1. GRINDING and PARTICLE SIZE REDUCTION
Keith Behnke
Dept. of Grain Science and Industry
Kansas State University
Manhattan, Ks

2. WHY DO WE GRIND? IMPROVED ANIMAL PERFORMANCE INCREASED MIX UNIFORMITY
IMPROVED PELLETING

3. MEASURING PARTICLE SIZE

4. PARTICLE SIZE TEST (ASAE STANDARD - S319)
This method involves using a sieve stack to determine the geometric mean particle size (dgw) and the geometric standard deviation (sgw).
Results can be obtained either graphically or through calculations.

5. ESTIMATING
PARTICLE
SIZE

6. A Quick Method for Estimating
PARTICLE SIZE
Minus 14 Mesh
(%)
Particle Size
(Microns)
90-95%
500
80-90%
600
70-80%
700
65-75%
800
60-70%
900
50-60%
1000
Source: Champion-Roskamp, Waterloo, IA.

7. METHODS OF GRINDING
Impact
Compression
Shear
Attrition

8. HAMMERMILLS

9. ADVANTAGES Ability to grind a wide variety of materials
Ease of maintenance, less maintenance cost
Versatility
Less complicated to operate
Less initial cost

10. DISADVANTAGES Energy consumption Produces a greater Sgw
Noise and dust pollution
Heat generation and moisture loss

11. ROLLER MILLS

12. ADVANTAGES- Rollermills
Electrical efficiency
Particle size uniformity
Less maintenance
Less dust pollution

13. DISADVANTAGES Rollermills
Higher initial cost
When maintenance is needed it is expensive
Can not effectively grind fibrous materials
Reduced throughput at small particle sizes

14. Roller Mills vs Hammermills
ENERGY COST
COMPARISON
Roller Mills vs Hammermills
Grinder Type
Particle Size
(microns)
Energy Cost
($/ton)
Savings
(%)
Hammermill
399
1.56
Roller Mill
432
1.31 16
718
.65
709
.47 28
2,040
.35
1,813
.05 86

15. PRE-GRINDING Vs. POST-GRINDING SYSTEMS

17. PRE-GRINDING SYSTEM Advantages Disadvantage
Longer grinding time a t full motor load
Gives a buffer for down time or maintenance on the grinder
Disadvantage
Requires more storage bins for both ground and raw ingredients

18. POST GRIND SYSTEM Advantages Disadvantages
Accommodates material changes
Does not require as many storage bins
Disadvantages
Less energy efficient
Directly affects the capacity of the facility

19. INNOVATIONS IN
GRINDING

20. THE FUTURE! GRINDING OPERATIONS * Hammer Design and Metallurgy
* Air Assist System Design
* Noise Control
* Automation and Routing
* Quick-Change Screens
* Quick-Change Hammer Gangs

21. THE FUTURE! GRINDING OPERATIONS * Vertical Shaft Hammermills??
-European Designs now available
-Air-Assist not recommended

22. THE FUTURE! GRINDING OPERATIONS * AUTOMATION???
-The One System That Clearly Should
Be Automated!!
-Start-up/Shut-Down, Routing
and Ingredient Changes
-Lights Out Operations??