Silverson Machines launched their ‘How to’ video series nearly 7 years ago and since then the library has become extensive, featuring nearly 40 videos on applications across the food, pharmaceutical, chemical and cosmetics industries. As well as these videos, Silverson have continually added videos on their mixers and processes, as well as viscosity guides, 30 second mixing guides and mixing science animations.
The range of applications and mixing tasks that can benefit from using high shear, as demonstrated in the videos, shows the versatility of the Silverson product range. Below we discuss some of the latest videos to be released.
How to make Paraffin Wax Emulsions
Wax emulsions are stable mixtures of one or more waxes in an aqueous phase. In this video, Silverson demonstrates how to make Paraffin wax emulsions using their high shear mixers. Paraffin wax emulsions commonly consist of micronised waxes, water and an emulsifying agent.
Mixing is usually carried out at temperature, so both phases are liquid when the emulsion is formed. To ensure stability, it’s essential to obtain the smallest possible globule size. Conventional mixing equipment does not impart the shear necessary to achieve this. While the two phases may appear to have emulsified together, once agitation stops, they will separate again. This leads to inconsistency between batches and poor product quality. High Shear mixers are ideal for this application. The more shear energy introduced into the mix, the smaller the suspended droplets will become, creating a fine stable emulsion. The Silverson high shear mixing action ensures the wax globules are finely dispersed into the water to give a stable finished product.
Interchangeable workheads for increased versatility
In this video, Silverson explains and demonstrates the uses and characteristics of the most common workheads and screens in their range. These workheads are at the heart of every Silverson rotor/stator mixer. The high speed rotation of the centrifugal type rotor draws materials into the workhead – lighter materials which float or raft on the surface of vessels will be drawn down into the workhead and heavier materials that sink to the bottom of the mixing vessel will be drawn upwards. The interchangeable heads and screens allow any machine to be adapted to perform a wide range of mixing operations including emulsifying, homogenising, disintegrating, dissolving, dispersing, blending, particle size reduction and de-agglomerating. So a Silverson mixer can be used in place of several pieces of mixing equipment, with changing from one head or screen to another a quick and simple process.
Aeration-free mixing using Silverson High Shear Mixers
This video demonstrates that when using a Silverson High Shear Mixer in place of conventional mixing equipment, a Silverson mixer can reduce or even eliminate aeration in the mixing process. Aeration can cause problems further along the production line, where containers are filled by weight rather than volume and it can also reduce the shelf life of the end product.
The circulatory pattern of mixing provided by a Silverson high shear mixer is all below the surface. This minimises and in some cases eliminates aeration in the finished product. This is demonstrated in the video using an In-Line mixer with product recirculating through a pipeline. The return pipe from the In-Line Mixer is situated in the tank below the liquid surface, so it’s a closed system and aeration is completely eliminated.
How to prepare samples for Aflatoxin testing
In this video, see how Silverson mixers can be used in the preparation of samples for aflatoxin testing as we demonstrate a typical 50:50 pistachio nuts and water mix. The high shear action of the Silverson mixer will rapidly disintegrate the nuts and form a homogeneous slurry with a fine uniform particle size.
Research has identified that preparation of samples by slurrying offers significant advantages over dry milling. For example, the heat generated by dry milling can degrade the aflatoxin, distorting results. Silverson mixers have been used for this research, and are now specified as standard equipment for sample preparation in several countries.
RPM vs. Peripheral Tip Speed
The latest video to be added to the Silverson Mixing Science series focuses on rpm (revolutions per minute) vs. Tip Speed. At Silverson we speak with customers who assume that because they ran their lab mixer at ten thousand rpm, they need a production mixer that runs at the same rpm. Whereas others think running their lab mixer at the same speed as production models will replicate the performance of the larger scale mixer. With this animation Silverson explains the difference between the two and why tip speed is the more important factor to consider when using High Shear mixers, especially when scaling up from Laboratory-scale to production mixers.