Vibrating Screen Lab Manual PDF

## DEPARTMENT OF CHEMICAL ENGINEERING Motilal Nehru National Institute of Technology Allahabad Prayagraj - 211004, UP (India) ### FMMO LAB MANUAL **Exp. Title:** VIBRATING SCREEN **Exp. No.:** 2 **AIM:** To determine the overall efficiency of a vibrating screen. **APPARATUS:** Vibrating screen,...

## DEPARTMENT OF CHEMICAL ENGINEERING Motilal Nehru National Institute of Technology Allahabad Prayagraj - 211004, UP (India) ### FMMO LAB MANUAL **Exp. Title:** VIBRATING SCREEN **Exp. No.:** 2 **AIM:** To determine the overall efficiency of a vibrating screen. **APPARATUS:** Vibrating screen, bucket beam balance, feed materials. **APPARATUS DESCRIPTION:** The vibrating screen consists of triple deck of screens of different screen opening. Mechanical vibrations are transmitted by an electron attached to the power shaft. Effective separation implies all over material and should be retained by the screen in overflow and all undersized particles in underflow, but in normal practical screens are not 100% effective. Screening is a method of separating particles according to size alone. In practice, the solids are dropped or thrown into a screening surface. The undersize or fines pass through the screen opening. Materials passed through a series of screens of different sizes are separated into two fractions. In most screen, the particles drop through the opening by gravity, coarse particle drop easily through the large opening in a stationary surface whereas with fine particles the screen surface must be agitated in same way. The concept of a vibrating screen experiment revolves around a practical investigation aimed at understanding and optimizing the performance of vibrating screens used in various industrial processes. Here are the key concepts and components of such an experiment: 1. **Vibrating Screen:** The core element of the experiment is the vibrating screen itself. The vibrations may be generated mechanically or electrically. Vibrating screen is a device with a screen surface that vibrates to separate particles into different sizes or grades based on their ability to pass through the screen mesh. 2. **Particle Separation:** The primary objective is to study how the vibrating screen effectively separates particles of different sizes. Particles are fed onto the screen surface, and the experiment assesses how they move and segregate. 3. **Vibration Dynamics:** The experiment considers the dynamics of the screen's vibration, including factors like vibration frequency, amplitude, and direction. These dynamics influence how particles move on the screen. 4. **Screen Design:** The experiment may explore different screen designs, including the size and shape of the screen deck, the type of screen mesh, and the arrangement of components like feeders and discharge chutes. 5. **Efficiency and Capacity:** Researchers measure the efficiency and capacity of the vibrating screen. Efficiency refers to how accurately the screen separates particles, while capacity indicates how much material the screen can process in a given time. 6. **Adjustable Parameters:** The experiment typically involves adjusting various parameters, such as vibration intensity, screen inclination, and screen mesh size, to assess their impact on particle separation and overall screen performance. 7. **Data Collection:** During the experiment, data is collected on particle sizes, separation efficiency, and other relevant parameters. This data is crucial for analysing and optimizing the screen's operation. 8. **Applications:** The experiment may explore the screen's suitability for specific industrial applications, such as mining, agriculture, food processing, or recycling. Researchers aim to determine how the screen can be tailored to meet the requirements of these applications. **Figure 1:** Vibrating Screen Apparatus - 1. 4-Sieve Screen - 2. Front Support - 3. Pressure Plate - 4. Side Board - 5. Screen Frame - 6. Sieve - 7. Standing Leg - 8. Spring - 9. Motor - 10. Eccentric Wheel - 11. Foundation **Comparison of screens:** The objective of a screen is to separate feed containing a mixture of particles of various size and separate it into 2 fractions on underflow that is pan through the screen and an overflow that is operated by the screen. Either one or both of these streams may be produced. An ideal screen would specify sharply separate so feed mixture is such a way that smallest particle in the overflow would be just largest particle in the underflow such as ideal separation defines and interval diameter, that makes the point of separation between the function. **PROCEDURE:** 1. Arrange a set of standard screens serially in a stack with the smallest mesh at the bottom and the largest at the top. 2. Place the pan at the bottom. 3. After placing (500 g) the sample, shake mechanically to obtain the oversize and undersize separately. 4. After shaking, weigh the particle from each mesh individually. Keep the pockets separately. 5. Place oversize particles, shake mechanically to obtain the oversize separately. 6. Place undersize particles, shake mechanically to obtain the undersize separately. Convert the weight into the mass fraction. **PRECAUTION:** 1. **Safety Gear:** Wear appropriate safety gear, including gloves and protective eyewear, to prevent injury. 2. **Calibration:** Ensure the vibrating screen is properly calibrated and maintained to avoid malfunctions. 3. **Particle Size:** Use particles of known sizes for calibration and testing to validate screen performance. 4. **Secure Setup:** Ensure the screen is securely mounted or placed on a stable surface to prevent accidents. 5. **Feeding Material:** Carefully feed material onto the screen to prevent overloading and maintain consistent flow. **FORMULA AND EQUATIONS:** **Material balance over screens:** Let F, B and D be the mass flow rate of feed, overflow and underflow respectively. XF, XD and XB be the mass fraction in the 3 streams. The mass fraction in the 3 streams. The mass fraction of undersized material in the feed, overflow and underflow are (1-XF), (1-XD) and (1- Хв). F=B+D FXF=BXB + D XD **Screening efficiency:** The efficiency of a screen is a measure of the success of a screen in closely separating material of the screen function perfectly all the bigger material would be in overflow and all the undersized material will be in the underflow. A common measure of screen efficiency is the ratio of oversized material that is actually I the overflow to the amount entering with the feed. Overall efficiency is given by $E = \frac{(XF-XB)(XD-XF)}{XD(1-XB)} * \frac{(Хp-ХВ)2(1-XF)XF}{(Хp-ХВ)2(1-XF)XF} * 100$ **OBSERVATION TABLE:** Weight of material = g | Sl. No. | Scree size (mm) | Feed, F (Kg) | Oversize/Overflow, B (Kg) | Mass fraction (Хв) | Undersize/Underflow, D (Kg) | Mass fraction (XD) | |---|---|---|---|---|---|---| | 1. | | | | | | | | 2. | | | | | | | | 3. | | | | | | | | 4. | Pan | | | | | | Error % = $\frac{Total feed - Total oversize}{Total feed} * 100$ Error % = $\frac{Undersize of Pan}{Total feed} * 100$