, NV
The data in the first three columns of Table 13.1 show the size distributions of a quartzgold ore obtained by sieving the material. What is the cumulative weight percent passing each sieve size? Also, construct a log-log plot of the cumulative percent versus particle size, and express the resulting relationship as an equation.
1. Compute the cumulative weight percent passing each sieve size. Add up the weights of samples retained on each screen (the weights are shown in the third column of Table 13.1). Express each as a percent of the total, obtaining the percents shown in the fourth column. Sum the cumulative amounts retained and subtract from 100, obtaining the cumulative percents passing. These are shown in the fifth column.
2. Express the relationship between cumulative percent passing and particle size as an equation. Plot cumulative weight percent passing ( y) as a function of particle size ( x) in microns (as denoted by size of sieve opening) on log-log paper, as in Fig. 13.1.
The straight-line portion of the plot can be expressed as y= cx b . This can be recast into a form that is especially useful for other size-reduction calculations (e.g., see Example 13.2), namely, the
