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Particle Size Reduction

Leland McKinney

Department of Grain Science & Industry

Kansas State University

How Do We Define Particle Size?


The Use of Different Procedures…


The Effects of Flow Agents…

Costs Associated with Particle Size

Reduction

0

2

4

6

8

10

0

1

2

3

4

1000 800 600 400Particle Size, microns

En

erg

y C

on

su

mp

tio

n,

kW

h/t

Pro

du

ctio

n R

ate

, t/h

aWondra, et al., 1992

Production Rate

Energy Consumption

How do we recover our costs

to grind?

Particle Size Effects on Diet ME in

Primiparous Sows

3,399

3,5723,601

3,745

3,300

3,600

3,900

1,200 900 600 400

ME

, kc

al/

kg

Particle Size, microns

Wondra et al., 1995

40

42

44

46

48

50

52

54

56

58

60

300 500 700 900 1100 1300

Particle Size (microns)

An

gle

of R

ep

ose

Particle Size x Mill Type x Added Fat (P<0.05)

Flowability

Goodband et al., 2006

Particle Size Uniformity Effects on

Diet Flowability

0% added fat, hammer-milled



0% added fat, roller-milled



Goodband et al., 2006

Flowability

Particle Size Effects on Diet

Flowability

Particle Size Uniformity Effects on

Finishing Pigs

831 831 840

700

750

800

850

900

950

2.7 2.3 2

288 288 272

100

200

300

400

500

2.7 2.3 2Sgw

AD

G,

g

Sgw

Gain

:Feed

, g

/kg

1

1.1 1.1

0.5

0.7

0.9

1.1

1.3

1.5

2.7 2.3 2Sgw

No

. o

f U

lcers

NS NS

NS

What About the Optimum Particle

Size for Poultry?

Particle Size Effects on Broilers

30.0

33.5

37.0

900 700 500 300

Particle size (microns)

AD

G (

g)

Sorghum

Corn

620

655

690

900 700 500 300

Corn

Sorghum

Ga

in:F

eed

(g

/kg

)

Sifter

A Different Approach…

61.9 61.0

56.1

51.6

47.1

30

50

70

0 25 50 75 100

107.8105.4

104.1

96.8

90.5

80

95

110

0 25 50 75 100

1.761.73

1.85

1.91.93

1.6

1.8

2

0 25 50 75 100

Clark, 2006

% Cracked corn added post-pelleting

AD

G,

g

Linear P<.001



AD

FI, g

FC

R

The Effects of Adding Cracked Corn to

Broiler Diets Post-Pelleting

2.68 2.68 2.69 2.66

0

1

2

3

4

0 15 25 35

4.46 4.42 4.43 4.44

2

3

4

5

6

0 15 25 35

1.665

1.65 1.648

1.669

1.62

1.64

1.66

1.68

0 15 25 35Dozier et al., 2006

NS NS

NS




The Effects of Adding Cracked Corn to Broiler Diets Post-Pelleting

AD

G,

kg

AD

FI, k

g

FC

R

7.7 7.6 7.7 7.8

5

6

7

8

9

10

0 25,25,25 10,20,30 20,30,40

1.883 1.895 1.896 1.888

1.6

1.7

1.8

1.9

2

0 25,25,25 10,20,40 20,30,40Dozier and Behnke, 2007


BW

G,

lbs


FC

R

NS

NS


94.0395.41

94.1 94.92

80

85

90

95

100

0 25,25,25 10,20,30 20,30,40

5.762 5.615 5.65 5.812

2

4

6

8



Liv

ab

ilit

y,

%

Carc

as

s W

t, l

bs


NS

NS


0.176 0.176 0.183 0.181

0

0.05

0.1

0.15

0.2

0.25

0 25,25,25 10,20,30 20,30,40

1.768 1.717 1.703 1.776

0

0.5

1

1.5

2

2.5

3


Ab

. F

at

Wt,

lb

s


Bre

ast

Meat

Wt,

lb

s

NS

NS

Implications

• 4000 T/Wk total pelleting capacity

• Corn makes up 70% of the diet (2,800 T/Wk)

• Modify system to add 35% of the corn post-

pelleting (980 T/Wk)

• 4000 T/Wk – 980 T/Wk = 3,020 T/Wk reduction

Reduce operating hours by 24.5%

Increase total weekly feed production by 32%

METHODS OF GRINDING

Hammermill

• Impact

• Attrition

Roller Mill

• Shear

• Compression

Hammermill Grinding

Screen

Disk Plate Hammers

Inlet

PrimaryDestructionZone

Acceleration Zone

FullHammerTip Speed Zone

Contact Point

"Regrind Chamber"

"Flow Director"

Hammermill Grinding

Impact

Attrition

Utilizing different sized screen?

