The mixing time is defined as the time required to reach a desired homogeneity.
The following elements will influence the mixing time. As a general rule, mixers operators look for a mixing time as short as possible in order to increase the productivity of their line.
Table 1 : parameters influencing the mixing time
The influence of the Froude number and the mixer volume are represented in the graph below :
Figure 1 : Mixing time = f(Fr,Volume) [Gericke]
Mixing time is also dependent on the sequence and place of filling the ingredients. In particular, the position of addition of micro ingredients is of prime importance. In case the micro ingredients are added on the side of a mixer, the mixing time can be greatly impacted. As a good practice, processes must be designed to have the small, minor and micro ingredients introduced in the middle of the mixer, in any case in the "active" area of the blender (the fluidization zone for instance).
Usual mixing time
The table below is presenting mixing time that can be expected from the most common types used in the industry. These are indicative values to have a rough idea when assessing a design or troubleshooting an existing system.
Table 2 : Typical mixing time
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