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GRINDING CHALLENGING RECIPES FOR PREMIUM PET FOOD? Pre-crushing protects your process and saves energy!
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by Volkan Aktan, Project Engineer Dry Grinding, Thomas Runde, Managing Director and Karsten Frese, Senior Project Engineer Dry Grinding, Tietjen Verfahrenstechnik, Germany
s a specialist in grinding technology, Tietjen Verfahrenstechnik always keeps an eye on the size reduction of mixed raw materials, especially in challenging applications such as pet food and aqua feed. Together with our worldwide customers and partners, we continue to optimise and search for the economically best solutions for targeted crushing according to customer requirements. Since 1959, Tietjen has been building hammer mills and individual grinding solutions in Hemdingen near Hamburg. To ensure that our customers achieve even better grinding results, we have recently also been looking more closely at optimising the pre-grinding process. Good grinding depends on the one hand on the technical design of the hammer mill itself (sieve surface, impact surface, motorisation, speed and sieve perforation) and on the other hand on the aspiration of the mill (air volume flow, air speed, filter type, filter surface). The grinding plant itself can only be optimally operated with appropriate, load-dependent controlled dosing of the input material. However, other components of a good overall system such as the pre-crushing system discussed here - also contribute to improved results
Why pre-crushing?
If raw material components are simply too hard for the fine grinding stage, then the grinding stage should be protected. Pregrinding is then strongly recommended. This is especially true for recipes with legumes such as peas and beans and with sugar beet pellets. 62 | June 2020 - Milling and Grain
For mixtures with a very wide grain spectrum, such as recipes for flours with legumes, pellets, cereals or rice, a pre-grinding for homogenisation for the further grinding process can be advantageous. A homogeneous structure can be ground more efficiently. This prevents screen damage and increases the availability of the hammer mill - from a technical and economic point of view! Pre-grinding guarantees the pre-crushing of hard ingredients with simultaneous homogenisation of the recipe, thereby optimally preparing the raw material for the actual fine grinding process.
How does it work?
The pre-grinding is dependent on the hammer mill that follows in the process. Depending on the maximum size of the components of the existing raw material, the first step can be a primary crusher or again a hammer mill. After a successful pre-grinding, a hammer mill can produce the final product in the second step. In the third and last step, a classifier mill can be integrated, if this should be necessary for the end product. The Tietjen Impact Classifier Mill (TICM), for example, can be used as a classifier mill. The impact classifier mill is designed for fine grinding in the production of fish and shrimp feed. The TICM can be used to grind various types of grain, peas, fish or poultry meal. It combines efficient grinding with precise classification in a single machine. The decisive advantage is the narrow particle size range with precise separation from 100Âľm to 400Âľm. In the medium size 1300 the TICM has a mill motor with 160kW and a classifier motor with 15kW. This classifier mill thus achieves a throughput capacity of 5t/h with a fineness requirement of 98% < 200 Âľm. If the final product is to be