The importance of expander use in the pelleting process
What’s its function?
The expander has been known in the oil milling industry for years and its use, combined with the pellet mill, begins in the 90s as a tool to sanitize the feed.
The expander can be integrated in any existing pelleting system without major supplementary space requirement or increasing specific energy consumption.
It combines temperature and pressure in the transit of raw materials to provide a crumb with improved nutritional value compared to conventional feeds. Conditioning of compound feed has become a critical step for a high-quality production, with the maximum exploitation of the nutritive value. In the past, in fact, many technical problems occurred because components of poor pelletability had been increasingly used.
The expander brings to the compound feed industry not only a machine which serves to achieve a quality improvement of the finished product while at the same time facilitating the sequence of operations, but also an alternative manufacturing process, which also does without pelletization completely.
✔ The use of expander in feed mills allows for an easy and economical improvement of pellet quality in terms of fines ratio and hardness in case of mixture of poor pellet-ability. The addition of binders and/or double pelleting are no longer required.
✔ When pelleting the expanded material, specific energy consumption of the pellet mill is considerably reduced so that the total energy consumption of expander and pellet mill combined is not higher than that of a conventional pelleting system.
✔ The use of the expander reduces the wear of the pellet mill’s parts. The pellet is no longer produced in the die under high pressure friction, because the adhesive properties of the material are activated in the expander. The pelleting press, therefore, only serves to shape the nearly pasty and expanded material. The material temperature is no longer increased during the pelleting process, but is lower in most cases after the pelleting press. Besides this, the flexibility is increased because given a constant pellet quality, the die thickness is reduced. Different formulas can be processed with one die without die exchange.