Fish is not just one of the staple foods in all the world's coastal regions, its high-quality constituents mean it is globally becoming a significant component of a healthy diet. Most of the residues are disposed of or processed into cheap animal feed, but the skins do for instance contain valuable proteins.
Look behind the scenes
One of the main global suppliers of catfish deals with customers in around 40 countries. The company does not just export the fish meat, it also produces high-quality by-products from the fish parts which would otherwise be designated as worthless residues. A key product is a collagen powder.
The powder is produced by enzymatic hydrolysis from the catfish skins derived from the production of fillets for the global market. The fish skins are around 18 cm long and also elastic and extremely slippery due to the humid environment, so the company needed suitable pump technology in order to be able to transport them for processing. An issue here was that the fish skins are mixed with hot water in an 80:20 ratio and come into the machine at a pressure of around 2 bar, which means they are moving very fast and there is a risk that unprocessed parts might slip through.
NETZSCH set up a hygienic solution for this in 2015 using closed pipes and a pump, which prevents contamination of the raw material and at the same time ensures cleanliness in the production environment. In order to make the skins suitable for conveyance, the system was combined with an upstream macerator which cuts the material up into short pieces of around 2 cm. A NETZSCH twin shaft macerator was therefore used, as its speed can be adjusted to the flow of the difficult medium mixture to achieve an ideal result in terms of cutting. The maximum flow rate for this version is 80 m³/h, with larger types being able to handle up to 270 m³/h.
The macerated pieces of skin flow out of the macerator directly into a T.Proc® rotary lobe pump which handles ongoing conveyance. The pump is particularly recommended for very lumpy media due to its large free ball passage. This design leaves a lot of space for the medium and at the same time enables the rotary lobes to be removed individually, if required, without any great effort.
Despite the unusual medium, both macerator and pump have been running without any issues since installation. The company is in fact planning to order additional NETZSCH pumps for other conveyance and processing tasks.