Presented by Sanjay Banerjee (303/11) Chandan Kumar (365/11) Rishi Rock (461/11) 4 th semester, Metallurgical & Materials Engineering N I T Jamshedpur

 Introduction  Types of Screening  Screening Surfaces  Process of screening  Classes of Screening  Screening Terminology  Capacity of Screens  Efficiency of Screens  Applications of Screening

When an ore is taking for extraction of a metal then it should be in specific size range. There are several ways of sizing of particle but the most important way is screening, which is can be practiced in different size range of particle i.e. coarser to finer particle range.

 Laboratory Screening-:Use for lab. practice, where the quality is more considerable.  Industrial Screening-: Use in industries, where economy & efficiency is considerable with quality.

 Parallel bars/rods-: usually made of steel bars, fixed in parallel positions by cross bars and spacers. These used for coarsest work.  Punched Plates-:made of metal or plastic sheets punched by dies of various patterns.  Woven-wire Screens-:Woven-wire screens are woven of gauged wires. These are used for finest size work.

 Screening machine consists of a drive that induces vibration  There are physical factors like vibration, g force, bed density, and material shape that make screening practical  The way a deck is vibrated differentiates screens.

 Grizzly Stationary  Grizzly moving  Vibrating Screen, Horizontal  Vibrating screen, inclined  Shaking Screens, Oscillating  Shaking Screen, Reciprocating  High Speed screen  Revolving screen  Sifter Screen

 Amplitude  Acceleration  Blinding  Brushing  Cloth, screening cloth  Contamination  Deck  Frequency  Gradation, grading  Shaker  Stratification  Mesh  Scalp, scalping

Capacity of screen depends on  The area of the screening surface.  The size of the opening on the screening surface.  Characteristics of the ore such as specific gravity, moisture content, temperature, and the proportion of fines.  The type of screening mechanism used.

Type of screen Grizzly Trommel Shaking screen Vibrating screen Capacity range per 24 hr per mm aperture (Tons/sq. ft )

 Fractional Efficiency-: This is steady state screening produces a variation in the mass of particles through the screen along its length. fractional recovery, R i is R i =100(Oo i /Ff i ) Where o i and f i are weight fractions retained between any two sieves  Gross Efficiency-: It is the ratio of mass flow rate of the solids coarser than screen size in feed stream to the mass flow rate of solids in the over size stream.

 To differentiate the particles in different size range.  For taking a specific size range of particle.

 ranjit.rds.net.in  books.google.co.in  Wikipedia.org  From other sites and books