Sieving technology in feed pellet production


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The appropriate feed processing technology and a proper set of feed processing equipment will offer you assured feed products. Thus feed milling technology plays quite a very important role in feed production. It ensures the benign and steady development of the feed industry. Technology also provides a technique guarantee for converting animal nutrition research into high quality feed products and makes a great contribution to improving feeding efficiency and the value of feedstuffs. Feed pellets, as a kind of palatable and nutritious feed, enjoy wide popularity in feeding poultry, livestock and aquatic animals. At present, more than half of the world’s feedstuff is processed by pelleting technology.

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Sieving technology in feed pellet production

  1. 1. Digital Re-print September | October 2013 Sieving technology in feed pellet production Grain & Feed Milling Technology is published six times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2013 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872
  2. 2. “ After a decade, we replaced our Tapco Heavy-Duty buckets with the Xtreme-Duty ones. If the new ones perform half as well as the originals, who knows how long they’ll last — maybe 20 years or more! ” Jamie Mattson Operations Manager JAMES VALLEY GRAIN, LLC Oakes, North Dakota, U.S.A. Jon Hansen Plant Operator JAMES VALLEY GRAIN, LLC. Why 10 Years is Just a Drop in the Bucket When it Comes to the Performance of Tapco Buckets calculated that the original Tapco buckets handled 169,297,881 bushels – and most of those buckets were the originals.” When James Valley Grain installed Tapco buckets in their new facility in 2001, nobody expected them to last this long. A lot of commodities of different density variations – like wheat, corn and soybeans – have run through the original 7.05-million-bushel terminal, which added extra wear on the STYLE CC-HD (HEAVY DUTY) buckets. Through the ® years, the volume of STYLE CC-XD (XTREME DUTY) material has gone way up, too. “Ten years is a long time for buckets to endure, especially running as hard as we do,” Mattson says. “Honestly, when we took them off, it was pretty incredible how well they wore. If the new ones perform half as well as the originals, who knows how long they’ll last – maybe 20 years or more!” “We went from five million bushels the first year to around 30 million the last four years,” Jamie Mattson, Operations Manager, James Valley Grain, says. “In fact, I just looked it up and Extend the longevity of your loadout legs with Tapco buckets. Find out why 75% of design engineers, contractors and bucket elevator manufacturers* trust Tapco to keep business moving. Anticipating even more volume, the plant recently decided to upgrade to Tapco CC-XD (Xtreme Duty) buckets – made with 35-50% more resin thoughout – not just at critical wear points. ELEVATOR BUCKETS - ELEVATOR BOLTS St. Louis, Missouri U.S.A. Tel.: +1 314 739 9191 • +1 800 AT TAPCO (+1 800 288 2726) • Fax: +1 314 739 5880 • *Grain Journal, Country Journal Publishing Co., Inc., Decatur, Illinois, U.S.A. The color blue, when used in connection with elevator buckets, is a U.S. registered trademark owned by Tapco Inc. © 2013 Tapco Inc.® All rights reserved.
  3. 3. FEATURE Sieving technology in feed pellet production by Amanda Zhou, Allance Machinery, China T he appropriate feed processing technology and a proper set of feed processing equipment will offer you assured feed products. Thus feed milling technology plays quite a very important role in feed production. It ensures the benign and steady development of the feed industry. Technology also provides a technique guarantee for converting animal nutrition research into high quality feed products and makes a great contribution to improving feeding efficiency and the value of feedstuffs. Feed pellets, as a kind of palatable and nutritious feed, enjoy wide popularity in feeding poultry, livestock and aquatic animals. At present, more than half of the world’s feedstuff are processed by pelleting technology. Feed pellet processing technology Feed pellets have been defined as ‘agglomerated feeds formed by extruding individual ingredients or mixtures by compacting and forcing through die openings by any mechanical process’. Basically, the purpose of pelletizing is to process finely divided, sometimes dusty, unpalatable and difficult-to-handle feed materials and, by way of heat, moisture and pressure, into larger particles. These larger particles are easier to Table 1: Example particle size distribution US sieve 12 Grams Percentage 0.03 0.02 16 1.64 1.20 20 27.21 19.88 25 43.29 31.64 30 40.33 29.47 40 17.09 12.49 Pan 7.25 5.30 Total 136.84 100 1/8’’ grind milo based ration 28 | September - october 2013 handle, more palatable and usually nutritious enough to ensure animal healthy growth. For the pelletizing process technology, it has the following steps. Grain material selecting and sieving Grain materials are sieved to remove the big and magnetic impurities. The sieving machine structure should be capable of avoiding material blocking and ensure a consistent smooth flow. The mass flow concept features once the feeder opens, the mass material will flow down without blocking, packing and will be graded automatically. Grain grinding Grinding or particle-size reduction is a major step in pelleted feed manufacturing. Grain grinding generally improves feed digestibility, acceptability, mixing properties, pellet quality, and increases the bulk density of some ingredients. According to research, feed pellet quality depends on the following factors: 40 percent diet formulation, 20 percent particle size, 20 percent conditioning, 15 percent die specifications, and 