Last year we rented three machines to a seaweed processing factory in southern Chile. Our client, Danisco Ingredients, uses carrageen seaweed as a raw material. They produce carrageenan, a food additive that is extracted from the seaweed.
Danisco purchases red, black and narrow leaf carrageen. The red is harvested by underwater divers using helmets and lead boots. The black washes up on the beaches, and the narrow leaf is picked by women and children from rocks at the ocean's edge.
The rental machines on test are a Vincent triple pass rotating drum dryer, a Vincent horizontal shredder with narrow blades, and a "soft squeeze" KP-6 press.
The VS-35 Shredder has worked very well, both on baled dry material and on seaweed fresh from the fishing boats. Initial plugging was overcome by going to a discharge screen with large 2-1/4" holes. The one remaining problem has been blade damage arising from rocks to which the seaweed is attached.
The dryer has also worked very well. The seaweed goes through a sticky stage as it is dried from 82% down to 18% moisture. However, it has not adhered to the inside of the dryer, so the product recirculation feature does not appear necessary.
Most tests were run feeding two to four pounds per minute into the dryer. Gas recirculation was not used in order to keep down the wet bulb temperature. The highest temperature material can reach in the dryer is the wet bulb temperature (dew point), and it is felt that the viscosity of the carrageenan produced might be adversely affected by exposure of the carrageen to high temperature.
It is not possible to remove any moisture at all from the seaweed with a screw press. We tried shredding, macerating, and adding lime; nothing worked. However, the press worked well at removing free water from previously dried seaweed that was later washed to remove sand and rocks. In one test moisture content was reduced from 68% to 60%.
A full scale wash/shred/dry/bale process has been proposed.
[February, 2009 A couple years ago Danisco relocated an old Vincent dryer to this factory. The engineer we worked with in 1998, Alejandro Martinez, is now the plant manager.]