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# Dry-Mixer mixing speed

## Typical mixing speed for common dry mixer designs

Section summary
1. Definition
2. What is the mixing speed for...

### 1. Definition

The mixing speed is a key parameter for process engineers having to optimize a dry mixing process. Indeed, the mixing time will strongly depend from the speed of the mixer agitator, as well as the impact of the process on the product. Generally, a quicker mixing speed will tend to reduce the mixing time but will create more damages (breakage) to the solids. The optimum mixing speed is of course dependent on the design of the mixer.

Some mixers having to reach a certain speed to ensure a good mix (Fr > 1.1 for double shaft paddle mixers using a fluidization principle for instance). This page is giving some references of typical mixing speed collected from different manafacturers and for different designs. It gives a reference, but actual calculations and suppliers recommendations should primarily be used.

### 2. Typical mixing speed

#### 2.1 What is the mixing speed for a ribbon blender

 Total Volume in liters Useful volume in liters Typical agitator speed in rpm Typical power requirement in kW 190 140 70 2.2 480 340 50 3.7 930 710 40 7.5 1590 1130 33 11.2 2460 1840 30 18.6 3170 2400 30 22.4 3650 2830 25 30 5180 4250 22 44.7
Note : ribbon blenders may be converted to single shaft paddle mixers as a design variation by some manufacturers. The speed references are similar.

#### 2.2 What is the mixing speed for a double shaft paddle mixer

The values below are highly depend on the paddle diameter, in order to reach Froude = 1.1, please refer to Froude calculation and the page on double shaft paddle mixer for more information. The diameter of the agitator can vary greatly from one manufacturer to another, if the mixer you consider is not in line with the diameters given below, please recalculate the mixing speed according to the Froude number.

 Total Volume in liters Typical agitator speed in rpm Agitator diameter in m 120 54 0.46 200 46 0.55 350 39 0.68 500 36 0.75 750 32 0.85 1000 30 0.95 1500 28 1.07 2000 27 1.19

#### 2.3 What is the mixing speed for a V blender / tumbler mixer

 Total Volume in liters Typical rotation speed in rpm Typical power requirement in HP 8 30 1.5 15 30 1.5 28 30 2 57 27 2.5 85 27 3 142 20 5 283 20 10 566 16 25 850 15 25 1133 14 30

#### 2.4 What is the mixing speed for a vertical cone screw blender - Nauta mixer

 Total Volume in liters Typical rotation screw speed in rpm Typical rotation speed swing arm in rpm Typical power requirement in HP 285 60 1 3 900 60 1 5 1800 60 1 7.5 3400 60 1 10