1. Mechanical Separation
Kevin Carl D. Tinsay
5ChE-C

2. Mechanical Separation: rotary Screen/trommel

3. In mechanical separation
In mechanical separation. Screening is the separation of mixture of particles of various sizes into two or more fractions by a screening surface.
In industries, rotary screen, or trommel is a unit, used mainly in Municipal and industrial waste, Mineral processing
It consists of a perforated cylindrical drum which is normally elevated at an angle at the feed end.
Physical size separation is achieved as the feed material spirals down the rotating screen, where the undersized material smaller than the screen apertures passes through the drum, while the oversized material exits at the other end of the drum
Introduction

4. For the equipment selection, rotary screen or trommel has steady performance and less noise, the structure is also simple and convenient and easy to maintenance. It’s well suited for mineral processes in which crushed coal can be screened and arranged it according to its size. To improve its efficiency of the equipment that uses coal by subjecting it to finer particles as raw material. Also, depending on the nature that each mesh can be replaced with another, it can cope up to the demand the industry wanted.
Rationale

5. Feedstock, operation, assumptions and constraints
1 Metric ton of Crushed coal will be screened in a batch rotary drum from 270, 150, 100, 65, to 48 mesh. Total time will be in 4 hours in which the downtime including cleaning, maintenance, will be 1 hour with a run time of 3 hour per batch. Operating hours will be 12 hours daily. Assumed that the coal being fed has already been crushed into a size reduction equipment.
Feedstock, operation, assumptions and constraints

6. Materials of construction
Copper is a valued building material because of its advantageous properties. These include corrosion resistance, durability, low thermal movement, light weight, radio frequency shielding, lightning protection, sustainability, etc. Copper is usually incorporated into roofing, flashing, gutters, downspouts, domes, spires, vaults, wall cladding, building expansion joints, and indoor design elements and for the equipment, copper will be used for the surface of the mesh
High Carbon steel is used when resistance to abrasion and impact is required. The steel wire mesh with high carbon content has good strength and is commonly utilized in agriculture, coal, gravel, mining, sand and stone separating, sizing and sorting applications. The material will be used for the mesh of the trammel as well as for the stand of the equipment.
Materials of construction

7. It is desired to collect fine particles(undersize) from a crushed coal/Gravel to process it into the distillation column to produce gasoline by screening through a 270, 150, 100, 65 and 48 mesh. The screen analysis of feed, undersize and oversize are given.
Mesh
Feed (%)
Oversize (%)
Undersize A (%)
Undersize B (%)
Undersize C (%)
Undersize D (%)
Undersize E (%)
270
0.34
0.4
0.38
0.29
0.15
0.36
0.2
150
0.18
0.22
0.3
0.1
100
0.06
0.04 65
0.08
0.25 48
0.03
Pan
0.43
0.23
0.27
calculations

8. Material Balance F = 1 MT Xf1 = .34 Xf2 = .18 Xf3 = .29 Xf4 = .10
Mesh 270
Mesh 150
Mesh 100
Mesh 64
Mesh 48 R
Xr1 = .4
Xr2 = .22
Xr3 = .10
Xr4 = .08
Xr5 = .20 A
Xa1 = .38
Xa2 = .20
Xa3 = .22
Xa4 = 0
Xa5 = 0 B
Xb1 = .29
Xb2 = .22
Xb3 = .06
Xb4 = 0
Xb5 = 0 C
Xc1 = .15
Xc2 = .30
Xc3 = .10
Xc4 = .22
Xc5 = 0 D
Xd1 = .36
Xd2 = .10
Xd3 = .04
Xd4 = .25
Xd5 = 0 E
Xe1 = .20
Xe2 = .18
Xe3 = .15
Xe4 = .20
Xe5 = 0

10. Sketch design

14. Assume angle of inclination = 5, Kv = 1
Assume angle of inclination = 5, Kv = 1.85 Assume residence time T = 3 Bulk density of coal = 𝐷=[ 𝑄𝑚 𝐷𝑏 𝐹 𝐾𝑣 𝑔 tan 𝑎 ] 𝑁= 1 2𝜋 ( 𝑔 𝑟 ) 𝐿= 0.113𝑇 (𝐷 .5 ) (𝑔 .5 )(𝐾𝑣)𝑡𝑎𝑛(𝑎)
rpm m m

15. Equipment Specification
Identification
Trommel
Method
Screening method
Function
To separate crushed coal by size, and to collect the finer particles
Operation
Batch operation
Type
Rotary screen
Materials handled
Crushed coal (Bulk Density = )
Dimensions
.26m diameter x m length
Material of construction
Copper, High carbon steel
Mesh used
270, 150, 100, 65, 48
Type of mesh
Tyler
Rotational Speed
rpm
Heuristics
Velocity correction factor
1.85
Trommel inclined angle
5̊̊
Residence time
3 mins
Gravity
9.8 m/s
Fillage Factor
25%
Equipment Specification

18. Thank you for listening!