Sieve Analysis – its 4 [Methods, Tests and Advantages]
Sieve analysis is a technique used for determining the size of particles in essential distributions such as the number of different size particles are responsible for the surface reaction, solubility, and flowability. For dry non-agglomerated particles, sieve analysis remains a cost-effective and precise measuring instrument. Separating particles by size is called sieving.
For quality control in many industries test sieve analysis is widely used and to measure particle size and dry relativity free-flowing materials the test sieve analysis is a simple and common practice.
The sieve shakers and accessories have to fulfill the requirements of national and international standards to guarantee a high degree of reproducibility and reliability. As part of the quality management system all the instruments used for the characterization of particle distributions have to be calibrated and subjected to test agent monitoring and to carry out the sample preparation with great care it is absolutely necessary. Sieve shakers are shown in fig below;
The sieve analysis is easy to handle, low investment cost, precise results in a comparably short time and the possibility to separate the particle size.
Methods Of Sieve Analysis:
The sample is subjected to vertical movement called vibratory sieving or vertical motion called horizontal sieving during sieving the sample and both movements are superimposed with tap sieve shakers. The particles are compared with the apertures of every single sieve during this process and by the ratio of the particle size to the sieve openings the probability of particle passing through the sieve mesh is determined.
The appropriate sieving method depends on the degree of fitness of the sample material and for the size range between 40 µm and 125 mm dry sieving is the preferred method.
There are the following methods for sieve analysis such as;
- Vibratory Sieving
- Horizontal Sieving
- Tap Sieving
- Air Jet Sieving
By the vibration of the sieve bottom the sample is thrown upward and due to gravitation force it falls back. The amplitude indicates the vertical oscillation height of the sieve bottom and the material is spread uniformly across the whole sieve area due to this combined motion.
In vertical direction the particles are accelerated and rotate freely and then fall back, an electromagnetic drive sets a spring system in motion and transfers the oscillations to the sieve stack in RETSCH sieve shakers. To a few millimeters the amplitude can be adjusted continuously.
Horizontal Sieve Analysis:
The sieves move in horizontal circles in a plane in horizontal sieve shaker and for needle-shaped, flat, long samples horizontal sieve shakers are preferably used.
By a vertical motion generated by a tapping impulse a horizontal, circular movement is superimposed in a tap sieving shaker and for various standards for particle size analysis tap sieving shakers are specified.
In tap sieving shakers the number of compressions between particles and sieve aperture is substantially lower which results in loner sieving time.
Air Jet Sieving:
For single sieving the air jet sieve is a sieving machine and during the process the sieve itself is not moved. By rotating jet of air the material on the sieve is moved and a vacuum cleaner is connected to the sieving machine generates a vacuum inside the sieve chamber and through a rotating slit nozzle it sucks in fresh air.
The air stream is accelerated and blown against the sieve mesh dispersing the particles when passing the narrow slit of the nozzle. With the low speed with the sieve mesh, the air jet is distributed over the complete sieve surface and is sucked in and into the vacuum cleaner the finer particles are transported through the mesh openings.
Tests Of Sieve Analysis:
There are two procedures of sieve analysis as given below;
- Dry Test Sieving Analysis
- Wet Sieving Test Analysis
Dry Test Sieving Analysis:
To determine the particle size of dry and free-flowing materials dry sieving is used and to allow particles to seek the openings in the wire mesh these sieves are used by shaking or vibrating the sieve.
The particles are able to separate on their own in dry sieving and dry test sieve is used in many industries like chemical, food and beverage, etc.
There are the following steps in dry sieving such as;
- For any hole or tears and to know high or low grades clean and inspect the screen desk and if necessary replace the screens.
- In each screen place clean pucks and to the top screen in the deck add the dried and cooled plus products.
- For a minimum of 15 minutes place the prepared deck on the sieve shaker.
- If the P80 is suspected to be greater than 300 mesh build additional sieves into a primary screen deck.
- Through the primary screen deck screen the coarse sample.
- To the standard deck add the minus products.
Wet Sieving Test Analysis:
Where there is a high concentration of fine particles that tend to stick together and won’t separate using just mechanical shaking then wet sieving is used and if the sieve particles are mixed with material like silt or clay they cannot fit through the openings and can clump together.
For quality control in the aggregate industry wet wash sieving is used.
There are following steps in this sieve as given below;
- For wet screening as indicated on the sizing work order clean and inspect the necessary screen.
- With labeled filter paper clean and prepare the filter pots.
- Through required screen wash weighed sample gently into a clean bucket by using cool tap water.
- In the screen filter the remaining plus product.
- To dry place the filter paper in the oven.
- In the bucket filter and dry the minus products collected.
Advantages Of Sieve Analysis:
There are the following advantages;
- The analysis includes instruments fast and easy handling.
- The results of particles are reproducible and accurate in this analysis.
- This method is time-saving.
- In this analysis the cost of instruments is lower.
Disadvantage Of Sieve Analysis:
There are the following disadvantages;
- With dry particles it only works.
- 50μm is the minimum limit of measurement.
- In size there is a possibility of further reduction by which errors are caused.