Greaves designs and manufactures a complete range of mixer types to meet processing needs across all industries. It is important to match the most appropriate and cost effective, technical solution for each case. Terminology sometimes varies between industries and the following guide is intended to illustrate the technologies Greaves can offer in finding a solution to clients’ specific mixing problems :-
Blending, Agitation and Suspension
Greaves axial and radial flow impeller mixers frequently provide the simplest and most cost effective solution for general blending and dissolving applications. They are robust and versatile, easy to clean and require minimum maintenance.
Alternative blade profiles are also employed to match specific applications – for example a “bow tie” type blade might be used where large quantities of powder are being added to liquids. A Helical Ribbon Spiral impeller can be used for blending two high viscous fluids, such as hydrocarbon lubricants
Blending, dissolving, equalisation, diluting, solid suspension, re-agitation
High Shear Mixers
Greaves has produced its range of High Shear Mixers since 1947. These versatile, high energy mixers are adaptable to a wide range of process and fluid types and can deliver dramatic reductions in process time compared to conventional mixers. This is achieved by altering direction of rotation and using additional impellers and/or adjustable deflector plates. The objective is always to accelerate the flow of process fluid to the shear head. The benefits are particularly great with high viscosity fluids where other High Shear mixers cannot perform. Greaves mixers are fitted with easily interchangeable shear heads whose profiles are designed for a specific process (e.g. particle disintegration) or are multi-process compatible.
Emulsification, homogenisation, solubilising, diluting
Greaves “HSD” mixers are fitted with a serrated tooth impeller whose aggressive shearing action is ideally suited to dispersing powders and agglomerates in liquids of medium viscosity (typically 80 to 150 poise)
The high speed of the mixer shaft coupled with the relative size of the impeller causes centrifugal displacement of the base fluid resulting in a powerful vortex. The vortex carries the powders/filler particles toward the mixer head. At the tip of the impeller blade the particles are subjected to intense shear forces created by the serrated teeth. From there they are returned at high velocity to the main process fluid batch and the cycle continues.
This range of specialist dispersers is designed with few mixing parts, so installation costs are kept to a minimum and they can be easily cleaned by running in a suitable solvent.
A wide range of impeller designs is available to match the physical characteristics of different powder/liquid combinations and viscosities.
Powder in liquid dispersions, High viscosity emulsions, de-agglomeration, homogenising, disintegration
Temperature, Vacuum & Pressure
The properties of the fluid being processed can often present challenges that mixer design alone will not fully accommodate. This is where Greaves is able to apply its extensive experience as a designer and manufacturer of complete fluid processing solutions. An integrated approach to design of the process vessel and incorporation of vacuum processing to de-gas or de-aerate during mixing is required to produce a stable product, a process widely adopted in the mixing of adhesives, coatings and sealants. High pressure capability and heating/cooling ensures optimisation of fluid condition throughout the mixing process(es). A combination of pressure and elevated temperature can also greatly reduce total process time by enabling pressurised discharge of high viscosity fluids such as lubricating grease.
Where fluids are highly reactive, flammable, or prone to explosion, a safe mixing environment is created by use of an inert gas atmosphere. Greaves is ATEX certified.
Flammable substances, volatile solvents.