Silverson mixer has been the leader in high shear mixing for over 60 years. The Silverson high-speed shear mixer is used for mixing liquid/liquid or liquid/solid mixtures at speeds up to 8000 r.p.m. The mixer body is raised or lowered electrically. It stops automatically at the higher and lower limits of movement. It has several accessories with the mixer, which can be interchanged depending on the mixing conditions required and the material being mixed.
Principle of Silverson Emulsifier Mixer
The principle of the Silverson mixer is based upon shearing force. It produces intense shearing
forces and turbulence by the use of high-speed rotors. Circulation of material
takes place through the head by the suction produced in the inlet at the bottom
of the head. Circulation of the material ensures the rapid breakdown of the
dispersed liquid into smaller globules.
Construction of Silverson Emulsifier Mixer
It consists of long supporting
columns and a central portion, Fig.1. The central portion consists of a shaft that
is connected to a motor at one end and the other to the head. Head carries
turbine blades. Blades are surrounded by a mesh, which is further enclosed by a
cover having openings. It consists of the following other accessories:
- General-purpose disintegrating head: Suitable for general mixing or disintegration of solids.
- Square hole high shear screen: High shear screen suitable for emulsion and fine colloid suspension preparation.
- Emulsion screen: Lower shear screen suitable for liquid/liquid and emulsion preparations.
- Axial flow head: Used in addition to one of the above screens to force liquid flow upwards This can reduce aeration or help maintain large suspensions, but high mixing speeds can cause liquid to be ejected from the mixing vessel.
Fig.1: Silverson High Shear Mixer
Working on Silverson Emulsifier Mixer
The precision-machined
Silverson work head generates exceptionally high shear rates in a three-stage
process that rapidly homogenizes the product to the required uniformity.
The high-speed rotation
of the rotor blades within the precision-machined mixing work head exerts a
powerful suction, drawing liquid and solid materials into the rotor/stator
assembly, Fig.2.(a).
The centrifugal force
drives the material towards the periphery of the work head where they are
subjected to a milling action in the precision-machined clearance between the
ends of the rotor blades and the inner wall of the stator, Fig.2. (b).
Finally, the intense
hydraulic shear wherein the materials are forced at high velocity out through
the perforations in the stator, then through the machine outlet and along with
the pipework. At the same time, fresh materials are continually drawn into the
work head, maintaining the mixing and pumping cycle, Fig.2. (c and d).
Fig.2: Working of Silverson Mixer
Advantages of Silverson Emulsifier Mixer
- It is efficient and rapid in operation and is capable of reducing mixing times by up to 90%.
- It is a speedy, versatile, self-pumping, aeration-free and efficient shear mixer.
- It is capable of producing a fine droplet or particle size, typically in the range of 2 - 5 microns.
- Being proficient reduces operating costs.
- The product passes through the homogenizer at a much faster rate, normally in a single pass.
- Being versatile it allows performing the widest range of mixing applications.
Disadvantages of Silverson Emulsifier Mixer
- It requires feed to be premixed and of uniform and fine globule or particle size.
- It may face the problem of mesh clogging.
- It requires more power.
Applications of Silverson Emulsifier Mixer
- It is used to mix, emulsify, homogenize, solubilize, suspend, disperse and disintegrate solids.
- It is used for the homogenization of a vast variety of products such as creams and ointments, lotions, sauces, and flavor emulsions.
- A homogeneous product is rapidly produced when blending liquids are of similar or greatly varying viscosities, eliminating problems of stratification.
- It is used to prepare emulsions in the range of 0.5 to 5 microns.
- Silverson mixers can disintegrate matter of animal, vegetable, mineral, or synthetic origin in a single operation.
- It is used to uniformly mill both solid and semi-solid materials into either solution or fine suspension.
- It is also used in rapid gelling. For example, solubilizing and dispersing gums, alginates, CMC, carpools, etc., resulting in an agglomerate-free solution within minutes.
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