Pre – Laboratory Report ChE 136
The Cuter, The Better Experiment 3 Size Reduction and Screening
Submitted by Jareol, Alexis L. Suquib, Keith Danae D. Vista, Alec Roger J.
Submitted to Engr. Dennis C. Ong
Submission date 27th Feb 2018
Table of Contents
I. Introduction ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ 1
II. Objectives ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ 3
III. Scope and Limitation ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ 3
IV. Materials and Methods ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ 3
V. References ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ 4
VI. Expected Results∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ ∙ 5
I.
Introduction
Since many particles are too large for their purposes, size reduction of solid materials are done during unit processes. The size of the solids are reduced in order the separation of various ingredients can be carried out. Overall, the terms crushing and grinding are used to imply the reduction of large solids to smaller particles. (Geankoplis, 1993) To reduce the size of solids, solid materials are fed into a machine specifically for size reduction. Then, they reduced in size by mechanical action. The feed particles are fractured, distorted and strained. New surfaces are created when the material fractures. (Geankoplis, 1993) Size reduction equipment can be classified into crushers, grinders, fine grinders, and cutters. Crushers are slow-speed machines which are used for rough reduction of large amounts of solids. Both grinders and fine grinders are used to reduce direct are used to reduce sized material directly to small sizes or powder. Grinders may operate in wet or in dry conditions. For definite sizes of materials, cutters are used. (Geankoplis, 1993) Particle size is influenced many properties of particulate materials, since the size of the material indicates quality and performance. This is apparent for po wders, suspensions, emulsions, and aerosols. Flow and compaction properties are also influenced by size and shape of powders. For instance, larger particles tend to flow quicker while smaller particles dissolve quicker. (Horiba Instruments, Inc., 2017) Particle size distribution analysis means the grading or separation of fine particles into variety of sizes (Groover, 2014). Mainly, it is a method of separating particles according to size alone (McCabe et. al., 1993). It is also known as sieving or screening analysis. Both the feed-to-size ratio reduction processes and the product are defined in terms of the particle size distribution. Plotting particle diameter (sieve opening screen) in mm μm against cumulative percent retained at that size is one common way of showing particle size distribution. Frequently, the plot is instead made as the cumulative amount as percent smaller than the stated size versus particle size as shown in Fig. 1 in Fig. 2. The same data are plotted as a particle distribution curve. The ordinate is found by taking the slopes of the 5- μm intervals of Fig. 1 and converting to percent by weight per μm. Mostly, comparisons and calculations of complete particle size analysis is necessary. (Geankoplis, 1993)
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Figure 1 . Particle size distribution curve: cumulative percent versus particle size. Geankoplis, C. J. (1993).
Figure 2. Particle size distribution curve: percent by weight versus particle size. Geankoplis, C. J. (1993).
In a screen analysis, the cumulative weight passing is needed to be identified. The accumulated weight passing is the total mass of aggregate within the sieve below the current sieve, not including the current sieve’s aggregate. The cumulative percent passing is the fraction of the cumulative weight passing in a current sieve to the total weight multiplied by 100 (Foust et al., 1980). It is calculated using the equation: % = ∗ 100 where W below is the cumulative weight passing in grams and Wtotal is the total mass retained in grams. A lot of industries which include food, pharmaceutics and chemistry, sieve analysis is used as the standard for production and quality control of powders and granules. The advantages of using sieve analysis comprise of easy handling, low investment cost and th e possibility to separate the particle size fractions. Thus, this method is an acceptable substitute for using laser light or image processing. (Retsch GmbH Haan, 2009) Throughout sieving, the sample is subjected to horizontal or vertical movement in accordance with a chosen method, and occasionally done using a sieve shaker. The horizontal or vertical moving or shaking causes a relative movement between the particles and the sieve. The particles either pass through the sieve or are collected on the sieve surface. (Retsch GmbH & Co. KG, 2004) Sieves are categorized according to their mesh number. The number of openings in one linear inch of a screen is called the mesh number. For instance, an 80-mesh screen means there are 80 openings across one linear inch of the screen. The size of the openings decreases when the mesh number increases. (Netafim, 2016)
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II.
