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What type of impeller ensures good dispersion?

Q: I have a 1-ton mixing tank with dimension of 1 m (dia) x 1.5m (H). The tank is used to mix two different kinds of liquids: Butter oil, viscosity of 50-80 Pa.s @ 45 degrees C; and emulsifier, viscosity of 800 mPa.s @ 20 degrees C. What type of impeller is good for mixing to have good dispersion, homogeneous and have some shearing force? How many hp for the motor is sufficient?

A: This type of application is usually handled with a high-speed disperser mixer.  The impeller is usually a saw-tooth disk impeller running at a high speed, 1,000 rpm (17 rps).  The recommended impeller diameter is 0.33 m driven by a 25 kW motor.  Most such mixers have a hydraulic raising and lowering system to access the vessel and move the impeller location vertically to ensure complete mixing.  Such mixers also have a variable speed drive to avoid splashing as the temperature increases and the viscosity decreases.
 

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