• Feeder

• Tip Speed

• Screen Area

• Hammer Pattern

• Hammer Position

• Air Assist System

Factors Affecting Hammermill

Performance

Feeders

Feeders

Rotary Pocket Feeder Screw Feeder

Uniform feed rate across the entire grinding surface

Results of over or uneven feeding a

hammermill

Groves from swinging hammer

Tip Speed > Depends on diameter & rpm (d*3.14)/12 * rpm

Nutritionists may be pushing you to grind to parameters

you are not set up for…

Model – Diameter 1200 1500 1800 3000 3600

Viking – 16” NA NA NA 12,500 15,000

Challenger – 22” NA NA 10,300 17,250 20,500

Impactor – 28” NA 10,900 13,100 21,900 NA

Standard – 38” 11,900 14,900 17,900 NA NA

Magnum/HM – 44” 13,800 17,200 20,700 NA NA

Int’l Magnum – 54” 16,900 21,900 NA NA NA

HM High Speed – 54” 16,900 21,900 25,400 NA NA

Motor RPM

Hammers

The hammer pattern needs to

provide equal loading on the pins

Hammer Pattern

2 – 3 HP/Hammer for coarse grind

< 1 HP/Hammer for very fine

Screen Area

Broken at 28/06/02: 11.00 Incorrect screen hole stagger can lead to

wear between the holes and premature

screen failure

Ticker screens = increase life =

reduced throughput

More holes = reduced life =

greater throughput

Hammermill Maintenance

Screens

•One set of hammers should wear out 2- 4 sets of screens

•Replacement screens should be equal thickness and open area as the originals

•Screen hole stagger should be correct

Hammermill Maintenance

Screens

• Creased or corrugated screen indicates

wrong stagger or incorrect hammer pattern

• Screens may be turned and rerolled to use

all edges

• Screens should be replaced when edges

dull, do not wait for screens to “blow out”

Air Assist System

• Air required is 1 ½ - 2

cfm of air per square

inch of hammermill

screen area.

• Air assist forms

negative pressure

inside hammermill.

Vertical shaft hammermill

Hammermill Grinding

Roller Mill Grinding Inlet

Rolls

2-high

3-high

Roller Mill Grinding

Corrugations Patterns Top Middle Bottom

Cracking Corn

Small grains

( > 700 µ)

Corn ( > 700 µ)

Corn ( < 600 µ)

Set-up depends on material,

which varies

5-5

6-6

5-5 10-12

4-5 8-10 12-14

12-14

Conditions to Avoid

Material accumulating in the nip of the top rolls

Bottom rolls too far open

Top rolls too close

Work not evenly divided between top and bottom


Normal Operation

Material passing directly through the nip of the top pair

Work evenly divided between and bottom rolls

Top pair open slightly, feeding evenly from end to end

Bottom pair "completing" the grind


Rolls in Parallel

Rolls out of Parallel

Rolls in Tram

Rolls out of

Tram

Roll Tram and Parallel


Uneven roll wear

Inconsistent grinding

Advantages

• Ability to grind a wide variety of materials

• Ease of maintenance, less maintenance cost (quick

change hammers)

• Versatility

• Less complicated to operate (automation)

• Less initial cost

Hammermill Summary

Disadvantages

• Energy consumption (Attrition)

• Noise and dust pollution

• Heat generation and moisture loss (shrink)

• Electrical efficiency (shear)

• Less maintenance (↑ difficulty, ↑ cost)

• Less dust pollution

Roller Mill Summary Advantages

Disadvantages

• Higher initial cost

• When maintenance is needed it is expensive

• Can not effectively grind fibrous materials

• Reduced throughput at small particle sizes

• Produces lower BD material

Thank you

Leland McKinney

Dept. of Grain Science

Tel: 785-532-4082

Email: [email protected]

particle size reduction - satradehub.org€¦ · costs associated with particle size reduction 0 2...

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