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

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

MEASURING PARTICLE SIZE

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.

ESTIMATING PARTICLE SIZE

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.

METHODS OF GRINDING Impact Compression Shear Attrition

HAMMERMILLS

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

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

ROLLER MILLS

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

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

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

PRE-GRINDING Vs. POST-GRINDING SYSTEMS

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

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

INNOVATIONS IN GRINDING

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

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

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