The aim of mixing operation is to distribute, in a homogeneous manner, the elements of the dosed formula. This operation, compared to a similar operation in other industrial sectors, has particularities:
- Very small percentage of liquid added,
- Organic or mineral powders with very different physical characteristics,
- Very low incorporation rate of certain powders (100 g / t), but with a very high activity.
Among the various mixer types that you can meet in animal feed industry or in related industries (grains, minerals and medicated feeds, premixes) :
- The most used mixer is the horizontal ribbon mixer with a ribbon agitator. A ribbon agitator consists of a set of inner and outer helical ribbons. The outer ribbon moves materials in one direction and the inner ribbon moves the materials in the opposite direction. The ribbons rotate and moves materials both radially and laterally for getting thorough blends in short cycle times. Plow mixers are usually dedicated to minerals or other microingredients. Plow mixers use wedge-like plows or specially angled paddles and a high-speed, solid shaft rotor within a horizontal, cylindrical tank.
- Paddle mixers and paddle ribbon mixers allow carrying out the mixing in various These double and triple action agitators insures rapid, homogeneous blending of the most difficult blending applications
- Twin shaft ribbon mixers or twin shaft paddle mixers. These mixers can improve the efficiency of the mixing processes.
In addition to micro and macro ingredients that are traditionally carried from the hoppers to the mixer, at least four types of liquids may be incorporated directly into the mixer:
– Fat (vegetable oils),
– Liquid by-products of sugar and fermentation industries, such as molasses.
– Amino acids
– Technical chemicals (different types of acids, …).
The two main parameters of the mixing operation are the mixing time and the filling rate. These two parameters have a direct impact on the production level of the plant, because it often has only one mixer.
The definition of maximum and minimum fill rate of a mixer depends on the mixer type and its manufacturer, usually between a 30% and a 70% of the maximum height of the horizontal mixing device (ribbons, paddles,etc.).
The notion of mixing time takes into account the evolution of the mixture quality as a function of time. Cycle time of conventional mixing comprising filling and emptying will usually be below six minutes.