THE MENHADEN FISHERY 155 



and agitator prevent the build-up of solids at the bottom of the tanks 

 during storage. Prior to shipment, the pH of the solubles is adjusted to 

 a level below 5.0 by the addition of acid. 



Drying. The press cake discharged from the screw presses, along with 

 the recovered suspended solids, is conveyed directly to a rotary dryer. 

 In some cases, the solids discharged from the screening and centrifuging 

 processes are recycled through a foots press before passing to the dryer. 

 During passage through the dryer, the press cake and solids are reduced 

 to scrap which has a moisture content of about 10 per cent. Both steam- 

 tube and direct-heat dryers are used, but the latter are more common. 

 From one to seven dryers may be employed, each having a capacity 

 ranging between 3}^ and 15 tons of scrap per hour. 



In recent years, a number of plants have produced a "full" or 'Svhole" 

 meal by adding back the solubles to the press cake before drying. The 

 rate at which the solubles are returned is variable but in some cases 

 may be adjusted to meet customer specifications. 



Storage of Scrap and Meal. As the scrap is discharged from the dryer, 

 it is carried by overhead conveyors to a large storage shed and deposited 

 in piles on the floor. The scrap partially cools as it falls to the floor from 

 the overhead distributing conveyor; however, the piles subsequently 

 must be turned and aerated to further cool the scrap. Most menhaden 

 processors use an antioxidant to control the build-up of heat which nor- 

 mally occurs in the scrap piles. This is added at some stage after the 

 scrap has left the dryer. If properly applied, antioxidants reduce some 

 of the problems of handling the scrap during cooling and permit bulk 

 storage of the dried material without the danger of fire, caking, or other 

 undesirable changes. The antioxidant most commonly used is butylated 

 hydroxy toluene, although others have been tested and found to be 

 satisfactory^*^. 



The scrap is handled in a number of different ways, depending on 

 storage and transportation facilities, customer specifications, climatic 

 conditions, and other factors. Much of the scrap is conveyed directly 

 from the scrap shed to a hammer mill where it is ground into meal. 

 From the hammer mill, the meal is automatically weighed into burlap 

 sacks which often are placed on pallets for storage. Recently, bulk stor- 

 age of the scrap or meal in warehouses or silos has become common 

 practice. Some companies place their scrap production in burlap sacks 

 which are then stowed in a warehouse to await shipment. 



Shipment of Products. Bulk scrap and meal usually are loaded into 

 freight cars or trucks by conveyors or blowers, whereas sacked material 

 is handled by fork-lift trucks. Companies which sack their scrap or meal 

 production for storage may empty the sacks prior to shipment. 



Crude oil and solubles are transported by railway tank car or tank 



