Batching and Mixing Charles Stark North Carolina State University
Batching & Mixing Objective Accurately weigh each ingredient Minimize batching time Produce a feed that has a uniform distribution of nutrients and medications
Ingredient Factors Particle size and shape Density Electrostatic charge Hygroscopicity Flowability Source: IMC 1995
Particle Size Specification Ingredients & Minerals Supplier specifications Customer specifications Example SBM, DDGS (600 1200 microns) Specifications based on screen size Thru a US # Premixes Carrier Particles per gram Source: IMC 1995
Feed Segregation Segregation occurs primarily as a result of differences in particle size, the difficulty of mixing multiple components can be reduced by making the sizes of the components as close as possible and also by reducing the absolute size of the particles. Source: IMC 1995
Ingredient Characteristics Particle size Shape Flat Round Density Wheat Midds Ground Corn SBM Limestone Source: IMC 1995
Particle Differences Large Particles - For coarse particles, the attractive force between two particles in contact is small compared with the weight of a particle, leading to a free flowing material. Small Particles - If the particle size is reduced, the weight of a particle falls more rapidly than the attractive force between the particles, and eventually the stage is reached where the particles stick together. Segregation is then prevented, because particles are no longer free to move relative to each other. Source: IMC 1995
Feed Mill Designs Pre-batch grind Post-mix grind Post-batch grind Post-pellet blend
Batching Equipment Micro Bin Systems Tote Bag Systems Scales Major Minor Weigh Buggy Liquid Pumps & Meters
Scales
Batching Scale Fill Test 200 lb 1/3 2/3 Major & Minor Scales Fill test evaluates full range of load cells Add test weights Record weight Remove weights Fill scale to 1/3 capacity Add test weights Record weight Remove weights Fill scale to 2/3 capacity Add test weights Record weight Document results
Batching Micro System Multiple Hopper Scale Single Hopper Scale
Batching - Totes Totes & Scales Tote Transfer
Liquid Ingredients Self Contained System Tank & Dike System
Liquid Addition Layout
Liquid Addition Equipment Meters Pumps
Mass Flow System Liquid Component Coriolis Meter
Mass Flow System Coriolis Meter
Batching Sequence Batching System Major Scale: Computer draws multiple bins to the major scale. Major Scale Minor Scale Micro Scale Computer switches to one bin and jogs at the end of the each ingredient. Major Ingredients Corn/Wheat SBM Midds DDGS
Batching Sequence Batching System Minor Scale Fill: Major Scale Minor Scale Micro Scale Computer draws single bins to the minor scale and jogs at the end of the each ingredient. Minor Ingredients Dical Limestone Salt Lysine
Batching Sequence Batching System Micro Scale Fill: Major Scale Minor Scale Micro Scale Computer draws single bins to the micro scale and jogs at the end of the each ingredient. Micro Ingredients Vitamins Trace Minerals Medications Amino Acids
Batching Sequence Batching System Scale Considerations: Major Scale Minor Scale Micro Scale Major Scale 80-90% Minor Scale 10-15% Micro Scale < 5%
Batching Sequence Batching System Major Scale Discharges First Major Scale Minor Scale Micro Scale Fills the dead space between the ribbons and tub.
Batching Sequence Batching System Micro Scale Minor Scale Discharges after a 5-10 second delay Major Scale Minor Scale Minor ingredients mix with the major ingredients
Batching Sequence Batching System Micro Scale Discharges after a 0-5 second delay Major Scale Minor Scale Micro Scale Micro tub or scales open and the material is transferred with a drag conveyor
Batching Batching System Mixing Time Horizontal Double Ribbon 30-60 second Dry Mix Micro Scale 120-180 second Wet Mix Major Scale Minor Scale Liquid Addition Volumetric (meter) Gravimetric (weighed) Liquid Ingredients: Spray Here Fat Molasses Choline Amino acids
Batching Sequence Batching/Mixing System Micro Scale Discharge Process Mixer opens and material drops to a surge hopper Major Scale Minor Scale
Batch Cycle Weighing 2 min Batch Cycle 4 mins Discharge 1 min Mixing 3 min Weighing 2 min Discharge 1 min Mixing 3 min
MIXING EQUIPMENT
Automation System
Automation Hardware PC Server PLC
PLC PLC Cards/Modules PLC
PLC Computer Inputs Theromcouple Micro Switch Hand Add Buttons Scale Indicator
PLC Outputs Motor Starter VFD
Batch Production Report
Recommended mix times Mixer Dry Mix Wet Mix Paddle 3 3 Twin Shaft Paddle 0.5 1 Double Ribbon 1-2 2-3 Twin Shaft Ribbon 0.75-1 2 Vertical 5-10 5-10 Source: Froetschner, 2007
Mixer Design Factors Dimensions Short x Wide Long x Narrow Ribbon/Paddle Angle Ribbon Width(s) Ribbon Tip Speed Total Surface Area
Mixer Sizes 200 CF Mixer Feed (lbs/cft) 35-7000 lbs 40 8000 lbs 45 9000 lbs
Horizontal Ribbon Mixer
Ribbon mixer Multiple ribbons
Double ribbon Single shaft
Double Ribbon Mixer Mixing Zones Feed Flow Main Mixing Zone Main Mixing Zone Typical mix time = 3-4 min
Double Ribbon Horizontal Mixer