5 percent cooling and drying. Apart from diet formulation, particle size is the first factor that will dictate about 20 percent of pellet quality and also has a significant effect on the other factors, such as decreasing the particle size of ingredients results in a greater surface area per unit volume for absorption of condensing steam and increases the surface area available for bonding. Moreover, penetration of heat and moisture to the core of a particle can be achieved in a shorter amount of time with small particles and a large surface area per unit of weight. But this is not a one-size-fits-all situation. The ideal finished particle size varies by the grain being processed, and depends on the species and life stage of the animal. Bearing all these in mind, selecting the proper method of grain particle size reduction is a critical decision. Hammer mills for grinding and sieving In general, both roller mills and hammer mills have been applied to the task of particle size reduction or grinding in feed pelletizing technology. The hammer mill has been traditionally used to produce the finer materials commonly used for pelleting, and for many mash feed applications. A hammer mill is essentially a steel box surrounding a rotor. Swinging hammers attached to the rotor flail out when the rotor spins. A screen covers the discharge opening to regulate the finished particle size. In the hammer mill, the motor drives the rotor to rotate at a high speed through the belt, and on the rotor there are series of hammers. When the materials get into the working area of hammers, the &feed millinG technoloGy Grain
  4. 4. FEATURE Table 2: Tip speed-feet/minute. Rotor diameter*RPM Diameter 1200RPM 1800RPM 3600RPM 19’’ NA 7536 17898 22’’ NA 10362 20724 28’’ NA 13194 38’’ 11938 17670 42’’ 13194 19782 44’’ 13823 20724 54’’ 16964 "Feed pellet production needs not only a complete proper set of equipment but efficient and cost-effective processing solutions" 25434 rotating hammers with high rotation speed strike them over and over until they are small enough to fit through a screen. A large amount of air also moves through the hammer mill, and it dragging any material small enough to make it through screen holes this becomes the final product - the larger products are brought back to the crushing area by the hammers for being re-crushed until they reach the required size. As materials move through the grinding chamber, they tend to approach hammer tip speed. Since reduction only occurs when significant energy is transferred from the hammer to the particle (large difference in velocities), less grinding takes place when the particles approach hammer tip speed. Many manufacturers incorporate devices within their mills to interrupt this product flow, allowing impact and reduction to continue. Tear circle hammer mills have a more positive, natural redirection of product at the inlet than ‘full circle’ design machines. Factors determining ground particle size: sieves Precision and consistency of the finished particle size have a strong effect on the digestibility of feed pellets. A finished particle size that is either too large or too small will have adverse effects on quality of pellets and animal performance. The primary factor determining finished parti- cle size is the measurement of the perforations in the screen covering the discharge area. The size of these perforations is equal to the maximum finished particle size of the material processed. Large particles will cause cracks and fractures in pellets. It is recommended that the hammer mill screens for grinding do not exceed 1/8 inch diameter. Better results can be achieved from use of a #7 (7/64 inch) screen. Smaller particles will increase horsepower efficiency by increasing the throughput of material through the die holes with less horsepower. The finer grind also extends the die life as it decreases the ‘grinding’ or milling of material on the solid surface between the holes on the die face. The ideal particle size range of 650 to Offices and Factory: Ctra. de Arenas km. 2,300 13210 Villarta de San Juan • Ciudad Real- Spain T: +34 926 640 475 • F: +34 926 640 294 grain silos &feed millinG technoloGy Grain hoppered silos Madrid Office: C/ Azcona, 37 • 28028 Madrid - Spain T: +34 91 726 43 04 • F: +34 91 361 15 94 September - october 2013 | 29
  5. 5. FEATURE 750 microns can easily and consistently be achieved through proper screen selection. In addition, screens can easily be changed to accommodate the processing goals of a variety of grains using the same hammer mill. Machinery sifting is the main screen technology applied in animal feed machinery at present. In the present market, punching, woven screen and bar grizzly are widely used as screen plates. The key part of screening equipment which affects sieving efficiency is screen surface. Factors determining ground particle size: tip speed Tip speed, in addition to screen size, has a significant influence on ground and sifted particle size. High tip speeds (>18,000 Ft/ min) will always grind finer and produce more fines than lower tip speeds. Low tip speeds (<13,000 Ft/min), on the other hand, produce a coarser granulation with fewer fines. As a rule, smaller screen hole sizes should be used with higher tip speeds, and larger screen hole sizes with lower tip speeds. Tip speed is simply a factor of mill diameter and motor RPM and is not easily changed on direct coupled machines. There are a few V-belt drive hammer mills on the market today. To produce a uniform granulation with few fines on materials like corn, wheat, grain sorghum, pelleted ingredients and solvent extracted meals, an intermediate tip speed is normally desirable. Hammer mills with a tip speed of 13,000-18,000 Ft/Min will produce a high quality finished product with excellent capacity and efficiency. 