ARTICLE 96 FEED & ADDITIVE MAGAZINE September 2024 A major misconception in our industry is negatively impacting the efficiency and quality of output of feed mills, and it’s about how to optimize particle size. Many operators see hammermill screen size as the end-all-be-all solution. But, an often overlooked approach that maximizes the capability of hammermills presents a better way to produce high-quality feed at lower costs. THE SIGNIFICANCE OF PARTICLE SIZE OPTIMIZATION IN FEED PRODUCTION By creating consistent feed quality, feed mills can deliver products that maximize feed conversion rate and lead to predictable operational costs. Particle size distribution plays a key role in achieving those goals. The big challenge of defining particle size distribution is that optimal size varies depending on the species, feed application, and even the age of the animals. In the face of this challenge, operators are relying solely on screen size, which is not sufficient in providing an adequate measure of particle size. Many times, the hole diameter of a screen gets the first and/or only look when attempting to change the particle size distribution. While it’s true that screens with larger hole diameters will produce a coarser grind and screens with smaller hole diameters will yield a finer grind, there may be better and more efficient ways to attain the desired result. Screens with larger hole diameters produce a coarser grind because they allow larger pieces to exit the grinding chamber. However, these larger screens will have little to no effect on the amount of fines being produced. That end of the distribution is controlled by the hammers and tip speed. So, if decreasing or increasing the amount of fines being produced is the goal, changing the screen size being used is not the best option. A hammermill with a high tip speed and heavier hammer pattern will produce a high volume of fines no matter what size of screen is being used. For a finer grind size, the screen can be effective in achieving the desired output. For coarser grinds, depending on screen size alone results in a larger standard deviation. Hammer pattern and tip speed are key variables that, in addition to screen size, help improve the process and achieve a more standard, quality product. This sieve analysis graph highlights the challenge of trying to achieve a coarse grind using screen size alone. This graph is showing distributions from (4) four different grinds. The x-axis is showing the different sieve screens with the largest being on the left side while the y-axis is showing the amount of A 360 APPROACH TO PARTICLE SIZE OPTIMIZATION Doug Kitch Technical Sales Manager CPM Industrial Solutions
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