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CHE4162 – PARTICLE TECHNOLOGY

EXPERIMENT 1: PARTICLE SIZE ANALYSIS

Preparation:

Revise the Particle Size Analysis Chapter of Rhodes, “Introduction to Particle Technology”, with

particular attention to different types of means, method of estimating the means, methods of

particle size measurement.

Objectives:

1. To measure particle size distribution of a sand sample by means of sieving apparatus.

2. Perform calculation for the collected data.

Particle size measurement by sieving:

Sieving is a simple, cheap method of size analysis suitable for particle size greater than 45 μm.

Sieving gives a mass distribution and a size known as the sieve diameter. If standard procedures

are followed and care is taken, sieving gives reliable and reproducible size analysis.

In making an analysis a set of standard sieves is arranged serially in a stack with the smallest

mesh at the bottom and the largest at the top. The sample is placed on the top screen and the

stack shaken mechanically for a definite time, about 20 min. As the sieves are shaken, the

particles fall through them until the sieve is reached in which the openings are too small for the

particle to pass. The particles retained on each sieve are removed and weighed, and the masses

are converted of mass fractions or mass percentages of the total sample.

The size of particles found on any sieve is expressed as an appropriate mean length between the

openings in the sieve above and that on which the particle rests. The results of a sieving analysis

are tabulated to show the mass fraction of each sieve increment as a function of the mesh size

range of the increment. A photograph of a set of sieves is shown in Figure 1.

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Figure 1. Photograph of the Retsch Sieve Shaker used to analyze particle size

Experimental procedure:

1. Collect 6-8 clean sieving trays of suitable mesh size range and stack them in appropriate

manner.

2. Place 300 g of sand in the tray. Make sure that the sieving trays are tightened properly into

the shaker.

3. Turn on the shaker. After 20 minutes, turn off the shaker.

4. Collect and weigh the particle retained in each sieve.

5. Carefully clean the sieves, following the instructions of the demonstrator.

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Report

Tabulate results of the raw data (mass of sand) in each sieve size range.

Provide plot of cumulative mass fraction undersize vs. particle diameter, and determine the

median diameter.

Provide plot of differential mass distribution, showing the mode.

Calculate the arithmetic mean and harmonic mean for the mass distribution.

Convert the mass distribution to appropriate surface distribution. State the assumptions.

Determine the arithmetic mean of the surface distribution. State the assumptions.

Compare the arithmetic mean of the surface distribution with the harmonic mean for the mass

distribution and comment on the comparison.

Sample calculation must be provided in the report. State the assumptions made in the

calculations.

Team self-assessment required includes the following:

a. The roles played by each team member in carrying out this assignment.

b. Summary of team meeting outcomes.

c. How well did you work together?

d. What would you do differently next time?