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MIXING EQUIPMENT


MIX POWDERS INTO LIQUIDS WITH EASE WITH SILVERSON HIGH SHEAR MIXERS In this article, Silverson Machines explain some of the problems


commonly associated with mixing powders into liquids, and how high shear mixers offer a solution


agglomerate-free solution within minutes. The mixer will incorporate the powder as


this process having a knock-on effect on processing further along the production line and the quality of the finished product. One of the main issues when adding powders


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into liquids is the formation of agglomerates. This can add to processing times in several ways. Firstly, before the powder has even been added to the liquid, some manufacturers will premix the powder with other powdered ingredients to separate the particles and so reduce the formation of agglomerates, as well as “weighting” them to aid wetting out. Although this will not eliminate them from the mix completely. Some types of mixers will take a very long time


to hydrate the powder. This usually occurs when a mixer simply moves the powder and liquid around the mixing vessel, slowly hydrating the outer layer of large agglomerates until the lumps are eventually incorporated. In some cases, this isn’t possible and as such further time is added to the mixing process due to a filtration stage where the un-hydrated powders are removed from the mix before it passes on for further processing. If the agglomerates are not removed during this stage the partially hydrated powder can continue hydrating during storage


ixing powders into liquids can be one of the more difficult mixing tasks for many manufacturers, with problems during


quickly as it is added into the vessel. The centrifugal force created by the rotor draws the powder and liquid down into the workhead where they are rapidly mixed. As such, there is no need for premixing powders to “weight” them down or reduce the formation of agglomerates. This also eliminates the risk of operator error during powder addition. The materials are then forced through the slots in the side of the workhead and projected back into the body of the mix. Any agglomerates are broken down as they pass through the slots. The vigorous movement in the vessel


created by the workhead ensures that in a short mixing cycle all the material passes many times through the workhead, progressively reducing the particle size and exposing an increasing surface area to the surrounding liquid, improving product quality, stability and repeatability between batches. Silverson offers a range of equipment for


or subsequent processing, leading to undesired changes in product viscosity, affecting the quality of the end product and batch-to-batch consistency. When a filtration stage is needed, this wastes


costly ingredients. Manufacturers often use more powder than is necessary in a formulation to compensate for poor yield and the unhydrated powder, lost during the filtration stage, further increasing mixing costs. Manufacturers can also try to avoid the


formation of agglomerates by slowly adding the powder to the liquid, but the effectiveness of this can vary depending on the operator, affecting repeatability and product quality. With the additional mixing times and


expense that the formation of agglomerates can cause, how can manufacturers streamline their mixing process and eliminate them?


The solution – High Shear Mixers Adding a high shear mixer to the existing process in place of conventional mixing equipment can cut processing times by up to 90%. Premixing of powders is not required, and the high shear action rapidly incorporates and disperses the powders, disintegrating any agglomerates and exposing an increasing surface area of the powder to the surrounding liquid. The result is an


incorporating powders into liquids. They have experience with mixing problematic powders, such as Carbopol, Bentonite, Xanthan Gum, etc. in a range of industries. For mixing at Laboratory scale the FMX5, a


small-scale version of the Flashmix, provides a simple, effective and hygienic means of powder/liquid mixing. The unit is suitable for small scale manufacturing and R&D work with a typical batch size of up to 10 litres. For large scale production the Silverson


Flashmix provides fast and efficient powder/liquid mixing. Unlike many powder/liquid mixers, which use vacuum to pull in powders, the Flashmix literally forces powder into the liquid stream. This not only allows it to disperse and hydrate large volumes of powders, it means it can be used at higher temperatures and with higher viscosity mixes. The Flashmix can be supplied with a


powder feed suction hose for powder incorporation, rather than the standard hopper. This enables the machine to suck powders into the mix straight from their original containers, minimising handling requirements. This is particularly useful for free-flowing powders prone to dusting.


Silverson Machines www.silverson.com


OCTOBER 2023 | PROCESS & CONTROL 35


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