The large fish are hashed while the smaller ones are passed through an electromagnet to remove metal before feeding directly into indirect steam cooker by a screw conveyor. The coagulated mass then enters the twin screw press. The products from the press(the presscake and press liquor) are treated as follows. The press liquor passes through a decanter then through a buffer tank before separation into oil, stickwater and fine sludge in the stickwater centrifuge. The presscake is mixed with stickwater concentrate and dried in an indirect steam dryer. The meal passes through a rolling screen before entering the hammer mill. The ground meal is automatically weighed out in bags by the scales, the bags are closed and conveyed to the store. Alternatively, the meal is stored in a holding and blending silo before bagging, pelleting or storing in bulk.
(2). Fish oil production line
Under average conditions one may estimate the volume of press liquor at about 70% of the raw material. There are fish oil, suspended and dissolved protein, vitamins and minerals. After passing through a decanter, the press liquor is separated into oil, stickwater and fine sludge in a stickwater centrifuge.
(3). The evaporating system
The stickwater is still of value, it contains dissolved and suspended protein, fat, vitamins and minerals. But the moisture content comes to 92%-94%. So the stickwater must be concentrated in multi-effect evaporators and the concentrate is thereby thoroughly mixed with the presscake, then go to drier. The product we get called whole fish meal.
(4). Environmental protection system(odor abasement)
The whole process is under a closed system. The malodors from cooker, press, drier are transported to a deodorizer. The soluble odors are dissolved in the cooling water and the dissoluble ones passed to a boiler then exhausted to the open air.