Objectives
The main objective of this experiment is to measure the particle size distribution of rice grains milled with use a size reducer found in Unit Operations Laboratory. Specifically, (1) to reduce the rice grain size using a size reducer, (2) to separate different sizes of the milled rice grains using a mechanical sieve shaker, and (3) to compare the particle size distribution of the milled rice grains and milled dried corn.
III.
Scope and Limitations
The experiment will be conducted at the Sotech Laboratory. The size reducer found in the Unit Operations Laboratory will be used for the experiment. The number of sieves will be based on the availability in the laboratory. Only rice grains and corn grains will be compared for size distribution.
IV.
Methodology A. Materials, reagents, and instruments
Size reduction apparatus Standard set of sieves Personal Protective Equipment (PPE) Sieve shaker Large Beakers (1 liter capacity) Analytical balance Rice grain Corn B. Procedure 1. Pre-experiment preparations a. Wear basic PPEs b. Prepare and clean the necessary apparatuses for the experiment c. Using a size reduction apparatus, pulverize approximately 250 grams of rice grain and corn using two different settings of screw tightness. Two screw tightness types would suffice. d. Weigh accurately the sample. e. Prepare the standard sieves in proper order arranged from the largest sieve diameter (smallest mesh number) on the top and the smallest sieve diameter (largest mesh number) on the bottom. The bottom most layer as well as the top cover should be a regular tray in the diameter size of the sieves. 3
2. Experiment proper a. Making sure that the bottom pan is in place, pour one sample into the top most sieve carefully. Make sure that there a re no spills. b. Cover the set of sieves with a pan and fit the setup into a sieve shaker. c. The shaking time should be at least five minutes, making sure that there are no more particles passing through d. Weigh the mass retained on each sieve and record the corresponding data according to the chart provided below. e. Calculate the fineness modulus f. Do the same for the other sample. g. If possible, do two trials. 3. Post-experiment a. Clean up all the apparatus used b. Dispose of the sample properly. c. Make sure the workplace is clean before leaving the laboratory V.
References
Geankoplis, C. J. (1993). Transport Processes and Unit Operations. United States of America: Prentice Hall. Groover, L. (2014, April 24). Understanding Sieve Analysis of Sand. Retrieved from http://www.slideshare.net/luwalagajohn/understanding-sieve-analysis-ofsand Horiba Instruments, Inc. (2017). A Guidebook to Particle Size Analysis. Retrieved from https://www.horiba.com/fileadmin/uploads/Scientific/eMag/PSA/Guidebook/pdf/PSA_Guide book.pdf McCabe, W. L., Smith, J. C., & Harriott, P. (1993). Unit Operations of Chemical Engineering. Singapore: McGraw-Hill Book Co. Netafim. (2016). Mesh vs. Micron Comparison Chart . Retrieved http://www.netafimusa.com/wp-content/uploads/2016/10/Mesh-vs-Micron.pdf
from
Retsch GmbH Haan. (2009). Sieve Analysis: Taking a closer look at quality. Retrieved from http://www.mep.net.au/wpmep/wp-content/uploads/2013/07/MEP_expert_guide_sieving_ en.pdf Retsch GmbH & Co. KG. (2004). The Basic Principles of Sieve Analysis. Retrieved from http://www.ninolab.se/fileadmin/Ninolab/pdf/retsch/documents/af_sieving_basics_2004_en.p df
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VI.
Expected Results
Table 1. Weight of samples before and after milling. Sample Weight before milling: M1 Weight after (grams) (grams)
milling: M2
Rice Corn
Table 2. Particle size distribution of samples. Sieves Rice Corn Weight Weight Weight Weight Before After Before After (grams) (grams) (grams) (grams) Sieve 1 (Mesh no. 60) Sieve 2 (Mesh no. 80) Sieve 3 (Mesh no. 140) Sieve 4 (Mesh no. 180) Sieve 5 (Mesh no. 200) Sieve 6 (Mesh no. 230) Collecting pan
Remarks
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