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MIXING EQUIPMENT


INDUSTRIAL STRENGTH HIGH SHEAR MIXING FOR CHEMICAL APPLICATIONS


Silverson Machines offer a wide range of high shear mixers that are ideal for chemical applications, as well as the ability to custom design mixers to suit customer requirements


he mixing challenges of the chemical industry are unique and ever-changing. Depending on the application, whether customers are looking to reduce mixing times, improve their emulsions, accelerate reactions, uniformly reduce particle size or disintegrate or dissolve solids, various problems can occur during the mixing process.


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In this article, Silverson Machines discuss the latest chemical applications which have been covered in their ‘How to’ video series. This series of videos demonstrate how Silverson mixers can be used for each specific application and recommended mixing equipment for that application.


Precision mixing for uniform battery slurry dispersions: Silverson High Shear mixers are increasingly being specified for the production of battery slurries due to the versatility and efficiency they bring to the manufacturing process. Formulations vary but generally slurries consist of an active ingredient in a solvent with binders and other additives for conductivity, flexibility and strength.


Whatever the formulation, the essential requirement of the mixing process is obtaining a homogeneous, stable slurry with a uniform, fine particle size. Agglomerates in the mixture can affect the coating quality and must be avoided. The positive mixing action of Silverson high shear mixers ensures an agglomerate-free dispersion and accelerates


the solubilisation of polymers dramatically reducing mixing times and ensuring a stable end product.


Active ingredients and additives for conductivity are generally used in premicronised form but particles do have a tendency to reagglomerate. The milling action generated in the gap between the tips of the rotor blades and the inner wall of the stator in the precision-engineered Silverson workhead will ensure active ingredients are finely dispersed into the medium with any reagglomerated particles being reduced down to the finest constituent parts. Typically an In-Line mixer is used for this process and Silverson offer high-capacity machines capable of handling higher viscosity slurries.


Pioneering graphene breakthroughs with high shear mixing: In the infancy of graphene research, Silverson mixers were used in one of the successful techniques used to extract graphene from graphite, through shear exfoliation. This process used the high shear of a rotor stator mixer to exfoliate defect-free, few-layer graphene from graphite in solvent systems or certain surfactants.


Now that research has moved on, the high shear energy of Silverson mixers is still proving essential for graphene formulations at a laboratory scale. The high shear energy ensures that the graphene is dispersed correctly throughout an entire mix so the desired end properties are achieved. GEIC (Graphene Engineering Innovation Centre) based at the University of Manchester have tested many formulations under microscopy and seen that the level of dispersion achieved with a Silverson Laboratory mixer, far outperforms conventional lab stirrers. Not only can the Silverson disperse the graphene effectively, it will also disperse any pigments, dispersants or resins in the formulation as well, completing the whole process.


One of GEICs main focuses is bridging the gap between what has been done in the laboratory and scaling up to pilot production, which is what industry needs in order to commercialise graphene products. To this end, the team at GEIC has recently purchased a production scale Silverson Batch Mixer. This has completely changed how they work on


10 JUNE 2024 | PROCESS & CONTROL


Above: Silverson High Shear mixers are increasingly specified for the production of battery slurries Below: The high shear energy of Silverson mixers is still proving essential for graphene formulations at a laboratory scale


collaborative projects with their partner companies from different industries and how they can provide large scale samples for them. Since using the Batch mixer, GEIC's production times have been reduced from several days to a few hours.


High shear seaweed pre-processing solutions: Another recent ‘how to’ video explains how Silverson High Shear mixers can be used in the pre-processing of seaweed. Depending on the type of seaweed being processed, a solids content of sixty percent or more can be achieved with Silverson mixers. Processing also varies depending on the end use, but Silverson has helped customers using seaweed for applications such as fertilisers and for addition to cosmetic products. Rapid resin solubilisation at ambient temperature: Resins are used in a wide range of products, for example varnishes, adhesives, inks and paints, surface coatings, laminates and sealants. Silverson mixers can be used for high speed disintegration and solubilisation of solids resins into solvents at ambient temperature.


With a conventional agitator it can take a long time to dissolve solid resins – even at high temperature – an agitator just moves the resin around in the tank, and it can take hours to complete solubilisation. With a Silverson mixer, mixing times can be reduced from hours to minutes. The intense mixing means that the entire contents of the vessel pass through the workhead many times in a short mixing cycle, maximising the surface area exposed to the solvent, accelerating the solubilisation process. The Silverson ‘How to’ video series can be found on the Silverson YouTube channel or the Silverson website.


Silverson Machines sales@silverson.co.uk www.silverson.co.uk


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