Paddle Mixer
Paddle mixer
Paddle Mixer Mixing Zones Feed Flow Main Mixing Some Mixing Main Mixing Main Mixing Some Mixing Main Mixing
Horizontal Paddle Mixer
Rotating Drum Mixer Mixing Zones
Drum Mixer
Ribbon Mixer - Counterpoise
Ribbon Mixer Counterpoise Mixing Zone http://www.hayes-stolz.com/
Forberg Fluid Bed Mixer
Forberg Mixer
Vertical Mixer
Vertical Mixer Mixing Zones Main Mixing Zone Main Mixing Zone Main Mixing Zone
Vertical Mixer
Mixer-Problems Liquid Spray Nozzle Material Build up
Mixer Problems Material on ribbons Material on paddles
Batching & Mixing Problems Fat sprayed on ribbon and shaft Fat lumps created by poor liquid application and mixing
MIXER UNIFORMITY ANALYSIS
Factors Affecting Uniformity Particle Shape Spherical, square, flat Particle Size Different particle size can separate during the handling process Density Heavy particles may settle out during conveying and discharge to a bin Static Charge Particles will adhere to equipment if not properly grounded Hydroscopicity Vitamins or Feed Additives may absorb water Adhesiveness Fats or molasses may adhere to equipment
What Represents the Goal of Mixing? Segregated Mix Perfect Mix Random Mix
Distribution of weighing errors
Are You Weighing Ingredients Correctly? Weighing Precision Variation in weighing within ingredients, expressed as Coefficient of Variation (CV) Weighing CV ranges on average of about 5% (0.6-11% CV)
Causes of Weighing Variation Hand-weighing ingredients People tend to overdose by about 1% when ingredients are weighed by hand Micro-ingredients and premix dose errors Micro-ingredients scales seem to be more variable than macro-ingredient scales because of the size of the call Descrepancies between call size and scale resolution Average weighing discrepancies in feed mill is about 2% but can range up to 20% For example, requesting 11.3 lbs of an ingredient when the scale has a resolution of only 2 lbs. Ratio of call size to scale resolution Weighing errors and CV decreases as the call size to scale resolution increases. For example, a call for 100 lbs to be weighed on a scale with a resolution of 5 lbs gives a call/scale resolution of 20, where as a call for the same 100 lbs on a scale with a resolution of 2 lbs gives a ratio of 50.
Mixer Uniformity Analysis Mixer Markers Single nutrient/ingredient Salt Synthetic Amino Acids (Lysine or Methonine) Dry Mix Uniformity Economical Accurate and precise at inclusion level Test twice per year Ten samples from the same batch of feed Sample mixer or a point closest to the discharge
Feed Quality Assurance Mixer Test Sample mixer Mixer or Surge samples provides information on dead spots in the mixer or mixer maintenance issues Sample surge Sampling during the discharge process provides representative samples of the feed as it moves through the system. Sample discharge conveyor
Mixer Uniformity Analysis - Quantab
Mixer Uniformity Analysis - Quantab Weigh 10 gram sample of feed into a dish Scale +/- 0.1 g
Mixer Uniformity Analysis - Quantab Fold filter paper to create a cone
Mixer Uniformity Analysis - Quantab Measure out 90 ml of HOT distilled water SAFETY Hot Water Burns!!
Mixer Uniformity Analysis Mix sample and water for 30 sec wait and re-mix for 30 sec. Place filter paper cone in cup Place Quantab strip into the filter cone Indicator strip at the top will turn black when complete
Mixer Uniformity Analysis - Quantab Read highest point on the strip Determine NaCl level based on the calibration chart on the bottle. Multiple by 10 (10:1 dilution)
Mixer Uniformity Analysis Calculations Calculation of Mixer CV Mean of samples Standard deviation of samples CV % = standard deviation x 100 mean
Mixer Uniformity Analysis Calculations NAME: ADDRESS: SAMPLE: DATE: QUANTAB READINGS 1 0.20 2 0.21 3 0.22 4 0.17 5 0.17 6 0.18 7 0.20 8 0.17 9 0.18 10 0.18 STANDARD DEVIA 0.02 MEAN 0.19 COEFFICIENT OF VARIATION (CV) 9.65
Micro Tracer Rotary Detector Method Materials Rotary Detector. Scale. Demagnetizer. Heating plate. Developing Solution. Filter paper 7.5 mm Grinder for pelleted feed Test Method Weigh 100 g sample Place filter paper on the spindle of the rotary magnet. Transfer the sample of feed to the top hopper of the Rotary Transfer the Microtracer to a scoop, demagnetize, then disperse over a large wetted filter paper on an aluminium plate. Then dry on hot plate to develop spots. Count the spots. Source: www.microtracers.com
MicroTracter Rotary Detector Source: www.microtracers.com
FS-Red/ Natural Yellow Spots Developed with 50% Water and Alcohol Source: www.microtracers.com
Mixer Uniformity Evaluation CV RATING CORRECTIVE ACTION < 10% Excellent None 10-15% Good Increase mixing time by 25-30% 15 20% Fair Increase mixing time by 50%, look for worn equipment, overfilling, or sequence of ingredient addition 20% + Poor Possible combination of all the above Consults extension personnel or feed equipment manufacturer
Double Ribbon Mixer RPM s
Double Ribbon Mixer Worn Ribbons
Double Ribbon Mixer Wrong Rotation
Double Ribbon Mixer Build-Up
Questions