38" diameter mills with 1800 RPM motors (17,800 Ft/Min) and 44" mills with 1200 or 1500 RPM motors (13,500 or 17,250 Ft/Min) are both used extensively in the processing of all kinds of feed ingredients. For finely ground products and tough to grind materials like soybean hulls, mill feed, and mixtures with animal protein products, a higher tip speed is needed because more energy is required to grind these kinds of materials. Normal tip speeds for fine grinding and fibrous materials are obtained on 42" and 44 inch mills operating at 1,800 RPM (19,500 and 20,000 Ft/Min), or 28 inch mills operating at 3,000 RPM and 54 inch mills operating at 1,500 RPM (21,000 Ft/Min). Recent developments in hammer mill grinding have included the use of 54 inch diameter mills operating at 1,800 RPM. This very high tip speed (>25,000 Ft/Min) is particularly well suited to fine grinding at high capacities and high efficiency. Because a larger screen (hole) sizes can be used while maintaining the fineness of the grind, operating costs are reduced as well. Mixing conditioning. The machine consists of cylindrical dies of different diameters to pelletize varying sizes of feed, which depends on the age, size and spices of animals involved. Most feeds produced are compressed pellets. Pelleted feeds have numerous advantages which include less feed wastage, uniform feed intake, and destruction of growth inhibitors. The ring die feed pellet mill is equipped with one or more layer conditioner to be added in the form of steam which softens the feed and partially gelatinizes the starch content of the ingredients, so as to process firmer (and for aquatic feed more stable) pellets. Generally speaking, the starch in grain materials can be ripened about 60-80% by hot air in conditioner so that high starch or molasses content pelleted feed can be processed. Mixing or blending can be either a batch process or a continuous process. Batch mixing can be done on an open flat surface with shovels or in containers shaped such as cylinders, half-cylinders, cones or twin-cones with fixed baffles or moving augers, spirals, or paddles. Continuous mixing proportions by weight or volume is a technique best suited for formula feeds with few ingredients and minimal changes. Different types of mixers, such as horizontal or vertical as well as special mixers like liquid mixers are used to achieve mixing. Pellets from dry pellet machines may exit at up to 88°C and 17-18% moisture. The temperature must be quickly reduced to ambient or less and the moisture level to 10-12% or less for proper storage and handling. Pellets must therefore be cooled and dried. Moist pellets, if they are going to be converted to dry pellets, also need drying although their temperature is not normally much elevated during manufacture. Pelleting Sifting Mechanically, the pelleting process involves forcing soft feed through holes in a metal ring die or flat die. The holes may be round or square, tapered or non-tapered. This is done either by using a locally fabricated pelleting machine, which is operated by diesel engine, electricity powered machine or manually, or by using automatic highly sophisticated machines with hot air or water Pellet sifting is the last process in pellet manufacturing and this equipment should be located just above the bagging or final discharge bin. A rotary sieve, as the specially designed sieving device, is used to grade and screen feed pellets having undergone the secondary crushing in the large or mediumsized animal feed manufacturing plant. The undesired feed pellets can be removed from cooled pellets to get uniform finished pellets. In order to get perfect product, more and more feed pellet plants choose proper sifters in their feed pelletizing process. Cooling Conclusion Feed pellet production needs not only a complete proper set of equipment but high efficient and costeffective processing solutions. A finer grinded material or mixture will produce a better quality pelleted feed at a lower cost both in terms of energy and maintenance. The fineness of the grind must be matched to both the particle size and capacity requirements of the entire feed manufacturing process. More inforMation: Email: Website: 30 | September - october 2013 &feed millinG technoloGy Grain
  6. 6. LINKS September - October 2013 This digital Re-print is part of the September | October 2013 edition of Grain & Feed Milling Technology magazine. Content from the magazine is available to view free-of-charge, both as a full online magazine on our website, and as an archive of individual features on the docstoc website. Please click here to view our other publications on first published in 1891 • The holistic approach to avoid losses in the feed mill In this issue: • • Sieving technology in feed pellet production • Mixed integer optimization: Traceability a new risk in maize production? • See the full issue • Visit the GFMT website • Contact the GFMT Team • Subscribe to GFMT a new step in formulation software • Weighbridges the workhorses of industrial weighing • High-precision sensors: the ideal solution for measuring grain humidity INCORPORATING PORTS, DISTRIBUTION AND FORMULATION A subscription magazine for the global flour & feed milling industries - first published in 1891 To purchase a paper copy of the magazine, or to subscribe to the paper edition please contact our Circulation and Subscriptions Manager on the link adove. INFORMATION FOR ADVERTISERS - CLICK HERE Article reprints All Grain & Feed Milling Tecchnology feature articles can be re-printed as a 4 or 8 page booklets (these have been used as point of sale materials, promotional materials for shows and exhibitions etc). If you are interested in getting this article re-printed please contact the GFMT team for more information on - Tel: +44 1242 267707 - Email: or visit