Processing of 125,000 Tonnes of Fish Waste into Fish Oil and Fish Meal
At Bioceval’s fish meal factory in Cuxhaven, Germany, around 125,000 tonnes of fish waste from the fish processing industry are processed into high-quality fish meal and fish oil every year. Plant manager Markus Beckmann is responsible for ongoing production operations as well as investments, repairs and personnel.
Delivery of the Raw Material
The raw materials are mostly delivered sorted by type and then processed into special fish meals and fish oils – raw salmon is turned into salmon meal, raw herring into herring meal.
Process Steps Prior to Grinding
Processing initially takes place in indirectly heated steam cookers, in which the raw material is heated and then the liquid phase is pressed out. The remaining solid phase is dried in disc dryers and transferred to the grinding and cooling plant at around 120 °C. There, the fish meal is first cooled to around 50 °C before it enters the Tietjen hammer mill. The hammer mill grinds the product – consisting of protein fractions, bones and other solid components – to a particle size of 98 % < 2 mm, resulting in a homogeneous, ready-to-sell fish meal.
Demanding Grinding: 8% Fat Content, 50°C Raw Material Temperature, Many Impurities
Two high-speed hammer mills were installed for Bioceval, which take the fish meal directly from the dryer. The product has a high fat content of around 8% and a temperature of around 50°C and contains typical impurities such as fish hooks, fish tags and plastic parts – a particular challenge for grinding..
Foreign Matter Removal Prior to Grinding
To reliably overcome these challenges, the AGS air gravity separator from Tietjen is installed upstream of the mill. Magnetic foreign matter is reliably extracted, non-magnetic impurities are retained in the heavy particle trap, thus protecting the grinding process and the stability of the mill.
Hammer Mill Is Optimally Designed for High Fat Content
The geometry of the impact plates, the design of the screens and the configuration of the beaters are optimally matched to the desired fineness and fat content of the fish meal. Another key to process stability is aspiration: it provides the necessary air volume for the AGS and hammer mill and is guided through a specially designed stainless steel filter with adapted filter bags and a generous filter area to prevent the filter hoses from clogging up quickly.
Grinding Crab Shells
In addition to fish meal, Bioceval also grinds crab shells, which place special demands on the plant technology due to their high abrasiveness. To cope with the increased wear, a Tietjen HM hammer mill with extended wear protection is used for this application.
The grinding chamber was fitted with additional Hardox linings, and components subject to heavy wear, such as impact plates, screens and beaters, were designed to withstand abrasive operation. This ensures high process reliability despite the aggressive product properties and significantly extends maintenance intervals.
Bioceval Recommends Tietjen Hammer Mills
Operations manager Mr Beckmann reports: “Overall, the stability of Tietjen hammer mills is significantly better than the products we had previously installed here.”
Long-term use has shown that the Tietjen hammer mills in Cuxhaven achieve significantly higher stability than previously used machines from other manufacturers. In addition to their robust construction, the reliable availability of spare parts and fast service are particularly impressive, minimising downtime. From the operator’s point of view, Tietjen has thus established itself as a preferred partner – a decision that would be made again at any time.
