Ploughshare Mixers
Ploughshare Mixers are ideal for mixing powders and granules and can be used for light paste-like or cream materials. The mixer is based on a proven mixing construction that provides a double mixing action ensuring fast and efficient blending. The constant rotation of the stainless steel blades drives the material to the top of the trough where it tumbles to the base and is once more folded back into the material mass.
Design, Construction, and Operation
The ploughshare mixer consists of a cylindrical drum containing plough shaped mixing elements that are mounted on a horizontal shaft. The agitator's shaft is positioned in the centre of the drum and has welded / bolted arms on which the “Plough” shaped mixing elements are mounted. The ploughshare mixer gets is name because of these plough shaped mixing elements. Independently driven high-speed choppers may be installed to disperse agglomerations and control granulation during the mixing process.
The plough shaft is powered by a drive system comprising of a motor, gearbox, and couplings. The shaft exits the mixer drum at either end through the end plates bolted or welded to the cylindrical shell. The area where the shaft exits the container is provided with a sealing arrangement to ensure that material does not travel from the container to the outside and vice-versa. The mixer assembly along with the drive system components viz. motor, gearbox, couplings, and bearing supports is mounted on a supporting frame.
In operation, material is loaded through the top inlet. The working volume (volume up to which material should be loaded) of the ploughshare mixer ranges from 30% to 70% of the total drum volume. The shaft rotates at higher speed, producing a plough tip speed of more than 200 metres per minute to effect a fluidizing action. The ploughs throw the material upward, and the material settles in a random pattern. The size, shape, positioning, and peripheral speed of the ploughs are coordinated in such a way that they produce a whirling, three-dimensional product movement. The turbulence and material movement within the mixer container prevents formation of dead-spots or low-movement zones and ensures fast and homogenous mixing. The ploughs are designed to lift the material from the inside wall of the container without squashing the particles against the wall
The profile and arrangement of the ploughs ensure that after mixing, the material is directed towards the centrally located discharge valve. For larger mixers, more than one discharge valve can be provided depending on the requirement of the downstream process. Flush bottom discharge valves are preferred to avoid any dead pockets within the mixer. These valves may be manually, pneumatically of hydraulically operated. Large side doors may be provided for cleaning access.
Areas of Application
Ploughshare mixers have applications in the following industries:
- Chemicals
- Pharmaceuticals
- Ceramics
- Agrochemicals
- Veterinary
- Adhesives
- Brake linings
- Confectionery products
- Detergents
- Waste treatment
Processes
- Dry powder mixing – e.g. Food flavoring/additives, Sponge/cake mixes, Cosmetics, Pharmaceuticals, Cement, Powdered rubber
- Paste mixing – e.g. Biscuit creams, dough, PVC pastes, Car body fillers/putties, Sugar/marzipan paste, Toiletry pastes, Tile adhesives and grouts
- Mixing of wet slurries – e.g. Filter cake re-slurrying, dough, Fiber glass resin dough putty
- Wet granulation
- Liquid coating of powders and granules
- Fat and oil incorporation
- Vacuum drying
- Hot air drying
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