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Feed milling 7_Particle_size_reduction.pdf
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- 2. Particle Size Reduction •Most of the ingredients used in livestock feeds require some type of grinding 2
- 3. 3 Feed Mill Design Whole corn Ground corn SBM Phosphates Carbonates Whole corn SBM Phosphates Carbonates Micros Micros Scale1 Scale 3 Scale 2 Scale 1 Scale 2 Scale 3 Pre-Grinding Post-Grinding
- 4. Hammermill Roller Mill §Most feed ingredients used in animal feeds, require some type of grinding § Hammermills are the most common choice for facilities producing pelleted diets Grinding Equipment
- 5. § Reduce segregationafter mixing § Improve pellet quality § Greater heat and moisture penetration during conditioning § Higher surface area for particles’ agglomeration during pelleting § Increase in the surface area of material exposed to the animal’s digestive system Surface area = 6a2 § However, not all animals benefit from a finer grind size § Chickens have their own grinding organ Adapted from Nunes, 2013 Benefits of Particle Size Reduction
- 6. We need tofocus on the macrostructure… without forgetting the microstructure Particle Size and Pellet Durability in Poultry
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- 8. Field Observations Proventriculus: Secretes digestive enzymesand acids Gizzard: Mechanical organ, controls reverse peristalsis
- 9. 9 Business Model VS. Macro structureis very important Macro structure is important, but don’t sacrifice microstructure Pay attention to other factors that influence pellet quality without compromising microstructure Commercial Feed Mill Integrated Feed Mill
- 10. Cracking, Crimping, Minimum Fines,Dust Coarse Grinding, Textured Feeds Grinding for Pelleting Corn, Wheat, Milo Grinding for Pelleting Oats, Barley, Fiber Grinding < 300 µm Pet food/Aqua Adapted from Kitch, 2018 Roller mill or Hammer Mill?
- 11. Factors to Consider •Target particle size § Coarse (mash diets) – Roller mill § Fine (pelleted diets) – Hammermills • Energy consumption § Roller mills use less electric energy, but are less efficient at lower particle size than hammermills • Maintenance cost § Roller mill – Re-corrugation, routine gap adjustments, daily particle size analysis § Hammermill – Screen and hammers replacement, rotation • Environment and safety § Roller mill – Lower noise and less dust § Hammermill – Requires dust control, high noise, risk of fire explosion 11
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- 13. Hammermills § Rotary pocketfeeder § Even feeding across mill width § Easy to automate § Available with self cleaning magnet § Considerations § Make sure that feeders are not broken and leaking product § Important if you change from grinding corn to wheat § Smaller grain
- 14. Advantages • Process awide range of materials • Lower initial cost • Minimal maintenance • Easy operation § Select Screen Size § Turn it on Disadvantages • Less uniform particle size • Higher energy costs • Noise and dust pollution • Generates more heat (shrink) Hammermills
- 15. • Screen Size §Small: Fine grinding § Large: Coarse grinding • Hammer Tip Speed, FPM § <13,000 Coarse § 13,000 to 18,000 Medium § >18,000 Fine Particle Size Controlled By: • Hammer Pattern • Heavy – Lower ratio of HP/Hammer Number § 2 HP/Hammer • Medium – Higher ratio of HP/Hammer Number § 2.5 -3.0 HP/Hammer • Hammer position • Coarse 3/8-to-1/2-inch gap from hammer tip to screen • Fine 3/16-to-1/4-inch gap from hammer tip to screen FPM = Feet per minute
- 16. 0 0 100 200 300400 500 600 Ingredient Particle Size ( µm ) 5 10 15 20 25 Energy (kWh / Ton ) Screen Size § The easiest variable to change, but may not be the best long-term solution o Larger hole diameter doesn’t always return a larger mean particle diameter o Larger hole diameter will typically lead to a larger standard deviation
- 17. § Sometimes thisis the easiest variable to change, but may not be the best long-term solution oLarger hole diameter doesn’t always return a larger mean particle diameter oLarger hole diameter will typically lead to a larger standard deviation oToo large may allow whole grain to pass through * Adapted from Kitch, 2022 Grinding Considerations – Screen Size
- 18. P = 2� r = � D P = 3.1416 x D P = 3.1416 x 38”/12 P = 3.1416 x 3.167 feet P = 9.94 feet Diameter, Inch Width RPM Tip Speed, FPM Tip Speed, m/s HP Range 38 48 1800 17,898 91 300 – 350 44 48 1800 20,730 105 300 – 450 54 48 1800 25,434 130 350 - 500 18 Motor = 1,800 rpm x 9.94 feet Feet/min = 17,898 Meter/sec = 91 Hammer Screen Width Variable frequency drives (VFD) on the main drive motor of hammermills can help to control particle size by adjusting the tip speed of the hammers Tip Speed
- 19. Patiño and Wang,2018 19 0.00 5.00 10.00 15.00 20.00 25.00 3360 2380 1680 1191 841 594 420 297 212 150 103 73 53 37 Amount Retained, % Sieve Size 812 902 1094 1215 Tip Speed m/s rpm Dgw Above 1191 µm, % Below 420 µm, % 91 1800 812 36 20.9 77 1530 902 43 17.9 64 1260 1094 55 15.6 50 990 1215 62 16.5 Corn was ground with 7.9 mm screens How to Modify Particle Size?
