Reclamation of waste products with Silverson High Shear Mixers


One way to reduce our impact on the environment is by using less and making more of what we already have. This is feeding through to production lines, especially in the food industry with more manufacturers making use of off-cuts and excess product.  While reclamation has traditionally been driven by the high cost of raw materials and difficulties with disposing of waste product, sustainability is increasingly playing a part in the growth in this process.

As such, Silverson Machines are seeing enquiries from more and more manufacturers who want to quickly and efficiently reprocess out-of-spec or waste product. A typical example would be in the confectionery industry where mis-shapen sweets need to be disintegrated and redissolved so that the sugar can be reclaimed and reused. How this is done using high shear mixers is demonstrated in Silverson’s ‘how to’ video on the reclamation of confectionery.

Confectionery may require reclamation or reworking for a number of reasons, for example when high speed production lines stop because of a problem downstream, such as a fault in coating machines or a breakdown in the packing line. Another cause of waste product is when sweets are rejected as being mis-shapen or otherwise out of specification. Ingredients produced on a continuous basis are often diverted into scrap bins until the line is running again, as stopping production may be difficult and costly.

The reclamation of confectionery waste can be difficult with conventional mixing, which in the past has resulted in product simply being scrapped. When using conventional mixing equipment such as agitators for this process long mixing times are required to completely solubilise the waste and obtain a uniform and usable product. Even after mixing for long periods of time, in some cases solubilisation is still incomplete resulting in an unsatisfactory consistency or un-usable product. Furthermore, addition of the waste or off spec confectionery to the vessel must be done carefully as large lumps and agglomerates in the mix can cause serious damage to agitators.

High Shear Mixers on the other hand can dramatically reduce processing times and improve product uniformity and consistency. As demonstrated in the ‘how to’ video, Silverson has developed a complete new system specifically for the reclamation of larger solids and agglomerated confectionery. The system consists of a jacketed vessel, fitted with a High Shear Bottom Entry mixer and an In-Line mixer in a recirculation system.

Large solids can be added directly into the vessel without the need for pre-grinding. The Bottom Entry mixer exerts a powerful suction which draws the materials down into the workhead, where they are rapidly reduced to granular size. When particle size is sufficiently reduced the In-Line mixer can be started. The materials are drawn into the recirculation line and pass through the In-Line mixer’s workhead which subjects the materials to intense high shear. The self-pumping unit then returns the product to the vessel as fresh ingredients are simultaneously drawn in.  The combination of heat, vigorous agitation and intense high shear accelerates the solubilisation process and quickly reduces the entire contents of the vessel to a homogeneous mixture without appreciable deterioration in product quality or flavour.

High shear has long been used for the reclamation of confectionery, with the high cost of raw materials such sugar and cocoa encouraging manufacturers to reclaim and rework “off-spec” product. But now this is expanding into other areas of the industry with cheaper processing costs, for example bakery products and excess pasta. The reclamation of these products works in a similar way; the excess product is incorporated into a liquid, usually water, and reduced down into a slurry. This slurry can then be used in subsequent batches of the product. For this process to be effective, the mixing equipment must be capable of disintegrating solid material down into a homogenous mixture which can be forwarded on for further processing.

The clarification and recycling of oil waste is another innovative way in which the food industry is trying to combat excessive wastage. In a recent case, a Silverson customer wanted to manage the amount of oil they were using by prolonging the usable life of vegetable oil, with the goal of eventually reducing the wastage to zero. The vegetable oil, which was being used in the batch frying process for their snack product, could be reused by incorporating a food grade powder which would reduce the Free Fatty Acid levels to below a threshold where it was safe to reuse. An impeller was unable to prevent a thick residue building up in the vessel due to the limited movement it was creating in the tank and this was affecting the ‘cleaning’ of the oil. The centrifugal force created using a high shear mixer, kept the product recirculating throughout the entire vessel while incorporating the powder. Once a high shear mixer was incorporated into their process line the amount of new oil being purchased by the company was reduced from 30,000 litres every week to 30,000 litres every two weeks, cutting their processing costs by 50%.

To discuss how we may be able to help you with reclamation of excess or waste product in your food application, please visit the Silverson website or contact


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