- 20. 38” Diameter (965mm) 1800rpm: 17,907 fpm (91m/s) or 203 mph (326 km/h) 44” Diameter (1118 mm) 1800rpm: 20,734 fpm (105m/s) or 235mph (378 km/h) 54” Diameter (1372 mm) 1800rpm: 25,446 fpm (129m/s) or 289 mph (465 km/h) 38 Series 44 Series 54 Series Rotor Diameter
- 21. • How manyHP does your main motor has? • How many hammers do you have in does your hammermill have? • More hammers = more working surface area = more fines • Less hammers = less working surface area = coarser grind, but greater standard deviation Example: Main motor = 300 HP 300/2 = 150 300/2.5 = 120 Your hammermill needs to have between 120 and 150 hammers Target 2 to 2.5 HP/hammer Adapted from Kitch, 2022 Number of Hammers
- 22. Grinding Considerations –Hammer Position • Coarse position Clearance is 7/16” (11-12mm) • Fine position Clearance is 7/32” (4- 5mm) Coarse Fine Coarse position Fine position
- 23. 23 General considerations -Magnets
- 24. 24 General considerations -Hammers Hammers show irregular wear due to uneven feeding from end to end VS.
- 25. 25 Normal wear Excessivewear Normal wear Excessive wear General considerations - Hammers
- 26. General Considerations –Screens • Hole Stagger Correct Incorrect Hammer travel
- 27. Major Minor Surge Hopper Corn 880µm SBM DDGS Carbonates, phosphates, salt, etc. Corn 1200 µm Solution in feeds for the integration 1. Add 3 to 10% of corn (~1200 µm) to the broiler diets 2. Increase inclusion of coarse corn as birds grow 3. Monitor 7-days BW Commercial and integrated feed mills face greater challenges, regarding optimum particle size Commercial/Integrated Feed Mills
- 28. Whole Corn Protect Your GrindingEquipment Magnet Magnet § Grinding area is typically located adjacent to the feed mill (outside) § Explosion panels are common *
- 29. • Commonly usedin the feed industry when diets are fed in a mash form Roller Mills
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- 31. • Material isground as it passes through a series of rolls (1 to 3 pairs) • Poultry – 1 to 2 pairs (>700 microns) • Finer grind – 3 pairs (~450 microns) 31 How Does the Roller Mills Work?
- 32. Particle Size Distribution 46 8 10 14 20 30 40 50 70 100 140 200 270 Pan U.S. Sieve, # 0 5 10 15 20 25 30 35 Amount retained, % Roller Mill - 712µ Hammermill - 708µ
- 33. Advantages • Low noiseoperation • Less heat increase and moisture loss – 0 – 3°F vs. Up to 10°F • Uniform particle size – Less fines and oversized particles • Energy savings – >15% • Less Moisture losses – <0.5% vs. 1-3% Disadvantages • High initial investment • More complicated to maintain § Roll adjustments and more frequent particle size analysis • Does not grind fibrous materials (barley, oats), high moisture grain Roller Mills
- 34. 34 Roller Mills Normal Operation Workdivided evenly Bottom pair slightly tighter Condition to Avoid Top rolls too close Bottom rolls too far open Material build up • Understanding how much work each set of rolls is doing is important • When setting the roll gaps, start with the top pair of rolls and work your way down. Once the rolls gaps have been set, check each motor’s amp load to make sure all pairs are doing a similar work.
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- 36. Process Control • Equipment §Maintain equipment according to manufacturers recommendations § Clean magnets daily § Inspect screens and hammers weekly § Adjust roll gaps daily; check roll parallel monthly • Visual inspection § Check appearance of ground grain § Check screens for holes 36
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- 38. Particle Size Analysis– ASABE S319.4 Sample 400 g 200 g 200 g 100 g 100 g Particle size analysis
- 39. Particle Size Analysis– ASABE S319.4 Adapted from Stark and Kalivoda, 2016 10 minutes Weigh the amount of material in each sieve
- 40. Particle Size Analysis– ASABE S319.4 VS
- 41. Particle Size Analysis– ASABE S319.4 The methodology of particle size analysis can significantly impact the final results It is important to understand how the test is being conducted at the laboratory to ensure the results are interpreted correctly 586 554 615 576 540 500 520 540 560 580 600 620 No Yes No No Yes Yes Yes No Yes Yes 10 min 10 min 15 min 15 min 15 min Particle Size, µm Kalivoda and Stark, 2016 Sieve agitator Dispersion agent Ro-Tap Time
- 42. • Corn particlesize influences grinding costs, grinding capacity, and broiler performance §It is important to quantify the degree of grinding that occurs in the pellet mill §Increase particle size as birds get older and monitor pelleting parameters and animal performance • Recommended particle size of ground corn (pre-grinding) in pelleted broiler diets • Starter, 1 to 14 days §900 - 1,000 µm • Grower and Finisher, 15 to 42 days §1,000 to 1,200 • Post grinding • 950 to 1,050 µm after mixer • 40 to 50% of particles above sieve US16 (1.18 mm) Conclusions
- 43. Thank You! Wilmer JavierPacheco, MSc., PhD. Extension Specialist and Associate Professor Auburn University wjp0010@auburn.edu